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Benzene degradation in waste gas by photolysis and photolysis-ozonation: experiments and modeling

Fariba Mahmoudkhani, Maryam Rezaei, Vahid Asili, Mahsasadat Atyabi, Elena Vaisman, Cooper H. Langford, Alex De Visscher

《环境科学与工程前沿（英文）》 2016年 第10卷 第6期 doi: 10.1007/s11783-016-0876-4

摘要： A photochemical model of benzene degradation compares well with experimental data obtained in the Lab. 62 reactions were needed to fully describe benzene degradation. A feasibility study shows that the photolysis of benzene is a cost-effective process. Experimental data and modeling results show that the degradation efficiency will increase when the combination of UV light and ozone is used. The degradation of benzene, a carcinogenic air pollutant, was studied in a gas-phase photochemical reactor with an amalgam lamp emitting ultraviolet light at 185 and 254 nm. Efficient benzene degradation (>70%) was possible for benzene mass flow rates of up to 1.5 mg·min . Adding ozone allowed benzene mass flow rates of up to 5 mg·min to be treated with the same efficiency. In terms of energy consumption, ozone doubles the efficiency of the process. A comprehensive mechanistic simulation model was developed incorporating a chemical kinetics model (62 reactions involving 47 chemical species), a material balance model incorporating diffusion and flow, a flow velocity model, and a light field model. The model successfully predicted the efficiency of the reactor, generally within 20%, which indicates that the model is sound, and can be used for feasibility studies. The prediction of the reactor efficiency in the presence of ozone was less successful, with systematically overestimated efficiency. Condensation of reaction products in the reactor is thought to be the main cause of model inaccuracy. Both experimental data and model predictions show that there is a synergistic effect between ozonation and ultraviolet degradation.

关键词： Photolysis     Ozone     Benzene     Waste gas     Simulation     Synergism    

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Ambient photolysis frequency of NO

Qi Zou,Keding Lu,Yusheng Wu,Yudong Yang,Zhuofei Du,Min Hu

《环境科学与工程前沿（英文）》 2016年 第10卷 第6期 doi: 10.1007/s11783-016-0885-3

摘要： • Chemical actinometer (CA) was built for NO photolysis frequency, j(NO ), analysis. • CA data (10% accuracy) were compared with spectroradiometer (SR) data. • Long-term j(NO ) measurement was validated by comparison of CA and SR. • Dis-benefit of aerosol on j(NO ) due toparticulate matter (PM ) control on O . The photolysis frequency of NO , j(NO ), is an important analytical parameter in the study of tropospheric chemistry. A chemical actinometer (CA) was built to measure the ambient j(NO ) based on a high precision NO instrument with 1 min time resolution. Parallel measurements of the ambient j(NO ) by using the CA and a commercial spectroradiometer (SR) were conducted at a typical urban site (Peking University Urban Environmental Monitoring Station) in Beijing. In general, good agreement was achieved between the CA and SR data with a high linear correlation coefficient ( = 0.977) and a regression slope of 1.12. The regression offset was negligible compared to the measured signal level. The j(NO ) data were calculated using the tropospheric ultraviolet visible radiation (TUV) model, which was constrained to observe aerosol optical properties. The calculated j(NO ) was intermediate between the results obtained with CA and SR, demonstrating the consistency of all the parameters observed at this site. The good agreement between the CA and SR data, and the consistency with the TUV model results, demonstrate the good performance of the installed SR instrument. Since a drift of the SR sensitivity is expected by the manufacturer, we propose a regular check of the data acquired via SR against those obtained by CA for long-term delivery of a high quality series of j(NO ) data. Establishing such a time series will be invaluable for analyzing the long-term atmospheric oxidation capacity trends as well as O pollution for urban Beijing.

关键词： Photolysis frequency of nitrogen dioxide     Chemical actinometer     Spectroradiometer     Tropospheric ultraviolet visible radiation model    

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Comparison of sequential with intimate coupling of photolysis and biodegradation for benzotriazole

Shunan Shan, Yuting Zhang, Yining Zhang, Lanjun Hui, Wen Shi, Yongming Zhang, Bruce E. Rittmann

《环境科学与工程前沿（英文）》 2017年 第11卷 第6期 doi: 10.1007/s11783-017-0953-3

摘要： Benzotriazole (BTA) is an emerging contaminant that also is a recalcitrant compound. Sequential and intimate coupling of UV-photolysis with biodegradation were investigated for their impacts on BTA removal and mineralization in aerobic batch experiments. Special attention was given to the role of its main photolytic products, which were aminophenol (AP), formic acid (FA), maleic acid (MA), and phenazine (PHZ). Experiments with sequential coupling showed that BTA biodegradation was accelerated by photolytic pretreatment up to 9 min, but BTA biodegradation was slowed with longer photolysis. FA and MA accelerated BTA biodegradation by being labile electron-donor substrates, but AP and PHZ slowed the rate because of inhibition due to their competition for intracellular electron donor. Because more AP and PHZ accumulated with increasing photolysis time, their inhibitory effects began to dominate with longer photolysis time. Intimately coupling photolysis with biodegradation relieved the inhibition effect, because AP and PHZ were quickly biodegraded and did not accumulate, which accentuated the beneficial effect of FA and MA.

