- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Effect of UV wavelength on humic acid degradation and disinfection by-product formation during the UV/chlorine process
摘要： The efficiency of the ultraviolet (UV)/chlorine process strongly depends on UV wavelength because chlorine photolysis and its subsequent radical formation are highly wavelength-dependent. This study compared the degradation of humic acid (HA) during the UV/chlorine process by low pressure mercury lamp (LPUV, 254 nm) and ultraviolet light-emitting diode (UV-LED, 275 and 310 nm). The results indicated that HA degradation followed the pseudo-first-order kinetics, and the fluence-based degradation rate constants (kobs) were significantly affected by UV wavelength and solution pH. HA degradation decreased greatly with increasing solution pH during the UV/chlorine process at 254 nm, while the opposite trend was observed at 275 and 310 nm. In the meantime, kobs decreased in the order of 275 nm > 254 nm > 310 nm at pH > 7.0. The changes of chlorine molar absorption coefficients at different UV wavelengths resulted in the variation of chlorine photodecay rates (kobs, chlorine), and the synergistic effects of kobs, chlorine and chlorine quantum yields (Φchlorine) affected HA reduction. The formation of disinfection by-products (DBPs) during the UV/chlorine process was also evaluated. A significant suppression on DBP formation and DBP-associated calculated theoretical cytotoxicity were observed at 275 nm high UV fluence and alkaline pHs. These findings in this study demonstrate that UV wavelength at 275 nm is more suitable for HA degradation by the UV/chlorine advanced oxidation process in practical applications.
关键词： Disinfection by-products,Ultraviolet light-emitting diode (UV-LED),UV/chlorine,Humic acid,Toxicity,UV wavelength
更新于2025-11-19 16:46:39
-
Construction of flower-like MoS2/Ag2S/Ag Z-scheme photocatalysts with enhanced visible-light photocatalytic activity for water purification
摘要： Flower-like MoS2/Ag2S/Ag nanocomposites have been elaborately designed and synthesized successfully for the first time. The prepared MoS2/Ag2S/Ag nanocomposites as a novel photocatalysts present effective photocatalytic performance for the photodegradation of congo red (CR), tetracycline hydrochloride (TC-HCl) and disinfection for Pseudomonas aeruginosa (P. aeruginosa). For the photodegradation of TC-HCl, the effect of the pH of the initial solution and photocatalysts dosage was investigated. Furthermore, intermediates of TC-HCl degradation were verified by GC–MS analysis and the possible pathway of the photodegradation was also proposed. The electron paramagnetic resonance (EPR) technique and trapping experiments verified the electron transport path is Z-scheme system (PS-C-PS). Among them, Ag as an electron mediator enhanced the electron transmission rate and accelerated the separation efficiency of photogenerated carriers.
关键词： MoS2/Ag2S/Ag,Photocatalytic,Tetracycline hydrochloride,Water disinfection,Z-scheme
更新于2025-09-23 15:23:52
-
Fabrication of electrochemically nonporous NiO–ZnO/TiO2 nanotubes/Ti plates for photocatalytic disinfection of microbiological pollutants
摘要： Nonporous NiO–ZnO/TiO2 nanotubes/Ti photocatalyst plates were fabricated via facile electrochemical method. The structural and morphological properties of the modified plates were investigated by scanning electron microscopy and X-ray diffraction, while their photoelectrochemical (PEC) characterizations were evaluated by transient photocurrent responses and electrochemical impedance spectroscopy. Antimicrobial activities of the fabricated plates against Escherichia coli bacteria and Candida albicans fungi were studied under UV light irradiation. The results indicated that the photocatalytic and PEC activities of the NiO–ZnO/TiO2 nanotubes/Ti plates are much higher than those of TiO2 nanotubes/Ti, ZnO/TiO2 nanotubes/Ti and NiO/TiO2 nanotubes/Ti. The synergetic effect among NiO, ZnO and TiO2 nanotubes motivated a fast charge separation as well as a slow electron/hole recombination, thus increasing the photocatalytic performance of the nonporous NiO–ZnO/TiO2 nanotubes/Ti photocatalyst plate.
关键词： Microbiological pollutants,Heterogeneous catalysis,Photocatalytic disinfection,NiO–ZnO hybrids
更新于2025-09-23 15:23:52
-
Inactivation efficiency of Bacillus endospores via modified flow-through PUV treatment with comparison to conventional LPUV treatment
摘要： Water is a fragile resource, consequently there is a pressing need to develop sustainable environmental-friendly disinfection technologies. This constitutes the first study to compare efficacy of continuous low-pressure UV (LPUV) to that of pulsed UV light (PUV) for UV disinfection performance in flow-through water systems. Bacillus endospores were used as these are frequently deployed as biodosimeters for drinking water UV reactor validation protocols. Results showed a PUV system output of 2,052 mJ/cm2 (energy below 300 nm) was required for a 2 log inactivation of B.pumilus endospores, whereas a lower LPUV system output of 12 mJ/cm2 produced a similar level of disinfection. Measurements of dose incident to the samples (which were 10.75 cm from the PUV light source) showed supplementation of cultivation media with manganese sulphate monohydrate (MnSO4.H2O) employed to enhance the rate of endospore formation for propagation was shown to increase the UV resistance of different Bacillus spp. to both irradiation approaches (P < 0.05). Conventional LPUV light that is commonly-used by the drinking water industry is a reliable and superior approach to PUV which requires substantial modification for effective disinfection of continuous flow-through water. Caution must also be exercised when manipulating media formulation to propagate endospores as this may lead to inconsistencies in reporting efficacy of intervention treatments with implications for validation and environmental evaluation.
