Fabrication of Schiff’s Base Chitosan-Glutaraldehyde/Activated Charcoal Composite for Cationic Dye Removal: Optimization Using Response Surface Methodology

Abstract

In this work, a ternary composite containing a Schiff base adduct (chitosan-glutaraldehyde) along with activated charcoal (Ch-Glu/AC) was successfully prepared that contains activated charcoal with cross-linked chitosan. The Schiff base adduct was obtained by reaction of a dialdehyde bifunctional cross-linker agent (glutaraldehyde; Glu), where various methods were employed to study the morphology, material crystallinity, surface area, and surface functional group of the ternary composite (Ch-Glu/AC). Ch-Glu/AC was applied as an adsorbent to remove a cationic dye (thionine dye, TH) from aqueous media. The effect of various independent variables on the adsorption process including adsorbent dose (A: 0.02–0.1 g), solution pH (B: 4–10), temperature (C: 30–50 °C), and time (D: 30–180 min) were investigated and optimized using response surface methodology-Box–Behnken design (RSM-BBD). The results demonstrated that TH dye adsorption on the Ch-Glu/AC surface obeyed the pseudo-first order (PFO) kinetic model, and the Freundlich isotherm was obeyed at equilibrium. The maximum adsorption capacity (qm) of the TH dye was 30.8 mg/g at 50 °C. The TH dye adsorption mechanism onto the composite surface was attributed to the electrostatic interaction, π-π interaction, and H-bonding. The findings of this work reveal the feasibility of Ch-Glu/AC as a candidate adsorbent for effective removal of cationic dyes from aquatic media.