Insights into the modeling, characterization and adsorption performance of mesoporous activated carbon from corn cob residue via microwave-assisted H3PO4 activation

Abstract

Microwave-assisted H3PO4 chemical activation was applied to convert corn (Zea mays) cob (CC) residue into mesoporous corn cob activated carbon (CC-AC) as a desirable adsorbent for cationic dye (methylene blue; MB) removal. The activation process was carried out by impregnating CC with phosphoric acid (H3PO4) (1:2 Wt.% mixing ratio) before being placed inside a microwave oven with activation power of 600 W for 20 min for CC-AC production. A Box-Behnken design (BBD) was applied to develop response model followed by numerical optimization in order to optimize the input adsorption variables (CC-AC dose, solution pH, temperature, and contact time) towards MB dye removal by CC-AC. The best numerical option for MB dye removal (99.7%) was recorded at following operation conditions: CC-AC dosage 0.1 g, solution pH 9.4, temperature 39.9 °C, and contact time 34.1 min. The adsorption results at these optimum conditions indicated the capability of CC-AC for uptaking 183.3 mg/g MB dye at equilibrium as determined by Langmuir isotherm. The consequence of this study suggested the feasibility of producing a high quality of mesoporous activated carbon for cationic dye removal by a relatively fast microwave process.