C-TiO2+Ni and ZnO+Ni Magnetic Photocatalyst Powder Synthesis by Reactive Magnetron Sputtering Technique and Their Application for Bacteria Inactivation (original) (raw)
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Magnetic Ni-Doped TiO2 Photocatalysts for Disinfection of Escherichia coli Bacteria
Journal of Electronic Materials, 2021
Ni-doped TiO 2 nanoparticles have been synthesized by a modified sol-gel method. The crystal phase composition, particle size, and magnetic and optical properties of the samples were comprehensively examined using x-ray diffraction analysis, transmission electron microscopy, Brunauer-Emmett-Teller surface area analysis, Raman spectroscopy, magnetization measurements, and ultraviolet-visible (UV-Vis) absorption techniques. The results showed that the prepared Ni-doped TiO 2 samples sintered at 400°C crystallized completely in anatase phase with average particle size in the range from 8 nm to 10 nm and presented broad visible absorption. The bactericidal efficiency of TiO 2 was effectively enhanced by Ni doping, with an optimum Ni doping concentration of 6% (x = 0.06), at which 95% of Escherichia coli were killed after just 90 min of irradiation. Density functional theory (DFT) calculations revealed good agreement with the experimental data. Moreover, the Ni dopant induced magnetic properties in TiO 2 , facilitating its retrieval using a magnetic field after use, which is an important feature for photocatalytic applications.
NiO/TiO2 Nanoparticles for Photocatalytic Disinfection of Bacteria under Visible Light
Journal of the …, 2011
NiO-TiO 2 composite nanoparticles have been prepared by a modified ammonia-evaporation-induced synthetic method, sintered at 4501C and characterized by powder X-ray diffraction, energy-dispersive X-ray spectroscopy, scanning electron microscopy, UV-visible diffuse reflectance spectroscopy, photoluminescence spectroscopy, and electrochemical impedance spectroscopy. Doping shifts the optical absorption edge to the visible region but increases the charge-transfer resistance and decreases the capacitance. Under visible light, the composite nanoparticles effectively catalyze the Escherichia coli inactivation. The prepared oxide is selective in photocatalysis; with UV light, its photocatalytic activity to degrade sunset yellow, rhodamine B, and methylene blue dyes is less than that of the undoped one. However, it degrades phenol faster than TiO 2 P25.
Current Applied Physics, 2013
Photocatalytic inactivation of six different species of bacteria using fluorescent light and TiO 2 was conducted. Up to five surface loadings of TiO 2 varying from 234-8662 mg/m 2 , impregnated on membrane filters were used with fluorescent light of constant illuminance of 3900 Lux for the inactivation of four ATCC bacteria (E. coli K-12, Pseudomonas fluorescens, Bacillus subtilis and Microbacterium sp.) and two other species of bacteria (Microbacteriaceae str. W7 and Paenibacillus sp. SAFN-007) collected from outdoor air in Singapore. A Gram-negative bacterium E. coli K-12 was the most effectively inactivated, while Gram-positive Bacillus subtilis exhibited the least response to the photocatalytic treatment. The inactivation rate increased with an increase in the TiO 2 loading, the maximum inactivation of most bacteria was achieved at an optimum TiO 2 loading of 1116-1666 mg/m 2. 100% of the E. coli K-12 was inactivated after 30 minutes of treatment at a TiO 2 loading of 1666 mg/m 2 , while inactivation of one log 10 was obtained for Microbacterium sp., Paenibacillus sp. SAFN-007 and Microbacteriaceae str. W7 after two hours. Preliminary experiments indicate that the photocatalytic inactivation using Degussa P25 is 1.83-5.41 times higher than that of Hombikat UV-100.
