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Effects of metal ions on the catalytic degradation of dicofol by cellulase

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Journal of environmental Sciences 2015年第7期27卷 163-168页

作者： Zihan Zhai Ting Yang Boya Zhang Jianbo Zhang Collaborative Innovation Center for Regional environmental Quality State Key Joint Laboratory of Environmental Simulation and Pollution ControlCollege of Environmental Science and Engineering Peking University School of public Health Peking University

A new technique whereby cellulase immobilized on aminated silica was applied to catalyze the degradation of dicofol, an organochlorine pesticide. In order to evaluate the performance of free and immobilized cellulase, experiments were carried out to measure the degradation efficiency. The Michaelis constant, Km, of the reaction catalyzed by immobilized cellulase was9.16 mg /L, and the maximum reaction rate, Vmax, was 0.40 mg /L /min, while that of free cellulase was Km= 8.18 mg /L, and Vmax= 0.79 mg /L /min, respectively. The kinetic constants of catalytic degradation were calculated to estimate substrate affinity. Considering that metal ions may affect enzyme activity, the effects of different metal ions on the catalytic degradation efficiency were explored. The results showed that the substrate affinity decreased after immobilization. Monovalent metal ions had no effect on the reaction, while divalent metal ions had either positive or inhibitory effects, including activation by Mn2＋, reversible competition with Cd2＋, and irreversible inhibition by Pb2＋. Ca2＋promoted the catalytic degradation of dicofol at low concentrations, but inhibited it at high concentrations. Compared with free cellulase, immobilized cellulase was affected less by metal ions. This work provided a basis for further studies on the co-occurrence of endocrine-disrupting chemicals and heavy metal ions in the environment.

关键词： Immobilization Cellulase Dicofol Metal ions Catalytic degradation

Reaction mechanism of dicofol removal by cellulase

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Journal of environmental Sciences 2015年第10期27卷 22-28页

作者： Ziyuan Wang Ting Yang Zihan Zhai Boya Zhang Jianbo Zhang Collaborative Innovation Center for Regional environmental Quality State Key Joint Laboratory of Environmental Simulation and Pollution ControlCollege of Environmental Science and EngineeringPeking University School of public Health Peking University

It remains unclear whether dicofol should be defined as a persistent organic pollutant. Its environmental persistence has gained attention. This study focused on its degradation by cellulase. Cellulase was separated using a gel chromatogram, and its degradation activity towards dicofol involved its endoglucanase activity. By analyzing the kinetic parameters of cellulase reacting with mixed substrates, it was shown that cellulase reacted on dicofol and carboxyl methyl cellulose through two different active centers. Thus, the degradation of dicofol was shown to be an oxidative process by cellulase. Next, by comparing the impacts of tert-butyl alcohol（a typical OH free-radical inhibitor） on the removal efficiencies of dicofol under both cellulase and Fenton reagent systems, it was shown that the removal of dicofol was initiated by OH free radicals produced by cellulase. Finally, 4,4′-dichlorodibenzophenone and chloride were detected using gas chromatography mass spectrometry and ion chromatography analysis, which supported our hypothesis. The reaction mechanism was analyzed and involved an attack by OH free radicals at the orthocarbon of dicofol, resulting in the degradation product 4,4′-dichloro-dibenzophenone.

关键词： Dicofol Cellulase Endo-glucanases activity Oxidative degradation OH free radical

Evaluation of sulfur trioxide detection with online isopropanol absorption method

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Journal of environmental Sciences 2018年第10期30卷 25-32页

作者： Jin Xiong Yuran Li Jian Wang Yang Yang Tingyu Zhu Beijing Engineering research Center of Process Pollution Control National Engineering Laboratory for Cleaner Hydrometallurgical Production Technology Institute of Process Engineering Chinese Academy of SciencesBeijing 100190 China University of Chinese Academy of Sciences Beijing 100049 China

