Valorization of toxic methylene blue dye adsorption by sodium alginate/carboxymethyl cellulose/activated carbon ternary composites

Abstract

In the present study, the performance of the sodium alginate/carboxymethyl cellulose/activated carbon (SA/CMC/AC) ternary composite microbeads containing different weight ratios of AC for the adsorptive removal of hazardous methylene blue (MB) from aqueous solutions. Firstly, the composite beads were prepared by adding AC with weight ratios of 10%, 20%, and 30% concerning the polymer amount. Then the composite beads were prepared by crosslinking in 2 wt. % CaCl2 solution. Initially, adsorption studies were carried out to determine the optimum properties, and the highest performance was obtained at pH = 7 and 298 K by using the composite containing 30% AC. Adsorption data were applied to several isotherms, and the Langmuir isotherm was found to be the best isotherm model for adsorption. The highest adsorption capacity was calculated as 308.6 mg/g at 298 K using this isotherm. Studies on adsorption kinetics revealed that the process followed a quasi-second-order kinetic model. FTIR-ATR analyses showed the interactions between dye molecules and the adsorbent and also indicated that the hydroxyl and carboxyl groups functioned as active adsorption sites. Furthermore, SEM analyses proved the presence of the dye particles on the surface of the adsorbent. This study demonstrated that the produced composite microbeads may be employed as a promising adsorbent for removing cationic contaminants from aqueous solutions.