2022
Visible light driven photocatalytically active mesoporous nanomaterials plays an indispensable role for antibacterial activity in low light applications. In this work, nanomaterials were handily prepared by varying the dopant concentrations from 0.25 to 1.0 Wt % using sol-gel method. All the prepared samples were characterized by Powdered X-ray diffraction (XRD), Scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), Ultraviolet-visible diffuse reflectance spectroscopy (UV/Vis-DRS), Transmission electron microscopy (TEM) and Brauner-Emmett-Teller (BET). The characterization results revealed that a photocatalytically active phase i.e.; anatase and rutile mixed phase was observed for co-doped catalyst samples. Due to substitutional doping of Mn and Ni by replacing Ti, the frequency shift of Ti-O-Ti in the catalyst samples was observed by FTIR. Further the catalyst shows roughmorphology, irregular particle shape with less particle size having high surface area, and reduced band gap energy. The photocatalytically active materials antibacterial activity was discerned by using Sphingomonas paucimobilis and Pseudomonas fluorescence. The result of antibacterial activity shows that among all nanocatalysts, NMT2 catalyst shows optimum zone of inhibition at 25.1 ± 0.2 mm for Sphingomonas paucimobilis and 18.1 ± 0.2 mm for Pseudomonas fluorescence compared to standard (chloramphenicol) value at 24.1 ± 0.1 mm and 23.1 ± 0.05 mm at 100 µg/mL respectively. KEYWORDS nanomaterials, photocatalysis, Ni/Mn-TiO 2 , antibacterial activity, agar-well diffusion method FOR CITATION Miditana S.R., Tirukkovalluri S.R., Raju I.M. Synthesis and antibacterial activity of transition metal (Ni/Mn) co-doped TiO 2 nanophotocatalyst on different pathogens under visible light irradiation. Nanosystems:
Zn and N Codoped TiO2 Thin Films: Photocatalytic and Bactericidal Activity
ACS Applied Materials & Interfaces, 2021
In this article, we explore a series of Zn and N co-doped TiO2 thin films grown using chemical vapour deposition. Films were prepared with various concentrations of Zn (0.4-2.9 at.% Zn vs Ti), and their impact on superoxide formation, photocatalytic activity and bactericidal properties were determined. Superoxide (O2 •-) formation was assessed using a 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium sodium salt (XTT) as an indicator, photocatalytic activity was determined from the degradation of stearic acid under UVA light and bactericidal activity was assessed using a Gram-negative bacterium E. coli under both UVA and fluorescent light (similar to what is found in a clinical environment). Compared with undoped TiO2, the 1.0% Zn, N : TiO2 thin film demonstrated a higher formal quantum efficiency in degrading stearic acid (2.5 × 10-5 vs 1.5x 10-5 molecules.photon-1) and a higher bactericidal activity (> 3 log kill under UVA and fluorescent light conditions vs < 0.5 log kill under UVA and fluorescent light conditions). The enhanced efficiency of the films was correlated with increased charge carrier lifetime, supported by transient absorption spectroscopy (TAS) measurements.
Photocatalytic TiO2-Based Nanostructured Materials for Microbial Inactivation
Catalysts, 2020
Pathogenic microorganisms can spread throughout the world population, as the current COVID-19 pandemic has dramatically demonstrated. In this scenario, a protection against pathogens and other microorganisms can come from the use of photoactive materials as antimicrobial agents able to hinder, or at least limit, their spreading by means of photocatalytically assisted processes activated by light—possibly sunlight—promoting the formation of reactive oxygen species (ROS) that can kill microorganisms in different matrices such as water or different surfaces without affecting human health. In this review, we focus the attention on TiO2 nanoparticle-based antimicrobial materials, intending to provide an overview of the most promising synthetic techniques, toward possible large-scale production, critically review the capability of such materials to promote pathogen (i.e., bacteria, virus, and fungi) inactivation, and, finally, take a look at selected technological applications.