Measurement of the SO3 concentration in flue gas is important to estimate the acid dew point and to control corrosion of downstream equipment. SO3 measurement is a difficult question since SO3 is a highly reactive gas, and its concentration is generally two orders of magnitude lower than the SO2 concentration. The SO3 concentration can be measured online by the isopropanol absorption method; however, the reliability of the test results is relatively low. This work aims to find the error sources and to evaluate the extent of influence of each factor on the measurement results. The test results from a SO3 analyzer showed that the measuring errors are mainly caused by the gas–liquid flow ratio, SO2 oxidation, and the side reactions of SO3. The error in the gas sampling rate is generally less than 13%. The isopropanol solution flow rate decreases 3% to 30% due to the volatilization of isopropanol, and accordingly, this will increase the apparent SO3 concentration. The amount of SO2 oxidation is linearly related to the SO2 concentration. The side reactions of SO3 reduce the selectivity of SO42- to nearly 73%. As sampling temperature increases from180 to 300°C, the selectivity of SO42- decreases from 73% to 50%. The presence of H2 O in the sample gas helps to reduce the measurement error by inhibiting the volatilization of the isopropanol and weakening side reactions. A formula was established to modify the displayed value, and the measurement error was reduced from 25%–54% to less than 15%.

关键词： SO3 measurement SO3 absorption H2SO4 SO2 oxidation Error source analysis

Size distributions and sources of elements in particulate matter at curbside,urban and rural sites in Beijing

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Journal of environmental Sciences 2012年第1期24卷 87-94页

作者： Jingchun Duan Jihua Tan Shulan Wang Jimin Hao Fahe Chai State Key Laboratory of environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing 100012China Key Laboratory of Computational Geodynamics Graduate University of the Chinese Academy of SciencesBeijing 100049China School of Environment Tsinghua UniversityBeijing 100084China

Size distributions of 29 elements in aerosols collected at urban,rural and curbside sites in Beijing were *** levels of Mn,Ni,As,Cd and Pb indicate the pollution of toxic heavy metals cannot be neglected in *** component analysis （PCA） indicates 4 sources of combustion emission,crust related sources,traffic related sources and volatile species from coal *** elements can be roughly divided into 3 groups by size distribution and enrichment factors method （EFs）.Group 1 elements are crust related and mainly found within coarse mode including Al,Mg,Ca,Sc,Ti,Fe,Sr,Zr and Ba;Group 2 elements are fossil fuel related and mostly concentrated in accumulation mode including S,As,Se,Ag,Cd,Tl and Pb;Group 3 elements are multi-source related and show multi-mode distribution including Be,Na,K,Cr,Mn,Co,Ni,Cu,Zn,Ga,Mo,Sn and *** EFs of Be,S,Cr,Co,Ni,Cu,Ga,Se,Mo,Ag,Cd,Sb,Tl and Pb show higher values in winter than in summer indicating sources of coal combustion for heating in *** abundance of Cu and Sb in coarse mode is about 2–6 times higher at curbside site than at urban site indicating their traffic *** burning may be the major source of Pb in Beijing since the phase out of leaded gasoline,as the EFs of Pb are comparable at both urban and curbside sites,and about two times higher in winter than that in summer.

关键词： ELPI enrichment factor curbside atmosphere heavy metal

Fast increasing of surface ozone concentrations in Pearl River Delta characterized by a regional air quality monitoring network during 2006–2011

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Journal of environmental Sciences 2014年第1期26卷 23-36页

作者： Jinfeng Li Keding Lu Wei Lv Jun Li Liuju Zhong Yubo Ou Duohong Chen Xin Huang Yuanhang Zhang College of environmental Sciences Engineering Peking University Guangdong Provincial environmental Monitoring Center

