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Final Report

Sustainable polymer technologies for controlling mercury pollution

Submitted to The Australian Government Department of the Environment and Energy

National Environmental Science Program

Emerging Priorities Funding

31 March 2017

Dr Justin M. Chalker Flinders University

[email protected]

www.chalkerlab.com

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Table of contents Project description and proposed outcomes 3

Details of operation and processes used to conduct the project, including personnel roles 4

Summary of progress and outcomes 5

Description of activities during the project period (reported against the project plan) 9

Statement on progress toward milestones 13

Statement on funds expended during project, including recipient contributions 14

Discussion of benefits and outcomes of the project 15

Evaluation of project against program’s objectives 28

Acknowledgments 29

Attachments (publications associated with project)

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The following project description and outcomes were proposed at the outset of the project. This information is provided here so that the reported outcomes can be assessed against the original proposal: Project Description This project will produce polymer materials to capture mercury pollution. Mercury is a heavy metal associated with a variety of industrial activities and is a toxic chemical that causes neurological damage and kidney disease. The key technology to be developed in this project features mercury-binding polymers made from sulfur and plant oils. To protect the environment and prevent human exposure to mercury, efficient and cost-effective methods are required for its remediation. Because sulfur is a by-product of the petroleum industry and plant oils are renewable, the mercury-capturing materials will be low-cost and prepared entirely from waste and sustainable feedstocks. Proposed Project Outcomes The outcomes from this project will comprise: a. Production of sustainable polymers that will provide a cost-effective solution to mercury pollution The polymers will be made from sulfur (a by-product of the petroleum industry) and renewable plant oils. This project will therefore provide beneficial outcomes on two fronts: new strategies in waste valorisation (converting industrial by-products to useful polymers) and using these polymers to capture highly toxic mercury pollution b. Validation of the polymers in capturing mercury from field samples that contain mercury The polymers will be tested for their ability to capture and/or stabilise mercury in water, soil, concrete, mine tailings, waste from the petroleum industry, and sediment contaminated with heavy metals c. Up-scaled production of polymers Continuous and/or parallel process for polymer production will be developed in the proponent’s laboratory for synthesis on a multi-kilogram scale in order to validate larger scale remediation in the field d. Field tests of the polymers in mercury remediation Pilot testing will be carried out in the field through collaboration with Australian Exploration Field Services and Maryborough Sugar and will focus on mercury pollution in soil and water due to mining and in fungicides used in cane growing. These tests will help guide the use of the polymers in other sectors that suffer mercury pollution

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Details of operation and processes used to conduct the project, including personnel roles This project was directed by Dr Justin M. Chalker at Flinders University. Laboratory testing and fieldwork was carried out by Dr Chalker with the support of Dr Louisa Esdaile (Research Fellow, Flinders University), Max Worthington (PhD candidate, Flinders University), Nicholas Lundquist (PhD candidate, Flinders University), Salah Alboaiji (Masters student, Flinders University), Renata Kucera (Honours student, Flinders University) and Maximilian Mann (Honours student, Flinders University). This core team was responsible for producing the polymers, testing mercury sorption, upscaling the polymer synthesis, and carrying out field trials on sugarcane fields to which mercury-based fungicides had been applied. The novel polymers produced in this project, formed by the reaction of elemental sulfur and unsaturated cooking oils, were first prepared by Max Worthington, Salah Alboaiji, and Renata Kucera, under the guidance of Dr Chalker. Max Worthington and Dr Chalker carried out the initial mercury sorption experiments for inorganic mercury in water, mercury metal in water and soil, and the fungicide 2-methoxyethylmercury chloride (MEMC).1 Nicholas Lundquist provided additional testing of the polymers as sorbents for MEMC and developed a kit for rapid MEMC remediation and disposal in aqueous solutions. Dr Louisa Esdaile developed the large scale synthesis of the polymers used in field testing, with assistance from Maximilian Mann. Field tests on sugarcane fields to which MEMC had been applied were facilitated by MSF Sugar and carried out by Dr Chalker, Dr Esdaile, Max Worthington, and Nicholas Lundquist. To further assess the scope of the polymers and their ability to sequester various forms of mercury, several academic collaborations were established during this project. Dr Deshetti Jampaiah, Dr Ylias Sabri, Dr Samuel Ippolito and Prof Suresh Bhargava of RMIT University contributed key experiments in the capture of mercury vapour. Katherine Muller and Dr Alexander Johs, based at Oak Ridge National Laboratory, contributed sorption experiments on inorganic mercury and inorganic mercury bound to humic matter. Inês Albuquerque of the Institute for Molecular Medicine (IMM) in Lisbon and Dr Gonçalo Bernardes of both the IMM and the University of Cambridge assessed the toxicity of the polymer and the toxicity of the mercury-polymer complexes. Polymer characterisation was facilitated by several academic collaborators and technical staff at Flinders University including Dr Christopher Gibson, Alexander Sibley, Dr Ashley Slattery, Dr Jonathan Campbell, Dr Cameron Shearer, Yanting Y Jason Young, Nick Adamson, Dr Jason Gascooke, Prof David Lewis, Prof Jamie Quinton, Prof Amanda Ellis, Prof Gunther Andersson, and Prof Joseph Shapter. Prof Martin Johnston also contributed to a microwave promoted synthesis of the featured polymers. Another aspect of the project plan was to assess the sulfur polymers as sorbents for metals other than mercury and other pollution such as perfluorinated alkyl substances (PFAS), crude oil and diesel. Key studies included sorption of iron (carried out by Nicholas Lundquist and Max Worthington), gold (carried out by Salah Alboaiji and Maximilian Mann), perfluorooctanoic acid (PFOA, carried out by Salah Alboaiji and Nicholas Lundquist, with assistance from Kymberley Scroggie—PhD candidate of Flinders University) and crude oil and diesel (carried out by Dr Chalker, Max Worthington, Nicholas Lundquist, Dr Louisa Esdaile, and Stephanie Legg—undergraduate researcher in the Chalker Lab).

1 2-Methoxyethylmercury chloride (MEMC) is a common fungicide used in the cultivation of sugarcane, potatoes and rice in several countries. In Australia, a commercial formulation of this fungicide is marketed for use in sugarcane farming under the trade name Shirtan. In this report, the active component of this fungicide will be referred to using the generic abbreviation MEMC.

