Metal-Aid

 

main menu

Progress reports semester 1 semester 2 semester 3 semester 4 semester 5

Progress reports

Metal-Aid fellows will provide semi-annual progress reports detailing their research to date. As the reports become available, they will be posted here.  See the side nav bar for reports by semester.

 

 

 

 

 

 

 

 

 

Semester 1

ESR 1 Marco Mangayayam: University of Copenhagen

Green rust minerals (GR) consist of Fe2+-Fe3+ hydroxide sheets that sandwich interlayer anions, water, and sometimes monovalent cations. Synthesis protocols for a suite of GR types via oxidation-precipitation of Fe2+ have been established and the synthesised GRs have been characterised with a suite of techniques. Initial results show that GR size and morphology as well as its reactivity with chlorinated solvents is substantially modified by changing interlayer anions and/or cation composition in the hydroxide layer. Short and long-term experiments have been set up to quantify the reduction of several environmentally relevant chlorinated pollutants with the various GR types (ie. tetrachloroethylene, cis-dichloroethylene, carbon tetrachloride).

ESR2 Sandra Navaz Rubio: GFZ

During this first semester I finished the first draft of a literature review and started with the co-precipitation synthesis of green rust sulphate in the presence of toxic metals (Cu, Ni and Zn). Structural properties of the resulting samples have been characterized using Powder X-ray diffraction and Raman spectroscopy. Changes in composition have been analyzed using SEM-EDX while ICP-OES analyses of the fate of the metals is ongoing. The preliminary XRD results suggest that these metals might be incorporated into the octahedral layers of the green rust structure, however, further research must be done to determine the incorporation mechanism and the extent of substitution that can be achieved.

ESR 3 Karen Maria Dietmann: University of Salamanca

Following an intense literature research about the synthesis of Layered Double Hydroxides (LDH) and their potential to remediate chlorinated solvents as well as heavy metals, the best possible candidates have been selected, synthesised and characterised for further research. Thereby, the composition of refined LDHs is based on that of already known and well researched LDHs. Different non-contaminant organic components have been used to change the hydrophobic state of the interlayer of the refined Layered Double Hydroxides. By doing so, their potential to remediate chlorinated solvents from groundwater and soil is enhanced. Currently, experiments are conducted to evaluate the mineral phase, which shows the best ability to retain chlorinated solvents from different aqueous media.

This picture gives insight into the synthesis of the synthesized Layered Double Hydroxides corresponding to the hydrotalcite-group. Depicted is the experimental setup for the reproducible synthesis of the selected phases, which has been conducted by coprecipitation under supersaturated conditions. In this procedure, a mixed solution of the metal cations magnesium and aluminium, is slowly added into a reaction vessel containing a solution of the selected anion together with a magnetic stirrer. The reaction vessel is then placed on a magnetic stirring plate to ensure the constant homogenisation of the mixed solution. As the addition of the metal cations leads to a decreasing of the pH value in the reaction vessel, a 1 molar solution of sodium hydroxide NaOH is dropwise added using a pH meter. Once the pH electrode log a pH value below the limit value the basic NaOH-solution is continuously added until reaching the target value of 9. The addition of the basic solution is then stopped automatically. As a result of this the pH value can be maintained constant within a range of ± 0.2. During the synthesis nitrogen is continuously bubbled into the reaction vessel to avoid any contamination by atmospheric carbon dioxide. Additionally, the beaker glass is closed with Parafilm (Bemis) to maintain a nitrogen atmosphere within the reaction vessel.

ESR 4 Weichao Sun: University of Copenhagen

Through our calculations, we found that all Fe ions might be in 3d6 (Fe2+) or 3d5 (Fe3+) high-spin configurations, this is also consistent with the high-spin occupation of the 3d orbitals for most iron oxides. Moreover, our calculations predict that in the single layered green rust, there are two kinds of iron ions, iron ions in the middle and on the edge of structure are different from each other. And for the single layered green rust, the charge is distributed on the surface unevenly.

ESR 7: Jeffrey Paulo Perez: GFZ

For my PhD project, I aim to examine and elucidate the interactions of GR with various metal contaminants in groundwaters. Based on the survey of literature that I did, I found that most of the GR studies focused on its reductive properties and its interactions with redox-active metals. Hence, I started investigating the sorptive properties of GRSO4. This will allow us to derive new data about surface interactions between freshly-precipitated GRSO4 and metal contaminants. Herein, I focused on the interaction of GRSO4 with arsenic species As(III) and As(V). I determined the effects of variable metal concentrations, ionic strength, pH and adsorbent loading have on GR and evaluate the performance of GRSO4 as an effective metal adsorption material. My goal is to evaluate the stability and recyclability of a GRSO4 adsorbent, and its ability to reduce within a short time metals in groundwaters below environmental standard limits.

To gain more insights into the reactions controlling the processes of GR interactions with contaminants, I will combine various in situ experiments and characterization methods to elucidate the structural changes and mechanisms in the GR pathways. I went to the Diamond Light Source, UK together with synchrotron specialists from our research group last February 10-13, 2017. By observing the formation pathway of delafossite, whose intermediate product is GRSO4, I learned about the set-up needed for conducting in situ and time-resolved scattering and diffraction experiments. This will help me in planning and applying for my own synchrotron beamtime proposal on October 2017.

In addition, I have been accepted to the upcoming “To.Sca.lake 2.0: Total Scattering for Nanotechnology on the Como Lake” summer school on May 29 to June 2, 2017 at Lake Como School of Advanced Studies, Como, Italy. The knowledge that I will gain in this course will be highly beneficial for my project, as it will help me better understand how total scattering can be used to quantify interactions between groundwater contaminants and GR materials at the nano-scale.

ESR 8 Flavia Digiacomo

Several studies* were dedicated to the dechlorination process of chlorinated solvents by green rusts in anaerobic conditions, essentially the sulphate GR(SO42-) and the chloride form of green rust GR(Cl-). Little is known about the role and the kinetic of the carbonate-containing green rust, GR(CO32-), in this kind of reactions. Laboratory experimental results suggest that GR(CO32-), which was synthesized by aerial oxidation of Fe(OH)2, is not stable in anoxic condition. It transformed within some days into a mixture of green rust carbonate and siderite.The questions are:

• Is GR(CO32-) more reactive than the other green rusts which contain in their interlayer different type of anion?

• Is GR(CO32-) able to reduce the chlorinated solvents within one day?

• Are the decay products of GR(CO32-) able to reduce the chlorinated solvents?

• If yes, which are the end-products after reaction with chlorinated solvents?

* Erbs et al. 1998; Lee and Batchelor 2002; Maithreepala and Doong 2005; Choi et al. 2007

ESR 9 Andrew Thomas: KIT

The aqueous Cr (VI) in these experiments was completely oxidized by green rust. Full transformation of green rust resulting from oxidation by Cr (VI) initially produced a Cr (III)-substituted goethite that destabilized to a product consisting primarily of Cr (III) substituted ferrihydrite after 7 days. Identification of Cr (III) bearing phases will not be possible until Cr (III)-bearing Fe (III) oxide reference standards are synthesized.

