The Box–Behnken design of the experiment approves that TiO 2–chitosan (1:1), adsorbent content of 2.5 g, temperature = 20 ☌, pH 7.4, solution volume of 100 mL, and contact time = 180 min are the condition that maximizes the COD removal (i.e., 94.5%).
Then, the effect of adsorption parameters, including TiO 2–chitosan mass ratio (1:1, 1:2, and 2:1), adsorbent content (0.25–2.5 g), temperature (20–50 ☌), pH (3–11), solution volume (100–500 mL), and contact time (30–180 min) on the COD reduction has also been monitored both experimentally and numerically. The FESEM, XRD, and FTIR tests have been employed to characterize TiO 2 nanoparticles, chitosan, and fabricated nanocomposites. In the present study, titanium oxide (TiO 2) nanoparticles, chitosan, and several nanocomposites containing different mass dosages of TiO 2 and chitosan have been applied as the adsorbent for COD removal from the industrial wastewater (Bouali Sina Petrochemical Company, Iran).
