Effective removal of Cr(vi) from aqueous solution by biochar supported manganese sulfide.

In order to remove hexavalent chromium (Cr(vi)) efficiently and simplify the adsorbent preparation process, we employed a single step method to prepare a new biochar supported manganese sulfide material. The nanoscale MnS particles were highly soldered on the biochar support surface, and this adsorbent displayed the effective removal of Cr(vi) (98.15 mg L-1) via synergistic effect between adsorption and reduction/precipitation under weak acid conditions (pH = 5.0-6.0). The adsorption kinetic data were described well by the pseudo second-order kinetic model, suggesting that the reaction process was a chemisorption process. The adsorption isotherm data were described well by the Redlich-Peterson model, further suggesting that this reaction was a hybrid chemical reaction-sorption process. In addition, the Dubinin-Radushkevich isotherm model with 8.28, 8.57, and 12.91 kJ mol-1 adsorption energy also suggests that it was a chemisorption process. The simple and eco-friendly preparation process, low-cost, and the high removal efficiency could make it a promising material for the purification of Cr(vi)-contaminated wastewater.