Metal removal from soil leachates using DTPA-functionalised maghemite nanoparticles, a potential soil washing technology

Abstract

There is significant current interest in the application of magnetic (magnetite or maghemite) nanoparticles functionalised with chelating agents for the environmental remediation of metal contaminated waters and solutions. Whilst there is a body of knowledge about the potential remediation efficacy of such engineered nanoparticles from studies involving synthetic solutions of single metals, there is relatively little data involving mixed-metal solutions and virtually no studies about nanoparticle performance in chemically complex environmental solutions representing those to which a scaled-up nanoremediation process might eventually be applied. Therefore, we investigated the ability of diethylenetriaminepentaacetic acid (DTPA)-functionalised, silica-coated maghemite nanoparticles to extract potentially toxic (Cd, Co, Cu) and "non-toxic" (Ca, Mg) metals from solution (initial [metal] = 10 mg L; pH range: 2-8) and to extract a wider range of elements (As, Ca, Cd, Co, Cr, Cu, Mg, Na, Pb, Zn) from leachate obtained from 10 different contaminated soils with variable initial pH, (semi-)metal and dissolved organic carbon (DOC) concentrations. The functionalised nanoparticles could extract the potentially toxic metals with high efficiency (in general >70%) from single metal solutions and with efficiencies that were either unaffected or reduced from the soil leachates. K values remained high (>500 L kg), even for the soil leachate extractions. Our findings show that DOC and relatively high concentrations of non-toxic elements do not necessarily reduce the efficiency of metal contaminant removal by DTPA-functionalised magnetic nanoparticles and thus demonstrate the remediation potential of such particles when added to chemically complex soil-derived contaminated solutions.

Chelating Extractants for Metals

“…Currently, there is considerable interest in the use of magnetic nanoparticles functionalized with chelating agents for the extraction of metals from solutions. Thus, the possibility of functionalization of nanoparticles of magnetite coated with silicon dioxide with compound 34 was investigated [52] to remove potentially hazardous (cadmium, Currently, there is considerable interest in the use of magnetic nanoparticles functionalized with chelating agents for the extraction of metals from solutions. Thus, the possibility of functionalization of nanoparticles of magnetite coated with silicon dioxide with compound 34 was investigated [52] to remove potentially hazardous (cadmium, cobalt, and copper) and "non-toxic" (calcium Ca and manganese Mn) metals from solutions.…”

Effects of nanometer magnesium hydroxide on soil cadmium form under different cadmium levels

“…In heavy metal-contaminated soils, the use of immobilization modifiers, such as limestone, zeolites, phosphates and organic materials, as well as nanobioremediation materials and their composites, can decrease effective composition of heavy metals or change their redox state. 4 This effectively reduces both the mobility and bioavailability of heavy metals in soil. Therefore, in situ passivation repair methods for soil heavy metal pollution have received significant attention.…”

Genetic Engineering-Facilitated Coassembly of Synthetic Bacterial Cells and Magnetic Nanoparticles for Efficient Heavy Metal Removal

“…Magnetic nanoparticles (MNPs) have been proven as a great tool of adsorption-based heavy-metal removal, since they could be easily synthesized and conveniently recycled with the aid of artificial magnetic fields. , By modification with specific ligands, such as heavy-metal-binding small molecules (e.g., ethylenediaminetetraacetic acid (EDTA), , diethylene­triamine­pentaacetic acid (DTPA), , thiol-containing 3-mercapto­propyl­trimethoxysilane (3-MPTS) and dimercaptosuccinic acid (DMSA)), and heavy-metal-capturing polymers (e.g., chitosan, , humic acid (HA), polyethyleimine (PEI), , cellulose, acrylic acid-crotonic acid copolymer), MNPs might exhibit high capacity of removing heavy metals from water and soils. However, the application of MNPs in large-scale heavy-metal removal are frequently challenged by high dosage of MNPs, and by expensive modification of the ligands.…”