This review provides insights on some unique properties of nanoparticles (NPs) that are present i... more This review provides insights on some unique properties of nanoparticles (NPs) that are present in soils. In addition, this review discusses the role of NPs in controlling or influencing single and/or coupled chemical, biological, and hydrological soil- and/or geo-processes, which directly or indirectly affect the mobility or may determine the ultimate fate of aqueous and sorbed (adsorbed or precipitated) chemical
Ground Water Monitoring and Remediation, Mar 17, 2023
Cr(VI) flushing from the vadose zone to the groundwater (with subsequent Cr(VI) removal in ground... more Cr(VI) flushing from the vadose zone to the groundwater (with subsequent Cr(VI) removal in groundwater by pump‐and‐treat system) is a promising remedial technique that has recently been used at field scale. This laboratory study was conducted to provide the technical basis to design a field soil flushing strategy. The objectives were to (1) quantify the relationship between sediment Cr(VI) and Cr(III) mass and release rates and subsequent Cr(VI) leaching; (2) investigate different methodologies to maximize Cr(VI) leaching, and (3) investigate methods to minimize leaching of remaining residual Cr. Characterization of Cr‐contaminated sediments (Hanford Site, WA) exhibited Cr(VI) showed that leach rates that were correlated to different Cr surface phases. Sediments with low leachable Cr(VI) (<2 μg/g) leached Cr rapidly, so slow infiltration of water in a single pulse was sufficient to leach most Cr. In contrast, sediments with high Cr (2 to 200 μg/g) released some Cr(VI) quickly but 10 to 50% Cr(VI) slowly (tens to hundreds of hours). Efficient unsaturated leaching of these sediments required a different infiltration strategy that includes: multiple slow leach pulses with time between flushing cycles; the use of a surfactant to increase Cr leaching from low‐permeability zones, and the use of a reductant (Na‐dithionite or Ca‐polysulfide) in the final leach water was highly effective at decreasing residual Cr leaching. This study clearly demonstrated that the methodology of basing laboratory Cr flushing on parameters such as Cr release mass and rates could be used to improve the efficiency of soil flushing at field scale.
This review provides insights on some unique properties of nanoparticles (NPs) that are present i... more This review provides insights on some unique properties of nanoparticles (NPs) that are present in soils. In addition, this review discusses the role of NPs in controlling or influencing single and/or coupled chemical, biological, and hydrological soil- and/or geo-processes, which directly or indirectly affect the mobility or may determine the ultimate fate of aqueous and sorbed (adsorbed or precipitated) chemical
Ground Water Monitoring and Remediation, Mar 17, 2023
Cr(VI) flushing from the vadose zone to the groundwater (with subsequent Cr(VI) removal in ground... more Cr(VI) flushing from the vadose zone to the groundwater (with subsequent Cr(VI) removal in groundwater by pump‐and‐treat system) is a promising remedial technique that has recently been used at field scale. This laboratory study was conducted to provide the technical basis to design a field soil flushing strategy. The objectives were to (1) quantify the relationship between sediment Cr(VI) and Cr(III) mass and release rates and subsequent Cr(VI) leaching; (2) investigate different methodologies to maximize Cr(VI) leaching, and (3) investigate methods to minimize leaching of remaining residual Cr. Characterization of Cr‐contaminated sediments (Hanford Site, WA) exhibited Cr(VI) showed that leach rates that were correlated to different Cr surface phases. Sediments with low leachable Cr(VI) (<2 μg/g) leached Cr rapidly, so slow infiltration of water in a single pulse was sufficient to leach most Cr. In contrast, sediments with high Cr (2 to 200 μg/g) released some Cr(VI) quickly but 10 to 50% Cr(VI) slowly (tens to hundreds of hours). Efficient unsaturated leaching of these sediments required a different infiltration strategy that includes: multiple slow leach pulses with time between flushing cycles; the use of a surfactant to increase Cr leaching from low‐permeability zones, and the use of a reductant (Na‐dithionite or Ca‐polysulfide) in the final leach water was highly effective at decreasing residual Cr leaching. This study clearly demonstrated that the methodology of basing laboratory Cr flushing on parameters such as Cr release mass and rates could be used to improve the efficiency of soil flushing at field scale.
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Papers by Nikolla Qafoku