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Summary of Progress and Outcomes Where results have been published, links to the open access papers are provided. For unpublished results, experimental details can be found in the section Discussion of benefits and outcomes of the project, beginning on page 15. Synthesis of polymers for capturing mercury: Novel materials were prepared by the co-polymerisation of canola oil and sulfur. Because used cooking oils were suitable in the synthesis and sulfur is a by-product of the petroleum industry, the polymers could be made entirely from waste. These materials were demonstrated to capture mercury metal, inorganic mercury, inorganic mercury bound to humic matter, mercury vapour, and organomercury compounds (including fungicides used in the Australian agriculture sector). The polymers were validated in removing these forms of mercury from air, water and soil. This outcome is important to the environment for two reasons: first, the use of waste as starting materials is important in managing the lifecycle of chemicals and second, the inexpensive polymers are effective at capturing diverse forms of mercury. Details on the material synthesis and characterisation of these polymers is provided in the open access publication Chem. Eur. J. 2017, 23, 1619-16230. For a discussion on sulfur polymers as sustainable options for environmentally beneficial applications see the associated open access publication Green Chem. 2017, 19, 2748-2761. Understanding the fundamental ways in which the polymers capture mercury pollution: In the case of mercury metal (either the liquid metal or the vapour), the polymer actually oxidises the mercury and converts it to a less-toxic form (cinnabar). Alkylmercury compounds appear to be oxidised to inorganic mercury, as inferred from spectroscopic experiments. For inorganic mercury, the polymer is a ligand that binds tightly to mercury and removes it from water. The sulfur polymers were tested against diverse forms of mercury including liquid mercury, mercury gas, multiple forms of inorganic mercury, inorganic mercury bound to humic matter, and organomercury compounds (including fungicides used in the Australian agriculture sector). To the best of our knowledge, this is the most comprehensive assessment of different types of mercury reported in a single study, published in the open access paper Chem. Eur. J. 2017, 23, 1619-16230. This is important because the majority of studies on mercury sorption focus narrowly on inorganic mercury such as mercury chloride and mercury nitrate. These are actually relatively easy to remove from water and do not represent mercury as it exists in most contaminated environments. In contrast, our study demonstrated that the polymers formed from sulfur and canola oil can capture challenging forms of mercury including liquid mercury in soil, mercury vapour in air, inorganic mercury bound to humic matter, and organomercury compounds. Assessment of other metals and pollutants captured by the polymers: Iron: The polymer was found to be effective at removing iron in the form of Fe3+ from water. This result is important in removing rust from water that is undesirable because of its colour and also because it promotes bacteria growth that can clog pipes. Details on this study are found in the open access publication RSC Adv. 2018, 8, 1232-1236. Gold: The polymer was tested in its ability to bind to gold in the form of Au3+. The polymer is highly effective at removing ionic gold from water and converts the gold to nanoparticles that bind to the surface of the polymer. These experiments (unpublished) were carried out because of their relevance to mercury pollution: because mercury was used historically in Australia to mine for gold, there is likely gold and mercury found together in legacy pollution from gold mining. More generally, the largest source of mercury pollution on the planet is from artisanal and small-scale gold mining—currently carried out by nearly 15 million people around the globe. Because the polymer binds to gold, we are currently working to use the polymer in a new form of mercury- and cyanide-free gold mining. Our team has published an open-access paper on the mercury problem in artisanal and small-scale gold mining, which describes how mercury is used in gold mining and

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how the chemistry community can help address this issue: Chem. Eur J. 2018, in press. DOI: 10.1002/chem.201704840. Perfluorinated alkyl substances (PFOS): The sulfur polymer was tested in the sorption of PFOS, a class of toxic compounds found in fire extinguishers commonly used by the defence and aviation sector. This pollution has become an increasing concern in Australia because PFOS from fire fighting measures has leached into ground water and domestic water supplies. While the sulfur polymers have a relatively low affinity for PFOS such as perfluorooctanoic acid (PFOA), the PFOA was discovered to form micelles that adhere to the polymer. This result will provide a foundation for future exploration and projects in which the polymer is tailored for increased affinity for PFAS. The polymer will also be explored as a support in filters for the removal of PFOS from ground water and domestic water supplies. Crude oil and diesel fuel: Particles or a powdered form of the sulfur polymer were found to be highly effective at removing crude oil and diesel fuel from water. When the polymer is added to crude oil on water, the polymer binds to the oil in seconds and the oil-polymer complex forms an aggregate that can be easily removed by filtration or skimming. The polymer can also be packed into a filter and oil-water mixtures can be separated in a continuous process in which the oil remains bound to the polymer and the purified water passes through the filter. The polymer can bind twice its mass in oil. The oil can be recovered by compressing the polymer and the polymer can be re-used. This study was recently accepted for publication in Advanced Sustainable Systems. A copy of the accepted manuscript and the experimental details is attached to this report. This outcome is important because it reveals an inexpensive sorbent, made entirely from waste, that can be used in the rapid remediation of oil spills. Lab-testing the polymers on field samples containing mercury pollution: The primary field sample examined was the mercury based fungicide 2-methoxyethylmercury chloride (MEMC). This fungicide is commonly used by sugarcane growers to prevent pineapple disease. The fungicide is applied to the sugarcane setts before or during planting. Laboratory tests were carried out at the operating concentrations used by sugarcane growers. A porous version of the sulfur canola oil polymer was effective at removing the mercury from this fungicide solution. After 24 hours of static incubation, the polymer typically removes 98% of the mercury from the MEMC solution. The polymer could also remove 73% of the mercury in a single pass through a column of the polymer or a column of polymer and soil. These results were published in an open access paper: Chem. Eur. J. 2017, 23, 1619-16230. In unpublished work, we have developed a kit in which the polymer is contained in porous bags and then placed in solutions of MEMC. The amount of mercury correlates with the colour of the solution (MEMC appears as a red/pink solution and the water turns clear as the mercury is bound to the polymer). When the water is clear, the bag can be removed from the solution and sent to a mercury recycler. It was also discovered that blends of the polymer and activated carbon are better than the polymer or carbon alone at removing MEMC from water. The aim is to make this kit available to growers so that unused solutions of MEMC are not simply buried or released into the environment and mercury is safely sequestered. Up-scaling production of polymers: A key milestone that was required before field testing was possible was to scale up the synthesis of the polymer. A process analysis led to a protocol that allows a 2.5 kg reaction scale to be carried out using an overhead stirrer with precise torque control. Briefly, canola oil (or unsaturated, waste cooking oil) is added to a 4.7 L stainless steel reactor and pre-heated to 180 ºC and then an equal mass of elemental sulfur is added slowly to the stirred mixture at a rate that maintains an internal temperature over 155 ºC. As the canola oil and sulfur react, they gradually form an opaque mixture (approximately 20 minutes reaction time). At this stage, sodium chloride (a mass 2.33 times greater than the combined mass of the sulfur and canola oil) is added at such a rate so as to maintain an internal temperature of 155 ºC or greater. After an additional 20 minutes, the torque experienced by the impeller of the overhead stirrer increases. At