关键词： Benzotriazole     Photolysis     Biodegradation     Inhibition     Electron donor    

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A photolysis coefficient for characterizing the response of aqueous constituents to photolysis

David R. HOKANSON,Ke LI,R. Rhodes TRUSSELL

《环境科学与工程前沿（英文）》 2016年 第10卷 第3期   页码 428-437 doi: 10.1007/s11783-015-0780-3

摘要： UV photolysis and UV based advanced oxidation processes (AOPs) are gaining more and more attention for drinking water treatment. Quantum yield ( ) and molar absorption coefficient ( ) are the two critical parameters measuring the effectiveness of photolysis of a compound. The product of the two was proposed as a fundamental measure of a constituent’s amenability to transformation by photolysis. It was shown that this product, named the photolysis coefficient, , can be determined using standard bench tests and captures the properties that govern a constituent’s transformation when exposed to light. The development showed the photolysis coefficient to be equally useful for microbiological, inorganic and organic constituents. Values of calculated by the authors based on quantum yield and molar absorption coefficient data from the literature were summarized. Photolysis coefficients among microorganisms ranged from 8500 to more than 600000 and are far higher than for inorganic and organic compounds, which varied over a range of approximately 10 to 1000 and are much less sensitive to UV photolysis than the microorganisms.

关键词： UV photolysis     disinfection     advanced oxidation     N-nitrosodimethylamine     quantum yield     absorption coefficient    

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Estimation of photolysis half-lives of dyes in a continuous-flow system with the aid of quantitative

Davoud BEIKNEJAD,Mohammad Javad CHAICHI

《环境科学与工程前沿（英文）》 2014年 第8卷 第5期   页码 683-692 doi: 10.1007/s11783-014-0680-y

摘要： In this paper the photolysis half-lives of the model dyes in water solutions and under ultraviolet (UV) radiation were determined by using a continuous-flow spectrophotometric method. A quantitative structure-property relationship (QSPR) study was carried out using 21 descriptors based on different chemometric tools including stepwise multiple linear regression (MLR) and partial least squares (PLS) for the prediction of the photolysis half-life ( ) of dyes. For the selection of test set compounds, a K-means clustering technique was used to classify the entire data set, so that all clusters were properly represented in both training and test sets. The QSPR results obtained with these models show that in MLR-derived model, photolysis half-lives of dyes depended strongly on energy of the highest occupied molecular orbital ( ), largest electron density of an atom in the molecule ( ) and lipophilicity (log ). While in the model derived from PLS, besides aforementioned and descriptors, the molecular surface area ( ), molecular weight ( ), electronegativity ( ), energy of the second highest occupied molecular orbital ( ) and dipole moment ( ) had dominant effects on logt values of dyes. These were applicable for all classes of studied dyes (including monoazo, disazo, oxazine, sulfonephthaleins and derivatives of fluorescein). The results were also assessed for their consistency with findings from other similar studies.

关键词： dye     photolysis half-life     quantitative structure-property relationship     continuous-flow     stepwise multiple linear regression     partial least squares    

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Predictive models on photolysis and photoinduced toxicity of persistent organic chemicals

Qing ZHANG

《环境科学与工程前沿（英文）》 2013年 第7卷 第6期   页码 803-814 doi: 10.1007/s11783-013-0547-7

摘要： Photodegradation is a major abiotic transformation pathway of toxic chemicals in the environment, which in some cases might lead to photoinduced toxicities. The data on photodegradation kinetics and photoinduced toxicities of organic chemicals are essential for their risk assessment. However, the relevant data are only available for a limited number of chemicals, due to the difficulty and high cost of experimental determination. Quantitative structure-activity relationship (QSAR) models that relate photodegradation kinetics or photoinduced toxicity of organic chemicals with their physicochemical properties or molecular structural descriptors may enable simple and fast estimation of their photochemical behaviors. This paper reviews the QSAR models on photodegradation quantum yields and rate constants for toxic organic chemicals in different media including liquid phase, gaseous phase, surfaces of plant leaves, and QSAR models on photoinduced toxicity of organic chemicals to plants, bacteria, and aquatic invertebrates. Further prospects for QSAR model development on photodegradation kinetics and photoinduced toxicity of refractory organic chemicals are proposed.

