Green Remediation of Hexavalent Chromium Using Naturally Derived Flavonoids and Engineered Nanoparticles

Conventional methods (e.g., bioremediation and zerovalent iron (ZVI)) for in situ remediation of chlorinated organic solvents may produce undesirable by-products and the use of nanoscale bimetallic particles has succeeded in eliminating some of these by-products. Palladium nanoparticles (PdNPs), bimetallic particles, ZVI particles with various oxidants, reductants, and nutrients have been shown to be useful in promoting contaminant transformation from toxic to benign forms. This chapter examines the most current information regarding metal contamination in water and the in situ remediation of inorganic contaminants, specifically chromium. We focus on the use of PdNPs for the catalytic conversion of Cr(VI) to Cr(III) using formic acid (FA) and sulfur. Based on the experimental results, this approach has shown that colloidal PdNPs enhanced the rate of reduction of Cr(VI). Along with the discussion of their enormous technological and economic potential, this chapter also discusses the use of naturally occurring flavonoids as reducing agents for Cr(VI).