ESR 10 Shikhar Nilabh: Amphos 21

This period has been intended to start implementing multiphase fluid transport formulation in COMSOL Multiphysics software. I have started with some benchmarking of simple formulation. I modelled the Buckley Leverett problem and McWorther problem with the help of repository models. However, my main accomplishment is the modeling of Kueper problem in Comsol and matching it with the benchmark model of Olaf Kolditz. Moreover, I also tried to model three phase flow of groundwater, air and DNAPL, and now this is still in progress. .

ESR 11 Tobias Linke: University of Iceland

After an initial literature research, the main objective was to map out the stabilities of the different iron mineral phases, especiaily green rust, under natural conditions and with special focus on Iceland. This is done by modelling the stability of mineral phases and aqueous species with PhreeqC. Especially the change of pH and redox conditions (Eh) as well as the initial iron concentration are considered. Together with other data (national soil map, satellite images etc.) this is used to preselect a further field site for sampling of soil samples as cores as well as soil water. The samples will be analysed regarding their mineral content, their elemental composition and their iron speciation.PhreeqC is also used to calculate the impact of the iron phases conceming metal transport in aqueous media. The uptake and release of heavy metals by iron phases is calculated along a redox gradient simulating the transfer of the minerals from inside the peat area to a drainage system or natural rivers and finally to the ocean. In addition, the impact of metal adsorption to organic soilmaterial (e.g. humic acids) is investigated by modelling. A field site was selected during an initial trip to potential work areas and permissions as well as samples were collected.

fThe photo on the left shows a typical man-made ditch which is built to drain the peat areas in Iceland. Because the cumulative length of all ditches in Iceland is around 35,000 km, it is important to understand their impact on the soil chemistry and mineralogy. The ditches contain high amounts of red particles that are assumed to be iron-oxyhydroxide particles. During an initial field trip samples were collected and first analyses were performed (see lower right photo) to gain an insight into the chemistry of the ditches. In addition to the red precipitates, “oily films” were observed (see upper right photo) on some water surfaces that need further investigations. Based on this observations and already existing data, computer models were realised to predict the chemical reactions in the water phase.

The PhreeqC program, in conjuction with the WATEQ4F database, has been used to model the potential of hydrous ferric oxides (ferrihydrite) to adsorb/desorb metals and other anions along oxidation and salinity gradients. Some of the results are presented in the diagram below. The table on the right shows the initial composition of a selected soil water sample under reduced conditions with a high iron content. In the figure, the concentrations of selected elements are normalized to 100 % and are shown under the first step marked with “red” (reduced conditions). After exposing the soil water to air (second step: “oxid”) and oxidizing the Fe2+ to Fe3+, ferrihydrite is formed, which takes up most of the elements by surface adsorption. This process could occur by natural or artificial draining of soils. According to the model, the precipitation of ferrihydrite leads to the near complete adsorption of As, Cu, P and Pb and then, in descending order, Zn (85%), Cd, Ni and Mn (18%).

In the second part of the model, the release of the adsorbed elements is shown by mixing the oxidised solution with increasing amounts of seawater. When the ferrihydrite enters the ocean, some of these metals will be immediately released to the coastal waters, though As and Pb are last after mixing more than 1:100,000 with seawater.

This figure shows that high amounts of different elements could be adsorbed to iron phases by oxidation and become removed from the soil. Furthermore, these elements become release during mixing with seawater if they are transported to the ocean as particles.

ESR 12 Markus Reischer: Niras

The critical data compilation is complete, allowing construction of a hydrogeological model. This model will be shared among the METAL-AID partners (in particular AMPHOS21), so that computer simulations can be performed with identical basis.

ESR 13 Adrian Schiefler: Capital Region of Denmark

A first set of field soil samples have been investigated by X-ray computed tomography to obtain a better understanding of the pore structure (porosity/permeability/mineralogy). The X-ray tomography setup is currently developed further to allow for in-situ and time-resolved monitoring of particle transport and aggregation behaviour under flow through artificial columns (beads pack) and through natural soil samples. Also, microcosm batch experiments were conducted to investigate biotic TCE degradation by microbial communities present in groundwater collected at the field site. The cultivated bacteria were able to degrade TCE to cisDCE but no further. Genomic characterization of the microbial communities is planned. Batch experiments to investigate the impact of Green Rust on microbial activity will follow.

ESR 14 Virginia Alonso de Linaje: AECOM/URS

I started my PhD in November 2016. During the first 6 months I went through extensive literature review on nanoparticle agents for soil remediation and chlorinated organic pollutants characteristics to determine research gaps that need to be filled. I also learnt about the pilot-test site, AECOM field procedures / Standard Operating Procedures (SOPs), business model, environmental business, and remediation project development. I had the opportunity to gain experience on safety and systematic procedures for field data collection and geochemical data visualization and interpretation.

Semester 2

ESR 1 Marco Mangayayam: University of Copenhagen

Modified green rusts (GR) have been synthesized by changing the cationic species in its brucite-like layer structure or by altering the host interlayer anion with organic molecules. Synthesis parameters for these modifications have been optimized from previous GR recipes via oxidation-precipitation method. The inorganic modification showed interesting features, which led to drastic change in its reactivity in comparison to the pristine GRs. Organic modification showed GR like structure, implying the success of the molecule intercalation in the interlayer. Further confirmation by suites of techniques is needed to affirm such results.In addition, sulfidized-zero valent iron has shown to be promising for field remediation and therefore current focus lies on streamlining synthesis of such particle as well as their reactivity for chlorinated solvent degradation.

The figure below shows the SEM image of hierarchical structure of zero valent iron modified with sulphide coating totest for reduction of chlorinated solvents.

ESR2 Sandra Navaz Rubio: GFZ

Small changes in cell parameteres observed in XRD patterns contribute to a reduction of the cell volume with increasing Ni concentration;  This might be evidence that Ni is replacing Fe(II) sites.  Furthermore, by imaging samples co-preceipitated with high Ni concentration in the TEM, I observed that they appear to have irregular edges and some "amorphous" areas which might be an effect of the incorporation of Ni.  However, a deepter study of this is necessary to ensure that it is not an artifact caused by beam damage.

ESR 3 Karen Maria Dietmann: University of Salamanca

In the past months my daily lab work was focused on the question if previously synthesised LDHs, which are related to the hydrotalcite-group, are effective regarding the remediation of chlorinated solvents from aqueous media. Additionally, I intensified my knowledge about different characterisation methods by attending various workshops.Sharing my latest results with other researchers at the 27th Goldschmidt conference, which was held in Paris from August 13-18, gave me new inputs and ideas to clarify some of my most urgent questions that came to my mind during the daily work in lab.