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40 N•cm of torque, the reaction is stopped. The resulting product (a soft rubber) is then removed from the reactor, ground to particles of a desired size and washed thoroughly with water to remove the sodium chloride. After isolating the polymer by filtration and then drying the polymer in open air or in a fume hood, quantitative yields are typically obtained. Using this method, more than 50 kg of the polymer have been prepared. This protocol will be published, open access, in the study associated with oil spill remediation (Advanced Sustainable Systems, in press). A copy of this manuscript is attached to this report. A protocol that is smaller in scale, but much faster was also developed using microwave reactors. Even conventional domestic microwave ovens can be used to react sulfur and canola oil. The microwave protocol was published, open access in RSC Adv. 2018, 8, 1232-1236. Pilot field test in mercury remediation: Three field sites in Queensland were identified in consultation with MSF Sugar. MEMC was used on two of the three sites this year and at the other site MEMC was used in previous years. All three sites were irrigated and the combined tailwater from all sites flows into a tailwater pit. The tailwater flows into a neighboring river during periods of high rainfall. In an attempt to capture any mercury contained in tailwater, bunded bags of the polymer (43 cm × 36 cm) were buried just under the surface of the ground at the end of the rows of the field or at the entrance to the tailwater pit. Each bag of the polymer was packed with approximately 220 g of the canola oil polysulfide polymer. The bag was constructed from cotton. The bag was held vertical with wooden dowel rods. (See images and additional details in the Discussion of benefits and outcomes of the project, beginning on page 15.) The bags were installed just after planting, when MEMC is applied and before irrigation was commenced. Three bags were installed at each of the two fields and also at the entrance to the tailwater pit. The bags were recovered after 5, 10, and 15 weeks to assess bound mercury. Soil samples were obtained when the bags were installed and also at the 5, 10, and 15 week marks. Soil was sampled at depths of approximately 0-10 cm from the surface, 12-22 cm from the surface, and 26-36 cm from the surface. Tail water was sampled when the bags were installed and also after 15 weeks. In the mercury analysis at the time the bags of polymer were installed (digestion, followed by cold vapour AAS for soil and polymer samples and ICP-MS for water samples), it was found that the field to which MEMC had been applied that season contained 0.3 mg/kg total mercury from the surface down to 22 cm below the surface and typically 0.04-0.06 mg/kg total mercury below 22 cm. At the tailwater pit, 0.3 mg/kg total mercury was found predominately in the soil at the surface and down to a depth 10 cm. At 12-22 cm below the surface, the mercury levels were 0.1 mg/kg and 0.06 mg/kg of mercury from 26-36 cm below the surface. The field to which MEMC was applied in previous seasons contained 0.04-0.06 mg/kg total mercury at all depths sampled. Water sampled from the tailwater pit contained <0.0001 mg/L over the course of the study. After 5 weeks, the polymer samples were found to have no more than 1 mg/kg of bound mercury, with the characteristic red colour of the MEMC observed predominately from the top of the bag down to 10 cm for the field to which MEMC was applied and also for the polymer bag installed at the tailwater pit. The mercury bound to the polymer installed at the field that was not treated with MEMC this season was below the limits of detection. After 10 and 15 weeks, all soil samples down to depths of 36 cm contained between 0.03-0.04 mg/kg of mercury. After 10 and 15 weeks no more than 1 mg/kg was detected on the polymer. These results suggest that the majority of the mercury is leached off of the field within the first 5 weeks and likely in the first irrigations after planting and applying MEMC. These results also suggest that the mercury is present predominately at depths of 0-22 cm from the surface. The polymer captured no more than 1 mg of mercury per kg of polymer and this occurred in the first 5

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weeks. Because the mercury appears to migrate across the surface of the field in the irrigation water, this suggests that future efforts to capture this runoff need to be focused on the first 5 weeks after commencing irrigation and install bunded sorbents above the surface of the soil down to a depth of 20 cm. For sorbents that are above ground, they would need to let water pass through them to capture the mercury. The low levels of mercury found in the tailwater suggests that dilution occurs before this water ultimately moves into the neighbouring river into which it feeds. For future field studies and efforts to contain mercury washed off of sugarcane fields, these results also suggest that speed is important because the bulk of the mercury was leached from the soil within the first five weeks of commencing irrigation. Preparing for such future studies, we have prepared and tested a new formulation of the polymer that is made from 80% of the polymer and 20% of activated carbon. The hypothesis was the high surface area of the carbon could improve the rate of uptake and the polymer can provide a mercury-binding support for the carbon to cover a great area of treatment. Preliminary test on MEMC samples indicates that this formulation is faster then either the polymer or carbon alone in removing MEMC from water (Discussion of benefits and outcomes of the project, beginning on page 15 for more details on the polymer and carbon blend). This blend may be effective as a bunded sorbent at the end of fields, near the inlet to tailwater pits, or in water filters used to treat tailwater.

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Description of activities during the project period (reported against the project plan) Note: the original project plan is indicated below in black text. The blue text below each activity specifies the progress toward these goals.

