Zinc nanoparticles encapsulated in porous biopolymer beads for reduction of water pollutants and antimicrobial activity

This work focuses on the preparation of composite beads from alginate crosslinked with copper at several loading percent and also loaded with ZnNPs. Th obtained samples were applied as catalysts for the reduction of the organic polluants 4-NP, MB, OG, MO, and CR in simple and binary systems. XRD results and TEM images confirmed the presence of ZnNPs in the polymer matrix. XRF and TGA analysis showed that the percentage of the cross-linking agent significantly influences the content of ZnNPs as well as the thermal stability of the resulting material. The catalytic activity of the composite beads showed that the Cu(4 %)-ALG(ZnNPs) sample was the best catalyst for all pollutants. In the simple system, the recorded rate constants for MB, MO, 4-NP, OG, and CR were 0.0133 s- 1, 0.0076 s- 1, 0.005 s- 1, 0.0042 s- 1, 0.0036 s- 1, respectively. The catalyst was more selective towards the cationic MB dye for binary systems. For antibacterial and antifungal applications, the different materials containing ZnNPs and their counterparts containing Zn2+ were found to be active across all bacterial strains (Gram positive and Gram negative) as well as fungi, and the Zn2+-containing composites in particular performed better across all bacteria and fungi.