Preparation Of Peanut Hull-based Activated Carbon By Microwave-Induced Chemical Activation

Activated carbon, with strong adsorption capacity due to its high specific surfacearea, adequate pore size distribution and relatively high mechanical strength, has hadbeen widely employed in air pollution control, food processing, catalysis as well aswastewater treatment. Despite its prolific use in adsorption processes, the biggestbarrier of its application by the industries is the high cost of adsorbent. The peanuthull, an agricultural solid waste abundantly available in China, was utilized as aprecursor for preparation of activated carbon via microwave induced phosphoric acidchemical activation.The central composite design (CCD) and response surface methodology (RSM)were utilized to optimize the process conditions, the effects of the concentration ofphosphoric acid, microwave power and radiation time on the adsorption property(expressed in terms of the iodine number) and yield of the activated carbon wereinvestigated by response surface methodology (RSM). The optimized conditions wereobtained: concentration of H3PO433.04(vol.%), microwave power500.70W andradiation time9.8min, under which the iodine number and the yield of the activatedcarbon reached813.11mg/g and42.12%, respectively. The surface characteristics ofcarbon were examined by pore structure analysis, scanning electron microscopy (SEM)and fourier transform infrared radiation (FTIR). FTIR spectrum of starting materialshowed many peaks belonging to different functional groups. SEM micrographsshowed that the external surface of the chemically activated carbon was full ofcavities compared with peanut hull. N2adsorption showed BET surface area of peanuthull-based activated carbon was952.6m2/g and total pore volume was0.8807mL/g.Then they were used as adsorbent for the removal of Remazol Brilliant Blue R(RBBR) from aqueous solution. The equilibrium data of the adsorption was fitted tothe Langmuir isotherm and the process was found to closely follow the model ofintraparticle diffusion, a pseudo-second-order chemisorption model.