ESR 4 Weichao Sun: University of Copenhagen

We calculated the single layer green rust structures with different Fe(II)/Fe(III) ratios and calculated the population. We assumed all the iron atoms are in high spin multiplicities, which means the Fe(II) has four unpaired electrons and Fe(III) has five unpaired electrons. In the structures, there are 19 iron atoms that I defined into three kinds: centre, inner and outer iron atoms. We found that in all the structures except with the ratios are 1/18 and 2/17, the outer iron atoms have more unpaired electrons, which means they are more likely supposed to be Fe(III), and have high reduction potential; the inner iron atoms have less unpaired electrons which are more likely supposed to be Fe(II). And all the centre iron atoms have least unpaired electrons. For all the structures, the unpaired electron of inner irons atoms change more with ratios changing. We can also clearly see that there are big gaps between the numbers of unpaired electrons of outer and inner iron atoms. All the results could indicate that for the single layer green rust, the redox reaction sites are more likely to be on centre parts of the structures.

ESR 5 Lisa Füllenbach: University College London

I was recruited to the Metal-Aid project on 1 September 2017.  During the coming reporting period, I will continue with literature research and work on batch experiments.  I will also attend the third meeting of the Metal-Aid project in Kaprun, Austria.  In the spring term of 2018, I will be enrolled as a teaching assistan for the Earth Sciences Department at UCL (courses and field trips).

ESR 6 Fieke Mulders: University College London

I was recruited to the Metal-Aid project on 1 July 2017.  Over the first months of my project I will focus on laboratory work: setting up experiments and developing those that are running.  The aim is to get some first results which could steer me in the right direction.  Furthermore, I would like to start with some outreach activities as well as some course work.  Additionally, I will attend project meetings.

ESR 7: Jeffrey Paulo Perez: GFZ

During the second reporting period, I investigated the interaction of green rust sulfate (GRSO4) with arsenic (As) species using batch adsorption experiments.  I examined various parameters to determine their influence on the adsoprtion of As on GR SO4.  Our results suggest that pH and ionic strength, expecially the presence of common groundwater species such as Mg2+ and PO43- affects As removal efficiency.  More importantly, GRSO4 is stable and can adsorb large amounts of As which exceeds the maxiumum uptake of common iron (oxyhydr)oxides present (near) subsurface environments. These results highlight the importance of GR mineral phases in the sequestration of As in anoxic groundwaters.

ESR 8 Flavia Digiacomo

The transport mechanism of green rusts (GRs) reactants was studied in water saturated column experiments. Column tests are among the main tools to a better understanding of the behaviour of the abovementioned particles as soon as they are injected in porous media. The mobility of GR particles was studied in a series of laboratory water-saturated column experiments, samples were collected each minute in order to build a conventional breakthrough curve (plot of relative concentration of a given substance versus time); the relative concentration (Crelative) is defined as the ratio of the actual concentration (C) to the source concentration (C0): Crelative = C/C0.

The figure below shows schematically how column experiments are carried out: injection of the suspension (or contaminant solution) using a peristaltic pump (flow rate 1,5 mL/min); collection each minute of the samples in small centrifuge tubes (1,5 mL); analysis of the outlet samples using UV-VIS spectrometer and ICP-OES and interpretation of the data using breakthrough curves (concentration versus time).

ESR 9 Andrew Thomas: KIT

Due to the results obtained from the kinetics experiments and further EXAFS analysis with a more complete set of reference standards, I now have a sufficiently complete understanding of the processes taking place in my experiments to publish my results and begin experiments to determine and optimize the efficacies of these particles in the field.

ESR 10 Shikhar Nilabh: Amphos 21

The field study in Copenhagen provided me with new insights to make multiphase and transport models accounting for the fluid and contaminant flow in the subsurface. I pivoted my work to include the fracture geometry in the subsurface. The literature review and case studies helped me develop dual porosity models accounting for transport in fracture and diffusion in Matrix. The model was further extended to study the back-diffusion phenomenon. After verifying these models, it was upscaled to the field-scale dimension. Currently I am focusing on developing multiphase multicomponent flow in the subsurface.

ESR 11 Tobias Linke: University of Iceland

During the second time period of this PhD project, different water and solid samples from a field site in Iceland were collected and analysed at the University of Iceland as well as at the University of Copenhagen. The conducted analysis gave first insights to the chemical composition and the mineral content of the different natural samples. The data were interpreted with a focus on natural iron cycling and phase transformation. Based on this work, the experiments to be conducted in the near future were planned. To gain additional knowledge of possible analytical and modelling techniques, different training workshops were attended. The first results of the work were presented at the international geochemical conference Goldschmidt 2017.

For more information about work performed during this reporting period, please click here.

ESR 12 Markus Reischer: Niras

I followed two lines of work. In one line, I set up a 3D flow and transport model using Modflow and MT3DMS with GMS as the graphical user interface. Due to current low concentration of contaminants in the groundwater at the test site, the consortium intends to shut down the pump and treat facility, that currently operates to contain the contamination to increase the concentration again for later experiments. Thus, I used my 3D flow and transport model to evaluate the safety of a pump shutdown. Results show that the pumping can be stopped for 1 year at least. In the second line of work, I tested the optical image profiler (OIP) for the detection of fluorescent tracers. This device was originally made for detection of hydrocarbons. I tested three different versions of the probe, that are optimised for different light wavelengths. Standard dye tracers could be detected with all probes. However, the sensitivity of the three types of probes varied based on the fluorescent tracer. The first field testing with Eosin injection in the groundwater showed that the tracer could be confidently detected. Further laboratory experiments are now in progress.

ESR 13 Adrian Schiefler: Capital Region of Denmark

I received training in both the procedure of PCR, the informatics to evaluate microbial community structure and x-ray tomography data analysis and finite element modelling. I learned about iron oxide synthesis and characterisation by various techniques. I made some first experiments in microbiology to progress the experimental setup for my intended studies. I was lucky to visit the Spring8 synchrotron research facility in Japan and have a first try to track Green Rust particle transport. However the particles seem to show too little absorption and mobility during my experiments to track them. I visited the Aquaconsoil conference in Lyon where I gave a presentation, made valuable contacts regarding all aspects of my PhD plan and met again with the ESRs of the Remediate ITN. And if lucky, I will be almost done with collecting my ECTS!

ESR 14 Virginia Alonso de Linaje: AECOM/URS

During the second semester, I gathered field data to develop a regional groundwater model for the pilot test site. As part of my secondment at the University of Salamanca I synthesized and characterized two types of layered double hydroxides (LDHs) with surfactants in the interlayer that I will use to adsorb chlorinated hydrocarbons from the groundwater.

Figure 1. Virginia during a field campaign collecting data to be used at the laboratory and to feed the groundwater model.
Figure 2. Laboratory set up for layered doubles hydroxides synthesis. A solution of Mg(NO3)2 and Al (NO3)3 is added at a low rate of 1 ml/min into a solution containing a known concentration of organics to be intercalated in the LDH interlayer. The pH is maintained at 9±0.5 by a controlled addition of NaOH. During the process the solution is stirred and nitrogen is burbled in the vessel. Organo-LDHs are aged for 24 h under nitrogen burbling.
Figure 3. Pulverized organo-LDHs. After drying during at least 72 h LDHs are powdered and stored in plastic bottles before using.

