Magnetically Recoverable and Reusable Titanium Dioxide Nanocomposite for Water Disinfection

Abstract

A bifunctional magnetic Fe3O4@SiO2@TiO2 or MS-TiO2 antimicrobial nanocomposite was prepared based on simple sol-gel methods with common equipment and chemicals. Reaction pH was found to influence the TiO2 upload in the nanocomposite. The alkaline condition produced the greatest TiO2 upload, while the acidic condition the least. Annealing at 300 °C turned the as-synthesized amorphous TiO2 into one with high content of anatase, the most photoactive form of TiO2. Irradiated by 365 nm UV light, a sample of 30 mg/mL of annealed nanocomposite containing 12.6 wt.% Ti was shown to be able to completely eradicate 104 CFU/mL of the laboratory-grown E. coli within 25 min, 25 min faster than the control when the 365 nm UV light was employed alone. The nanocomposite demonstrated consistent antimicrobial performance over repeated uses and was easily recoverable magnetically due to its high magnetization value (33 emu/g). Additionally, it was shown to reduce the bacterial count in a real surface water sample containing 500–5000 CFU/mL of different microbes by 62 ± 3% within 30 min. The irradiating 365 nm UV light alone was found to have generated little biocidal effect on this surface water sample. The nanocomposite is promising to serve as an effective, safe, and eco-friendly antimicrobial agent, especially for surface water disinfection.

Templated Mesoporous Silica Outer Shell for Controlled Silver Release of a Magnetically Recoverable and Reusable Nanocomposite for Water Disinfection

“…Our early studies show that the thin-silica-coated MNP cores were highly stable upon harsh water and heat treatments, which if not coated would oxidize under these highly oxidative environments and become much less magnetically responsive. 16,46 Silica structure may be weakened upon reacting with the moisture in the air. The synthetic conditions employed here, however, were shown to correspond to a very stable silica structure in water.…”

“…In recent years, advances in nanomaterials have triggered large interest in specifically designed nanocomposite materials for water treatment. The concept of a synergistic combination of two or more nanocomponents into a large one has become a very successful strategy in materials science for achieving highly efficient and specific goals in materials’ property, such as adding new structural and functional properties superior to those of the individual pure components. − …”

Advanced Nanostructured Coatings Based on Doped TiO2 for Various Applications

“…Other composites based on TiO 2 have also been proposed as a solution to easily retrieve the photocatalyst powder from the solution to reuse and recycle. Therefore, Keeley et al [87] reported on a sol-gel Fe 2 O 3 -SiO 2 -TiO 2 composite that led to the complete inactivation of E. coli (initial concentration 10 4 CFU/mL) from distilled water under UV light and within 25 min. The photocatalyst was also successful in the disinfection of a real surface water sample containing 500-5000 CFU/mL of different microbes with a 62 ± 3% bacterial count reduction within 30 min.…”