Process Optimization and Adsorptive Mechanism for Reactive Blue 19 Dye by Magnetic Crosslinked Chitosan/MgO/Fe3O4 Biocomposite

Abstract

A new biocomposite cross-linked glutaraldehyde-chitosan/MgO/Fe3O4 (CTS-GL/MgO/Fe3O4) adsorbent with magneto-responsiveness was prepared and applied for the removal of reactive blue 19 (RB-19), a synthetic textile dye. The prepared CTS-GL/MgO/Fe3O4 was structurally characterized using spectroscopic (XRD, FTIR, SEM–EDX), and its physicochemical properties were evaluated using potentiometry and pHpzc analyses. The influence of various adsorption parameters (A: CTS-GL/MgO/Fe3O4 dosage; B: initial solution pH; C: process temperature; and D: contact time) on the removal efficiency of RB-19 was statistically optimized using Box-Behnken design (BBD). The analysis of variance (ANOVA) indicates the presence of five significant statistical interactions between the adsorption parameters, as follows: AB, AC, AD, BC, and BD. The equilibrium dye uptake by the Freundlich isotherm model indicates heterogeneous adsorption, while the kinetics of adsorption was well-described by the pseudo-second-order model. The maximum adsorption capacity of CTS-GL/MgO/Fe3O4 towards RB-19 was 193.2 mg/g at 45 °C. This work highlights the development of a recoverable magnetic biocomposite adsorbent with favourable adsorption capacity towards a model textile dye with good separation ability by using an external magnetic field. Moreover, separation of the magnetic adsorbents from the treated solution is easy and convenient apply to continuous flow systems, which is highly preferred for industrial applications.