Removal of Chromium (VI) by Modified Zeolite with Nanoscale Zero-Valent Iron (nZVI) from Water

Considering chromium major risks such as lung and skin cancer, and also sever effects on kidney and liver; present study was conducted to investigate removal of Cr(VI) using zeolite clinoptilolite from aqueous solution.
Zeolite clinoptilolite with the size of 4 mm was used to remove Cr (VI) from aqueous solution in present study. Potassium dichromate (K2Cr2O7) and double distilled water were used to prepare aqueous solution of Cr(VI). Residual concentrations of Cr(VI) were measured by a spectrophotometer at 540nm.
The results showed that increasing absorbent mass increased removal capacity and equilibrium time. Decreasing pH from 11 to 4 increased and from 4 to 2 decreased chromium removal efficiencies. Optimum time for zeolite contact was 70 min. In overall, pretreated zeolites (nZVI -modified zeolites) had the highest adsorption (i.e.85%) for Cr(VI), however, adsorption rate for untreated zeolites was less than 25%.
In general, the results show that zeolite modified by nZVI is a high efficiency method to remove Cr(VI) from groundwater.