Study of aniline/ɛ-caprolactam mixture adsorption from aqueous solution onto granular activated carbon: Kinetics and equilibrium

Abstract

Adsorptive properties of aniline (AN) and ɛ-caprolactam (CPL) onto a granular activated carbon (GAC) were investigated in single and binary systems via batch adsorption experiments. As AN and CPL are toxic to environment, and they could be present in effluents from CPL manufacturing industries. The effects of pH, GAC dosage, initial adsorbate concentration and temperature on their removal were investigated. The adsorption kinetics of AN and CPL in single and binary systems were studied and was found to conform to pseudo-second order kinetic model. A competitive effect between solutes was observed since lower uptakes as well as slower adsorption kinetics of each solute were obtained in binary adsorption system. The boundary layer diffusion rate was defined as the rate limiting mechanism for AN adsorption on GAC in single and binary system, while the adsorption rate of CPL was found to be governed by particle diffusion. Adsorption isotherm data was fitted to Langmuir and Sips isotherm models for single adsorption system. For the binary solute system, the modified extended Langmuir model was developed to predict the experimental data. The reusability properties of GAC were demonstrated by adsorption–desorption cycle.