Photocatalytic Activity and Antibacterial Behavior of Fe3+-Doped TiO2/SnO2 Nanoparticles
Energy Research Journal, 2010
Problem statement: Since bacteria mainly causes damage on fresh vegetables and fruits during transportation to market, anti-bacterial TiO 2 photocatalyst was applied for their packaging films. However, it has been known that pure TiO 2 exhibits low photocatalytic property due to rapid recombination of photo-activated electrons and holes. Doping with metal or metal oxide shows the improvement of photocatalytic activity and disinfection effect. Approach: Fe 3+ was considered to dope into TiO 2 /3SnO 2 photocatalyst in order to enhance the photocatalytic property and bacterial inactivation efficiency. The Fe 3+ doped TiO 2 /3SnO 2 nanoparticles were prepared by sol-gel method and calcined at 400 °C for 2 h. The synthesized powders were characterized by XRD, BET and SEM. Photocatalytic activity and bacteria killing effect were determined by means of degradation of methylene blue solution and inactivation of E. coli bacteria, respectively. These tests were performed under UV and visible light irradiations. Results: Fe 3+ doping into TiO 2 /3SnO 2 has an effect on inhibition of anatase crystal growth, led to the enlargement of the composite specific surface area. Therefore, the photocatalytic activity of Fe 3+ doped TiO 2 /3SnO 2 composite in proper concentration was greater than those of pure TiO 2 and TiO 2 /3SnO 2 and 0.5 mol% Fe 3+ doping exhibited the highest photocatalytic activity and E.coli inactivation efficiency. The E. coli was completely killed within 90 min under UV irradiation or 99.7% inactivated under visible light exposure. Conclusion: Fe 3+ doped TiO 2 /3SnO 2 nanoparticles were successfully synthesized and identified as 100% anatase phase. The 0.5mol% Fe 3+ -doped TiO 2 /3SnO 2 which has particle size of 12.89 µm and specific surface area of 117.61 m 2 g −1 , exhibited the highest activity and disinfection efficiency. An attractive feature of Fe 3+ doped TiO 2 /3SnO 2 photocatalytic disinfection is its potential to be activated by visible light. Therefore, these composite TiO 2 nanoparticles can be utilized for fresh food packaging films.
Photocatalytic inactivation of microorganisms using nanotubular TiO2
Applied Catalysis B: Environmental, 2011
Photocatalysis is a well known process for deactivation contaminations in aqueous solutions. However, enhancing the photocatalytic process efficiency remains a challenge and a subject of extensive research. In this paper, nanotubular TiO 2 oxide layer with high surface area was grown and was used as a photocatalyst, inactivating Escherichia coli bacteria and other microorganisms, as well. The photocatalytic process was studied and optimized, subsequent to filtration of the nutrient broth, using saline solution. The double layer capacitance in the interface between the oxide and the solution was measured with the use of electrochemical impedance spectroscopy method and the isoelectric point was found to be at a pH value of 6.8. This result was correlated to the photocatalytic bacteria's inactivation rate in different pH solution. One of the advantages of using immobilized TiO 2 over a powdery photocatalyst is its ability to be recycled and reused. This was well studied with photocatalytic inactivation cycles of the E. coli bacteria along with MeO degradation. It was found that while no concern of reusing the TiO 2 during MeO degradation do exist, the need for a regeneration treatment after several cycles of inactivation E. coli bacteria emerges. Finally, E. coli bacteria were deactivated under a direct sunlight irradiation. This process is proven to be an efficient method for a future commercial photocatalytic cell fabrication.
Environmental and Climate Technologies
Water contamination by various bacteria, viruses and other pathogens is a great threat to human health. Amongst other Advanced Oxidation Processes TiO2 photocatalysis is considered as one of the most efficient treatment for the polluted wastewater disinfection. Usually, the wastewater produced by higher risk objects, such as hospitals, implicates diverse contaminants, but efficiency of most of the Advanced Oxidation Processes is tested by using only single pathogens and information on inactivation of bacteria mixtures is still limited. In this study, photocatalytical inactivation of three commonly found bacterial pathogens (gram-positive (Micrococcus luteus) and gram-negative (Salmonella enterica, Escherichia coli)) was investigated. Efficiency of traditional photocatalytic disinfection process using single bacterial pathogens was compared to the one observed for their mixtures. The impact of photocatalytical process parameters and treatment time on bacteria disinfection efficiency ...