关键词： quantitative structure-activity relationship (QSAR) models     photodegradation     persistent organic pollutants     environmental media     mechanisms    

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chemical descriptors into quantitative structure-property relationship models for prediction of the photolysis

Yueping BAO, Qiuying HUANG, Wenlong WANG, Jiangjie XU, Fan JIANG, Chenghong FENG

《环境科学与工程前沿（英文）》 2011年 第5卷 第4期   页码 505-511 doi: 10.1007/s11783-011-0318-2

摘要： Quantitative structure-property relationship (QSPR) models were developed for prediction of photolysis half-life ( ) of polychlorinated biphenyls (PCBs) in water under ultraviolet (UV) radiation. Quantum chemical descriptors computed by the PM3 Hamiltonian software were used as independent variables. The cross-validated value for the optimal QSPR model is 0.966, indicating good prediction capability for lg values of PCBs in water. The QSPR results show that the largest negative atomic charge on a carbon atom ( ) and the standard heat of formation (Δ ) have a dominant effect on values of PCBs. Higher values or lower Δ values of the PCBs leads to higher lg values. In addition, the lg values of PCBs increase with the increase in the energy of the highest occupied molecular orbital values. Increasing the largest positive atomic charge on a chlorine atom and the most positive net atomic charge on a hydrogen atom in PCBs leads to the decrease of lg values.

关键词： photolysis     polychlorinated biphenyls (PCBs)     quantitative structure-property relationships (QSPRs)     quantum chemical descriptors    

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Toward better understanding vacuum ultraviolet–iodide induced photolysis via hydrogen peroxide formation

《环境科学与工程前沿（英文）》 2022年 第16卷 第5期 doi: 10.1007/s11783-021-1489-0

摘要：

• UV/VUV/I– induces substantial H2O2 and IO3– formation, but UV/I– does not.

关键词： Vacuum ultraviolet     Hydrogen peroxide     Iodate     Hydroxyl radical     Redox transition    

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Kinetics and mechanisms of reactions for hydrated electron with chlorinated benzenes in aqueous solution

Haixia YUAN,Huxiang PAN,Jin SHI,Hongjing LI,Wenbo DONG

《环境科学与工程前沿（英文）》 2015年 第9卷 第4期   页码 583-590 doi: 10.1007/s11783-014-0691-8

摘要： The reactions between chlorinated benzenes (CBzs) and hydrated electron ( ) were investigated by the electron beam (EB) and laser flash photolysis (LFP) experiments. Under the EB irradiation, the effects of irradiation dose, initial concentration and the number of Cl atoms on the removal efficiencies were further examined. At 10 kGy, the removal efficiencies of mono-CB, 1,3-diCB, 1,2-diCB and 1,4-diCB were 41.2%, 87.2%, 84.0%, and 84.1%, respectively. While irradiation dose was 50 kGy, the removal efficiencies increased to 47.4%, 95.8%, 95.0%, and 95.2%, respectively. Irradiation of CBzs solutions has shown that the higher the initial concentration, the lower the percentage of CBzs removal. In addition to this, the dechlorination efficiencies of 1,2-dichlorobenzene (1,2-diCB), 1,3-dichlorobenzene (1,3-diCB) and 1,4-dichlorobenzene (1,4-diCB) were much higher than that of chlorobenzene (mono-CB). The kinetics of the reactions was achieved with nanosecond LFP. The rate constants of second-order reaction between with mono-CB, 1,2-diCB, 1,3-diCB and 1,4-diCB were (5.3±0.4) × 10 , (4.76±0.1) × 10 , (1.01±0.1) × 10 and (3.29±0.2) × 10 L·mol ·s , respectively. Density functional theory (DFT) calculations were performed to determine the optical properties of unstable CBzs anion radicals, and the main absorption peaks lied in the range of 300–550 nm. The primary reaction pathway of CBzs with was gradual dechlorination, and the major products were Cl and benzene (CBzs(-Cl )). Furthermore, biphenyl (or chlorobiphenyl) was observed during the LFP, which was probably formed by recombination of benzene radicals.

关键词： chlorinated benzenes     hydrated electron     electron beam     laser flash photolysis    

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Photolysis and photooxidation of typical gaseous VOCs by UV Irradiation: Removal performance and mechanisms

