Dyes adsorption properties of KOH-activated resorcinol-formaldehyde carbon gels-kinetic, isotherm and dynamic studies

Abstract

This work was aimed to evaluate the adsorption properties of KOH-activated resorcinol-formaldehyde carbon gels for cationic methylene blue and anionic congo red removal from water. The activated carbons were characterized for surface chemistry and textural properties. The surface area of 427 m2/g and 433 m2/g were obtained for resorcinol-to-catalyst ratios of 100 and 2000, respectively. The carbon gels demonstrate a site-selective adsorption, where the maximum methylene blue capacity is 135 mg/g, while that of congo red is 16 mg/g. The equilibrium data fitted well with Langmuir model, where the adsorption could be described as a hybrid of physical-chemical process controlled by film diffusion. The dynamic data also support that the kinetics was controlled by external mass transfer or film diffusion for suitable application in dye wastewater treatment.