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Box-Behnken design to optimize the synthesis of new crosslinked chitosan-glyoxal/TiO2 nanocomposite: Methyl orange adsorption and mechanism studies

Mohammad, AbdulKarim-Talaq, Abdulhameed, Ahmed Saud, Jawad, Ali H.
International journal of biological macromolecules 2019 v.129 pp. 98-109
adsorbents, adsorption, aqueous solutions, biosorbents, chitosan, crosslinking, electrostatic interactions, experimental design, hydrogen bonding, methyl orange, models, nanocomposites, nanoparticles, pH, polymers, response surface methodology, sorption isotherms, temperature, titanium dioxide
A crosslinked chitosan-glyoxal/TiO2 nanocomposite (CCG/TNC) was synthesized by loading different ratios of TiO2 nanoparticles into polymeric matrix of crosslinked chitosan-glyoxal (CCG) to be a promising biosorbent for methyl orange (MO). Box–Behnken design (BBD) in response surface methodology (RSM) was applied to optimize various process parameters, viz., loading of TiO2 nanoparticles into CCG 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). The highest MO removal efficiency of 75.9% was observed by simultaneous interactions between AB, AC, and BC. The optimum TiO2 loading, adsorbent dosage, solution pH, and temperature were (50% TiO2: 50% chitosan labeled as CCG/TNC-50), 0.09 g/50 mL, 4.0, and 40 °C. The adsorption of MO from aqueous solution by using CCG/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 isotherm model with maximum adsorption capacity of 416.1 mg/g. The adsorption mechanism included electrostatic attractions, n-π stacking interactions, dipole–dipole hydrogen bonding interactions, and Yoshida H-bonding.