In-Sun Kang, Jinying Xi, Hong-Ying Hu

《环境科学与工程前沿（英文）》 2018年 第12卷 第3期 doi: 10.1007/s11783-018-1032-0

摘要： Photodegradation by ultraviolet irradiation (UV) is increasingly applied in volatile organic compound (VOC) and odor gas treatments. In this study, 27 typical VOCs, including 11 hydrocarbons and 16 hydrocarbon derivatives, at 150–200 ppm in air and nitrogen gas were treated by a laboratory-scale UV reactor with 185/254 nm irradiation to systematically investigate their removal and conversion by UV irradiation. For the tested 27 VOCs, the VOC removal efficiencies in air were within the range of 13%–97% (with an average of 80%) at a retention time of 53 s, which showed a moderate positive correlation with the molecular weight of the VOCs ( = 0.53). The respective contributions of photolysis and photooxidation to VOC removal were identified for each VOC. According to the CO results, the mineralization rate of the tested VOCs was within the range of 9%–90%, with an average of 41% and were negatively correlated to the molecular weight ( = 0.63). Many of the tested VOCs exhibited high concentration particulate matters in the off-gases with a 3–283 mg/m PM range and a 2–40 mg/m PM range. The carbon balance of each VOC during UV irradiation was analyzed based on the VOC, CO and PM concentrations. Certain organic intermediates and 23–218 ppm ozone were also identified in the off-gases. Although the UV technique exhibited a high VOC removal efficiency, its drawbacks, specifically low mineralization, particulate matters production, and ozone emission, must be considered prior to its application in VOC gas treatments.

关键词： VOCs     UV photodegradation     Particulate matters     Ozone    

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Treatment technologies for aqueous perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA)

Chad D. VECITIS, Hyunwoong PARK, Jie CHENG, Brian T. MADER, Michael R. HOFFMANN

《环境科学与工程前沿（英文）》 2009年 第3卷 第2期   页码 129-151 doi: 10.1007/s11783-009-0022-7

摘要： Fluorochemicals (FCs) are oxidatively recalcitrant, environmentally persistent, and resistant to most conventional treatment technologies. FCs have unique physiochemical properties derived from fluorine which is the most electronegative element. Perfluorooctanesulfonate (PFOS), and perfluorooctanoate (PFOA) have been detected globally in the hydrosphere, atmosphere and biosphere. Reducing treatment technologies such as reverses osmosis, nano-filtration and activated carbon can? remove ?FCs ?from ?water. ?However,? incineration ?of the concentrated waste is required for complete FC destruction. Recently, a number of alternative technologies for FC decomposition have been reported. The FC degradation technologies span a wide range of chemical processes including direct photolysis, photocatalytic oxidation, photochemical oxidation, photochemical reduction, thermally-induced reduction, and sonochemical pyrolysis. This paper reviews these FC degradation technologies in terms of kinetics, mechanism, energetic cost, and applicability. The optimal PFOS/PFOA treatment method is strongly dependent upon the FC concentration, background organic and metal concentration, and available degradation time.

关键词： fluorochemical (FC) degradation technologies     perfluoroctanesulfonate (PFOS)     perfluorooctanoate     (PFOA)     oxidation     reduction     photolysis     thermolysis     review    

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标题 作者 时间 类型 操作

Benzene degradation in waste gas by photolysis and photolysis-ozonation: experiments and modeling

Fariba Mahmoudkhani, Maryam Rezaei, Vahid Asili, Mahsasadat Atyabi, Elena Vaisman, Cooper H. Langford, Alex De Visscher

期刊论文

Ambient photolysis frequency of NO

Qi Zou,Keding Lu,Yusheng Wu,Yudong Yang,Zhuofei Du,Min Hu

期刊论文

Comparison of sequential with intimate coupling of photolysis and biodegradation for benzotriazole

Shunan Shan, Yuting Zhang, Yining Zhang, Lanjun Hui, Wen Shi, Yongming Zhang, Bruce E. Rittmann

期刊论文

A photolysis coefficient for characterizing the response of aqueous constituents to photolysis

David R. HOKANSON,Ke LI,R. Rhodes TRUSSELL

期刊论文

Estimation of photolysis half-lives of dyes in a continuous-flow system with the aid of quantitative

Davoud BEIKNEJAD,Mohammad Javad CHAICHI

期刊论文

Predictive models on photolysis and photoinduced toxicity of persistent organic chemicals

Qing ZHANG

期刊论文

chemical descriptors into quantitative structure-property relationship models for prediction of the photolysis

Yueping BAO, Qiuying HUANG, Wenlong WANG, Jiangjie XU, Fan JIANG, Chenghong FENG

期刊论文

Toward better understanding vacuum ultraviolet–iodide induced photolysis via hydrogen peroxide formation

期刊论文

Kinetics and mechanisms of reactions for hydrated electron with chlorinated benzenes in aqueous solution

Haixia YUAN,Huxiang PAN,Jin SHI,Hongjing LI,Wenbo DONG

期刊论文

Photolysis and photooxidation of typical gaseous VOCs by UV Irradiation: Removal performance and mechanisms

In-Sun Kang, Jinying Xi, Hong-Ying Hu

期刊论文

Treatment technologies for aqueous perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA)

Chad D. VECITIS, Hyunwoong PARK, Jie CHENG, Brian T. MADER, Michael R. HOFFMANN

期刊论文