| Summary: | Hybrid cross-linked chitosan-glyoxal/TiO2 nanocomposite (Chi-Gly/TNC) was prepared and employed for the adsorption of reactive orange 16 dye (RO16) from aqueous solution. Response surface methodology (RSM) with 4-level Box–Behnken design (BBD) was applied to optimize RO16 removal efficiency. Various process parameters, viz., loading of TiO2 nanoparticles into Chi-Gly polymeric matrix (A: 0–50%), adsorbent dose (B: 0.04–0.14 g/50 mL), solution pH (C: 4–10), and temperature (D: 30–50°C) were selected for optimization process. Analysis of variance (ANOVA) was incorporated to judge the adequacy of model. The significant simultaneous interactions between input variables on RO16 removal efficiency were clearly observed by interactions between AB, AD, BC, and BD. Applying the method of the desirability function, optimization of TiO2 loading (50% TiO2: 50% chitosan labeled as Chi-Gly/TNC-50), adsorbent dose (0.09 g/50 mL), solution pH ~ 4.0, and temperature at 40°C gave a maximum of 93.2% RO16 removal efficiency by Chi-Gly/TNC-50. The adsorption of RO16 from aqueous solution at optimum input variables by using Chi-Gly/TNC-50 in batch mode was evaluated. The kinetic results were well described by the pseudo-first order kinetic, and the equilibrium data were in agreement with Langmuir and Freundlich isotherm models with maximum adsorption capacity of 390.5 mg/g. The adsorption mechanism was attributed to the dipole-dipole hydrogen bonding interactions, Yoshida H-bonding, n-π stacking interactions, and electrostatic attractions. © 2019 Desalination Publications. All rights reserved.
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