scholarly journals Photocatalytic inactivation of Escherichia coli under UV light irradiation using large surface area anatase TiO 2 quantum dots

2019 ◽  
Vol 6 (12) ◽  
pp. 191444
Author(s):  
Faheem Ahmed ◽  
Chawki Awada ◽  
Sajid Ali Ansari ◽  
Abdullah Aljaafari ◽  
Adil Alshoaibi
Keyword(s):  
Escherichia Coli ◽  
Quantum Dots ◽  
Specific Surface ◽  
Band Gap ◽  
Surface Area ◽  
Ultraviolet Light ◽  
Light Irradiation ◽  
Rapid Synthesis ◽  
E Coli ◽  
Photocatalytic Inactivation

In this study, high specific surface areas (SSAs) of anatase titanium dioxide (TiO 2 ) quantum dots (QDs) were successfully synthesized through a novel one-step microwave–hydrothermal method in rapid synthesis time (20 min) without further heat treatment. XRD analysis and HR-TEM images showed that the as-prepared TiO 2 QDs of approximately 2 nm size have high crystallinity with anatase phase. Optical properties showed that the energy band gap ( E g ) of as-prepared TiO 2 QDs was 3.60 eV, which is higher than the standard TiO 2 band gap, which might be due to the quantum size effect. Raman studies showed shifting and broadening of the peaks of TiO 2 QDs due to the reduction of the crystallite size. The obtained Brunauer–Emmett–Teller specific surface area (381 m 2 g −1 ) of TiO 2 QDs is greater than the surface area (181 m 2 g −1 ) of commercial TiO 2 nanoparticles. The photocatalytic activities of TiO 2 QDs were conducted by the inactivation of Escherichia coli under ultraviolet light irradiation and compared with commercially available anatase TiO 2 nanoparticles. The photocatalytic inactivation ability of E. coli was estimated to be 91% at 60 µg ml −1 for TiO 2 QDs, which is superior to the commercial TiO 2 nanoparticles. Hence, the present study provides new insight into the rapid synthesis of TiO 2 QDs without any annealing treatment to increase the absorbance of ultraviolet light for superior photocatalytic inactivation ability of E. coli .

scholarly journals Removal of E. coli from stormwater by bioretention system: parameter optimization and mechanism

2020 ◽  
Vol 81 (6) ◽  
pp. 1170-1179
Author(s):  
Jianwei Liu ◽  
Peng Yue ◽  
Yan He ◽  
Mengfei Zhao
Keyword(s):  
Escherichia Coli ◽  
Specific Surface ◽  
Surface Area ◽  
Parameter Optimization ◽  
System Parameter ◽  
Key Factors ◽  
Factors Affecting ◽  
E Coli ◽  
Bioretention System ◽  
Better Than

Abstract Four bioretention simulation columns were used to study the removal effects and influencing factors of Escherichia coli (E. coli) in stormwater. The mechanism of E. coli removal in the bioretention system was also analyzed. The results show that the removal effects of the four new composite filters are better than that of the conventional filter. The specific surface area and porosity of the filter may be the key factors affecting the removal effect; the increase of the filter depth is beneficial to the removal of E. coli; the area is conducive to the removal of E. coli. Excessive depth of the submerged zone will reduce the E. coli removal effect; drying will reduce the E. coli removal effect, but it can be restored by rewetting.

TiO2 antifouling coating based on epoxy-modified tung oil waterborne resin

2021 ◽  
pp. 096739112110111
Author(s):  
Hailiang Hu ◽  
Minmin Chen ◽  
Mengye Cao
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Antimicrobial Activity ◽  
Survival Rate ◽  
Light Irradiation ◽  
Fouling Resistance ◽  
Tung Oil ◽  
E Coli ◽  
Antifouling Coating ◽  
Waterborne Epoxy

The eco-friendly functionalized TiO2/polymer antifouling (AF) coating was successfully synthesized by dispersing TiO2 nanoparticles in waterborne epoxy-modified tung oil resin. The AF effectiveness of coating was evaluated toward Staphylococcus aureus ( S. aureus, ATCC6538), Escherichia coli ( E. coli, ATCC8739) and diatom ( Cyclotella sp., FACHB-1635). The nanoTiO2/polymer AF coating showed good antimicrobial activity both under the light and dark conditions by comparison with the pristine TiO2 nanoparticles and bulk polymer. Under light irradiation for 50 min, the AF coating showed only 8.4% and 8% survival rate for S. aureus and E. coli. In addition, The AF coatings exhibited favorable inhibition efficacy toward the growth and adhesion of Cyclotella sp., and the efficacy was enhanced with the increase of TiO2 content. It can be concluded that TiO2 nanoparticles endow the AF coatings with promoted fouling resistance properties.

