14 results on '"Yongmei Liang"'
Search Results
2. Abundance of organosulfates derived from biogenic volatile organic compounds: Seasonal and spatial contrasts at four sites in China
- Author
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Yingge Ma, Cheng Huang, Binyu Kuang, Peng Lin, Yongmei Liang, Jian Zhen Yu, and Yuchen Wang
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Aerosols ,Air Pollutants ,China ,Volatile Organic Compounds ,Environmental Engineering ,Range (biology) ,Chemical interaction ,Seasonality ,medicine.disease ,Pollution ,Inorganic sulfate ,Mass Spectrometry ,Aerosol ,chemistry.chemical_compound ,chemistry ,Abundance (ecology) ,Environmental chemistry ,medicine ,Environmental Chemistry ,Environmental science ,Seasons ,Sulfate ,Waste Management and Disposal ,Isoprene - Abstract
Atmospheric organosulfates (OSs) derived from biogenic volatile organic compounds (BVOCs) encode chemical interaction strength between anthroposphere and biosphere. We report BVOC-derived OSs in the summer of 2016 and the winter of 2017 at four locations in China (i.e., Hong Kong (HK), Guangzhou (GZ), Shanghai (SH), and Beijing (BJ)). The spatial coverage of three climatic zones from the south to the north in China is accompanied with a wide range of aerosol inorganic sulfate (4.9–13.8 μg/m3). We employed a combined targeted and untargeted approach using high-performance liquid chromatography-Orbitrap mass spectrometry to quantify/semi-quantify ~200 OSs and nitrooxy OSs derived from four types of precursors, namely C2-C3 oxygenated VOCs, isoprene, monoterpenes (MT), and sesquiterpenes (ST). The seasonal averages of the total quantified OSs across the four sites are in the range of 201–545 (summer) and 123–234 ng/m3 (winter), with the isoprene-derived OSs accounting for more than 80% (summer) and 57% (winter). The C2–3 OSs and isoprene-derived OSs share the same seasonality (summer >winter) and the same south-north spatial gradient as those of isoprene emissions. In contrast, the MT- and ST-derived OSs are of either comparable abundance or slightly higher abundance in the winter at the four sites. The spatial contrasts for MT- and ST-derived OSs are not clearly discernable among GZ, SH, and BJ. HK is noted to have invariably lower abundances of all groups of OSs, in line with its aerosol inorganic sulfate being the lowest. These results indicate that BVOC emissions are the driving factor regulating the formation of C2–3 OSs and isoprene-derived OSs. Other factors, such as sulfate abundance, however, play a more important role in the formation of MT- and ST-derived OSs. This in turn suggests that the formation kinetics and/or pathways differ between these two sub-groups of BVOCs-derived OSs. more...
- Published
- 2021
Catalog
3. Ferrate(VI) decomposition in water in the absence and presence of natural organic matter (NOM)
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Yang Deng, Chanil Jung, Nina M. Goodey, Yongmei Liang, and Thomas D. Waite
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chemistry.chemical_classification ,General Chemical Engineering ,Natural water ,0208 environmental biotechnology ,Kinetics ,02 engineering and technology ,General Chemistry ,010501 environmental sciences ,01 natural sciences ,Decomposition ,Industrial and Manufacturing Engineering ,Natural organic matter ,020801 environmental engineering ,chemistry.chemical_compound ,chemistry ,Environmental Chemistry ,Humic acid ,Organic matter ,Water treatment ,Ferrate(VI) ,0105 earth and related environmental sciences ,Nuclear chemistry - Abstract