关键词： Bacillus endospores,Pulsed UV,Low-pressure UV,Disinfection,Media formulation
更新于2025-09-23 15:23:52
-
405 nm and 450 nm photoinactivation of <i>Saccharomyces cerevisiae</i>
摘要： Photoinactivation of bacteria with visible light has been reported in numerous studies. Radiation around 405 nm is absorbed by endogenous porphyrins and generates reactive oxygen species that destroy bacteria from within. Blue light in the spectral range of 450–470 nm also exhibits an antibacterial effect, but it is weaker than 405 nm radiation, and the photosensitizers involved have not been clarified yet, even though flavins and porphyrins are possible candidates. There are significantly fewer photoinactivation studies on fungi. To test if visible light can inactivate fungi and to elucidate the mechanisms involved, the model organism Saccharomyces cerevisiae (DSM no. 70449) was irradiated with violet (405 nm) and blue (450 nm) light. The mean irradiation doses required for a one log reduction of colony forming units for this strain were 182 J/cm2 and 526 J/cm2 for 405 nm and 450 nm irradiation, respectively. To investigate the cell damaging mechanisms, trypan blue staining was performed. However, even strongly irradiated cultures hardly showed any stained S. cerevisiae cells, indicating an intact cell membrane and thus arguing against the previously suspected mechanism of cell membrane damage during photoinactivation with visible light at least for the investigated strain. The results are compatible with photoinactivated Saccharomyces cerevisiae cells being in a viable but nonculturable state. To identify potential fungal photosensitizers, the absorption and fluorescence of Saccharomyces cerevisiae cell lysates were determined. The spectral absorption and fluorescence results are in favor of protoporphyrin IX as the most important photosensitizer at 405 nm radiation. For 450 nm irradiation, riboflavin and other flavins may be the main photosensitizer candidates, since porphyrins do not play a prominent role at this wavelength. No evidence of the involvement of other photosensitizers was found in the spectral data of this strain.
关键词： photoinactivation,porphyrin,450 nm irradiation,flavin,Saccharomyces cerevisiae,disinfection,405 nm irradiation
更新于2025-09-23 15:23:52
-
Effects of chlorination, ultraviolet and ozone disinfection on the biotoxicity of triclosan
摘要： The contamination of triclosan, which is a widely used antimicrobial agent, is of emerging concern for its potential toxicity to aquatic organisms and human beings. Chlorination, UV254 irradiation and ozonation are the main disinfection methods used in water treatment processes. Though studies have shown that triclosan could react with free chlorine and ozone, and undergo photolysis under UV irradiation, few of them focused on the effects of disinfection processes on the biotoxicity of triclosan. In the present study, the potential risk of triclosan in water before and after lab-scale disinfection processes, including chlorination, UV254 irradiation and ozonation, was evaluated by bioassay. The results showed that both acute toxicity and genetic toxicity of triclosan was increased by chlorination and UV254 disinfection but decreased by ozone disinfection. In other words, ozonation would be a preferential disinfection method for triclosan-containing surface waters. This finding will help us to choose an appropriate disinfection method for water treatment. Furthermore, it is proved that bioassay could be a feasible way for risk evaluation when concentrations of antibiotics in surface waters or drinking waters are very low.
关键词： bioassay,triclosan,disinfection
更新于2025-09-23 15:23:52
-
Effect of photochemical advanced oxidation processes on the formation potential of emerging disinfection by-products in groundwater from part of the Pannonian Basin
摘要： This study evaluates the effect of photochemical advanced oxidation processes (AOPs) (O3/UV, H2O2/UV and O3/H2O2/UV) on the formation potential (FP) of emerging disinfection by-products including nitrogenous by-products (N-DBPs) and haloketones (HKs) in groundwater from part of the Pannonian Basin (AP Vojvodina, Republic of Serbia). Among the N-DBPs, the haloacetonitrile (HAN) precursor contents were 9.83 ± 0.59 μg/L while precursors of halonitromethanes, particularly trichloronitromethane (TCNM) were not detected. Similarly, precursors of HKs as carbonaceous DBPs were also not detected in raw water. Ozonation alone and H2O2/UV process with a lower UV dose maximally decomposed HAN precursors (about 70%) while during O3 based AOPs, HANFP varied significantly. Application of UV photolysis and H2O2/UV processes with increasing UV dose doubled the HANFP. Ozone alone, O3/UV and H2O2/UV slightly increased HKs formation potential, particularly 1,1-Dichloro-2-propanone FP (0.93 ± 0.21 to 2.01 ± 0.37 μg/L). None of the investigated treatments influenced the formation of TCNM precursors. The effect of the applied treatments on bromide incorporation was the most evident for HANs.
