Testing methods for antimicrobial activity of TiO2 photocatalyst (original) (raw)
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Songklanakarin Journal of Science and Technology
Titanium dioxide photocatalysts were synthesized by sol-gel process, by varying the reaction conditions, acids, water content, and trivalent (Al, B) dopants. The characterizations of products were determined by XRD, SEM, BET, and UV-vis spectroscopy. The samples were mainly amorphous with a small amount of anatase, rutile, or a mixture of anatase and rutile, with a crystallite sizes of about 5-10 nm. The antibacterial activity of the synthesized TiO2 samples were investigated qualitatively and semi-quantitatively. Five types of bacteria, Escherichia coli ATCC25922, Psudomonas aeruginosa ATCC27853,Bacillus subtilis BGA, Staphylococcus aureus ATCC25923, and methicillin-resistant S. aureus (MRSA) DMST 2054, were used for the inactivation experiment employing the agar dilution method. All the synthesized samples showed inactivation activity with varying degree of efficiency. Two of them showed a much higher activity than Degussa P25.
Developments in photocatalytic antibacterial activity of nano TiO2: A review
Korean Journal of Chemical Engineering, 2016
TiO 2 , which is one of the most explored materials, has emerged as an excellent photocatalyst material for environmental and energy fields, including air and water purification, self-cleaning surfaces, antibacterial and water splitting. This review summarizes recent research developments of TiO 2-based photocatalyst used for photocatalytic antibacterial applications. Several strategies to enhance the efficiency of TiO 2 photocatalyst are discussed, including doping with metal ions, noble metals, non-metals, and coupling with other materials. The mechanism of photocatalytic antibacterial activity in the presence of nano-sized TiO 2 is also discussed. The modified TiO 2 photocatalyst significantly inhibits the growth of bacterial cells in response to visible light illumination. TiO 2 photocatalysis appears to be promising as a route of advanced oxidation process for environmental remediation.
Bactericidal effects of titanium dioxide-based photocatalysts
Chemical Engineering Journal, 2005
The photocatalytic degradation of E. coli in water by various catalysts was investigated in a batch spiral reactor. Commercial Degussa P25 (P25), as well as novel magnetic and hydrothermally prepared photocatalysts (MPC and HPC) were investigated in a slurry system. P25 was found to be the most effective catalyst, followed by the HPC and the MPC. Cell destructions followed first order kinetics. Non-buffered samples displayed a greater bactericidal efficiency which was attributed to a decrease in electrostatic repulsions between TiO 2 and E. coli and also elevated stress on E. coli at acidic pH. Buffered (NaHCO 3 ) samples showed a decrease in bactericidal efficiency due to HCO 3 − ions competing with oxidising species and blocking (by adsorption) the TiO 2 particles. The optimum catalyst loading for P25 and HPC was 1 and 2 g/L for MPC and was attributed to mass transfer effects (bulk diffusion, available active site and shadowing). An immobilised P25 system was found to be more efficient than the MPC and comparable with the HPC in suspension. The addition of silver to the immobilised system was found to enhance the photocatalytic degradation.
A Review on Green Synthesis of TiO2 NPs: Photocatalysis and Antimicrobial Applications
Polymers, 2022
Nanotechnology is a fast-expanding area with a wide range of applications in science, engineering, health, pharmacy, and other fields. Nanoparticles (NPs) are frequently prepared via a variety of physical and chemical processes. Simpler, sustainable, and cost-effective green synthesis technologies have recently been developed. The synthesis of titanium dioxide nanoparticles (TiO2 NPs) in a green/sustainable manner has gotten a lot of interest in the previous quarter. Bioactive components present in organisms such as plants and bacteria facilitate the bio-reduction and capping processes. The biogenic synthesis of TiO2 NPs, as well as the different synthesis methods and mechanistic perspectives, are discussed in this review. A range of natural reducing agents including proteins, enzymes, phytochemicals, and others, are involved in the synthesis of TiO2 NPs. The physics of antibacterial and photocatalysis applications were also thoroughly discussed. Finally, we provide an overview of c...
Proceedings of the 2nd World Congress on Civil, Structural, and Environmental Engineering, 2023
Biological pollution is one major cause of the degradation of indoor air quality. It was shown that microbial communities from outdoor might impact significantly the communities detected indoor. In addition, microbial contamination of the surfaces of building materials and their release into the indoor air also significantly affect indoor air quality. Preventing the growth or at least reducing the amounts of microorganisms growing on indoor building materials is essential for reducing health risks for building occupiers. Photoactive TiO2 has been widely studied as a photocatalyst that enable the inactivation of various bacterial strains. In this paper, we compare the antifungal activity of nanoparticles of TiO2 on Aspergillus niger spores and its antibacterial activity on Escherichia coli under low light irradiation, near to common indoor values. The antimicrobial activity of TiO2, expressed as log reduction, was assessed under UV irradiation in a sludge mixture of sterile water, suspension and nanoparticles of TiO2. The results showed a strong bactericidal activity of TiO2 on E. coli and a weak fungicidal activity against A. niger. Different parameters including concentration of TiO2, intensity of light, and duration of contact between TiO2 and microbial cells and spores, were investigated and significantly affected the antibacterial activity of TiO2 while poorly affected its antifungal activity. Results of this study confirmed previous investigations on antibacterial activity of TiO2 on E. coli and bring new insight on antifungal activity on the spores of A. niger. The effectiveness of the antimicrobial activity is enhanced by the duration of contact between suspension and TiO2 nanoparticles through the stirring experiments for 2H, 4H and 24H.
