Comparison study of Ag(I) and Au(III) loaded on magnetic thiourea-formaldehyde as disinfectants for water pathogenic microorganism’s deactivation

Abstract

Magnetic disinfectants were achieved through the polymerization of thiourea and formaldahyde in the presence of magnetite nano particles (MTUF), the as-prepared MTUF was loaded with Ag(I) or Au(III). The obtained disinfectants (MTUF-Ag and MTUF-Au) were test for some selected pathogenic strains deactivation. The toxicity of MTUF before and after Ag(I) or Au(II) loading was estimated. The antimicrobial activity tests of MTUF-Ag and MTUF-Au were carried out against Escherichia coli, Salmonella typhimurium and Pseudomonas aeruginosa as examples of Gram negative bacteria; Listeria monocytogenes, Staphylococcus aureus, Enterococcus faecalis, and Bacillus subtilis as examples of Gram positive bacteria; Candida albicans as representative for fungi. The results showed that the minimum inhibitory concentration (MIC) of MTF-Ag against Escherichia coli, Salmonella typhimurium, Listeria monocytogenes, Staphylococcus aureus and Candida albicans were 1.5, 2.0, 1.5, 1.0 and 2.5 mg mL−1, respectively after 40 min of contact time. While MTUF-Au showed higher MIC concentrations: 6.0, 4.0, 4.0, 4.0 and 6 mg mL−1 for the mentioned strains, respectively. The studied MTUF-Ag and MTUF-Au were successfully tested for deactivation of the studied pathogenic microorganism’s water and wastewater samples. It can be concluded that, MTUF-Ag and MTUF-Au are good candidates for water disinfection.