The kinetics of ferrate(VI) decomposition in natural water were assessed in the absence and presence of natural organic matter (NOM) (pH = 7.50, [Fe(VI)] = 54 µM, DOC = 0.00–10.00 and 1.00–8.57 mg/L for a simulated natural water and six real natural waters, respectively). Without NOM, Fe(VI) decomposition in simulated natural water exhibited a biphasic kinetics pattern, i.e. a 2nd-order reaction with respect to Fe(VI) concentration followed by a 1st-order reaction. However, an additional instant Fe(VI) loss was observed at the onset in the presence of NOM for both simulated and real natural waters, thereby rendering Fe(VI) decay with NOM a unique three-stage kinetics pattern. The initial instant Fe(VI) loss was caused due to the homogenous Fe(VI) self-decay and the rapid reactions between Fe(VI) and NOM. The latter accounted for a major fraction of the initial Fe(VI) loss and was in direct proportion with the initial DOC (DOC0) (Δ[Fe(VI)]0DOC = αNOM DOC0; αNOM = 1.45 µM Fe(VI)·L/mg DOC for the simulated natural water, and 0.66–1.35 µM Fe(VI)·L/mg DOC for the six natural waters). Fe(VI) decomposition experiments with different Suwannee River NOM isolates revealed that hydrophobic NOM fractions (i.e. fulvic acid (FA) and humic acid (HA)) caused a more significant initial Fe(VI) loss than the hydrophilic group (HPI), suggesting that Fe(VI) preferentially reacted with hydrophobic NOM molecules rather than hydrophilic compounds. Furthermore, an approach developed for the estimation of αNOM revealed a linear correlation between αNOM and specific UV absorbance (SUVA) (αNOM = 0.27SUVA + 0.18, R2 = 0.71). This study provides essential information regarding Fe(VI) decomposition for the determination of Fe(VI) dose and exposure for effective water treatment. more...
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- 2018
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4. Sludge aging stabilizes heavy metals subjected to pyrolysis
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Huanlong Peng, Tong Guan, Liang Xu, Wei He, Yongmei Liang, Yukun Wu, and Wei Liu
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Chromium ,Scanning electron microscope ,Health, Toxicology and Mutagenesis ,0211 other engineering and technologies ,chemistry.chemical_element ,02 engineering and technology ,010501 environmental sciences ,01 natural sciences ,Waste Disposal, Fluid ,chemistry.chemical_compound ,Adsorption ,Metals, Heavy ,Fourier transform infrared spectroscopy ,0105 earth and related environmental sciences ,021110 strategic, defence & security studies ,Sewage ,Extraction (chemistry) ,Public Health, Environmental and Occupational Health ,General Medicine ,Phosphate ,Pollution ,Copper ,chemistry ,Crystallization ,Pyrolysis ,Water Pollutants, Chemical ,Nuclear chemistry - Abstract
In this study, we analyzed the effects of sludge aging pre-treatment on the stabilization mechanisms of heavy metals during sludge pyrolysis. First, the form of copper (Cu) and chromium (Cr) was conducted using the sequential extraction procedure proposed by the European Community Bureau of Reference (BCR). The stabilization mechanisms for the sludge pyrolysis of Cu and Cr were then analyzed using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Results indicate the following: 1) with aging pre-treatment, the improvement in adsorption performance and the formation of newly crystallized materials, like polyhydroxy copper phosphate and chromium phosphate minerals, occur concurrently with the stabilization of heavy metals during pyrolysis; 2) after four weeks of aging, active functional groups like amino and carboxyl groups were significantly sharpened, and caused sustained complexation of the heavy metals. Results suggested that the aging pre-treatment aided the stabilization of heavy metals during sludge pyrolysis. Notably, the aging effect can decrease the potential ecological risk of heavy metals. more...
