Inactivation effect and mechanisms of combined ultraviolet and metal-doped nano-TiO2 on treating Escherichia coli and Enterococci in ballast water

Abstract

The discharge of ship ballast water (containing large amounts of alien organisms) has caused severe ecological hazards to marine environments. In this study, three metal elements (Ag, Fe, and Gd) were doped to nano-TiO 2 material respectively (content: 0.4%, 0.7%, and 1.0%) to improve inactivation effect of Escherichia coli and Enterococci in ballast water. Experimental results indicate that compared with the sole ultraviolet (UV) and the UV and original nano-TiO 2 , the UV and metal-doped nano-TiO 2 increased the bacterial inactivation rate to different extents. For each metal element, high external metal content (1.0%) corresponded to high inactivation effort. The doping of Ag resulted in optimal inactivation effort, and the addition of Fe and Gd caused unobvious effort. At the end of the inactivation process (20 s), the UV and 1% Ag-doped nano-TiO 2 reached the highest logarithmic sterilization rates (0.915 for Escherichia coli and 0.805 for Enterococcus ). The doping of Ag, Fe, and Gd did not change the anatase phase TiO 2 crystal form, and 1% Ag-doped nano-TiO 2 had the smallest particle diameter and the evenest distribution of nanoparticles. Compared with the sole UV, the UV and Ag-doped nano-TiO 2 treatment resulted in higher malondialdehyde contents (0.0646 μmol/L for Escherichia coli and 0.0529 μmol/L for Enterococci ) and lower superoxide dismutase activities (0.672 U/mL for Escherichia coli and 0.792 U/mL for Enterococci ), which were in accordance with high inactivation rates in these cases.

Advances in the application of functional nanomaterial and cold plasma for the fresh‐keeping active packaging of meat

“…Ultraviolet, on the other hand, can stimulate the activity of functional nanomaterials. However, the penetration ability of ultraviolet into packaging material can also affect the efficiency of the process (Wang et al, 2020). Consequently, incorporating plasma technology into functional nanoparticles can synergistically boost the action of nanomaterials, resulting in stronger inhibition of microbes on the surface of packed meat products and extended shelf life.…”

Inactivation of SARS-CoV-2 and Other Human Coronaviruses Aided by Photocatalytic One-Dimensional Titania Nanotube Films as a Self-Disinfecting Surface

“…Interestingly, it has been shown that sole UV radiation (dose <2 J cm –2 ) alone does not lead to complete microbial inactivation. In comparison, T_NPs and UV-based microbial inactivation facilitate reduced UV dose and/or irradiation time, along with increased inactivation efficiency. − …”