Arsenic immobilization in soil using starch-stabilized Fe/Cu nanoparticles: a case study in treatment of a chromated copper arsenate (CCA)-contaminated soil at lab scale

The present study investigates the possible use and effectiveness of starch-stabilized Fe/Cu nanoparticles for in situ immobilization of arsenic in contaminated soils. For this purpose, 0.04 wt.% starch-stabilized Fe/Cu nanoparticles were synthesized and tested through batch and column tests for the immobilization of arsenic in a loamy soil contaminated by chromated copper arsenate (CCA). When the CCA-contaminated loamy soil was treated with 0.4 g/L of starch-stabilized Fe/Cu nanoparticles (0.04 wt.%) at a soil-to-liquid ratio of 0.1, water-leachable arsenic was reduced by 92% and the toxicity characteristic leaching procedure (TCLP) leachability was reduced by 98%. Column elution experiments showed that through application of starch-stabilized Fe/Cu nanoparticles to CCA-contaminated soil, nearly all water-soluble arsenic was transferred to the nanoparticle phase. The TCLP leachability of arsenic remaining in the soil column was reduced by 70% due to the immobilization of arsenic by nanoparticles. In addition to an extremely high arsenic sorption capacity, starch-stabilized Fe/Cu nanoparticles exhibited excellent mobility in the soil environment. Both the high sorption capacity and the excellent mobility in the soil environment suggest potential for application of these nanoparticles to the contaminated soil for potential in situ arsenic immobilization.