Reducing the Leachability and Bioaccessibility of Arsenic in Soils using Supported Nano Titanium Dioxide

We herein report the development and testing of a novel material, namely activated carbon-supported nano titanium dioxide (ACTD) for the immobilization of arsenic in soil. This material, which was prepared using a sol-gel method, effectively reduced the toxicity characteristic leaching procedure (TCLP) leachability and physiologically based extraction test (PBET) bioaccessibility of As(III) in soil samples. Upon processing the soils for 56 d at an ACTD dosage of 0.25 mmol g^?1, the TCLP leachability of As(III) was reduced by 82.7–97.7%, while the bioaccessibility was lowered by 58.6–81.2%. In addition, sequential extraction resulted in an 11.5–96.0% decrease in the mobile-As(III) and the mobilizable-As(III) fractions, but an increase in the residual-As(III) fraction upon treatment with ACTD. These observations indicate that the application of ACTD could result in an 80% reduction in As(III) environmental leaching, thereby confirming that ACTD appears suitable for the treatment of arsenic-contaminated soil.