. (i) Synthesis of polymers that have complementary forms useful for capturing mercury pollution. [Dec 2016 – Apr 2017] This first project activity will commence on signing of this Funding Agreement. The recipient’s previous research has demonstrated that sulfur and limonene can react to form a wax-like material that can capture mercury salts from water. This project will investigate new forms of the polymer that are more mechanically and thermally durable. This will expand their utility, and make them more suitable in devices such as air or water filters. Thermal stability would also be useful in capturing mercury vapour in flue stacks of coal-fired power plants, a significant source of mercury pollution. The initial approach will feature increased cross- linking by using polyunsaturated plant oils. Details of Progress: By substituting limonene for canola oil (or other unsaturated cooking oils), the polymer is a rubber that is more durable and more stable to higher temperatures than the original polymer. This was a critical discovery because the polymer can now be used more easily as filtration media or a solid sorbent for mercury. Additionally, the material can be made with higher surface area by preparing the polymer in the presence of sodium chloride, a porogen. Simply soaking the polymer in water removes the sodium chloride and leaves high surface area pores that enhance mercury capture. Canola oil is far cheaper than limonene and even used cooking oil is suitable in the synthesis. The polymer is therefore far more economical than originally designed. For all subsequent results discussed in this report, performance refers to the canola oil polysulfide (the polymer prepared from sulfur and canola oil). For full details of the canola oil version of the polymer, see the attached manuscript: Laying Waste to Mercury: Inexpensive Sorbents Made from Sulfur and Recycled Cooking Oils. Link: Chem. Eur. J. 2017, 23, 1619-16230.

. (ii) Understanding the fundamental ways in which the polymers capture mercury

pollution. [Jan 2017 – Mar 2017] The project will use state of the art spectroscopic and imaging techniques (SEM, EDX, XPS, XRD, confocal Raman, and Auger spectroscopy) to understand how mercury binds to the polymers. This information is critical to understand the material lifetime, stability, leaching, and how to deploy it in the field. These experiments will also provide important benchmarks for assessing the performance in remediated field samples. Finally, this information will also help determine if mercury (or other metals) can be recovered from the polymer after remediation. In a typical experiment, the polymer will first be exposed to the contaminated sample. This will be accomplished by static incubation with fluid samples, stirred exposure to fluid samples, continuous exposure of contaminated fluid to a bed of polymer, and/or milling the polymer with contaminated solids. The polymer and sample will then be analysed to determine changes in composition and their associated rates. For polymers that have bound metals, standard leaching experiments will then be carried out to assess stability. Details of progress: The canola oil polysulfide was tested against a variety of mercury sources in air, water and soil. For mercury metal (liquid mercury or mercury vapour), the metal reacts with the polymer to form the stable and non-toxic metacinnabar. The product does not leach mercury to levels higher than 0.7 ppb in water (below limits safe to drink). The product was confirmed by x-ray diffraction. Inorganic mercury (tested as mercury chloride) binds as mercury-rich nanoparticles, as determined by X-ray analysis (EDS). When the polymer binds to mercury(II), it also does not leach into water. For organic

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mercury, we are currently using various X-ray techniques to understand how it is bound to the polymer and preliminary results suggests it is also converted to an inorganic mercury bound to sulfur. These experiments are directly related to mercury-rich fungicides used in the sugarcane industry. Finally, sulfate release was measured. Very low levels of sulfate were released from the polymer. This is very important because sulfate release can stimulate bacteria that methylate mercury. We believe this is not an issue with our polymer. Accordingly, we recommend consideration of the polymer for in-situ remediation where it binds to mercury in water, soil or sediment in contaminated ecosystems and then the polymer is left in the environment. For additional details on the characterization of binding to diverse forms of mercury see the attached manuscript: Laying Waste to Mercury: Inexpensive Sorbents Made from Sulfur and Recycled Cooking Oils. Link: Chem. Eur. J. 2017, 23, 1619-16230.

. (iii) Assessment of other metals and pollutants captured by the polymers. [Jan 2017 –

May 2017] While mercury is the primary focus of this project, the polymer may also capture other metals and pollution. In cases where there are mixtures of metals (e.g. mine tailings and other industrial waste), this information is critical. Accordingly, the polymers will be tested in their binding to other materials including (but not limited to) cadmium, gold, arsenic, lead, selenium, iron, zinc and polyfluorocarbons. Controlled, standardised samples will be tested first, and then mixtures of these materials with mercury. This study will reveal if any of these materials interferes with the capture of mercury. Polymer stability and operational performance at various pH and temperatures will also be assessed. This data may lead to an outcome that is useful in the control of pollution other than mercury. Details of Progress: The polymer was tested against a variety of environmental contaminants. It was found that the polymer was effective at binding to iron(III), the polyfluorocarbon perfluorooctanoic acid (a toxin found in fire extinguishers) and oil spills. For additional details see the Discussion of benefits and outcomes of the project, beginning on page 15. For the iron(III) study: RSC Adv. 2018, 8, 1232-1236 The oil spill application was accepted for publication in Advanced Sustainable Systems (manuscript attached to this report).

. (iv) Lab-testing the polymers on field samples containing mercury pollution. [Mar 2017 – Jun 2017] The polymers will be tested in their ability to capture and/or stabilise mercury in water, soil, concrete, mine tailings, waste from the petroleum industry, and sediment contaminated with heavy metals. They will also be tested on samples of the fungicide commonly used in cane growing (methoxymethylmercuric chloride, also known as Shirtan). Mercury removal performance will be measured using standard analytical techniques such as atomic absorption spectroscopy (AAS) or inductively coupled plasma mass spectrometry (ICP-MS) for liquid samples. For solid samples both extraction from the contaminated media and stabilisation in situ will be studied. For in situ remediation, the polymer will be assessed in its ability to capture the mercury in the solid (e.g. soil) and prevent leaching into water and air. This lab testing is relevant to regions in Queensland where mercury fungicides are used in sugarcane production. Key parameters that will be elucidated in this activity are the amount of polymer and time required for a typical remediation. Both batch and continuous processes will be tested to help inform the way in which the polymers can be used to capture mercury from fluids. Details of Progress: The primary results obtained in this project activity pertain to capturing various forms of mercury: mercury metal in water, mercury metal in soil, mercury metal vapour, inorganic mercury chloride from water, inorganic mercury nitrate from water, inorganic mercury(II) bound to natural organic matter (Hg-NOM), and 2-

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methoxymethylmercuric chloride (as a fungicide formulation). The non-porous polymer is effective at remediating mercury metal in water, mercury metal in soil, inorganic mercury chloride from water, and inorganic mercury nitrate from water. For more challenging mercury samples such as mercury metal vapour, inorganic mercury(II) bound to natural organic matter (Hg-NOM), and 2-methoxymethylmercuric chloride (as a fungicide formulation), the porous version of the polymer was most effective. For additional details on the characterization of binding to diverse forms of mercury see the attached manuscript: Laying Waste to Mercury: Inexpensive Sorbents Made from Sulfur and Recycled Cooking Oils. Chem. Eur. J. 2017, 23, 1619-16230

