Preparation, characterization and evaluation of adsorptive properties of orange peel based activated carbon via microwave induced K2CO3 activation

This work explores the feasibility of orange peel, a citrus processing biomass as an alternative precursor for preparation of activated carbon (OPAC) via microwave assisted K2CO3 activation. The operational parameters, chemical impregnation ratio, microwave power and irradiation time on the carbon yield and adsorption capability were investigated. The virgin characteristics of OPAC were examined by pore structural analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, nitrogen adsorption isotherm, elemental analysis, surface acidity/basicity and zeta potential measurement. The optimum conditions resulted in OPAC with a monolayer adsorption capacity of 382.75 mg/g for methylene blue and carbon yield of 80.99%. The BET surface area, Langmuir surface area and total pore volume were identified to be 1104.45 m2/g, 1661.04 m2/g and 0.615 m3/g, respectively. Equilibrium data were simulated using the Langmuir, Freundlich, Dubinin–Radushkevich, Redlich–Peterson, and Toth isotherms, and kinetic data were fitted to the pseudo-first-order, pseudo-second-order and Elovich kinetic models.