Sustainable approaches for dye removal using enzymatic hydrolysis residue of corncob as an adsorbent

Abstract

In this study, the potential of enzymatic hydrolysis residue of corncob (EHRC), an intrinsic byproduct of biorefinery, as dye adsorbent was surveyed. The chemical and structural analysis indicated that EHRC and raw corncob had numerous active functional groups and a large, rough adsorption surface. These properties, more prominent in EHRC, underlined the material’s efficiency in dye adsorption. EHRC and raw corncob were more favorable for the adsorption of methylene blue (MB) than methyl orange. The adsorption capacities of both EHRC and raw corncob increased with increasing initial dye concentration, and adsorption occurred rapidly. The adsorption capacity of EHRC did not change much when the solution pH was greater than the pH at point zero charge (pH PZC , 3.78). The process modelling demonstrated that adsorption of MB onto EHRC well fitted by the pseudo-second-order and Langmuir isotherm models. The adsorption was a spontaneous exothermic reaction based on thermodynamic analysis. These results showed that EHRC could be used as an efficient and cheap adsorbent.