Antibacterial activity of functionalized natural zeolites (NZ-AgNPs) and its application in bacteriological water treatment and commercial paints

Abstract

Developing advanced materials with efficient antibacterial properties to guarantee human health protection is urgent. This study aimed to evaluate the antibacterial performance of natural zeolite (NZ) functionalized with silver nanoparticles (Ag NPs), obtained from a green reducing method using Moringa oleifera seed extract (NZ-AgNPs), against a Gram-negative bacteria, namely Escherichia coli (E. coli). Moreover, two applications were tested: bacteria adsorption for water treatment, namely Escherichia coli, and its incorporation in commercial paints. The proposed modifications were confirmed by advanced characterization techniques (TEM, SEM, EDX, FTIR, XRD, and ZP). The antibacterial activity assay was conducted using minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The results demonstrated the advantages of using an inorganic support for carrying biocidal agents. The required amount of Ag NPs, when it was supported onto NZ (NZ-AgNPs), was four times less to exhibit the bactericidal effect against Escherichia coli than Ag NPs on their own since they had the same MBC value (1.56 mg ml⁻¹). The observed adsorption behavior corroborates such findings and demonstrates that 0.01 g of the proposed composite achieved 100 % of E. coli removal and 9.85 log reduction. Regarding commercial paint experiments, the NZ-AgNPs successfully demonstrated the potential to inhibit bacterial growth with an inhibition zone (IZ) of 41 mm. Using inorganic carriers, as NZ, for controlling the biocidal compound release can bring economic and environmental advantages because zeolite is a natural material and the saved amount of biocidal agent, namely Ag NPs, are desirable features of a new antibacterial additive’s generation.