Application of response surface methodology for enhanced synthesis of chitosan tripolyphosphate/TiO2 nanocomposite and adsorption of reactive orange 16 dye

In this work, Box-Behnken design (BBD) in response surface methodology (RSM) was applied to optimize the synthesis condition of crosslinked chitosan-tripolyphosphate/TiO2 nanocompsite (CCTPP/TiO2 NC) as well as the adsorption conditions of reactive orange dye (RO16) from aqueous solution. The key input factors in this optimization process were loading of TiO2 nanoparticles into CCTPP 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 degrees C). The analysis of variance (ANOVA) was performed to evaluate the adequacy of the model, and significant factors were successfully indicated (p < 0.05). The experimental results indicate that the highest RO16 removal efficiency of 92.7% was observed by significant interaction effects between AB (p-value = 0.02) and AC (p-value < 0.0001). The optimum TiO2 loading, adsorbent dosage, solution pH, and temperature were (50% TiO2: 50% chitosan labeled as CCTPP/TiO2 NC-50), 0.09 g/50 mL, 4.0, and 40 degrees C. The adsorption of RO16 from aqueous solution by using CCTPP/TiO2 NC-50 in batch mode was evaluated. The adsorption kinetic results were well described by the pseudo-second order kinetic. The adsorption isotherm followed Freundlich model. The adsorption capacity of CCTPP/TiO2 NC-50 for RO16 was 618.7 mg/g. The adsorption mechanism included electrostatic attractions, n-pi stacking interactions, dipole-dipole hydrogen bonding interactions, and Yoshida H-bonding.(C) 2019 Elsevier Ltd. All rights reserved.