Modeling and mechanistic approach for acid red 88 dye removal by hydrothermally synthesized magnetic chitosan-grafted with side chain salicylaldehyde

Abstract This research used the hydrothermal process to cross-link biopolymer magnetic chitosan (CS/Fe3O4) with an aromatic aldehyde (salicylaldehyde, SA) for the adsorption of acidic azo dye (AR88) from an aqueous environment. Analyses of VSM, pHpzc, CHNS, XRD, SEM-EDX, FTIR, and BET were used to determine the properties of CS-SL/Fe3O4 material. Using the Box-Behnken design (BBD), the effects of A: CS-SL/Fe3O4 dose range from 0.02–0.1 g, B: [AR88] concentration (10–50 mg/L), C: pH (4–10), and D: duration (10–90 min) on the adsorption performance of CS-SL/Fe3O4 toward AR88 dye were systematically investigated. In this research, the Freundlich isotherm and pseudo-second-order kinetic models were applicable to describe the adsorption rate of AR888 molecules. The maximum adsorption capacity (qmax) of the hydrothermally cross-linked CS-SL/Fe3O4 for AR88 dye was 137.3 mg/g. Multiple mechanisms, including electrostatic attraction, π-π stacking, n-π interaction, and H-bonding, are responsible for AR88 adsorption by CS-SL/Fe3O4. This study demonstrates that hydrothermal preparation of cross-linked CS-SL/Fe3O4 offers an effective and promising adsorbent for removing acidic dyes from polluted water.