Semester 3

ESR 1 Marco Mangayayam: University of Copenhagen

Aluminium substituted green rusts (Al-GRs) with either chloride or sulphate in the interlayers have been fully characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and synchrotron based pair distribution function (PDF) analysis. Suites of Al-GRs were also used to understand their oxidation behaviour in dry state using in-situ PDF. Ultimately, we have an initial hypothesis on the full-reduction mechanism of Al-GR towards carbon tetrachloride in comparison to the pure, Al-free GR minerals.

As an alternative to GR, sulphidized zero valent iron (sZVI) has been shown to be a promising reactant for fast (within days) degradation of a suite of chlorinated solvents. Initial results show that sZVI are more pollutant selective than pure zero valent iron. Morover, structural characterisation of these compounds show that the shell material of sZVI is not enriched in iron sulphide phase(s), thereby challenging the widely accepted reduction mechanism of the nanoparticle. This is an ongoing study to further constrain the structure of these particles and their reactivity with the pollutants we see at the Skovlunde Byvej.

Analysing the particle's structure in the atomic scale needs high spatial quality and resolution. The picture below shows the beam line 11-ID-B set-up at Advanced Photon Source, which is responsible in capturing high energy diffraction data. The image captured can then be used for atomic pair distribution analysis. This semester, I focused on understanding and performing pair distribution function (PDF) analysis to characterise the particles that we are developing in the laboratory. This helped us resolve the structure and hypothesised mechanisms involved during the particle's reactivity.

ESR2 Sandra Navaz Rubio: GFZ

The time-resolved co-precipitation experiments show that the removal of Ni from solution increases after 24h of the end of the reaction.  This might mean that adsoprtion and/or crystal overgrowth play an important role in the removal process.  Furthermore, by analyzing the Ni/Fe ratio, I observed that the major removal takes place during GR precipitation and not during the precipitation of the precursors, schwertmannite and goethite.

TEM images show interesting changes in the morphology and particle size of the GR.  Also, the Fast Fourier Transforms of High-Resolution TEM images suggest that the crystallinity of the N co-precipitated GRs might be lower than the pure one, but this needs to be fully assessed in the future.

ESR 3 Karen Maria Dietmann: University of Salamanca

The latest experiments on so far synthesised Layered Double Hydroxides gave promising results regarding the retention of chlorinated solvents from aqueous media. Further experiments will be conducted to confirm the results and provide relevant information about the capability of the tested Layered Double Hydroxides to the field group. In a collaboration with AECOM (Madrid, Spain) the most promising samples are tested under real conditions on their field site.

Below is a SEM picture showing a modified hydrotalcite. This image was taken during my secondment at the University of Copenhagen,

ESR 4 Weichao Sun: University of Copenhagen

We calculated the energies of all the possible electron configurations of the structure with seven iron atoms. The high-spin multiplicity structure has the lowest energy, which indicates the high-spin state is the most stable. The 37-iron atoms single layer GR has similar properties as the smaller structures, demonstrating that our 19 atom cluster used for the majority of the calculations provides reasonably converged properties with respect to cluster size. The tendency is consistent for all the three different sizes of single layer green rust structures. The population analysis indicates that the redox reaction sites are more likely on the inner position, i.e. on Fe atoms not located at the edge of the sheet. The inner Fe atoms change their electron population significantly more than the edge Fe atoms in response to a change in total charge of the cluster.

ESR 5 Lisa Füllenbach: University College London

As a relative newcomer to the Metal-Aid project, I am still in the initial stage of getting my experiments set up andrunning. Going through the literature and many discussions with my supervisor and colleagues have been very fruitfulin this process. Meanwhile, I have received training in using SUPCRTBL and PHREEQC as a tool to model chemicalreactions and reaction pathways and gained deeper insights into heavy metal immobilisation strategies using variousiron minerals as sorbents and reducing agents.

ESR 6 Fieke Mulders: University College London

Over the last months I have focused on designing experiments which allow me to measure dissolution and precipitation rates of minerals, whilst familiarizing myself with several analytical techniques that allow me to both measure changes in the solid and solution composition. I have received training on the XRD, the SEM and ICP-OES/MS and I am in the process of developing flow through dissolution experiments. The latter has proved to be challenging: how do you flow fluid through your reactor without losing your solid material.

ESR 7: Jeffrey Paulo Perez: GFZ

During the third semester, I started my secondment at University of Copenhagen to investigate the formation of green rush from ferric oxyhydroxide in the presence of arsenic and silica.  The fate and speciation of arsenic was examined by a suite of solid-state characterization techniques and aqueous analyses.  I, together with Marco Mangayayam (ESR1), also performed arsenic adsorption experiments with the Al-modified green rusts to determine the effect of varying degrees of Al substiution on its reactivity.  In addition, I also collaborated with Markus Reischer (ESR12) and Adrian Schiefler (ESR13) to collect As-contaiminated groundwater samples from our site in Collstrop, which is managed by the Capital Region of Denmark (CRD).  We are using these samples to investigate the stability and performance of green rust in real As-contaminated groundwaters.

ESR 8 Flavia Digiacomo

GR(SO42-) seems to be very promising for reduction of chromium(VI). Its role in that process was tested by carrying out column experiments using self-made column reactors under O2 free conditions. To avoid any kind of possible surface changes that may occur due to the ageing process, GR(SO42-) suspensions were used within one week after synthesis.The effect of operating parameters such us flow rate and inlet metal ion concentration was investigated by changing one parameter and keeping constant the other one: the breakthrough curves were obtained by changing the inlet chromium(VI) concentration from 0,26 to 260 mg/l at two different flow rates (1 and 3 ml/min).

The obtained results showed that the inlet chromium(VI) concentration and the flow rate affect the capacity of GR(SO42-) in the immobilization process of chromium(VI). The plots built with data collected from the column experiments which have been performed so far have shown that by increasing the inlet chromium(VI) concentration, the breakpoint time decreased: at lower inlet chromium(VI) concentrations breakthrough occurred very late. From the data obtained by performing the laboratory experiments we can conclude that the life time of reactants is strongly affected by the concentration of the contaminant present in the field site. This must be considered in the planning phase of the remediation technique at field scale

The figure below shows the schematic working set-up used for the reactivity experiments (free oxygen conditions): the collected water samples were analysed spectrophotometrically (determination of the Cr(VI) content) and via inductively coupled plasma optical emission spectrometry (ICP-OES, determination of the total Cr concentration). After the injection of chromium(VI) solution, the filling material of the column (sand mixed with sulphate green rust) was treated, filtered and analysed via XRD.

ESR 9 Andrew Thomas: KIT

From the spectroscopy and microscopy results obtained, I have been able to determine the predominant mechanism of the chromate-green rust reaction under conditions characteristic of chromate contaminant plumes.  This knowledge will inform further experiments with cation-substituted green rusts and flow-through columns.  Initial batch reactions with Mg-, Zn-, and Al-substituted green rusts indicate that the mecanism of reaction for these particles is more favourable, so these particles will be further tested in flow-through column reactions.  In addition, column experiments with pure green rusts suggest that the same mechanism observed in the pure green rust batch reactions will predominate under flow conditions.