(v) Up-scaling production of polymers. [Feb 2017- May 2017] The polymers must be synthesised on a multi-kilogram scale in order to validate larger scale remediation in the field. A continuous and/or parallel process for polymer production will be developed in the recipient’s laboratory. The first approach will be to use a suite of DrySyn reactors that can accommodate nine parallel reactions of 100-150 grams. This will allow approximately 1 kg of material to be produced each run. For continuous synthesis, an extrusion technique will be investigated where the sulfur and plant oil is reacted in a twin-screw extruder and expelled as polymer product. This technique could provide up to 5 kg/hour on a pilot scale. Several kilograms of polymer are required for field testing, so upscaling will be an important milestone. Details of Progress: The strategy for scaling-up the synthesis to 1 kg was recently achieved by using an overhead stirrer and a cast-iron 4L reactor. This required significant optimization and effort to understand the complicated mixing requirements and thermodynamics of the polymerization. Our lab now has the ability to prepare 1-3 kg of material over the course 2 days. This capability facilitated field trials. Demonstrating the large scale synthesis will also facilitate commercial interest in the production and use of this sorbent. The upscaling will be reported in a manuscript recently accepted in Advanced Sustainable Systems (this is the same paper in which the oil spill remediation is reported).

. (vi) Pilot field test in mercury remediation. [June 2017 – Dec 2017] Guided by the results

on the field samples, pilot testing on a larger scale will be carried out in the field. This will be done in collaboration with Australian Exploration Field Services and will have one focus on mercury pollution in soil and water due to gold mining. The collaboration with Australian Exploration Field Services will focus on a mine site in Bendigo and removal of mercury from water and calcine sands (with EPA permissions pending). In these tests, a filter will be constructed that is packed with the optimised polymer. A solar-powered pump will be used to cycle water through the filter. The mecury captured by the polymer will be detected by XRD analysis, and mercury concentration in water can be assess by ICP-MS. For soil and sands, XRD analysis will be used to show that the mercury (or other metals) are attached to the polymer and leaching studies will be carried out to determine if the polymer bound mercury is mobile under the conditions encountered in the field. For mercury contaminated soil and water, field testing will also be considered in Queensland regions where mercury fungicides are used in sugarcane production. Field access is to be coordinated with guidance from the Maryborough Sugar. The data obtained in these studies will provide information on how much polymer is required for full remediation in similar sites in Australia.

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Details of Progress: Field testing focused on sugarcane fields, with guidance from MSF Sugar. Due to the timing of the growing season, these field tests took priority over the Bendigo remediation activity. Please see the description on page 7-8 for the field trials.

. (vii) Final Assessment and Completion of Project [Jan 2018 – Mar 2018] Data from field

samples and field tests will be reviewed so that polymer performance can be assessed. The polymer properties will be tuned to meet these needs and provide optimised materials for mercury capture. This may involve modifying sulfur content, thiol content, type of oil and other parameters that may improve the polymer to meet an identified need. Details of Progress are provided in this report.

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Statement on progress toward milestones The following milestones have been met, as per the following schedule:

Long Form Funding Agreement in relation to Sustainable polymer technologies for controlling mercury pollution page 51

Schedule 3 – Milestone Schedule

No. Milestone description Milestone date Amount (excluding GST)

1 Signing of Agreement by the Department

Commencement Date Not applicable

2 Delivery of draft Project Plan to the Department

Within 40 days of the Commencement Date

Not applicable

3 Acceptance of final Project Plan by the Department

30 January 2017 $63,000

4 Delivery of Progress Report to the Department

31 July 2017 Not applicable

5 Delivery of Final Report to the Department 2017-18

31 March 2018 Not applicable

6 Acceptance of Final Report by the Department 2017-18

30 April 2018 $17,000

7 Delivery of Financial Information report for the entire Activity, showing that no funds remain unspent is provided to the Department.

Declaration that the Project has been completed.

Within 40 Business Days after the end of the Project Period or the earlier termination of this Agreement.

Not applicable

8 Acceptance of the Financial Information report by the Department

Not applicable

Complete

Complete

Complete

Submitted

Complete

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Statement on funds expended on the project The project is within budget and all project funds ($80,000) will be spent by the final day of the project, 31 March 2018. In the progress report submitted 31 July 2017, a variation was requested and approved to use funds ($15,419) towards the salary of an academic researcher (Research Fellow) to assist with field-testing. This position was filled and the hired scientist was a critical part of completing the field trials. The actual salary expenditure through 31 March 2018 is $12,055 and $3500 was used as a scholarship for a PhD student that contributed to the field tests (note that PhD students receive scholarships, rather than salaries). The funds originally allocated for “specialised glassware, reactors, mechanical stirrers, pumps, oven, benchtop mixers and centrifuge, pipettes, and equipment for the synthesis of polymers” were re-allocated to the salary costs of the appointed scientist and the remainder was used for field tests and consumable expenses. Additionally, the budget item “specialised glassware, reactors, mechanical stirrers, pumps, oven, benchtop mixers and centrifuge, pipettes, and equipment for the synthesis of polymers” (originally contained in the project budget) was paid using the $10,000 of cash support from Flinders University because this is for permanent equipment. All remaining funds were used for chemical supplies, consumables, and field-testing expenses. Summary of expenditures during the project: Expenditure Amount Spent or Committed Salary for Research Fellow $12,055 Chemical supplies and consumables for the synthesis, analysis, and lab testing of the polymers

$24,042

Funds for instrument access to analyse polymers and field samples, including analysis of field samples

$2532

Field testing (travel, accommodation, field testing consumables) $15,178 Funds to support research students (including top-up funding for one PhD student and funding for one summer research scholarship)

$13,500

Publication costs $6305 Contribution towards conference travel and registration to report results

$6388

Total Expenditures $80,000 Total Commonwealth Contribution $80,000 Funds Remaining from 31 March 2018 $0 Recipient Contributions Cash $10,000 In-kind to date Portion of salary and on-costs for Dr Chalker (Flinders University) [0.3 FTE + 30% on costs]

