Adsorption of Methyl Orange from Aqueous Solution Using PVOH Composite Films Cross-Linked by Glutaraldehyde and Reinforced with Modified α-MnO2.

A poly(vinyl alcohol) (PVOH) composite cross-linked with glutaraldehyde (GL) containing α-MnO2 modified with stearic acid (ST) was fabricated as an efficient sorbent for capturing methyl orange (MO) dye from the water system. We investigated the factors affecting MO adsorption in detail. The adsorption process showed a high dependence on the pH value. The highest removal efficiency (96.5%) was obtained at pH 2. The adsorption isotherm study indicated that the linear Freundlich isotherm was a more appropriate model for the adsorption process. The adsorption kinetics study revealed that the adsorption data matched with a nonlinear pseudo-first-order model. Physical adsorption interactions, including electrostatic interactions, hydrogen bonds, and dipole-dipole forces, play dominant roles in this process. Thermodynamic investigations confirmed that MO adsorption was spontaneous and exothermic with physical interactions. The outcomes demonstrated that the cross-linked PVOH-GL/α-MnO2-ST composite could be a hopeful sorbent for the efficient uptake of MO molecules from polluted waters.