Based on the observation by a Regional Air Quality Monitoring Network including 16 monitoring stations, temporal and spatial variations of ozone （O3）, NO2 and total oxidant （Ox） were analyzed by both linear regression and cluster analysis. A fast increase of regional O3 concentrations of 0.86 ppbWyr was found for the annual averaged values from 2006 to 2011 in Guangdong, China. Such fast O3 increase is accompanied by a correspondingly fast NOx reduction as indicated by a fast NO2 reduction rate of 0,61 ppbV/yr. Based on a cluster analysis, the monitoring stations were classified into two major categories - rural stations （non-urban） and suburban/urban stations. The 03 concentrations at rural stations were relatively conserved while those at suburban/urban stations showed a fast increase rate of 2.0 ppbV/yr accompanied by a NO2 reduction rate of 1.2 ppbV/yr. Moreover, a rapid increase of the averaged O3 concentrations in springtime （13%/yr referred to 2006 level） was observed, which may result from the increase of solar duration, reduction of precipitation in Guangdong and transport from Eastern Central China. Application of smog production algorithm showed that the photochemical O3 production is mainly volatile organic compounds （VOC）-controlled. However, the photochemical O3 production is sensitive to both NOx and VOC for O3 pollution episode. Accordingly, it is expected that a combined NOx and VOC reduction will be helpful for the reduction of the O3 pollution episodes in Pearl River Delta while stringent VOC emission control is in general required for the regional O3 pollution control.

关键词： O3 cluster analysis temporal variation smog production algorithm Pearl River Delta

Phosphate-induced differences in stabilization efficiency for soils contaminated with lead, zinc, and cadmium

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Frontiers of environmental Science & Engineering 2018年第2期12卷 97-105页

作者： Jie Ren Zhuo Zhang Mei Wang Guanlin Guo Ping Du Fasheng Li College of Water Sciences Belling Normal Unive~ity Beijing 100875 China State Key Laboratory of environmental Criteria and Risk Assessment Chinese Research Academy of Environmental Sciences Beijing 100012 China

Phosphates can cost-effectively decrease the mobility of Pb in contaminated soils. However, Pb always coexists with other metals in soil, their competitive reactions with phosphates have not been tested. In this study, the abilities of KHzPO4, K2HPO4, and K3PO4 to stabilize Pb, Zn, and Cd in soils contaminated with a single metal or a ternary metal for different phosphorus/metal molar ratios were investigated. Results indicated that the stabilization efficiency of KH2PO4, K2HPO4, and K3PO4 for Pb, Zn, and Cd in single metal contaminated soil （P/M ratio 0.6） was 96.00%-98.74%, 33.76%-47.81%, and 9.50%-55.79%, respectively. Competitive stabilization occurred in the ternary system, Pb exhibited a strong competition, the stabilization efficiency of Zn and Cd reduced by 23.50%- 31.64%, and 7.10%--39.26%, respectively. Pyromorphite and amorphous lead phosphate formed with excess KH2PO4 or K2HPO4 addition, while K3PO4 resulted in the formation of a hydroxypyr- omorphite precipitate. Amorphous Zn and Cd phosphates and hydroxides were the primary products. The immobilization rate of Zn and Cd depends on pH, and increased significantly in response to the excess phosphate application. This approach provides insight into phosphate-induced differences in stabilization efficiency in soils contaminated with multiple metals, which is of theoretical and engineering significance.

关键词： Heavy metals Metal-contaminated soil Phosphate Competitive stabilization

Physiological and Antioxidant Responses of Germinating Mung Bean Seedlings to Phthalate Esters in Soil

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Pedosphere 2014年第1期24卷 107-115页

作者： MA Ting-Ting P.CHRISTIE LUO Yong-Ming TENG Ying Key Laboratory of Soil Environment and Pollution Remediation Institute of Soil ScienceChinese Academy of Sciences University of Chinese Academy of Sciences Agri-Environment Branch Agri-Food and Biosciences Institute Yantai Institute of Costal Zone research Chinese Academy of Sciences

Single phytotoxicity of two representative phthalate esters(PAEs),di-n-butyl phthalate(DnBP)and bis(2-ethylhexyl)phthalate(DEHP),was tested in mung bean(Vigna radiata)seedlings germinated for 72 h in soils spiked with varying concentrations(0-500 mg kg^(-1)soil)of DnBP or *** added at up to 500 mg kg^(-1)soil exerted no significant effect on germination but both pollutants significantly inhibited root elongation(P<0.01),DEHP inhibited shoot elongation(P<0.01)and DnBP depressed biomass on a fresh weight basis(P<0.05).Seedling shoot and root malondialdehyde(MDA)contents tended to be stimulated by DnBP but inhibited by ***,increases in superoxide dismutase,peroxidase,ascorbate peroxidase and polyphenol oxidase activities,as well as glutathione(GSH)content,were induced at higher concentrations(e.g.,20 mg kg^(-1))of both *** of proline in both roots and shoots and the storage compounds,such as free amino acids and total soluble sugars,in whole plant was induced under the stress exerted by both *** general responses of mung bean seedlings indicated higher toxicity of DnBP than DEHP on primary growth,during which root elongation was a more responsive *** and GSH were more sensitive parameters in the roots than in the shoots and they might be recommended as physiologically sensitive parameters to assess the toxicity of PAE compounds in soils in future long-term studies.

