Facile synthesis of polymer-based magnesium hydroxide nanocomposites for photocatalytic degradation for methylene blue dye and antibacterial application

Photocatalysis has been considered as a potential technology to detoxify and clean up water contaminated with toxic chemicals and harmful microorganisms. Herein, the pure magnesium hydroxide (Mg(OH)(2)) and Mg(OH)(2)-PVP/PVA nanocomposites were synthesized by precipitating the aqueous MgNO3 with NaOH. Poly(vinyl alcohol) (PVA) and poly(vinylpyrrolidone) (PVP) were used as the polymer matrix. Formation of Mg(OH)(2), Mg(OH)(2)-PVP, and Mg(OH)(2)-PVA nanocomposites was confirmed by the presence of X-ray diffraction peaks corresponding to Mg(OH)(2) (38.02 degrees), PVA (21.72 degrees), and PVP (20.15 degrees), and the infrared peaks, OH of Mg(OH)(2) (similar to 3700 cm(-1)), C-N of PVP (1650 cm(-1)), and CH3 -CO of PVA (1098 cm(-1)). The PVP altered the morphology of Mg(OH)(2) from rice-like to circular grains; PVA resulted in flake sheet structure. PVA and PVP lowered the bandgap of Mg(OH)(2) (2.4 eV) by 0.1 eV and 0.34 eV, respectively. Under UV-visible light irradiation, Mg(OH)(2)-PVA exhibited maximum photocatalytic efficiency and degraded 93% aqueous methylene blue (20 ppm, 100 mL) within 2 h, whereas Mg(OH)(2) and Mg(OH)(2)-PVP were degraded 55% and 69%, respectively. Mg(OH)(2)-PVA exhibited stable efficiency for four reuse cycles. The antibacterial activity was assessed using Escherichia coli (E.coli), MTCC 443 strain. Among all, Mg(OH)(2)-PVA (100 mg/mL) exhibited the highest antibacterial activity, the zone of inhibition. Collectively, Mg(OH)(2)-PVA (18 mm) was close to a positive control (20 mm), and the minimum inhibitory concentration was 4 mg/mL. Overall, Mg(OH)(2)-PVA nanoflake was found to be an efficient and reusable UV-visible light photocatalyst for water treatment in terms of removing organic pollutants and microbial disinfection of bacteria.

Automated summary

The nanoflake Mg(OH)(2)-PVA composite demonstrated efficient performance in photocatalytic water treatment, removing organic pollutants and disinfecting bacteria.