Effective removal of a cationic dye from an aqueous solution by modified chitosan-zinc oxide nanoparticles beads

Abstract

Synthetic dyes like basic dyes are among the disturbing contaminants in wastewater, causing environmental pollution, thereby attracting a quest for a potent and sustainable adsorbent for effective treatment. This study utilized sustainable chitosan-zinc oxide nanoparticles beads (Cht-ZnO) fabricated under a nitrogen gas environment for the removal of Basic Blue 3 (BB3) dye from an aqueous solution. The characteristics of Cht-ZnO were examined using FTIR, TGA, SEM, EDX, and XRD, revealing a functional adsorbent with improved stability. The influence of adsorption conditions, including initial concentration, pH, contact time and adsorbent dosage, was studied. The O−H, C−O and C = O on Cht-ZnO contribute as binding sites for BB3 adsorption. Experimental studies revealed that 0.01 g of Cht-ZnO added into a 400 mg/L of BB3 at pH 12 can remove 98% of BB3 from an aqueous solution within 60 min. Freundlich isotherm best describe the adsorption, while the monolayer adsorption capacity qmax of 1250 mg/g was obtained. The kinetics conforms to pseudo-second order (R2 = 1), in which chemisorption was the rate limiting process. The Cht-ZnO regeneration was feasible after BB3 adsorption, indicating its potential for repeated use. The prepared Cht-ZnO adsorbent is a viable contender for wastewater treatment applications due to its effectiveness in removing BB3 from aqueous solutions.