Publications by authors named "Qian-yuan Wu"
Periodate (PI) shows promising potential as an oxidant for wastewater treatment; however, its impact on the toxicity of wastewater remains unknown. Here, we found that with 100 μM PI addition, the cytotoxicity of wastewater increased from 4.8 to 7.
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- * A new palladium-palladium oxide (Pd-PdO) heterostructure demonstrates exceptional performance, with a significantly higher catalytic efficiency for converting toxic chlorophenols into phenol compared to conventional catalysts.
- * The success of this Pd-PdO system hinges on optimized interactions between two types of palladium sites that enhance hydrogen generation and its role in the dechlorination process, facilitating both detoxification and resource recovery.
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- The KrCl-excimer lamp emits far-UVC light at 222 nm, which is more effective than conventional UVC light at 254 nm for degrading and detoxifying harmful organic pollutants, specifically chlorophenols.
- UV222 demonstrated significantly higher efficiencies in photolyzing chlorophenols, being 1.4 to 34.1 times faster than UV254, particularly with protonated versions due to better light absorption and quantum yields.
- The study found UV222 to enhance dechlorination rates to 95% compared to 60% with UV254, although the presence of radical sensitizers could complicate the process, producing toxic intermediates but also aiding in detoxification.
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- The KrCl* excimer lamp (UV222) is a mercury-free alternative to low-pressure mercury lamps (UV254) for UV-based advanced oxidation processes, offering higher photon energy and better performance.
- A comprehensive study was conducted on various oxidants like hydrogen peroxide and persulfate, revealing that UV222 significantly enhances oxidant activation, with increased efficacy for degrading micropollutants compared to UV254.
- PDS proved to be the most effective oxidant under UV222, achieving much higher rates of micropollutant elimination and requiring less energy, despite some interference from other water constituents.
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- Reusing reclaimed water involves the risk of generating harmful disinfection by-products (DBPs), which require careful management to ensure safety.
- A study found that treating water with low HO/O ratios led to higher toxicity due to increased levels of bromate and adsorbable organic bromine (AOBr), which were not a concern at higher HO/O ratios.
- The research suggests that maintaining a higher HO/O ratio can reduce the formation of harmful substances and associated toxicity, indicating the importance of treatment method adjustments to mitigate risks in reclaimed water usage.
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- Vacuum-UV (VUV), specifically at 185 nm, is effectively used to purify reverse osmosis permeate water, crucial for electronics-grade ultrapure water production.
- The study revealed that various anions present in low concentrations significantly impact the VUV oxidation of acetaldehyde, a common contaminant in this water.
- Bicarbonate minimally affects the process, while nitrate and chloride notably hinder acetaldehyde removal rates and mineralization, highlighting the need for deeper research into how these anions alter VUV photochemistry in water.
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- * UV222 and UV254 show similar effectiveness in inactivating E. coli, but UV222 treatment prevents reactivation by causing extensive damage to the bacteria's DNA and cell membrane.
- * Overall, using UV222 for disinfection may be a better option for water treatment as it minimizes the chance of bacterial recovery after treatment.
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- * The study found that while VUV shows better performance in activating hydroxyl radicals (HO) for contaminant degradation, its effectiveness varies greatly with the depth of water, whereas UV/HO maintains a more consistent performance regardless of conditions.
- * Environmental factors like chloride and nitrate concentrations significantly inhibit the VUV process due to competitive absorbance, though some hydroxyl radicals are still generated from the photolysis of these substances, impacting the overall oxidation efficiency.
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- - Ozonation of wastewater with bromide produces toxic organic bromine, but combining ozone with ferrate(VI) significantly reduces toxicity levels of wastewater to mammalian cells, especially when bromide levels are low.
- - When bromide concentrations are higher, ozonation alone actually increases toxicity due to organic bromine formation, while the O/Fe(VI) combination effectively suppresses both total organic bromine and associated toxicity.