scholarly journals Optimized Synthesis Temperature and Time to Obtain Crystalline Carbon Nitride with Enhanced Photocatalytic Activity for Phenol Degradation

2020 ◽  
Vol 20 (6) ◽  
pp. 1392
Author(s):  
Leny Yuliati ◽  
Mohd Hayrie Mohd Hatta ◽  
Siew Ling Lee ◽  
Hendrik Oktendy Lintang
Keyword(s):  
Photocatalytic Activity ◽  
Specific Surface ◽  
Band Gap ◽  
Surface Area ◽  
Carbon Nitride ◽  
Phenol Degradation ◽  
Synthesis Temperature ◽  
Band Gap Energy ◽  
Synthesis Time ◽  
Gap Energy

In this work, the crystalline carbon nitride photocatalysts were synthesized by an ionothermal technique with varied synthesis temperature of 500, 550, and 600 °C, and synthesis time of 2, 4, and 6 h. Fourier transform infrared spectra showed the successful formation of the prepared carbon nitrides from their characteristic vibration peaks. X-ray diffraction patterns suggested that the same phase of poly(triazine imide) and heptazine could be observed, but with different crystallinity. The optical properties showed that different temperatures and synthesis time resulted in the different band gap energy (2.72–3.02 eV) as well as the specific surface area (24–73 m2 g–1). The transmission electron microscopy image revealed that the crystalline carbon nitride has a near-hexagonal prismatic crystallite size of about 50 nm. Analysis by high-performance liquid chromatography showed that the best photocatalytic activity for phenol degradation under solar light simulator was obtained on the crystalline carbon nitride prepared at the 550 °C for 4 h, which would be due to the high crystallinity, suitable low band gap energy (2.82 eV), and large specific surface area (73 m2 g–1). Controlling both the temperature and synthesis time is shown to be important to obtain the best physicochemical properties leading to high activity.

scholarly journals Utilization of Mn-Doped ZnSe/ZnS Core/Shell Quantum Dots for Rapid Detection of Escherichia coli O157:H7 and Methicillin-Resistant Staphylococcus aureus

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Thi-Diem Bui ◽  
Quang-Liem Nguyen ◽  
Thi-Bich Luong ◽  
Van Thuan Le ◽  
Van-Dat Doan
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Quantum Dots ◽  
Fluorescent Labeling ◽  
Core Shell ◽  
Bacterial Cells ◽  
Bacterial Strains ◽  
Methicillin Resistant ◽  
E Coli ◽  
Mn Doped

In this study, Mn-doped ZnSe/ZnS core/shell quantum dots (CSQDs) were synthesized in aqueous solution using polyethylene glycol as a surface stabilizer and successfully applied in the detection of Escherichia coli O157:H7 and methicillin-resistant Staphylococcus aureus (MRSA) for the first time. The CSQDs were conjugated with anti-E. coli antibody and anti-MRSA antibody via protein A supported by 1-ethyl-3-(-3-dimethylaminopropyl)carbodiimide hydrochloride for fluorescent labeling of the intact bacterial cells. The detection was performed for the bacterial strains cultivated in Luria-Bertani liquid medium. The obtained results indicate that E. coli O157:H7 and MRSA can be detected within 30 min at a high sensitivity of 101 CFU/mL. This labeling method based on the highly fluorescent CSQDs may have great potential for use in the food industry to check and prevent outbreaks of foodborne illness.

scholarly journals Synthesis of Carbon Doped TiO2 Quantum Dots for Photocatalytic Sterilization under the Visible Light Irradiation and the Mechanisms

2019 ◽  
Vol 118 ◽  
pp. 01013 ◽  
Author(s):  
Wei Xiong ◽  
Altair T.F. Cheung ◽  
Michael K.H. Leung
Keyword(s):  
Quantum Dots ◽  
Visible Light ◽  
Visible Light Irradiation ◽  
Superoxide Radical ◽  
Light Irradiation ◽  
Doping Amount ◽  
E Coli ◽  
Carbon Doped ◽  
Chemical States ◽  
Self Protection

In this article, the carbon doped TiO2 (C-TiO2) quantum dots (QDs) were prepared through the hydrothermal method and calcination. The size of the C-TiO2 QDs is about 5.7 nm. The doping amount of carbon can be tuned by adjusting the volumes of the carbon source, ethylene glycol added. The carbon atoms are proved to be doped into the interstitial sites of TiO2 lattice and induce the change of chemical states of Ti 2p and C 1s. The doping of carbon leads to the increasing photocatalytic sterilization of E. coli under the visible light irradiation. The survival rate of E. coli cells over C-TiO2 is only 1.5 % after 6 h. The reactive oxygen species (ROS), such as hydroxyl radical and superoxide radical, are considered as the primary factors for the photocatalytic sterilization. Due to oxidative stress of the attack by ROS, the enzyme activity per cells increases for self-protection during the photocatalytic sterilization.