Coatings, 2014
In damp environments, indoor building materials are among the main proliferation substrates for microorganisms. Photocatalytic coatings, including nanoparticles of TiO 2 , could be a way to prevent microbial proliferation or, at least, to significantly reduce the amount of microorganisms that grow on indoor building materials. Previous works involving TiO 2 have already shown the inactivation of bacteria by the photocatalysis process. This paper studies the inactivation of Escherichia coli bacteria by photocatalysis involving TiO 2 nanoparticles alone or in transparent coatings (varnishes) and investigates different parameters that significantly influence the antibacterial activity. The antibacterial activity of TiO 2 was evaluated through two types of experiments under UV irradiation: (I) in slurry with physiological water (stirred suspension); and (II) in a drop deposited on a glass plate. The results confirmed the difference in antibacterial activity between simple drop-deposited inoculum and inoculum spread under a plastic film, which increased the probability of contact between TiO 2 and bacteria (forced contact). In addition, the major effect of the nature of the suspension on the photocatalytic disinfection ability was highlighted. Experiments were also carried out at the surface of transparent coatings formulated using nanoparticles of TiO 2 . The results showed significant antibacterial activities after 2 h and 4 h and suggested that improving the formulation would increase efficiency.
Chemical engineering transactions, 2020
In this study, the TiO2 nanoparticles were coated on the monolithic surface by a dip-coating technique. Characterization of synthesized samples was determined by X-ray diffraction. Antibacterial application of the samples was investigated under simulated solar irradiation on Escherichia coli (E. coli) bacteria. A 5.7 log CFU mL-1 decrease of E. coli was observed with TiO2 nanoparticles after 3 h irradiation, whereas the number of surviving E. coli cells decreased by 2.7 log CFU mL-1 with monolithic TiO2 at the same irradiating condition. Despite the reduction of photocatalytic antibacterial effect, the results confirmed the photocatalytic antibacterial activity of monolithic TiO2 under simulated sunlight irradiation as well as revealed its potential in practical water treatment applications.
Vojnotehnicki glasnik, 2018
, for her kind help in the preparation of microorganisms and their measurements during the experimental research, as well as for her useful suggestions. Also, the first author is especially grateful to colleague Dr Antonije Onjia, Ph. D. Sci Ch. Eng., Associate Professor at the Faculty of Technology and Metallurgy, University of Belgrade, owner and long lasting director of the Anahem Laboratory d.o.o., for his generous help and the opportunities to support necessary analyses during the first author's scientific research work done in his lab. The photocatalytic and coupled photocatalytic-microbiological experiments were carried out in the Laboratory of the Department for Organic Chemistry at the Faculty of Technology and Metallurgy, University of Belgrade, which the first author used for scientific research work during her PhD study in Inorganic Chemical Technology and Chemical Engineering. The microbiological activity experiments were carried out in the Laboratory of Biochemical Engineering and Biotechnology at the FTM BU. The synthesis and part of characterization of TiO 2 nanoparticles were carried out in the Center for Solid State
Evaluation of bactericidal activity of TiO
2009
Titanium dioxide photocatalysts were synthesized by sol-gel process, by varying the reaction conditions, acids, water content, and trivalent (Al, B) dopants. The characterizations of products were determined by XRD, SEM, BET, and UV-vis spectroscopy. The samples were mainly amorphous with a small amount of anatase, rutile, or a mixture of anatase and rutile, with a crystallite sizes of about 5-10 nm. The antibacterial activity of the synthesized TiO 2 samples were investigated qualitatively and semi-quantitatively. Five types of bacteria, Escherichia coli ATCC25922, Psudomonas aeruginosa ATCC27853, Bacillus subtilis BGA, Staphylococcus aureus ATCC25923, and methicillin-resistant S. aureus (MRSA) DMST 2054, were used for the inactivation experiment employing the agar dilution method. All the synthesized samples showed inactivation activity with varying degree of efficiency. Two of them showed a much higher activity than Degussa P25.
Applied Catalysis B: Environmental, 2013
This study aimed at comparing the photocatalytic efficiencies of various TiO 2 based photocatalysts for phenol degradation and bacteria inactivation under illumination with visible light. Commercial undoped anatase and rutile (both from Aldrich), Aeroxide P25 (Evonik Industries), nitrogen-doped anatase (Sumitomo TP-S201, Sumitomo Chemical Inc.), nitrogen and sulphur co-doped anatase (Kronos VLP7000, Kronos Titan GmbH), and our custom-synthesized nitrogen-and iron-doped TiO 2 , as well as nitrogen and sulphur co-doped Aeroxide P25 and silver-and gold-deposited Aeroxide P25 were studied. The photocatalytic efficiency of different types of titanium dioxide based photocatalysts was determined by inactivation of Escherichia coli K12 bacteria and by phenol decomposition. Electron spin resonance (ESR) in combination with spin trapping was used to get insight into the reactive oxygen species (ROS)-mediated photocatalytic processes in the presence of TiO 2 -based photocatalysts. ESR results confirmed that titanias which generated OH • radicals were efficient in E. coli disinfection, whereas titanias that were unable to produce OH • radicals did not reveal significant bactericidal action. Three of our home-made titanias (iron-, nitrogen-, nitrogen/sulphur) as well as the commercial nitrogen/sulphur codoped Kronos VLP7000 TiO 2 showed higher efficiency of phenol degradation than the well-established reference photocatalyst, Aeroxide P25, but showed much lower (if any) activity for bacteria inactivation, including Kronos VLP7000, which revealed extremely high efficiency for phenol decomposition. Interestingly undoped Aldrich rutile (with large particles -100-700 nm) had the highest efficiency for inactivation of E. coli and also had fairly high activity of phenol degradation. of many model microorganisms were carried out in the presence of TiO 2 -based photocatalysts.