Effect of temperature and time on crosslinking of modified Poly(Vinyl Alcohol) materials for Pb(II) removal from aqueous solutions ☆

This study investigates the enhancement of water resistance in Poly(Vinyl Alcohol) (PVA) membranes through cross-linking with L-glutamic acid using a solid-phase esterification process. Additionally, by incorporating Poly(Ethylene Glycol) (PEG), porosity is introduced to the cross-linked membrane, increasing surface area and improving swelling capacity, which enhances its adsorption performance for Pb(II) ions. The cross-linking and porosity effects were confirmed by measuring the membrane’s crosslink density and its swelling behavior in water. The optimal conditions, achieved at 130°C for 60 minutes, resulted in a crosslink density of 92.89%. With PEG addition, water swelling increased to 131.77%, a 51% increase compared to the PVA/L-glutamic acid membrane. The modified PVA-c-glu/PEG membrane demonstrated remarkable Pb(II) ion adsorption, achieving a maximum capacity (Qe) of 66.29 mg/g at 30°C with an initial Pb(II) concentration of 114.08 mg/L at pH=7, using a 0.05 g sample over 2 days. In contrast, untreated PVA showed a much lower Qe of 11.79 mg/g, underscoring the effectiveness of the modification.