$53,845

PhD student Salary [1 FTE]

$35,049

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Project findings, outcomes and discussion The following finding and outcomes are to provide key experimental findings that have direct relevance to environmental remediation of mercury and other pollution. Outcome 1. A polymer was prepared by reacting canola oil and sulfur. The polymer removes both inorganic mercury and mercury metal from water:

Discussion: A polymer made entirely from waste cooking oil (canola oil) and sulfur can remove both inorganic mercury and mercury metal from water. As the polymer approaches saturation, it changes colour. This property might find use in sensing or assessing the lifetime of a filter that uses the polymer to capture mercury. The mercury also did not leach to more the 0.7 ppb when placed in water and neither the polymer nor polymer bound to mercury were toxic to liver cells. Relevant publication: Chem. Eur. J. 2017, 23, 1619-16230

Mercury chloride capture

A B C D A B C D

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1

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3

Canola oil polysulfide (50 wt% S) After capturing HgCl2

• Removes > 90% of HgCl2 from water (ICP-MS) • Chromogenic response (brown to grey) • No leaching into water (0.6 ppb after 24hr)

Worthington, Kucera, Albuquerque, Gibson, Sibley, Slattery, Campbell, Alboaiji, Young, Muller, Adamson, Gascooke, Jampaiah, Sabri, Ippolito, Lewis, Quinton, Ellis, Johs, Bernardes, Chalker. Submitted.

Mercury metal capture from water

A B C D A B C D

1

2

3

1

2

3

After reaction with Hg metal

• Removes > 99% of Hg (metal) from water • Chromogenic response (brown to black)

Canola oil polysulfide (50 wt% S)


16

Outcome 2. When mercury metal is mixed with soil, it disperses into tiny beads that adhere to soil. This so-called “mercury flour” is extremely difficult to remediate. The top image shows mercury flour and scanning electron micrograph of the 50 micron mercury bead. The bottom image shows how the polymer can remove this mercury by simple milling. The mercury, bound to the polymer as relatively non-toxic metacinnabar, can be isolated by mechanical sieving. (Note the black product indicates the mercury is trapped on the polymer)

Discussion: For sediment or soil contaminated with liquid mercury, milling with the sulfur polymer may be a strategy for converting the mercury to a more stable and less toxic cinnabar form. This strategy might be applicable to contaminated estuaries or battery sands. Relevant publication: Chem. Eur. J. 2017, 23, 1619-16230

Mercury flour A B C D

1

2

3

Loam (< 0.5 mm)

Loam: 4% Hg by mass 50 µm


Remediation of Mercury Flour A B C D

1

2

3

50 µm

24 h, rt 1. Hg(0) in Soil

2. Sieving

a.

b.

Soil: 4% Hg by mass


17

Outcome 3. A porous polymer was prepared by reacting sulfur and canola oil in the presence of sodium chloride. After the reaction is complete (typically 20 minutes), the solid product is removed and soaked in water to remove the sodium chloride. As the sodium chloride dissolves in the water, micron-scale pores are left in the polymer. These pores increase surface area and improve capture of mercury. The polymer has the physical consistency of a sponge-like rubber.

Discussion: The porous form of the sulfur polymer was critical in capturing challenging forms of mercury such as inorganic mercury bound to humic matter and mercury gas. The porosity improves both rate and capacity of mercury capture. This form of the polymer is also effective at oil spill remediation. Relevant publication: Chem. Eur. J. 2017, 23, 1619-16230

Porous$canola$oil$polysulfide$A B C D

18

Outcome 4. The porous polymer prepared from canola oil and sulfur is highly effective at capturing the fungicide 2-methoxyethylmercury chloride (MEMC or Shirtan). To increase the rate of capture the polymer can be blended with activated carbon. The carbon-polymer blend is much faster and has a higher mercury capacity than either the carbon or polymer alone

Discussion: MEMC is a bright red/pink colour and this colour is correlated with the mercury concentration. After treatment with the polymer or activated carbon, the mercury is bound to the sorbent and the water is clear. Typically 98% of the mercury or more is captured in these experiments. When activated carbon is blended with the polymer, the blend is easier to filter and binds more mercury faster than either the polymer or the carbon alone. In the bottom panel, the mercury was removed (>98%) in 30 minutes. We plan to develop bunded ‘teabags’ of the polymer carbon blend for the disposal of MEMC solutions that are unused by sugarcane growers. The carbon, polymer blends are also more suitable for future field studies in removing mercury from water. Notably, the carbon is prepared from coconut husks so the material is still entirely renewable. Relevant publication: Chem. Eur. J. 2017, 23, 1619-16230. The carbon-polymer blends will be published in due course.

Mercury Fungicide Remediation

A B C D A B C D

1

2

3

1

2

3

• Polymer Removes > 98% of Hg (organomercury) from Shirtan operating solution (static incubation, 24 hours, ICP-MS)

0"

20"

40"

60"

80"

100"

Shirtan"(untreated)"

Shirtan"+"polymer"

%"M

ercury"Rem

aining"in"Sam

ple"

Removing"Mercury"from"Shirtan"


Blend AC control

•  Activated carbon adsorbs to surface of porous COP •  Blend is easier to remove/filter than activated carbon

alone •  Porous COP also removes shirtan increasing efficiency

0 10 20 30 40 50 60 70 80 90

100

Blend AC control control

Per

cent

age

rem

oved

(%)

Shirtan removal using canola oil polysulfide and activated carbon blend

1 cm

19

Outcome 5: The porous canola oil polysulfide is effective at capturing mercury gas.

Discussion: When mercury is delivered in a nitrogen carrier gas using a mass flow controller, the canola oil polysulfide can react with the mercury gas and trap it on the surface of the polymer. The resident time and mercury removal efficiency is a promising lead for new technologies for controlling mercury emissions encountered during coal combustion and petroleum refining. Currently we are testing the polymer-carbon blends in mercury vapour capture for the development of materials suitable for flue gases and also personal protective masks that prevent mercury inhalation. Relevant publication: Chem. Eur. J. 2017, 23, 1619-16230

Mercury Metal Capture from Air

A B C D A B C D

1

2

3

1

2

3

• Removes ~67% of Hg (vapor) at 75 °C (45 mg Hg/Nm3, 0.1 L/min)

< 1 second residence time

Oil & Natural Gas

Coal combustion Worthington, Kucera, Albuquerque, Gibson, Sibley, Slattery, Campbell, Alboaiji, Young, Muller, Adamson, Gascooke, Jampaiah, Sabri, Ippolito, Lewis, Quinton, Ellis, Johs, Bernardes, Chalker. Submitted.

