Natural and H2SO4 modified plane sawdust as a low-cost adsorbent: Removal of anionic and cationic dyes from aqueous solutions

Natural and H2SO4-modified plane (Platanus orientalis L.) sawdust were used for the adsorptive removal of cationic methylene blue (MB) and anionic indigo carmine (IC) dyes from aqueous media to suggest a new and cost-effective method for wastewater treatment applications. The influences of initial pH values, concentrations of MB and IC, period of contact, dosages of the natural and modified plane sawdust, and the presence of foreign ions on the adsorption of dyes were investigated in the experimental studies to describe the best conditions of the most efficient adsorption processes. Initial pH values were optimized to be between 6.0-8.0 for MB and 2.0 for IC. Experimentations of Boehm titration, FTIR analysis, pHpzc value, and moisture content determinations were utilized to characterize the natural and modified sawdust materials. Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models were used to evaluate the sorption mechanism. Maximum adsorption capacities of natural plane sawdust (NPS) and H2SO4-modified plane sawdust (MPS) calculated from the Langmuir isotherm model were 55.56 and 38.46 mg g-1 in MB adsorption, and 55.82 and 55.55 mg g-1 in IC adsorption, respectively. Results showed that the natural and H2SO4-modified plane sawdust serve as low-cost and efficient materials in the adsorptive removal of MB and IC dyes for industrial wastewater treatment applications.