Effects of operating variables in adsorption for azo textile dye from wastewater: Optimization of process parameters by Box-Behnken design of RSM: Isothermal and kinetic studies

Abstract

The removal of dye from azo textile dye using raw wheat bran adsorbent prepared by coating on low-density Polypropylene (PP) particles has been studied by batch experimental studies. The batch adsorption studies have been performed for 36 h. Box–Behnken design of response surface methodology (RSM) is utilized to ascertain the impact of initial concentration, adsorbent dose, and pH on the removal of dye. The data obtained from experimental parameters have been analyzed through the fitting of kinetic models such as Pseudo-first order, Pseudo second-order model, Intraparticle diffusion, and Elovich model for dye removal along with correlation or regression coefficient (R²) values. The statistical analyses of the results collected in reaction kinetic modeling portray the superiority of the Pseudo second-order model for both dye removal. In the dye removal, the higher R² values are seen in case of better suitability of the Pseudo second-order model. The isotherms of adsorption experiments have been performed by employing different adsorption isotherm models such as Dubinin–Radushkevich, and Halsey. It is observed that both isotherms reflect the equilibrium data for dye removal.