- Published
- 2019
5. Solar photolysis of soluble microbial products as precursors of disinfection by-products in surface water
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Jie Wu, Huanlong Peng, Yongmei Liang, Jian Ye, Weiwei Shi, Wei Liu, and Meirou Wu
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Environmental Engineering ,Health, Toxicology and Mutagenesis ,0208 environmental biotechnology ,Portable water purification ,02 engineering and technology ,010501 environmental sciences ,Wastewater ,01 natural sciences ,Water Purification ,chemistry.chemical_compound ,Rivers ,Environmental Chemistry ,Organic matter ,Effluent ,0105 earth and related environmental sciences ,chemistry.chemical_classification ,Chloramine ,Photolysis ,Sewage ,Chemistry ,Public Health, Environmental and Occupational Health ,General Medicine ,General Chemistry ,Models, Theoretical ,Pollution ,020801 environmental engineering ,Disinfection ,Trihalomethane ,Activated sludge ,Environmental chemistry ,Sunlight ,Water treatment ,Water Pollutants, Chemical ,Disinfectants - Abstract
In the Pearl River Delta area, the upstream municipal wastewater is commonly discharged into rivers which are a pivotal source of downstream drinking water. Solar irradiation transforms some of the dissolved organic matter discharged from the wastewater, also affecting the formation of disinfection by-products in subsequent drinking water treatment plants. The effect of simulated solar radiation on soluble microbial products extracted from activated sludge was documented in laboratory experiments. Irradiation was found to degrade macromolecules in the effluent, yielding smaller, more reactive intermediate species which reacted with chlorine or chloramine to form higher levels of noxious disinfection by-products. The soluble microbial products were found to be more active in formation of disinfection by-products regard than naturally-occurring organic matter. The results show that solar irradiation induced the formation of more trihalomethane (THMs), chloral hydrate (CH) and trichloronitromethane (TCNM), causing greater health risks for downstream drinking water. more...
- Published
- 2017
6. Fluorescence characteristics of natural organic matter in water under sequential exposure to UV irradiation/chlor(am)ination
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Qianjun Guo, Zheng-bo Ma, Wei Liu, Yongmei Liang, and Zai-li Zhang
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chemistry.chemical_classification ,Chloramine ,chemistry.chemical_element ,medicine.disease_cause ,Fluorescence ,Natural organic matter ,chemistry.chemical_compound ,Fluorescence intensity ,chemistry ,polycyclic compounds ,Chlorine ,medicine ,Organic matter ,Irradiation ,Ultraviolet ,Water Science and Technology ,Nuclear chemistry - Abstract
The organic matter in International Humic Substances Society Natural Organic Matter (IHSS NOM) water exposed to ultraviolet (UV) irradiation and chlor(am)ine sequentially under practically relevant conditions was characterized based on fluorescence spectra. IHSS NOM water exposed to UV irradiation or chlor(am)ine alone was also evaluated. Both chlor(am)ine alone and UV/chlor(am)ine exposure showed similar chlor(am)ine demand and fluorescence spectra. UV irradiation and UV/chlorine exposure diminished the fluorescence intensity of IHSS NOM water, while UV/chloramine exposure resulted in increased fluorescence intensity. When compared with the results obtained following chlor(am)ination alone, IHSS NOM water showed decreased chlorine decay and increased chloramine decay after UV irradiation/chlor(am)ination. Additionally, IHSS NOM water exposed to UV/chloramine and chloramine showed less disinfection by-product (DBP) formation than water subjected to UV/chlorine and chlorine. Overall, these findings indicate that UV irradiation degrades NOM molecules to low-molecular-weight fractions, facilitating the subsequent reaction with chlor-(am)ine. However, chlorine and chloramine play different roles in the reaction. Chlorine degradation and substitution dominates the process of UV/chlorine exposure, while chloramine substitution is the major reaction during UV/chloramine exposure. more...
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- 2013
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7. Effluent Particle Size and Permeability of Polyvinylchloride Membranes after Sodium Hypochlorite Exposure
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Xue-bo Qin, Bing Chen, Xin Yang, Wei Liu, Yongmei Liang, Jun Lu, and Zai-li Zhang
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Environmental Engineering ,Chromatography ,Fouling ,Chemistry ,Sodium ,chemistry.chemical_element ,Hypochlorite ,Chloride ,chemistry.chemical_compound ,Membrane ,Permeability (electromagnetism) ,Sodium hypochlorite ,medicine ,Environmental Chemistry ,Particle size ,General Environmental Science ,Civil and Structural Engineering ,medicine.drug - Abstract
Sodium hypochlorite (NaOCl) is a common cleaning agent for treating ultrafiltration (UF) membranes. Although it efficiently removes fouling, NaOCl accelerates membrane degradation and reduces membrane integrity. In this paper, new and polluted polyvinylchloride hollow fiber membranes were treated with NaOCl solutions. The effects on the membrane were evaluated by using transmembrane pressure, bovine serum albumin permeability, particle-size distribution of the effluent (PSDE), attenuated total reflectance-Fourier transform infrared spectroscopy, and field emission scanning electron microscopy. The membrane pore size increased after exposure to solutions with a NaOCl mass fraction of 1%. The PSDE was successfully used to test membrane integrity. When the NaOCl mass fraction was more...