ESR 10 Shikhar Nilabh: Amphos 21

I have been working on multiphase fluid flow in subsurface. In this reporting period, I have studied the multiphase fluid flow in fractures. I built the small-scale models which shows the DNAPL infiltration in the fracture before it meets the aquifer. A significant inference from the model is that the DNAPL remains intact in the dead-end fractures even after the contaminant source is removed. This acts as a secondary source for diffusion in the matrix and transport in the aquifer through fractures. Later, due to back-diffusion, the contamination is prolonged in the groundwater. This is a very important result since the understanding of the processes occurring in the vadose zone are poorly understood due to the complexity in geological characterisation of this part of the system. Numerical modelling helps discern which transport processes are relevant.

Parallel to this, I am currently working on the modelling of transport and settlement of nano-particles once it is injected in the subsurface. This is the beginning of the second big part of the PhD project which is about the simulation of the injection and reactivity of the particles in the polluted aquifer.

ESR 11 Tobias Linke: University of Iceland

Within the past four months, further solid and liquid samples were collected and analysed. These new samples cover a longer time period, which is essential to understand natural variations caused by precipitation, weather and other natural effects. Therefore, this work will be continued throughout the next months. Also the sampling techniques were improved and new methods were included in the existing work.

During a field trip in November new samplers were installed into certain depths at the studied field site. These samplers allow the collection of lager sample volumes for chemical analysis of soil water. At the same time, soil cores were taken, described and catalogued. The soil cores allow a correlation of the newly installed samplers to certain depths in the previous described soil profile.

Over the winter, the new samplers and their surrounding have time to equilibrate. The first samples will be taken in spring as soon as the temperatures rise about freezing point.

ESR 12 Markus Reischer: Niras

In the past half year, I have been studying experimentally and in the field if GeoProbe's direct push, Optical Image Profiler can detect dissolved fluorescent molecules to enable tracking of the water movement and identification of possible preferential water flow. In this reporting period, I have explored if image processing allows extraction of additional information, testing if the fluorescence of different tracers can be deconvoluted, if signal to noise ratio can be improved, and if parameters describing the fluorescence as function of grain size can be derived.

Generally, regression analysis showed various correlations between the fluorescence and the sediments geometric mean grain size, specific surface area, pore space volume and the solution volume exposed to the measurement window of the OIP. Furthermore image stacking improved the precision in the quantification of fluorescence.

ESR 13 Adrian Schiefler: Capital Region of Denmark

Much time went into the optimization and preparation of the new experimental setup. A number of methods have been identified to investigate the impact of the altered particle for injection on microbial populations and bioaugmentation cultures. The feasibility and scope for applying tomography to investigate particle transport has been reassessed and will be subjected to experimental validation.

ESR 14 Virginia Alonso de Linaje: AECOM/URS

During this reporting period, batch experiments were carried out to evaluate adsorption capacity and stability of organo-layered double hydroxide (organo-LDHs). Trichloroethylene and 1,1,2 trichloroethane were adsorbed into organo-LDHs. Preliminary results show that when 1-dodecanesulfonate is intercalated into the LDH interlayer adsorption uptake increases when compared to LDHs with dodecyl sulphate. When a mixture of compounds is present in groundwater (ex. polluted groundwater from Spanish site) there is certain selectivity when adsorbing one compound vs. another. Further data are needed to better understand this process. Stability studies for synthesized organo-LDHs were performed with polluted groundwater and synthetic groundwater that mimics groundwater conditions at the Spanish field site. Preliminary results suggest that certain amount of organo-LDHs are dissolving into the solution (pH=7-8) probably at the edges of the crystals but crystal structure is invariant. Organo-LDHs have been placed in sample holders and dialysis tubing at the Spanish site to further study their stability under natural groundwater conditions over longer periods of time.

Semester 4

ESR 1 Marco Mangayayam: University of Copenhagen

New experimental data show that sulphidised zero valent iron (sZVI) show reducing capacity over an extended period of ageing in simulated groundwater. We explain this by the preferential formation of Fe oxyhydroxides that do not interfere with the particle’s reactive surface sites. Moreover, experiments show that groundwater chemistry heavily controls sZVI transformation pathways and ultimately its long-term performance. As such, it is important to account for these prior to field injection and subsequent studies are needed to further validate the asumption.

The SEM image shows aggregates consisting of spherical sZVI particles and large, hexagonal “green rust” platelets. The formation of this secondary Fe phase (green rust) is likely from the anaerobic oxidation of water by sZVI particle over time.

ESR2 Sandra Navaz Rubio: GFZ

My results show that GRSO4 can efficiently remove Ni2+ from solution both via co-precipitation and adsorption.  Up to 87% of th initital Ni2+ can be removed hrough co-precipitation with GRSO4.  There is a linear relationship between the Ni/Fe ratio in the solids versus that in the supernatant.  Furthermore, Ni2+ causes a decrease in GRSO4 crystallinity, as deduced from the high resolution TEM imaging and the analysis of the fast Fourier transforms (FFTs).


On the other hand, the results of the adsorption experiments also show a high rate of removal (75-95%) at 24 hours and even at a concentration as high as 500pm we have not reached the maximum adsorption capacity of GRSO4.

ESR 3 Karen Maria Dietmann: University of Salamanca

During the past months my daily lab work was focused on retention experiments to specify the retention potential of the so far synthesised samples. Research stays at various project partners, namely University of Copenhagen, GFZ Potsdam and University of Iceland were realised to analyse the experimental samples with additional techniques not available at the University of Salamanca and to share newest data with fellow project members. Latest results were shared at 25th Scientific Reunion of the Spanish Clay Society in Zamora, Spain and at the International Carbon Conference 2018 in Reykjavík, Iceland.

ESR 4 Weichao Sun: University of Copenhagen

We calculated a few single layer green rust molecules in different multiplicities. The results indicated that within all the different occupation states, the highest occupation state has the minimum energy. In the figure, we took medium size structure with minus eight charge as an example, the energies of every occupation have been calculated, the figure shows that the state with 33 unpaired electrons, which is the highest multiplicity state, has the minimum energy.

ESR 5 Lisa Füllenbach: University College London

Over the past 7 months I have started on my experimental work and have presented the first results in seminars, project meetings and at international conferences. In my work I focussed on developing an efficient and representative experimental set-up to investigate the uptake of aqueous metal species during the dissolution of the iron carbonate siderite (FeCO3) which has great potential as a low-cost material for in situ remediation techniques.

First results: During dissolution of natural siderite in an acidic solution, the pH of the solution increases and the released ferrous iron oxidizes to form iron (hydr)oxide precipitates. These precipitates are of nano-particulate size and act as sorbents for the heavy metals (Pb, Cu) present in the solution (Fig. 1). This process slows over time due to passivation of the siderite surface; however, the overall reaction rates also depend on the initial siderite grain size, solid-liquid ratio, and on the atmosphere in which the reaction occurs (oxic vs. anoxic). This in turn implies that the process of heavy metal uptake may be adjusted according to faster or slower rates if required. The results shown are from experiments conducted at ambient laboratory conditions. I have now commenced conducting complementary experiments in an anaerobic chamber to investigate the role of pO2 in the dissolution-oxidation-precipitation-adsorption process. .

