Facile fabrication of PVB-PVA blend polymer nanocomposite for simultaneous removal of heavy metal ions from aqueous solutions: Kinetic, equilibrium, reusability and adsorption mechanism

The available poly (vinyl butyral) (PVB)-based materials are potential media for wastewater treatment, however, their high butyral contents and low quantity of hydroxyl groups cause their low adsorption efficiency for heavy metals removal. Here, a new polymer blend nanocomposite of PVB-poly (vinyl alcohol), (PVB-PVA), incorporated with different contents of stearic acid-grafted epsilon-manganese oxide nanoflowers, (PVB-PVA/SA epsilon-MnO2), was prepared through blending, solution casting and solvent evaporation techniques. According to the results, PVB-PVA/SA-epsilon-MnO2 nanocomposite containing 6 wt% SA-epsilon-MnO2 showed the maximum efficiency of 99.88%, 94.26% and 87.12%, respectively, for the adsorptive removal of Cu2+, Cd2+ and Pb2+ metallic ions from aqueous solutions. The binary and ternary adsorption of the heavy metal ions in aqueous solutions indicated a high adsorption affinity towards Cu2+. Kinetic modeling revealed that the adsorption of Cu2+, Cd2+ and Pb2+ ions follow the diffusion-chemisorption model (R-2 = 0.99, RMSE = 0.31-0.56). The adsorption isotherms modeling confirmed that the Langmuir isotherm well-fitted the adsorption data of the target ions on the nanocomposite surface (R-2 = 0.96-0.99, RMSE = 3.20-9.68), suggesting a homogeneous monolayer surface adsorption with the maximum adsorption capacity of 172.54, 112.89 and 111.23 mg/g for Cu2+, Cd2+ and Pb2+ ions, respectively. The reusability of PVB-PVA/SA-epsilon-MnO2 nanocomposite presented the removal efficiency of 94.50%, 92.05% and 88.60%, respectively, for Cu2+, Cd2+ and Pb2+ ions after five successive sorption/ desorption cycles. The great adsorption performance of PVB-PVA/SA-epsilon-MnO2 towards the heavy metal ions could be attributed to the important role of various types of physicochemical interactions (e.g., electrostatic interactions and surface complexation) in the adsorptive removal process.

Automated summary

The new PVB-PVA/SA-ε-MnO2 nanocomposite demonstrates high adsorption efficiency for Cu2+, Cd2+, and Pb2+ ions in aqueous solutions, with the ability for repeated use, mainly attributed to various physicochemical interactions such as electrostatic interactions and surface complexation.