Adsorption of hexavalent chromium from wastewater using microcrystalline cellulose

Abstract

In this study, microcrystalline cellulose (MCC) was utilised as an adsorbent for the removal of Cr(VI) from synthetic wastewater. FTIR spectroscopy confirmed the main characteristic infrared absorption bands of cellulose in the MCC. The MCC had a relatively low BET-specific surface area of 2.05 m2 g-1. SEM revealed that the MCC had a short-fibre, rod-shapedmorphology. XRD analysis confirmed the MCC semi-crystalline structure. Batch adsorption studies showed that the optimal conditions for the removal of Cr(VI) from the wastewater using the MCC were an initial Cr(VI) concentration of 10 mg L-1, an adsorbent dosage of 20 g L-1 and a Cr(VI) solution pH of 1. The MCC required 96 h to reach equilibrium, and the equilibrium removal efficiency was 83 %. The point of zero charges of the MCC (pH 6.2) and occurrence of Cr(III) in solution during the adsorption process suggests that the Cr(VI) removal mechanism from the wastewater by the MCC was adsorption coupled by reduction. The pseudo-second-order (PSO) model provided the best fit for the experimental kinetics data. The Freundlich isotherm provided the best fit to the experimental equilibrium data. Compared to commercial adsorbents, the adsorption capacity of the MC was relatively low at 3.92 mg g-1.