Efficient treatment of rice byproducts for preparing high-performance activated carbons

This work deals with finding an appropriate treatment process to enhance the utilization of rice by-products as precursors for producing efficient activated carbons. In this respect, biological and chemical pretreatments of the rice by-products were assessed. Chemical constituents and thermogravimetric analysis were examined to characterize the treated rice straw and rice husks samples; while, textural properties, scanning electron microscopy, and adsorption capacity in aqueous medium (Methylene blue and Inodine-value) were analyzed to evaluate the role of treatment approach on efficiency of produced activated carbons. Results revealed the beneficial effect of biological treatment, especially cellulase with rice husks, in providing greater surface area (1000 m(2)/g) and yield x S-BET (777 m(2)/g) of the produced activated carbon. However, alkali treatment of rice straw amply surpasses methylene blue adsorption capacity; (247 mg/g). Langmuir model and Pseudo-second order kinetic model had the best fits. The thermodynamic parameters (Gibbs free energy and enthalpy changes), indicate that the adsorption process was thermodynamically favorable and endothermic in nature. (C) 2018 Elsevier Ltd. All rights reserved.