- - Enhanced toxicity reduction is linked to the production of reactive iron and oxygen species that improve the breakdown of precursors in wastewater, making the O/Fe(VI) method a safer alternative compared to ozonation alone in varying bromide conditions.
Ozone, hydrogen peroxide, and peroxymonosulfate disinfection of MS2 coliphage in water.
Environ Sci Process Impacts
May 2024
Article Synopsis
- - The study investigates how well different oxidants—ozone (O), peroxymonosulfate (PMS), and hydrogen peroxide (HO)—can inactivate the MS2 coliphage virus in water, which is important for preventing viral disease spread.
- - Results showed that to achieve a significant 4-log reduction in virus levels, all three oxidants needed specific doses and a contact time of 30 minutes, but ozone was the fastest, requiring only 0.5 minutes.
- - In secondary effluent, all three oxidants effectively inactivated the virus and removed dissolved organic matter, but ozone was found to be the most efficient option overall for disinfection.
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- - Ozonation in water treatment can create harmful byproducts called brominated disinfection byproducts (Br-DBPs), but using sunlight can help reduce these risks, although how this happens is not well understood.
- - A study found that sunlight exposure reduced adsorbable organic bromine levels by 63% in reclaimed water, indicating that specific harmful compounds (mostly CHOBr types) were decreased or eliminated after irradiation.
- - The research proposed pathways for how these Br-DBPs transform under sunlight, revealing that the resulting photoproducts are generally less toxic than the original compounds, enhancing our understanding of their degradation in environmental conditions.
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- * This study successfully incorporated single-atom silver (Ag) onto ultrathin carbon nitride (UTCN) to create AgUTCN, enhancing its photocatalytic properties without altering its structure.
- * With Ag doping, the forbidden band gap of UTCN was reduced, improving photocatalytic performance, achieving 85% pollutant degradation under visible light, and highlighting oxygen as the key reactive species in breaking down pollutants like Acetaminophen.
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- Permanganate is used in water treatment to remove organic pollutants and reduce harmful by-products but its effects on specific disinfection by-products (Cl-DBPs) were previously unclear.
- This study analyzed how permanganate preoxidation changes dissolved effluent organic matter (dEfOM) and leads to the formation of unknown Cl-DBPs, using advanced mass spectrometry techniques.
- Results showed that permanganate treatment reduced the formation of unknown Cl-DBPs by 30%, especially targeting certain harmful compounds, and altered the dEfOM structure, potentially improving water treatment efficiency.
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- Vacuum ultraviolet (VUV) irradiation effectively oxidizes pollutants but doesn't necessarily reduce their toxicity, highlighting the need for more research in real wastewater scenarios.
- In this study, VUV irradiation was found to significantly decrease the cytotoxicity and genotoxicity of secondary effluents when tested on Chinese hamster ovary cells, with reductions of 57%-63% and 56%-61% respectively after 36 minutes.
- Hydroxyl radicals generated during VUV irradiation contributed largely to these reductions in toxicity, while the overall removal of dissolved organic carbon (DOC) was only 15.8%-20.0%, indicating that VUV treatment primarily affects smaller molecular weight compounds and alters chemical properties associated with toxicity.
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- Disinfection through chloramination produces toxic byproducts, with this study focusing on the differences in cytotoxic effects between reclaimed water (chloraminated effluent organic matter, EfOM) and drinking water (chloraminated natural organic matter, NOM).
- The research found that chloraminated EfOM caused 1.7 times higher cytotoxicity compared to chloraminated NOM and generated more reactive nitrogen species, impacting cell health more severely.
- Evidence of cellular damage, such as increased DNA/RNA damage and higher protein carbonyl levels, indicated that chloraminated EfOM led to more cell death and irretrievable damages than chloraminated NOM, particularly affecting the cell cycle.
Electroneutral carbonyls (ENCs) with low molecular weights (e.g., aldehydes and ketones) are recalcitrant to single water treatment process to achieve ultralow concentration.