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- 2013
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8. Effects of ozone and ozone/peroxide pretreatments on disinfection byproduct formation during subsequent chlorination and chloramination
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Yongmei Liang, Xin Yang, Baiyang Chen, Wanhong Guo, Lu Liu, Wei Liu, and Jinfeng Peng
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Environmental Engineering ,Ozone ,Health, Toxicology and Mutagenesis ,chemistry.chemical_element ,Water Purification ,chemistry.chemical_compound ,Bromide ,Chlorine ,Environmental Chemistry ,Organic chemistry ,Organic Chemicals ,Hydrogen peroxide ,Waste Management and Disposal ,Chloramination ,Chloramine ,Bromine ,Chloramines ,Water Pollution ,Hydrogen Peroxide ,Oxidants ,Pollution ,Disinfection ,chemistry ,Environmental chemistry ,Water treatment ,Water Pollutants, Chemical - Abstract
Ozone (O3) and ozone/hydrogen peroxide (O3/H2O2) can be used in water treatment facilities to remove many organic micropollutants with taste, odor, and color implications. The effects of O3 and O3/H2O2 on the formation of disinfection byproducts (DBPs) in subsequent chlorination and chloramination processes, however, are not well determined. In this study, we compared the yields of a series of regulated and emerging DBPs during sequenced O3-Cl2, O3/H2O2-Cl2, O3-NH2Cl, and O3/H2O2-NH2Cl oxidation of 11 samples, each with different hydrophobicity, bromide concentration, soluble microbial products, and humic substances. For most water, pretreatment with O3 and O3/H2O2 increased the formation of chloral hydrate (CH), trichloronitromethane (TCNM) and haloketones (HKs) but lowered the yields of haloacetonitriles (HANs) during chlorination processes. Compared with O3 alone, O3/H2O2 in combination generated more CH and HKs during chlorination, and their extents of formation appeared to depend on the O3 doses. In terms of chloramination, both O3 and O3/H2O2 reduced THM, HAA, and HAN formation significantly without increasing CH, TCNM, or HKs. These results suggest that O3 or O3/H2O2 pretreatments may provide some benefits for the chloramination process in controlling regulated and emerging DBPs in waters without high bromide content. more...
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- 2012
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9. Precursors and nitrogen origins of trichloronitromethane and dichloroacetonitrile during chlorination/chloramination
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Wanhong Guo, Yongmei Liang, Qianqian Shen, Jinfeng Peng, and Xin Yang
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Acetonitriles ,Environmental Engineering ,Halogenation ,Nitrogen ,Health, Toxicology and Mutagenesis ,chemistry.chemical_element ,Gas Chromatography-Mass Spectrometry ,chemistry.chemical_compound ,Hydrocarbons, Chlorinated ,Environmental Chemistry ,Organic chemistry ,Asparagine ,Chloramination ,Pyrrole ,chemistry.chemical_classification ,Alanine ,Chloramines ,Tryptophan ,Public Health, Environmental and Occupational Health ,General Medicine ,General Chemistry ,Hydrogen-Ion Concentration ,Pollution ,Amino acid ,chemistry ,Glycine ,Tyrosine ,Gas chromatography - Abstract
The formation of trichloronitromethane (TCNM) and dichloroacetonitrile (DCAN) was investigated during chlorination and chloramination of 31 organic nitrogen (org-N) compounds, including amino acids, amines, dipeptides, purines, pyrimidones and pyrroles. Tryptophan and alanine generated the greatest amount of TCNM during chlorination process and asparagine and tyrosine yielded the highest amount of TCNM during chloramination process. Tryptophan, tyrosine, asparagine, and alanine produced more DCAN than other org-N compounds regardless of chlorination or chloramination. TCNM and DCAN formation was higher by chlorination than by chloramination. NH 2 Cl:org-N molar ratios, reaction time, and pH affected N-DBPs formation in varying degrees. TCNM and DCAN yields were usually high during chloramination of tyrosine, asparagine, and methylpyrrole under the following reaction conditions: NH 2 Cl:org-N molar ratios greater than 10, reaction time for 1 d, and at pH 7.2. NH 2 Cl as a major nitrogen origin in TCNM and DCAN was confirmed via labeled 15 N-monochloramine during chloramination of tyrosine, asparagine and methylpyrrole. In contrast, the majority of nitrogen in TCNM originated from glycine, and that in DCAN originated from pyrrole. Based on the intermediates identified by gas chromatography/mass spectrometry (GC/MS), a pathway scheme was proposed for TCNM and DCAN formation. more...