关键词： emerging disinfection by-products,ozone,bromide incorporation,photochemical advanced oxidation processes
更新于2025-09-23 15:23:52
-
Experimental Research on Sensing Characteristics of Adhesive-encapsulated FBG under Alcohol-disinfection Environment
摘要： Fiber Bragg grating (FBG) has proven to be the most suitable sensing element for force feedback of surgical robots because of its special advantages such as small size and physical robustness. In current reports, researchers packaged FBGs in surgical instrument by attaching them to external surface or embedding into shaft grooves by using adhesive because its good liquidity and operability compared with other packaging methods such as metal package and glass solder package, and the adhesive is often without covering because strict space requirement of tiny surgical instruments. However, due to the need of repeated disinfection, surgical instruments have to be exposed to chemical disinfectant excessively, which may leads to chronic corrosion of adhesive, and thus influences the sensing characteristics of the integrated FBGs. To address this concern, this paper investigates the sensing characteristics of adhesive-encapsulated FBG under disinfection environment. We simulated a common disinfection environment by using 75% alcohol, and three adhesive-encapsulated FBGs were soaked in it for long term. The sensing performances of FBGs have been tested periodically and the experimental results demonstrate that the FBGs are available with good sensing characteristics within the first 50 days. While after 50 days, the sensing performances of the three FBGs become worse gradually, and finally the adhesive layers of the three FBGs completely detached from the specimen in the 75th day, 80th day and 95th day, respectively. We hope the investigation could provide valuable reference for better application of FBG in force feedback of surgical robots.
关键词： Fiber Bragg grating (FBG),robot sensing,force feedback,alcohol-disinfection environment,surgical robot
更新于2025-09-23 15:22:29
-
In-situ ion exchange synthesis of Ag2S/AgVO3 graphene aerogels for enhancing photocatalytic antifouling efficiency
摘要： Efficient charge separation and cycle stability are critical for water purification by semiconductor photocatalyst. Herein, novel Ag2S/AgVO3 graphene aerogels (Ag2S/AgVO3@GAs) were synthesized via an in-situ ion exchange method. The series of characterization results verified that the Ag2S/AgVO3@GAs synergistically integrate the excellent properties of the Ag2S and AgVO3 into the macroscopic porous graphene aerogel. Furthermore, owing to the chelation of chitosan (CS) for AgVO3 and the ion exchange between well-dispersed AgVO3 and Na2S, the Ag2S can in situ grow on AgVO3, which prevents Ag2S and AgVO3 agglomeration/shedding in the photocatalytic reaction and contributes to the enhanced photocatalytic activity and cyclic stability. Benefiting from the unique structure, the Ag2S/AgVO3@GAs with excellent stability displayed the outstanding photodegradation efficiency for methyl orange (97% removal rate in 40 min) and disinfection activity for Escherichia coli (100% antibacterial efficiency in 36 min).
关键词： Photodegradation,Disinfection,Charge transfer,Three-dimensional graphene aerogel,Heterojunction
更新于2025-09-23 15:22:29
-
Two-dimensional g-C3N4/TiO2 Nanocomposites as Vertical Z-scheme Heterojunction for Improved Photocatalytic Water Disinfection
摘要： Developing highly active photocatalysts towards effective microorganism inactivation is a green and energy-smart strategy in response to the growing demands to water quality under the background of the water crisis. Here, a vertical face-to-face heterojunction was fabricated by horizontally assembling TiO2 nanosheets with {001} facets exposed on graphitic carbon nitride (g-C3N4) sheets through a facile hydrothermal driving coupling. The vertical heterojunction could almost completely disinfect 103 CFU/mL E. coli within 30 min under solar light, which was more efficient than the physically mixed composite and pure g-C3N4 and TiO2. The two-dimensional (2D) morphology provides ample surface area in forming the vertical heterojunction and enables intimate contact which is advantageous to charge transfer between g-C3N4 and TiO2. A Z-scheme charge transportation mechanism is confirmed through band structure analysis and reactive species (RSs) probing and trapping experiments. In comparison with physically mixed composite and the single-phase counterparts, the nanocomposite based on Z-scheme electron transfer mode effectively prompts charge pair dissociation and subsequently encourages bacterial inactivation by boosting the generation of RSs. The constructing vertical Z-scheme heterojunction highlights the potential of 2D nanomaterials for accelerated water sterilization.
关键词： photocatalysis,Z-scheme heterojunction,vertical heterojunction,two-dimensional materials,water disinfection
更新于2025-09-23 15:21:21