20

Outcome 6: Field trials in mercury remediation. The mercury containing fungicide MEMC was monitored in soil and trials in preventing mercury runoff in tailwater were carried out. See page 7-8 of this report for additional details

Soil and water analysis were carried out at three sites, indicated in the image above (obtained from Google Maps). Note that the image above was acquired at a different time than the trials and does not reflect the water and crop levels during the study. Location 1 was a freshly planted sugarcane field to which MEMC had been applied. The field test started before the first irrigation. Location 2 is at the end of sugarcane plot to which MEMC had been applied in previous seasons. Location 3 is an entry to a tailwater pit. Irrigation tailwater flows into this pit from plots marked A, B, C, and D. In periods of rainfall, the tailwater can overflow into a neighbouring river. The strategy for the trials was to place three bunded ‘bags’ of polymer at each of locations 1, 2, and 3. The bags were buried and then removed at 5, 10, and 15 weeks to determine if mercury was captured. Mercury content of soil at these locations was monitored for comparison and also to understand the migration of the mercury through the soil and irrigation water.

Location 3

Location 1

River

Location 2

Irrigation flow

Irrigation flow

Tailwater pit

A

B

C

D

21

Above: Bunded bag of polymer (220 g) in a cotton bag (43 cm × 36 cm) and installation in the ground.

Bunded polymer installed at location 1


22


Bunded polymer installed at location 3 (entry to tailwater pit)

23

Bunded polymer after removal from ground

At 5, 10, and 15 weeks the bags were removed from the ground. 20 g samples of the polymer were then digested and analysed for mercury content using cold vapour atomic absorption spectroscopy. No more than 1 mg/kg of mercury was detected in the polymer, and this level was consistent from week 5 to week 15. The mercury in the soil at various depths was also analysed. The data for the field to which MEMC was applied is shown below. Each data point is the average of three samples.

Discussion: The most useful information from this field study is the assessment of mercury levels in the soil and how they migrate over time. In the plot above, several important conclusions can be drawn: 1) the mercury due to MEMC application resides predominately from the top soil down to 22 cm below the surface. Below 22 cm, there is only trace mercury. 2) The mercury from MEMC is washed from the soil when irrigation is commenced. The mercury level at all depths dropped by 1 order of magnitude over the first 5 weeks and likely was washed into tailwater primarily on the first irrigation sessions. 3) Any bunded sorbents must be rapid act on the tailwater washing over the surface of the soil and down to a depth of approximately 20 cm. The newly formulated carbon-polymer blend (page 18) was developed in response to this discovery. Future studies (including field studies) will evaluate this material on tailwater. Additionally, the cotton weakened and could tear easily over the 15 weeks so it will be protected by an additional mesh.

0"

0.05"

0.1"

0.15"

0.2"

0.25"

0.3"

0.35"

0" 5" 10" 15"

Total&m

ercury&in&so

il&&(m

g/kg)&&

Week&of&sampling&

Mercury&Levels&in&Soil&During&Field&Test&

Soil depth 0-22 cm from surface

Soil depth 22-36 cm from surface

24

Outcome 7. The canola oil polysulfide polymer is effective at removing iron(III) from water.

Discussion: In many countries the discharge of water high in iron is regulated by environmental agencies. The image below shows how the polymer can remove iron(III) and de-colourise the solution. The polymer was removed by filtration after treatment. Removing iron from drinking water is desirable for taste and aesthetic profile, but removing iron from wastewater is also important because it can promote the growth of bacterial that lead to clogged pipes. Relevant publication: RSC Adv. 2018, 8, 1232-1236.

Before treatment with polysulfide

After treatment with polysulfide

50 mg/L Fe3+ 1.3 mg/L Fe3+

25

Outcome 8. The porous or low-density version of the canola oil polysulfide is an excellent sorbent for removing oil from water.

Discussion: Oil spills are a perennial threat to aquatic ecosystems. Inexpensive sorbents to remove and recover oil from water are needed to address this problem. The porous polymer prepared from canola oil and sulfur is inexpensive, highly porous, and hydrophobic: it should therefore absorb oil. Because mechanically the polymer behaves as a sponge, it is compressible. This property allows the oil to be recovered. In the top image, the polymer absorbs the oil within seconds and coagulates, allowing easy removal from water. Simple mechanical compression enables recovery of the oil. The polymer is also effective at separating crude oil from seawater (bottom image). The polymer can either be added directly to the oil and the aggregate can be skimmed, or the polymer can be used in a filter. This study has been accepted for publication in Advanced Sustainable Systems (manuscript attached to this report).

Porous$Polysulfides$in$Oil$Spill$Remedia1on$

A B C D

1

2

3

1

2

3

Porous polysulfide captures oil in seconds (up to 2 g oil / g polymer) Elastic properties allow mechanical recovery and polymer reuse

Worthington, Lundquist, Shearer, Campbell, Gascooke, Gibson, Albuquerque, Shapter, Andersson, Lewis, Bernardes, Chalker. Unpublished results

26

Outcome 9. The polymer prepared from sulfur and canola oil adheres to micelles formed from perfluorocarbons found in fire extinguishers.

Discussion: While the polymer is not very effective at low PFOA concentrations, the perfluorinated substance still has affinity for the polymer when it forms micelles. The polymer may therefore be useful in preventing leaching of these toxic fluorinated materials into groundwater. This is a recent and emerging problem in Australia. At present, the polymer may be most useful as a soil additive to trap PFCs at the site where they are released. The polymer is not effective at removing PFCs such as PFOA from water at low concentrations. This preliminary result has led to funding requests as part of the ARC Special Research Initiative.

Perfluorocarbon pollution from fire fighting foams

A B C D

1

2

3

1

2

3

Perfluorocarbons such as perfluorooctanoic acid (PFOA) are commonly used in fire fighting foams. Leaching into groundwater is cause for concern for the environmental and public health.