关键词： glutathione malondialdehyde phytotoxicity root elongation storage compounds

Regeneration performance and carbon consumption of semi-coke and activated coke for SO_2 and NO removal

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Journal of environmental Sciences 2015年第8期27卷 37-43页

作者： Song Ding Yuran Li Tingyu Zhu Yangyang Guo School of Chemistry and Chemical Engineering Guizhou University national Engineering Laboratory for Hydrometallurgical Cleaner Production Technology Institute of Process Engineering Chinese Academy of Sciences

To decrease the operating cost of flue gas purification technologies based on carbon-based materials, the adsorption and regeneration performance of low-price semi-coke and activated coke were compared for SO2 and NO removal in a simulated flue gas. The functional groups of the two adsorbents before and after regeneration were characterized by a Fourier transform infrared（FTIR） spectrometer, and were quantitatively assessed using temperature programmed desorption（TPD） coupled with FTIR and acid–base titration. The results show that semi-coke had higher adsorption capacity（16.2% for SO2 and 38.6% for NO） than activated coke because of its higher content of basic functional groups and lactones. After regeneration, the adsorption performance of semi-coke decreased because the number of active functional groups decreased and the micropores increased. Semi-coke had better regeneration performance than activated coke. Semi-coke had a larger SO2 recovery of 7.2% and smaller carbon consumption of 12% compared to activated coke. The semi-coke carbon-based adsorbent could be regenerated at lower temperatures to depress the carbon consumption, because the SO2 recovery was only reduced a small amount.

关键词： Functional groups SO2 recovery Adsorption Carbon consumption

Mechanism of Hg^0 oxidation in the presence of HCl over a commercial V_2O_5–WO_3/TiO_2 SCR catalyst

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Journal of environmental Sciences 2015年第10期27卷 76-83页

作者： Ruihui Liu Wenqing Xu Li Tong Tingyu Zhu research Center for Process Pollution Control National Engineering Laboratory for Hydrometallurgical Cleaner Production TechnologyInstitute of Process EngineeringChinese Academy of Sciences School of Resources and Materials Northeastern University at Qinhuangdao Branch

Experiments were conducted in a fixed-bed reactor containing a commercial V2O5/WO3/TiO2 catalyst to investigate mercury oxidation in the presence of HCl and O2. Mercury oxidation was improved significantly in the presence of HCl and O2, and the Hg^0 oxidation efficiencies decreased slowly as the temperature increased from 200 to 400℃. Upon pretreatment with HCl and O2 at 350℃, the catalyst demonstrated higher catalytic activity for Hg^0 oxidation. Notably,the effect of pretreatment with HCl alone was not obvious. For the catalyst treated with HCl and O2, better performance was observed with lower reaction temperatures. The results showed that both HCl and Hg^0 were first adsorbed onto the catalyst and then reacted with O2 following its adsorption, which indicates that the oxidation of Hg^0 over the commercial catalyst followed the Langmuir–Hinshelwood mechanism. Several characterization techniques, including Hg^0temperature-programmed desorption（Hg-TPD） and X-ray photoelectron spectroscopy（XPS）, were employed in this work. Hg-TPD profiles showed that weakly adsorbed mercury species were converted to strongly bound species in the presence of HCl and O2. XPS patterns indicated that new chemisorbed oxygen species were formed by the adsorption of HCl, which consequently facilitated the oxidation of mercury.

关键词： Mercury Hydrogen chloride Vanadium-based catalyst Oxidation Mechanism