A comparative evaluation of hexavalent chromium treatment in contaminated soil by calcium polysulfide and green-tea nanoscale zero-valent iron

► We compare hexavalent chromium treatment in soil with two reductive agents. ► Calcium polysulfide reduced 99% of soil-bound and 100% of leachable Cr(VI). ► Green-tea nanoscale zero-valent iron reduced 30-66% of soil bound Cr(VI). ► nZVI acidified soil pH, resulting in metals (Cr, Fe, Pb) leaching. ► Calcium polysulfide caused short-term high sulfur release.