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- 2012
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10. Molecular characterisation of ambient aerosols by sequential solvent extractions and high-resolution mass spectrometry
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Chunming Xu, Yongmei Liang, Bin Jiang, Zhiheng Wang, Quan Shi, Yahe Zhang, and Jingyi Zhang
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chemistry.chemical_classification ,Total organic carbon ,Chromatography ,010504 meteorology & atmospheric sciences ,Context (language use) ,010501 environmental sciences ,Mass spectrometry ,01 natural sciences ,Organic compound ,Solvent ,chemistry.chemical_compound ,chemistry ,Geochemistry and Petrology ,Chemistry (miscellaneous) ,Environmental Chemistry ,Organic matter ,Acetonitrile ,0105 earth and related environmental sciences ,Dichloromethane - Abstract
Environmental contextOrganic compounds generally make a large contribution to ambient aerosol fine particles, and can influence atmospheric chemistry. Solvent extraction before mass spectrometry is widely used for the determination of organic compounds in aerosols, but the molecular selectivity of different solvents is unclear. We extracted an aerosol sample with various solvents and show how the organic compound profile obtained by mass spectrometry changes depending on the extracting solvent. AbstractFor a comprehensive characterisation of organic compounds in aerosols, samples collected on a hazy day from Beijing were sequentially extracted with various solvents and analysed by Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Electrospray ionisation (ESI) was used for the MS analysis. Aerosol samples were extracted in an apolar-to-polar solvent order of n-hexane (n-C6), dichloromethane (DCM), acetonitrile (ACN) and water, and also extracted in reverse sequence. The separated fractions were defined as non-polar, low-polarity, mid-polarity and high-polarity organic compounds respectively. Approximately 70 % of the total organic carbon (TOC) was extractable, of which the water-soluble organic carbon (WSOC) and non-polar organic carbon accounted for 30 and 25 % of the TOC respectively. Non-polar and low-polarity compounds with a high degree of molecular condensation such as oxidised polycyclic aromatic hydrocarbons (PAHs) and nitrogen-containing compounds (CHN) were extracted by n-C6 and DCM. Water-soluble organic matter (WSOM) was predominant with aliphatic and aromatic organosulfates (CHOS) and nitrooxy-organosulfates (CHONS). Most oxygen-containing compounds (CHO) and oxygen- and nitrogen-containing compounds (CHON) with high double-bond equivalents (DBEs) and long carbon chains tended to be extracted into organic solvents. more...
