Adsorption of Cr(VI) from Aqueous Solution by Activated Carbon Prepared from Agricultural Solid Waste

Activated carbons were prepared from mixed precursors of rice straw and rice husk using phosphoric acid (ACP) and steam (ACS) as chemical and physical activating agents, respectively. The adsorbents were characterized by FTIR and BET. The efficiency of ACP and ACS in adsorbing Cr(VI) was tested in a batch system. The effect of different parameters such as contact time, sorbate concentration, pH, and temperature were investigated. Adsorption of Cr(VI) ions obeyed Langmuir isotherm and followed the pseudo-second order model. Different thermodynamic parameters: Delta G degrees, Delta H degrees, and Delta S degrees were evaluated, which indicated that the sorption was favorable, spontaneous, and endothermic in nature. The ACP and ACS were found to be both effective and economically feasible.