ESR 6 Fieke Mulders: University College London

Both under anoxic and oxic conditions organic acids affect the dissolution rate of siderite. Citric and oxalic acid facilitate the oxidation of Fe(II) in the crystal structure. Such a change in oxidation affects both the rate and mechanism of siderite dissolution. Such a change in dissolution rate and dissolution mechanism could potentially impact the effectiveness of siderite as a remediating agent.

ESR 7: Jeffrey Paulo Perez: GFZ

These past months, I have been continuously analyzing data that I collected during my secondment at KU. These are results from the GR formation kinetic experiments with arsenic species. In addition, I have also published two papers. The first paper was a proof-of-concept of GR modification using organic guests in the interlayer space (10.1016/j.egypro.2018.07.023). Our results show that GR layers can accommodate aromatic sulfonates, which can potentially enhance its ability to degrade halogenated benzene contaminants in the groundwater. The second paper was on the removal of arsenic species using GRSO4 (10.1016/j.scitotenv.2018.08.163). In this paper, we have shown that GR is among the best performing iron (oxyhydr)oxides in reduced natural environments for the removal of arsenic. Our synthetic GRSO4 can remove up to 160 mg of As(III) and 105 mg of As(V) per g of GR. This unprecedented arsenic uptake makes GR an important redox-active mineral in contaminated soils and groundwater.

ESR 8 Flavia Digiacomo

During the last semester I have been focused on the study of the interaction between chromate, Cr(VI) and sulfate green rust (GRSO4) by means of reactivity column experiments. During my secondment at KU, I had the chance to repeat a set of experiments already performed at KIT. The analysis of the effluent was performed in-time by using a UV-Vis spectrometer coupled with a flow-through cell. The higher resolution data confirmed the previously obtained results, moreover it helped to understand how the immobilization process of chromate proceeds within a porous matrix. Whilst green rust reactants represent a promising technology for the reduction/adsorption of many heavy metals, sulphidized zero valent iron (sZVI) has shown to be effective against chlorinated solvents. That is why, parallel to the reactivity experiments, I have been working on the transport experiments of sZVI into fine quartz sand. At the beginning of my secondment at KU, I learnt from Marco Mangayayam (ESR1) how to synthesize sZVI, then I started the injection of these particles into a homogeneous sand bed reactor. Preliminary tests have shown that if we want to increase the mobility of this reactant into porous media, further proper modifications of the sZVI suspension must be done. .

ESR 9 Andrew Thomas: KIT

During this reporting period, I successfully synthesized a series of cation-substituted and adsorbent-treated green rusts, reacted them with hexavalent chromium, characterized the products using x-ray diffraction and transmission electron microscopy, and characterized the stability of the products by treating them with synthetic Mn (IV) oxides. I found that all treatments, with the exception of Zn substitution, increased the resistance of the product to oxidation by Mn oxides in comparison to pure green rust sulfate. In addition, products with higher stability typically showed a breakdown in the c-direction crystal structure as well as dissolution of the crystals’ interior domains. Further XAFS study of the Cr speciation in these samples will help to link Cr speciation and stability to the crystal structure of the reaction products.

ESR 10 Shikhar Nilabh: Amphos 21

I have been working on multiphase flow as well as particle injection modeling, and this period has been specially devoted to make the mathematical models more robust. On the particle modeling side, I made multi-scale models – the pore scale model describes the flow of nano-particles in a single pore wall, 1Dimensional column scale model to simulate column experiments for particle injection and a small scale 3Dimensional model representing the fate of nano-particles in a tank column. Currently, I am progressing with working on the column experiment data, with the aim of understanding the governing parameters and functions.

On the other hand, I incorporated mass transfer function in the multi-phase model thus enabling the flux exchange between fractures and sandy aquifer. This enables me to simulate the fate of DNAPL in a complex fracture-clay matrix system overlying a sandy aquifer. The model characterizes simultaneous two-phase flow and dissolution of DNAPL in the vadose zone, formation of secondary sources for contamination and the formation of DNAPL pool and ganglia in the aquifer.

ESR 11 Tobias Linke: University of Iceland

Throughout the past months, my daily work was focused on the collection and the analysis of solid and liquid samples from within the soil and the surface runoff. The new soil water samplers, that were installed last winter, turned out to be very efficient and gave us new insights into the in situ soil conditions. During an extensive field trip reference profiles in Iceland were visited and samples were taken. This created the base for a comparison of described profiles with the newly gathered data during my studies. Additionally, samples and knowledge was exchanged with other students from the network during visits and secondments as well as during the International Carbon Conference ICC 2018 which was held in Reykjavik, Iceland.

ESR 12 Markus Reischer: Niras

In this reporting period I have continued studying Geoprobe’s direct push probe the Optical Imaging Profiler (OIP). By applying ex-situ image processing I have shown that this allows: 1) differentiation between fluorophores with differently colored emission allowing dual tracer injection; 2) grain size determination; 3) detection of changes in sediment color, which can be related to variation in redox conditions.

A fluorophore can potentially be attached to solid reactants, so that the dispersal of the particles in the subsurface can be determined with the OIP. However, the attached fluorophore should not be quickly degradable by the sulphidized zero valent iron (sZVI) reactant developed by Marco Mangayayam (ESR1). Tests show that fluorescence disappears within hours for sulphurrhodamine B and eosin Y, upon exposure to sZVI. On the other hand, fluorescence remains for fluorescein. This shows two things 1) That sulphorhodamine B and eosin Y are either degraded or adsorbed and quenched by the particles. Given that both of the possibilities are detrimental to the fluorescence, fluorescein or fluorescein-like compounds are better candidates for tagging the sZVI. 2) That one could rely on co-injection with the sZVI of two tracers with differently colored emission and different reactivity with the sZVI. If the transport properties of the two tracers are similar, sZVI in the subsurface would be revealed by the presence of only the unreactive tracer. Thus, we have an alternative strategy for indirect detection of sZVI with the OIP..

ESR 13 Adrian Schiefler: Capital Region of Denmark

Using the contaminated waters extracted at our test site, I have successfully enriched for a microbial consortia able to degrade TCE all the way to ethene. I further developed an assay to quantify the potentially adverse effects of the reactant particles towards indigenous microbial consortia and their dehalogenation potential. This assay is currently being tested using a pure strain, Shewanella oneidenesis, under both aerobic and anaerobic conditions, and with different reactant types and concentrations, before applying it to the enriched culture. .

ESR 14 Virginia Alonso de Linaje: AECOM/URS

Batch experiments were carried out to evaluate the sorption capacity and understand the mechanism of sorption for different families of chlorinated hydrocarbon compounds (chloroethanes, chloroethenes, chloromethanes) into organo-layered double hydroxides (organo-LDHs). The influence of some factors such as: (a) physical and chemical properties of chlorinated hydrocarbons, (b) composition and morphology of the sorbent, or (c) physicochemical characteristics of groundwater were studied in order to optimize the sorption of pollutants in natural environments. At the same time, Mg3Al-CO3 and Mg3Al-DS hydrotalcites were placed in two wells in the Innovation Garage. The solids were collected at different times and characterized using different solid-state techniques to assess their stability over time in natural environments.