Hypothesis: Porous, hydrophobic polysulfide polymers will be effective PFC sorbents

F3C OH

OF F

F F

F F

F F

F F

F F

PFOA: PFOS: F3C

F F

F F

F F

F F

F F

F FSO

O OH

FF

A B C D

1

2

3

Alboaiji, Scroggie, Worthington, Perkins, Chalker Unpublished results

Fluorine clearly detected by EDS PFOA bound as micelles

PFOA binds to hydrophobic polysulfide at high concentrations

~50% reduction over 24 hours (9 mg/mL PFOA) 2 grams polysulfide per 5 mL PFOA solution

27

Outcome 10 The canola oil polysulfide polymer binds to ionic gold (Au3+)

Discussion: The canola oil polysulfide binds to ionic gold and can easily be converted back to gold metal by incineration. This discovery provides a key lead in the development of mercury-free and cyanide-free gold mining. Current work is focused on converting gold from ore into a water-soluble ionic form, for subsequent capture by the polymer. Artisanal gold mining relies on the use of mercury to extract gold from ore and is the largest source of mercury pollution on the planet. We are working toward a sustainable, safe and efficient gold mining process that can support the livelihood of more than 15 million people that currently mine for gold using mercury. We have published an open-access review on The Mercury Problem in Artisanal and Small-Scale Gold Mining: Chem. Eur J. 2018, in press. DOI: 10.1002/chem.201704840.

Mercury-free gold mining using canola oil polysulfide A B C D

Alboaiji, Gascooke, Chalker. Unpublished.

98% of Au(III) removed from water (UV, ICP-MS) (5 mL of 5 mg/mL AuCl3, 250 mg porous polysulfide, 90 min) Gold metal can be recovered after TGA or by roasting the polysulfide gold complex in furnace (600 ºC, 3 min) Current goal: sustainable, simple method to leach Au(III) from ore, for subsequent recovery with polysulfide

1PageEDAX TEAM

13-10-17

10/13/2017 1:49:36 PMCreation:

rg-chalkerAuthor:

polysulfideSample Name:

Area 19

Notes:

2PageEDAX TEAM

Selected Area 1

20 10013 75 30 1.92 125.4Resolution:(eV)Amp Time(µs):Live Time(s):Takeoff:Mag:kV:

Selected Area 1

eZAF Smart Quant Results

Element Weight % Atomic % Net Int. Error % Kratio Z R A F

C K 37.91 69.55 1090.21 7.41 0.1212 0.7763 0.5955 0.4118 1.0000

O K 2.20 3.03 129.29 9.77 0.0073 0.7349 0.6023 0.4521 1.0000

S K 32.43 22.29 4339.03 1.70 0.2095 0.6666 0.6529 0.9620 1.0070

CrK 6.56 2.78 364.37 3.76 0.0429 0.6136 0.7218 0.9929 1.0735

AuL 20.90 2.34 151.23 11.96 0.1226 0.5009 0.9561 1.0265 1.1405

SEM micrograph: gold on polymer EDS: gold on polymer Mercury-free gold mining using canola oil polysulfide A B C D

1 mg Au (recovered after TGA)

10 mg Au (furnace)

2PageEDAX TEAM

EDS Spot 1

10 24032 77 30 1.92 125.4Resolution:(eV)Amp Time(µs):Live Time(s):Takeoff:Mag:kV:

EDS Spot 1

eZAF Smart Quant Results

Element Weight % Atomic % Net Int. Error % Kratio Z R A F

C K 1.53 18.22 4.96 21.00 0.0120 1.1383 0.4032 0.6932 1.0000

O K 0.96 8.58 3.82 35.43 0.0066 1.0158 0.3915 0.6797 1.0000

AuM 96.92 70.55 134.10 5.79 0.5693 0.5370 0.5596 1.0748 1.0182

S K 0.60 2.66 1.76 71.11 0.0047 0.8834 0.4287 0.8938 1.0006

EDS analysis of recovered Au

Alboaiji, Gascooke, Chalker. Unpublished.

98% of Au(III) removed from water (UV, ICP-MS) (5 mL of 5 mg/mL AuCl3, 250 mg porous polysulfide, 90 min) Gold metal can be recovered after TGA or by roasting the polysulfide gold complex in furnace (600 ºC, 3 min) Current goal: sustainable, simple method to leach Au(III) from ore, for subsequent recovery with polysulfide

28

Evaluation of project against program’s objectives

The project aligns with a new high priority need for environmental decision-makers which is not

being delivered through other mechanisms.

The issues of mercury remediation are high priority for the Commonwealth as it assesses the

impacts and obligations of the Minamata Convention and the prospect of ratification. The studies

completed in this project will inform how to comply with future regulations in mercury emissions.

Additionally, new technologies are provided through these studies that may create flexibility in

responding to diverse types of mercury pollution.

The project has an end-user focus.

The polymer sorbents for mercury and oil are designed to be used by end-users in the capture of this

pollution. These end users include sugarcane growers, environmental agencies and oil spill response

workers.

The project will deliver practical and tangible outcomes.

The results of the project are practical in that an entirely new polymer was made from inexpensive

feedstocks and it the synthesis is scalable. This novel material was used in field trials on mercury

remediation and provides the basis for a novel strategy in capturing diverse forms of pollution

including mercury, oil, perfluorinated alkyl substances, and iron. Additionally, a key lead was

uncovered that may lead to sustainable mercury- and cyanide free gold mining.

The project involves trial programs to improve the physical environment.

Field trials were carried out on sugarcane fields to determine the movement of mercury based

fungicides in soils and also to test a new sorbent in preventing the mercury leaching into tailwater.

The information in these trials offers critical information for the management of mercury release

from agricultural areas that rely on mercury-based fungicides.

The project has a clear path to measurably improve the environment.

The goal of the field trials was to prevent mercury from leaching into watercourses. Additionally,

the outcomes in the remediation of oil spills and PFAS pollution are promising leads to improve the

environment through future remediation projects.

29

Acknowledgments We are grateful to the Australian Government Department of Environment and Energy and the financial support through the National Environmental Science Program Emerging Priorities Funding. We thank John McDougall of the Department of the Environment and Energy and his role in managing this project. MSF Sugar is gratefully acknowledged for their assistance in identifying sites for field trials. We also thank all members of our Flinders team and our collaborators for their time, effort and dedication to this diverse project in sustainable chemistry and environmental science.

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