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- Ferrate [Fe(VI)] combined with biochar effectively degrades pollutants in wastewater and reduces disinfection byproducts (DBPs) and cytotoxicity during post-chlorination.
- The combination significantly lowered cytotoxicity levels from 12.7 to 7.6 mg-phenol/L and decreased total organic chlorine and bromine concentrations in treated samples.
- Advanced mass spectrometry revealed a substantial reduction in DBP molecules, especially phenols and unsaturated compounds, indicating that Fe(VI)/biochar treatment enhances oxidation and adsorption processes that lower harmful byproducts in wastewater.
Micro-bubble aeration is an efficient way to promote ozonation performance, but the technology is challenged by extensive energy cost. Here, a ceramic ultrafiltration membrane was used to achieve ozone micro-bubble (0-80 µm) aeration in a simple way at gaseous pressures of 0.14-0.
View Article and Find Full Text PDFThe high-valent cobalt-oxo species (Co(IV)=O) is being increasingly investigated for water purification because of its high redox potential, long half-life, and antiinterference properties. However, generation of Co(IV)=O is inefficient and unsustainable. Here, a cobalt-single-atom catalyst with N/O dual coordination was synthesized by O-doping engineering.
View Article and Find Full Text PDFPharmaceutical and personal care products (PPCPs) are frequently detected in water bodies and have potential risks to human health and the ecosystem. The degradation of eight structurally diverse PPCPs by ammonia/chlorine was systematically investigated in this study. Compared with chlorination, ammonia/chlorine markedly enhanced PPCP degradation, and the degradation efficiencies of most PPCPs were greater than 70%.
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- Byproducts like chlorate and bromate formed during sulfate radical-based processes (UV/PMS) raise concerns because they can lead to increased toxicity in treated wastewater.
- Treatment with peroxymonosulfate (PMS) can result in the formation of organic halogens, with toxicity levels escalating significantly for mammalian cells.
- While UV/PMS reduces some toxicity through the degradation of byproducts, the study suggests that PMS's ability to create higher concentrations of toxic organic halogens calls for more attention compared to the more commonly studied chlorate and bromate byproducts.
Disinfecting reclaimed water for safe reuse can produce toxic disinfection by-products such as adsorbable organic bromine (AOBr). Irradiating stored reclaimed water with sunlight is a "green" and free method for eliminating some toxic disinfection by-products, but the effects of irradiation with sunlight on ozonated reclaimed water containing bromide are not well understood. In this study, AOBr was found at concentrations of 171-180 (µg Br)/L in ozonated reclaimed water containing bromide at a concentration of 2 (mg Br)/L and dissolved organic carbon at a concentration of ∼5 (mg C)/L.
View Article and Find Full Text PDFVacuum-UV (VUV) (wavelength 185 nm)/ UV (wavelength 254 nm) are applied to improve performances of UV-based advanced oxidation processes. However, the improvements were strongly affected by water depth because of poor VUV transmittance in water. In this study, VUV/UV and peroxydisulfate (PDS) were used to degrade carbamazepine.
View Article and Find Full Text PDFVacuum ultraviolet/ultraviolet (VUV/UV) oxidation using a low-pressure mercury lamp emitting dual wavelengths (185 nm (VUV) and 254 nm (UV)) significantly varies in performance along the light-path (l), which has not been fully characterized. Therefore, VUV/UV oxidation in solution was investigated at various l in terms of the degradation kinetics and mineralization pathway of representative aldehydes with various alkyl-chain lengths. Oxidative degradation of parent aldehydes with shorter alkyl chains was less efficient, specifically the pseudo-zero-order rate constant (k) of formaldehyde was only 51% of that of propionaldehyde (k = 0.
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- * Researchers developed carbon nanotubes combined with cobalt (Co) nanoparticles, exploring their effects on ORR activity and reactivity through various treatments.
- * The new catalyst shows impressive selectivity and ORR performance, capable of generating hydrogen peroxide (HO) at a rate of 323 mg L/h under neutral conditions without needing additional oxygen.