Figure 1 shows the experimental approach to evaluate the behaviour and long term stability of layered double hydroxides in natural environments. Mg3Al-CO3 and Mg3Al-DS (inorganic and organic hydrotalcites) were lowered into different wells at the Innovation Garage and the Spanish Site during 2018.

Semester 5

 

ESR 1 Marco Mangayayam: University of Copenhagen

This semester, I published an article on the structure and reactivity of sulphidised zero-valent iron (sZVI) by one-pot synthesis in Environmental Science & Technology. We elucidated the structure using high-energy X-ray techniques and found that sZVI synthesised this way exhibit a nanocrystalline metallic Fe core surrounded by a shell that is dominated by amorphous Fe(OH)2 and to a lesser extent amorphous FeS. This shell highly controls sZVI reactivity with chlorinated ethenes. Specifically, the presence of this shell enhanced reduction of TCE , while it decreased cis-DCE reduction. Aging experiments in simulated groundwater showed that the sZVI shell underwent oxidation and re-crystallisation processes, which negatively impacted its TCE removal efficiency. Despite this, sZVI still outperforms unsulphidised ZVI in terms of TCE removal over prolonged periods in simulated groundwater systems. To read more: https://pubs.acs.org/doi/10.1021/acs.est.8b06480

ESR2 Sandra Navaz Rubio: GFZ

To date we know that GR can efficiently remove Ni and Zn from solution, but little is known about how these metals affect the process of GR formation from solution.  The aim of the titration experiments is to study whether the pathway of GR formation changes and then elucidate the mechanism of incorporation of these metals inside the GR structure.

ESR 3 Karen Maria Dietmann: University of Salamanca

During the past months my daily lab work was focused on retention experiments to specify the retention potential of selected samples. Experiences about doing a PhD abroad, receiving funding from the Horizon 2020 research and innovation programme under a Marie Skłodowska-Curie grant and generally being part of a large, international and interdisciplinary network during PhD were shared with master/ undergraduate students and general public during workshops at the USAL and the European Researcher´s Night 2018 in Reykjavík, Iceland.

ESR 4 Weichao Sun: University of Copenhagen

In this period, I have finished the calculations of single layer green rust and the article is almost ready for submission. I have started the calculations of aluminium substitution impact on green rust and I also completed my secondment at Niras. At Niras I assisted ESR12 in the set up and full operation of two tank experiments where we tested the mobility of iron reactants through injection. During this secondment I learned about various particle injection techniques and how to trace injected particles using the geoprobe. Moreover, I was introduced to hydrogeological monitoring and data analysis. I also joined a field site investigation run by Niras at Hagfors, Sweden, where I was helping with sample collection during subsurface particle injection to study the particles transportability in situ.

ESR4 and ESR5 taking samples from the tank while the particles were being injected.

Weichao helping to operate probe to monitor the injecgted paticles, Hagfors, Sweden

ESR 5 Lisa Füllenbach: University College London

The geochemistry of polluted sites, such as mine tailings and contamination plumes, can be very complex, and the treatment often requires a combination of neutralization agents and metal-binding materials that immobilize hazardous aqueous species under both oxygenated and reduced conditions. Siderite (FeCO3) poses great potential to simultaneously remediate toxic metals and acidity in either redox environment, hence it is also a promising material for in situ remediation purposes (e.g. injection). During this past 6-month period, I have investigated the dissolution of this highly soluble iron carbonate in acidic aqueous solutions, as it produces alkalinity and provides a source of highly reactive, redox sensitive ferrous iron (Fe2+) that acts as precursor for iron (hydr)oxides, which function as effective adsorbents of heavy metals. In my experiments, I particularly focused on the effect of oxygen on the redox sensitive dissolution-precipitation mechanisms that control the rate of metal uptake from an acidic aqueous solution to simulate oxygen-free environments as they occur within increasing depth in soils and the subsurface. Besides the effect of oxygen, the type of metal in solution – its redox sensitivity in particular – plays an important role in the overall removal mechanisms, as under oxygen-free conditions the strong reducing potential of ferrous iron can promote the reduction of dissolved oxidized metal species such as copper (Cu2+; Fig. 1), of which the reduced state often represents their less mobile form

ESR 6 Fieke Mulders: University College London

The oxidation of Fe(II) to Fe(III) has significant implications for solution chemistry; ferrous Fe is highly soluble, but its oxidized counterpart readily precipitates forming Fe(III)-hydroxides. Fe(III)-hydroxides form colloids in natural waters to which heavy metals adsorb, thereby effectively remediating contaminated soils. Additionally, the insolubility of Fe(III) makes it unavailable for biota that require Fe(II) to live.

The oxidation rate of Fe(II) in natural waters strongly depends on the pH. This pH dependency has been attributed to aqueous complexes formed under different pH condition, whereby the oxidation kinetics of Fe2+, found at low pH (<4), is sluggish, while Fe(OH)2, found at high pH (>5), oxidizes relatively fast. In natural soils, however,  not only can the pH be attributed to changes in the Fe(II) oxidation rates, but additionally ligands and organic acids - naturally present in soils - can form aqueous complexes with Fe(II) and Fe(III) thereby affecting the oxidation rate of Fe(II). My results show that oxalic acid, at low pH (<4) increases oxidation rates, while at high pH (>4) it hinders Fe(II) oxidation. First modelling efforts indicate that at higher pH Fe(II) forms a stable complex with oxalic acid, thereby hindering oxidation. The model additionally supports previous experimental results on the effect of EDTA on Fe(II) oxidation, predicting correctly that EDTA hinders Fe(II) oxidation.

ESR 7: Jeffrey Paulo Perez: GFZ

Last December, I performed arsenic (As) K-edge X-ray absorption spectroscopy (XAS) measurements at the European Synchrotron Radiation Facility (ESRF) on my green rust (GR) samples synthesized by co-precipitation and by FE2+- catalyzed transformation of As-bearing ferrihydrite.  Specifically, I wanted to determine the oxidation state (X-ray absorption near-edge spectroscopy, XANES) and the local bonding environment (extended X-ray absorption fine structure, EXAFS) of arsenic in my GR samples.  These XAS results will help me investigate the potential role of GR phases in controlling the mobility and toxicity of arsenic in contaminated groundwaters and soils.

