Synthesis of Chitosan/Maleate-Alumoxane nanocomposite membranes for adsorption of anionic dye

Chitosan/Mal-A nanocomposite membranes were synthesized and used for adsorption of Reactive Yellow 84 (RY 84) from aqueous solution. The membranes were prepared by solution-casting method with 2 wt% Chitosan (Cs) and various ratios of Mal-A (0.3-0.9 wt%). FTIR and SEM analyses were used to characterize the Cs-based membrane. The results showed that a dense-thin-face layer associated with an open-structure layer was formed in the composite membrane containing 0.5 wt% Mal-A. Membrane performance was investigated as dye removal and permeate flux. The significant effects of the operating variables including pH, initial concentration of dye, and Cs/Mal-A dose, were evaluated on RY removal efficiency using response surface methodology (RSM). The results obtained from the experimental data were presented with the quadratic regression model. The adsorption kinetics and equilibrium isotherm were well described by the pseudo-second order and the Langmuir model, respectively. Adding Mal-A nanoparticles to the Cs matrix (0.5wt%) improved liquid permeability by 21% compared with the Cs membrane, while dye removal efficiency for both membranes remained approximately 100% at acidic pH and under a trans-membrane pressure of 3 bar. The protonation of the amine groups in CS/Mal-A results in a positive charge on the membrane surface which causes a complete removal of the anionic dye. The permeability improvement of similar to 57.2% for the composite membrane was achieved at a pressure difference of 5 bar, which corresponded to an efficiency reduction of 10%.