Crystal violet removal from waste water by sulfonated poly (glycidyl methacrylate) nano-adsorbent: optimization by response surface methodology, isotherms, kinetics, and thermodynamics studies

Abstract

The removal of crystal violet (CV), from wastewater contaminated with dyes, was achieved by employing sulfonated poly (glycidyl methacrylate) (SPGMA) nano-adsorbent. Plackett–Burman design was utilized for screening the various sorption parameters. Optimal adsorption conditions were obtained by utilizing response surface methodology applying the Box–Behnken design in this respect. The adsorption was quite successful, reaching 255.5 mg/g under the optimum conditions, according to a second-order polynomial model. The data obtained indicated that the adsorption process adhered to the Freundlich isotherm, which suggests that the SPGMA adsorbent had a heterogeneous surface with varying energy sites and that many layers of CV sorption occurred. Furthermore, the adsorption kinetics of CV molecules onto SPGMA nanoparticles can be accurately characterized by the second-order equation. In order to understand the diffusion mechanism, various adsorption models were examined, specifically the film and intraparticle diffusion models. Additionally, the Boyd model was utilized to determine the precise step that controls the rate of adsorption for the CV ions. The Boyd diffusion model determines that the process rate is limited by film diffusion. The adsorption behavior at various temperatures demonstrates the endothermic nature of the CV adsorption process, the lack of order at the solid/liquid interface during adsorption, and confirms the feasibility of the method. Furthermore, the adsorption process was confirmed using FTIR, SEM, and EDAX analysis, respectively, of the SPGMA adsorbent before and after the CV removal process.