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- 2018
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11. The occurrence of disinfection by-products in municipal drinking water in China's Pearl River Delta and a multipathway cancer risk assessment
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Yisen He, Wei Liu, Yongmei Liang, Wanhong Guo, Jianmin Mo, Yongjian Liu, Xin Yang, and Wenhui Gan
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China ,Environmental Engineering ,Haloacetic acids ,Chloral hydrate ,Dichloroacetic acid ,Risk Assessment ,chemistry.chemical_compound ,Rivers ,Neoplasms ,medicine ,Environmental Chemistry ,Ingestion ,Humans ,Cities ,Trichloroacetic Acid ,Waste Management and Disposal ,Chloroform ,Dichloroacetic Acid ,Drinking Water ,Pollution ,Disinfection ,Trihalomethane ,chemistry ,Environmental chemistry ,Water treatment ,Public Health ,Seasons ,Hydrate ,Water Pollutants, Chemical ,medicine.drug ,Disinfectants ,Trihalomethanes - Abstract
Disinfection byproducts were measured in the finished drinking water from ten water treatment plants in three Chinese cities - Guangzhou, Foshan and Zhuhai. A total of 155 water samples were collected in 2011 and 2012. The median (range) of trihalomethane (THM) and haloacetic acid (HAA) levels were 17.7 (0.7-62.7) μg/L and 8.6 (0.3-81.3) μg/L, respectively. Chloroform, dichloroacetic acid and trichloroacetic acid were the dominant species observed in Guangzhou and Foshan water, while brominated THMs predominated in water from Zhuhai. Haloacetonitriles, haloketones, chloral hydrate and trichloronitromethane were usually detected at levels ranging from unquantifiable ( more...
- Published
- 2012
12. Ageing of polyvinylchloride membranes in ultrafiltration of drinking water by chemical cleaning
- Author
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Zai-li Zhang, Bing Chen, Xue-bo Qin, Xin Yang, Yongmei Liang, Tingjin Ye, Wei Liu, Jun Lu, Yukun Huang, and Wangxin Luo
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Cleaning agent ,Chromatography ,biology ,Fouling ,Chemistry ,Environmental engineering ,Ultrafiltration ,chemistry.chemical_compound ,Membrane ,Permeability (electromagnetism) ,Sodium hypochlorite ,biology.protein ,Water treatment ,Bovine serum albumin - Abstract
Sodium hypochlorite (NaOCl) is a common cleaning agent in ultrafiltration (UF) treatment. Despite the efficiency of fouling removal, acceleration of degradation and loss in membrane integrity are caused. In this paper, hollow fiber membranes made from polyvinylchloride (PVC) were treated with different concentration of NaOCl solution for different periods of time, and both virgin and polluted membranes were taken into study. Effects on the membrane were evaluated using transmembrane pressure (TMP), bovine serum albumin (BSA) permeability, and FESEM analysis. Enlargement of pore size was observed after exposure to NaOCl less than 1%, and twist and wrinkles appeared when NaOCl was above 1%, which caused TMP and BSA rejection first declined and rose then. Polluted membranes had worse situation than virgin ones during NaOCl cleaning. 1% NaOCl should be avoided in cleaning. more...
- Published
- 2011
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13. Effects of UV irradiation and UV/chlorine co-exposure on natural organic matter in water
- Author
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Yongmei Liang, Xin Yang, Zai-li Zhang, Wei Liu, and Yiyue Xu
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Environmental Engineering ,Ultraviolet Rays ,chemistry.chemical_element ,Photochemistry ,medicine.disease_cause ,chemistry.chemical_compound ,Halogens ,polycyclic compounds ,medicine ,Chlorine ,Environmental Chemistry ,Irradiation ,Waste Management and Disposal ,Chloramination ,Chromatography, High Pressure Liquid ,Humic Substances ,Chloramine ,Chemistry ,Chloramines ,Water ,Disinfection by-product ,Pollution ,Halogen ,Photocatalysis ,Chromatography, Gel ,Spectrophotometry, Ultraviolet ,sense organs ,Ultraviolet ,Disinfectants - Abstract
The effects of co-exposure to ultraviolet (UV) irradiation (with either low- or medium-pressure UV lamps) and free chlorine (chloramine) at practical relevant conditions on changes in natural organic matter (NOM) properties were investigated using four waters. The changes were characterized using the specific disinfection by-product formation potential (SDBPFP), specific total organic halogen formation potential (STOXFP), differential UV absorbance (∆UVA), and size-exclusion chromatography (SEC). The results for exposure to UV irradiation alone and for samples with no exposure were also obtained. The SDBPFPs in all UV-irradiated NOM waters observed were higher than those of non-irradiated samples. UV irradiation led to increases in STOXFPs as a result of chlorination, but no changes, or only small decreases, from chloramination. UV irradiation alone led to positive ∆UVA spectra of the four NOM waters; co-exposure to UV and chlorine gave larger negative ∆UVA spectra than those obtained by chlorine exposure alone. No obvious changes in SEC results were observed for samples only irradiated with UV light; co-exposure gave no detectable changes in the abundances of small fractions for exposure to chlorine only. Both UV photooxidation and photocatalytic oxidation appear to affect the reactivity of the NOM toward subsequent chlorination, and the magnitude of the changes is generally greater for medium-pressure lamps than for low-pressure lamps. These results suggest that applying UV disinfection technology to a particular source may not always be disinfection by-product-problem-free, and the interactions between UV light, chlorine, and NOM may need to be considered. more...
