Statistical physics modeling and evaluation of adsorption properties of chitosan-zinc oxide nanocomposites for the removal of an anionic dye

The development of rapid methods to synthesize cost-effective adsorbents for the dye removal is an emerging and relevant topic in the field of wastewater purification. This study focuses on the preparation of zinc-oxide nanoparticles (NPs) impregnated chitosan (CS@ZnO) nanocomposite beads via mechanical stirring (MS) and microwave-assisted (MA) routes. The beads were characterized and utilized for the removal of Eriochrome BlackT (EBT) dye. Results showed that the CS@ZnO-MA beads provided the best adsorption capacities for EBT removal (40.9 +/- 0.83 mg g-1) at pH 3.5. The best composite (CS@ZnO-MA) can be regenerated 5 times without significantly affecting its adsorption properties and can remove 71 % of EBT dye from a multi-pollutant solution. The novelty of this study relies on the facile preparation and impregnation of the biopolymer with metal-oxide NPs, which render high adsorption capacity, mechanical strength and high specific surface area of the CS to contribute in the removal of dye molecules from textile wastewater. An enhanced statistical physics model revealed that the adsorption mechanism of EBT dye molecules on these composites was multimolecular. The study indicates an effective synthesis route that can be implemented to prepare new adsorbents using CS at a large-scale for water treatment.

Automated summary

The development of cost-effective adsorbents for dye removal in wastewater purification is a growing and important area of research. This study focuses on the preparation of zinc-oxide nanoparticles impregnated chitosan nanocomposite beads for the removal of Eriochrome BlackT dye. Results demonstrate that the microwave-assisted preparation of the composite beads provides the highest adsorption capacities and removal efficiency. The novelty of this study lies in the easy preparation method and the high adsorption capacity, mechanical strength, and specific surface area of the composite material, which effectively remove dye molecules from textile wastewater.