Efficient removal of aqueous hexavalent chromium by activated carbon derived from Bermuda grass

In this study, a novel raw material, Bermuda grass had been devised for the synthesis of activated carbon (BGAC) and enhanced the pore volume by potassium hydroxide. The effects of different factors on activated carbon products by orthogonal experiment was optimized. The synthesized BGAC was characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) analysis, energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS) and then, Cr(VI) removal batch experiments were conducted to investigate the Cr(VI) removal performance. Kinetic model and Weber-Morris diffusion model were fitted to the Cr(VI) removal process indicated that the chemisorption was the predominant removal mechanism and intraparticle diffusion was the sole rate-controlling mechanism. Langmuir isotherms could fit the experimental date well, which revealed that the adsorption of Cr(VI) ions was monolayer adsorption and the maximum adsorption capacity could be reached at 403.23 mg g^-1. The results also promulgated that BGAC had an excellent potential on Cr(VI) removal. The removal processes were considered to comprise adsorption, reduction, precipitation and other ways through the study of the removal mechanism.