- Published
- 2010
14. Molecular composition of urban organic aerosols on clear and hazy days in Beijing: a comparative study using FT-ICR MS
- Author
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Jingyi Zhang, Quan Shi, X. H. Hilda Huang, Bin Yu Kuang, Yongmei Liang, Jian Zhen Yu, Chunming Xu, and Bin Jiang
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chemistry.chemical_classification ,Astrochemistry ,Haze ,Ozone ,010504 meteorology & atmospheric sciences ,Chemistry ,CHON ,Fluorescence spectrometry ,Polycyclic aromatic hydrocarbon ,Context (language use) ,010501 environmental sciences ,01 natural sciences ,Aerosol ,chemistry.chemical_compound ,Geochemistry and Petrology ,Chemistry (miscellaneous) ,Environmental chemistry ,Environmental Chemistry ,0105 earth and related environmental sciences - Abstract
Environmental contextChina has been experiencing severe particulate pollution and frequent haze episodes in recent years. We compare the molecular composition of urban organic aerosols on clear and hazy days in Beijing by high-resolution mass spectrometry. The comparative study shows that oxidation, sulfation and nitrification processes actively involve precursors of anthropogenic origin in the Beijing polluted urban atmosphere. AbstractHaze has frequently affected many cities and threatened human health in China. Detailed knowledge of the chemical composition of secondary organic aerosol provides fundamental information in the study of the formation mechanism of haze and its adverse effects on human health. In our work, dichloromethane and water extracts of ambient aerosols collected on hazy and clear days in Beijing were characterised by negative-ion electrospray ionisation and Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Formulae in four elemental compositional groups, namely CHOS, CHONS, CHO and CHON, were identified relying on the ultrahigh resolution and mass accuracy of FT-ICR MS. Significantly more compounds were detected and the peaks were much more intense in the hazy day samples, especially for the CHOS, CHONS and CHON formula groups. Organosulfates (OS) and nitrooxy-organosulfates (nitrooxy OS) were the major forms of CHOS and CHONS formulae respectively, and their numbers more than tripled on the hazy days. Under the severely polluted conditions in Beijing, the compositional distribution of the OS and nitrooxy OS exhibited distinct features such as intense peaks of low double-bond equivalent (DBE) (DBE=0, 1 for OS and DBE=1, 2 for nitrooxy OS) and low degree oxidation, of medium DBE (DBE=2, 3 for OS and DBE=3, 4 for nitrooxy OS), and of high DBE (DBE ≥ 4 for OS and DBE ≥ 5 for nitrooxy OS). The likely respective candidates for these could be aliphatic OS having a low degree of oxidation, biogenic OS and many aromatics and polycyclic aromatic hydrocarbon (PAH)-derived OS. The CHON formulae observed on hazy days were double those on clear days and had higher DBE values and larger O/N ratios. Slightly more CHO compounds were detected in the hazy-day samples and they had higher DBE values and more oxygen atoms. The comparative study suggests that oxidation, sulfation and nitrification processes actively involve precursors of anthropogenic origin in the Beijing polluted urban atmosphere. more...
- Published
- 2016
- Full Text
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