Removal of High Concentration of Chromium Hexavalent Wastewater From Groundwater by S-NZVI

Sulfide-modified nanoscale zerovalent iron (S-nZVI) is attracting a lot of attention due to its ease of production and high reactivity with hexavalent chromium (Cr (VI)). However, until now, the most commonly used is the use of NaS2O4 sulfide nano zero valent iron. The study on the removal of hexavalent chromium from water by nanometer zero-valent iron with calcium sulfide is not comprehensive enough. Herein, the removal of high concentration of hexavalent chromium from wastewater by nanometer zero-valent iron with calcium sulfide and its structure were carefully investigated. Scanning electron microscopy (SEM) with EDS analysis demonstrated that sulfur was incorporated into the zero valent iron core and homogeneously distributed within the nanoparticles. S-nZVI had an optimal Cr (VI) removal capacity of 200mg/L, which was >100% higher than for pristine nZVI. Different molar ratio of polycalcium sulfide and zero-valent iron, initial zero-valent iron addition amount, initial pollutant concentration and initial pH value have different effects on the removal effect. While the S/Fe=0.2, 200mg/L initial Cr (VI) concentration, 2g/L S-nZVI additive amount, pH<5, have the optimum removal rate. Contrast to pristine nZVI, S-nZVI can efficiently sequester high concentration of hexavalent chromium from different contaminated groundwater matrices.