Removal of Hexavalent Chromium from Aqueous Using Biochar Supported Nanoscale Zero-Velent Iron

Abstract

A novel biochar carried nanoscale zero-valent iron (NZVI) particles were synthesized by means of liquid phase reduction method that can overcome the aggregation of NZVI particles. The Composite material of the biochar-NZVI can effectively improve the removing rate of hexavalent chromium Cr(VI) in the application of water treatment. The experimental results showed that the remove rate of Cr(VI) was up to 96.8% by using biochar-NZVI when the mass ratio of biochar and NZVI was of 5:1, the rate was enhanced by about 35.9% than that of the same dose pure NZVI. The analyzed results of TEM and BET showed that the biochar-NZVI had higher dispersion and specific surface area than pure NZVI, which was the key reason for biochar-NZVI with high removing efficiency of Cr(VI). The apparent rate constant kobs decreases from 0.1041 to 0.0235 min(-1) as the initial concentration of Cr(VI) increased from 25 to 125 mg/L in the solution, indicating that the reaction velocity decreases with the increased initial concentration of Cr(VI) in the solution. The removal efficiency reached to 92.1% when the pH value of the solution containing biocha-NZVI treating Cr(VI) increased from 4.48 to 8.36, showing that the biochar carried NZVI has high removing rate of Cr(VI) in a wide range of pH value.