Effect of Anatase/Rutile Phase Ratio on the Photodegradation of Methylene Blue under UV Irradiation

2020 ◽  
Vol 998 ◽  
pp. 78-83
Author(s):  
Yi Yi Zaw ◽  
Du Ang Dao Channei ◽  
Thotsaphon Threrujirapapong ◽  
Wilawan Khanitchaidecha ◽  
Auppatham Nakaruk
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Activity ◽  
Specific Surface ◽  
Band Gap ◽  
Surface Area ◽  
Calcination Temperature ◽  
Organic Compounds ◽  
Specific Surface Area ◽  
Uv Irradiation ◽  
Rutile Phase

Titanium dioxide (TiO2) is known as one of the widely used catalysts in photocatalysis process. Recently, the photocatalysis of TiO2 has been implied in water purification and treatment, particularly dyes and organic compounds degradations. Naturally, the TiO2 can be found in three phases including anatase, rutile and brookite; each phase has its own specific properties such as grain size, stability and band gap energy. In this work, the effect of calcination temperature on the structure, morphology and photocatalytic activity were investigated. The data suggested that the anatase/rutile ratio of TiO2 can be controlled through the calcination process. The phase transformation data strongly indicated the liner function between percentage of rutile phase and calcination temperature. The BET analysis provided the consistent data with XRD patterns by showing that the specific surface area was decreased by increasing calcination temperature. The photodegradation of methylene blue under UV irradiation proved that the mixed phase of anatase/rutile ratio at 78.5/21.5 provided the highest photocatalytic activity. The phase composition ratio can influence the nanoparticles properties including band gap, specific surface area and energy band structure. Therefore, the control of anatase/rutile ratio was an alternative to enhance the photocatalytic activity of TiO2 nanoparticles for dyes and organic compounds degradations.

scholarly journals A novel quartz-crystal microbalance humidity sensor based on solution-processible indium oxide quantum dots

RSC Advances ◽  
2019 ◽  
Vol 9 (66) ◽  
pp. 38531-38537 ◽  
Author(s):  
Hao Kan ◽  
Min Li ◽  
Hui Li ◽  
Chong Li ◽  
Jian Zhou ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Specific Surface ◽  
Surface Area ◽  
Indium Oxide ◽  
Quartz Crystal Microbalance ◽  
Specific Surface Area ◽  
High Performance ◽  
Humidity Sensor ◽  
Quartz Crystal ◽  
High Specific Surface Area

A high-performance QCM humidity sensor was prepared based on In2O3 QDs with a high specific surface area.

Effect of ozone on prophage induction in different strains of Escherichia coli K-12 lysogenic for lambda

1984 ◽  
Vol 26 (6) ◽  
pp. 706-709 ◽  
Author(s):  
Pierre L'Hérault ◽  
Young Sup Chung
Keyword(s):  
Escherichia Coli ◽  
Ultraviolet Light ◽  
Lytic Cycle ◽  
Prophage Induction ◽  
E Coli ◽  
Different Strains ◽  
K 12 ◽  
Lambda Prophage

Ozone was tested for its effect upon induction of lambda prophage in two different strains of Escherichia coli K-12. Based on the induction index and when compared to ultraviolet light, ozone appeared to be a weak, if any at all, inducer of the lytic cycle in E. coli. This is in agreement with other studies which have suggested that this agent is a weak inducer of the SOS functions.Key words: SOS functions, ultraviolet light, mutagen, ozone.

Rapid Fluorogenic Enumeration of Escherichia coli in Selected, Naturally Contaminated High Moisture Foods

1987 ◽  
Vol 70 (6) ◽  
pp. 991-993
Author(s):  
Paul L Poelma ◽  
Clyde R Wilson ◽  
Wallace H Andrews
Keyword(s):  
Escherichia Coli ◽  
Ultraviolet Light ◽  
Ground Beef ◽  
Most Probable Number ◽  
High Moisture ◽  
Probable Number ◽  
Pork Sausage ◽  
E Coli

Abstract An assay for the enzyme glucuronidase was used to determine the presence of Escherichia coli in selected, naturally contaminated high moisture foods. Raw pork sausage, ground turkey, and ground beef were inoculated into tubes containing the substrate 4-methylumbelliferyl beta-D-glucuronide (MUG) in lauryl tryptose (LT) medium. After incubation at 35°C for 24 h, the inoculated LT-MUG tubes were examined under longwave ultraviolet light for the presence of a fluorogenic glucuronidase end product. A fluorescing tube indicated the presumptive presence of E. coli. The 10 day most probable number method of the AOAC and the LT-MUG procedure gave comparable recoveries of E. coli.

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