pH-dependent framework of chitosan loaded with nanoparticles copper/magnesium oxides for statistically optimized neutral red dye and acid red 88 dye removal
摘要
Herein, chitosan biopolymer (CHT) was loaded with copper oxide (CuO) and magnesium oxide (MgO) nanoparticles to fabricate a pH-dependent CHT/CuO/MgO nanocomposite adsorbent for removal of anionic dye namely acid red 88 (AR88) and cationic dye namely neutral red dye (NR) from contaminated wastewater. The surface area and pore diameter of CHT/CuO/MgO were found to be 0.195 m2/g and 8.10 nm respectively. The experimental adsorption conditions, including removal time (20–300 min) for AR88 and (2–30 min) for NR, CHT/CuO/MgO nanocomposite dose (0.02–0.06 g per 100 mL), and solution pH (4–10) were statistically optimized and validated by using Box-Behnken design (BBD) and desirability function approach respectively. The desirability function approach results show high dependency and selectivity of dye removal on dye solution pH. For example, the best AR88 dye removal (88.6%) was observed at acidic dye solution pH = 5.7 by using 0.06 g per 100 mL of CHT/CuO/MgO nanocomposite dose at 265 min of contact time. On the other hand, the best NR dye removal (98.4%) was observed at basic dye solution pH = 8.1 by using 0.05 g per 100 mL of CHT/CuO/MgO nanocomposite dose at 29 min of contact time. The adsorption isotherm study indicates Langmuir isotherm model is the best model to explain the adsorption of AR88 dye and NR dye onto the surface of CHT/CuO/MgO nanocomposite with maximum adsorption capacities of 106.8 mg/g and 83.5 mg/g at 25 °C, respectively. Thus, CHT/CuO/MgO nanocomposite presents itself as a smart and pH-dependent zwitterion adsorbent for the removal of cationic and cationic dyes from contaminated water.