I was also awarded with a Research Mobility Grant (5,000 GBP) from the Royal Society of Chemistry to fund my research visits to the Leeds Electron Microscopy and Spectroscopy Centre (LEMAS) at the University of Leeds.  This research project is focused on using the state of the art transmission electron microscope at LEMAS to elucidate the interaction between GR and As at the nanoscale.  From this research project, we have published a paper that shows that GR can oxidize under the electron beam, regardless if the analysis is performed using conventional or cryogenic TEM.  The paper can be accessed here: https://doi.org/10.1016/j.micron.2019.02.002

ESR 8 Flavia Digiacomo

Over the past months I have been performing reactivity and transport column experiments using two very promising reactants such as sulfidised zerovalent iron nanoparticles (s-ZVI) and sulfate green rust (GRSO4). Data is confirmed by the replicates performed with different methods and in different laboratories. Results showed that both present a significant potential for the immobilization of hexavalent chromium. On the other hand, to enhance their longevity and delivery capabilities into soils and sediments, their surface properties need to be modified before injection. Further experiments and analysis are currently ongoing to gain a better understanding of the efficiency and behavior of the mentioned particles.

The picture shows three examples of UV-vis spectrum used for the in situ monitoring of the concentration of particles either contaminants injected into a column.

ESR 9 Andrew Thomas: KIT

During this reporting period, I used synchrotron-based XAS to characterize samples produced by reacting green rust solid solutions with Cr (VI). Using XANES-based fitting, I found that the distribution of Cr in these samples between relatively-soluble Cr (III) hydroxides and Cr (III)-bearing Fe oxides was quantifiable and shows a correlation with the stability of Cr (III) in these reaction products. In addition, more accurate diffraction data obtained by KU scientists during previous synchrotron measurements allowed the identification of nanoparticulate goethite in most samples as well as elucidation of a potential reaction mechanism.

ESR 10 Shikhar Nilabh: Amphos 21

My work for this semester has been focused on testing and upscaling my conceptual models. The models were tested with real data obtained from laboratory to understand the governing processes for the fate of particles and contamination and to derive important parameters. Upscaling these models helped me predict the behaviour of particles on the field scale. For remediation, one significant step is to characterize the aquifer, understand the contamination distribution, secondary sources of contamination.

A multicomponent multiphase model has been built to understand all the physical processes controlling the distribution of contaminants. On the other hand, a reactive transport model for sZVI particles was developed to predict the efficiency of the remediation strategy. Currently, I am working on combining both of these models so as to develop an end-to-end predictive tool for long term remediation processes. This does not only include the study of degradation of contaminant, but also tells about the source zone depletion, and remediation strategy optimization.

ESR 11 Tobias Linke: University of Iceland

After the International Carbon Conference 2018, where the Metal-Aid project was presented by the different ESRs, the fellow early stage researchers based in London, Lisa Füllenbach and Fieke Mulders, stayed for an additional week. They visited the field in southern Iceland, where Tobias Linke has done most of his field work, and got hands-on training in surface and soil water sampling and analysing. Furthermore, they were able to collect samples for their own research. In the following weeks, water samples from Iceland and experimental samples from ESR Karen Dietmann (USAL) were analysed and interpreted. Further analysis for trace elements in water and solid samples were prepared and conducted during a research stay at University of Leeds at the end of January 2019. For a better characterisation of the solid samples, which were collected during several field sessions in Iceland, I went to the University of Salamanca, Spain. During this secondment, I got access to use numerous characterisation techniques, which helped to gain a lot of new and interesting data about collected samples. These data will be analysed and finally published in the upcoming months.

ESR 12 Markus Reischer: Niras

Because the optical imaging profiler allows direct detection of fluorescence, we continued investigating experimentally particle labelling strategies for sulifidized Zero Valent iron (sZVI).  No recipes exist for labelling of sZVI, so as a first step we studied labelling of other particles (iron oxides, aluminium (hdro-)oxides and cellulose using published labelling procedures.  Cellulose was of interest because carboxymethyl cellulose is used as a stabilizer of sZVI which increases the particle mobility.  The typical labelling route consists of decorating the particle with an organic molecule containing a reactive group where a fluorophore can be attached (Figure 1).  These tests show that we can label aluminum hdyroxide and aluminium oxide, microcrystalline cellulose and maghemite.  However, the methods could not readily be extended to magnetite and sZVI.  Furthmore, one dye (Riboflavin) was reduced by sZVI, accompanied by a loss of its flluorescence.  Potentially, this feature can be used together with a non-reactive fluorophore, as a fluorescent probe cocktail to confirm the presence of sZVI in the subsurface directly.

ESR 13 Adrian Schiefler: Capital Region of Denmark

An ATP based viability assay to assess the toxicity of bare and sulfidised zero-valent iron (ZVI) nanoparticle towards bacteria has been developed and validated under aerobic conditions. The obstacle of any such assay lies in the interference of particles and/or their oxidation products. We have overcome this limitation by serially diluting the particle effect out, while exploiting the high sensitivity of ATP quantification to back-calculate the original signal. Typically, after 3-5 dilutions (1:1 in exposure medium) stable results are obtained while detected signals are lying in the linear range of the method. We validated the assay against the classically employed colony-forming-units (CFU) method and find good qualitative agreement, while the ATP based assay consequently shows slightly higher viabilities than the CFU method in absolute terms. We suggest this might be due to either a) the ATP per viable cell ratio shifting during exposure, and/or b) cells being absorbed to particles and not turning out as viable upon incubation in the CFU method.

ESR 14 Virginia Alonso de Linaje: AECOM/URS

During this reporting period, previously placed inorganic and organic hydrotalcite (HT) were collected from the Innovation Garage and Spanish Site after 6 months of being exposed to natural groundwater conditions. Results derived from sample characterization with various techniques showed that the intercalated anion and groundwater chemistry strongly influence the long-term stability of HT. Moreover, precipitation of mineral phases on the surface of the HT might reduce the contact of the sorbent with groundwater potentially reducing their sorption capacity over time.At the same time, various post-synthesis treatments were studied to enhance sorption HT with intercalated CO3 and NO3.

Figure 1 (a) SEM image of organo-hydrotalcite after being exposed for 4 months to groundwater from Innovation Garage. (b) The EDX spectra of (a). (Photo credit Kim N. Dalby)

Our Services

Marketing

Nullam vitae lectus dui. Donec vulputate ac tortor id convallis. Sed nisi mauris, laoreet vitae lacus at, viverra viverra neque. Curabitur nec aliquam lacus.

Public Relations

Maecenas aliquam vitae urna sit amet elementum. Cras consequat libero nisi, vel condimentum nibh eleifend ut. Donec consequat arcu.

Digital Media

In tellus ipsum, ullamcorper vitae justo sit amet, mattis consequat tortor. Suspendisse risus urna, posuere id orci ut, facilisis accumsan ipsum.

Testimonials

Quisque non tempus lacus, non placerat arcu. Donec nibh ipsum, pharetra nec pellentesque at, mattis ut lorem. Fusce dapibus tristique neque, eget ultricies lorem tincidunt vitae. Aliquam erat volutpat. Suspendisse non sem a leo mattis dapibus. Duis vel ornare arcu. Quisque at malesuada tortor.

Integer vulputate ultricies nisl, sed vehicula justo accumsan non. Aenean quis semper metus. Maecenas adipiscing, leo a facilisis tempor, mi quam feugiat eros, ullamcorper porttitor elit turpis ac risus. Lorem ipsum dolor sit amet, consectetur adipiscing elit.