Adsorption mechanism of nonsteroidal anti-inflammatories in wastewater using regenerable adsorbent (CCL): statistical modelling isotherm, kinetics and thermodynamic comparative studies

Abstract

ABSTRACT The study was performed to investigate the biosorption mechanism of Diclofenac Sodium and Ketotifen Fumarate onto CCL biosorbent using isotherms models (Langmuir, Freundlich). Effects of parameters influencing the biosorption such as temperature, pH, biosorbent dose, contact time and biosorbate initial concentration were all investigated and optimised using a batch system. The comparison between various models indicates that the nonlinear form of Langmuir model was the best way to describe the equilibrium data that were approved using error functions: the coefficient of determination (R2), Average relative error (ARE), the sum of the squares of the errors (SSE), Marquardt’s percent standard deviation (MPSD), Hybrid fractional error function (HYBRID), Sum of the absolute errors (SAE) and ‘sum of the normalised errors (SNE)’ parameter. The kinetics experimental data was best predicted by the pseudo-second-order model. The adsorption mechanism identified external mass transfer as the principal measure of velocity control step. Thermodynamically, the process is spontaneous, exothermic and the adsorption was more favourable at lower temperatures. It was found that the regeneration is required as it changes the surface morphology of the biosorbent. Therefore, CCL biosorbent is considered as cost-effective and eco-efficient for removing Diclofenac and Ketotifen adsorbate from aqueous media by adsorption technique especially with its low cost preparation and regeneration.