1
|
Lastre-Acosta AM, Rocha CM, Mendes MA, Teixeira ACSC, do Nascimento CAO. Sunlight-driven environmental photodegradation of 2-chlorobiphenyl (PCB-1) in surface waters: kinetic study and mathematical simulations. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:42231-42241. [PMID: 34677777 DOI: 10.1007/s11356-021-17010-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 10/08/2021] [Indexed: 06/13/2023]
Abstract
Polychlorinated biphenyls (PCBs) are a family of highly toxic, resistant, and persistent organic pollutants, among which 2-chlorobiphenyl (PCB-1) is one of the simplest. Most studies on PCBs' photochemistry are limited to their direct photolysis, while the important role of reactive photo-induced species (RPS) (hydroxyl radicals, HO●; singlet oxygen, 1O2; and triplet excited states of chromophoric dissolved organic matter, 3CDOM*) in removing PCBs in natural waters through indirect photolysis has not yet been evaluated. In this work, the rate constants of the reactions between aqueous PCB-1 and RPS were obtained under simulated solar radiation (450-W Xenon lamp and an AM 1.5 global filter) by competition kinetics, and the effects of the initial pollutant concentration and the physicochemical characteristics of the water were investigated. The direct photolysis quantum yield of PCB-1 in the range 290-800 nm was found as 1.60 × 10-2 mol Einstein-1. The value of kPCB-1,HO● = (6.80 ± 0.09) × 109 L mol-1 s-1 is in good agreement with the literature. For 1O2, kPCB-1,1O2 = (1.13 ± 0.20) × 106 L mol-1 s-1, while for 3CDOM*, kPCB-1,3CBBP* = (2.44 ± 0.04) × 109 L mol-1 s-1 and kPCB-1,3AQ2S* = (3.36 ± 0.04) × 109 L mol-1 s-1 were obtained using 4-benzoylbenzoic acid (CBBP) and anthraquinone-2-sulfonate (AQ2S) as CDOM proxies, respectively. These results show that the main pathways involved in PCB-1 photodegradation are the reactions with HO● and 3CDOM* together with direct photolysis. In addition, the photodegradation of PCB-1 in sunlit waters was simulated using the kinetic model APEX (Aqueous Photochemistry of Environmentally Occurring Xenobiotics). According to simulations, a greater influence of the water depth and dissolved organic carbon concentration (DOC) on the persistence of PCB-1 is expected, being only slightly influenced by the concentrations of nitrite, nitrate, and bicarbonate. Finally, based on data reported for Brazilian surface waters, the average half-life (t1/2) of PCB-1 is expected to vary from 2 to 14 days. In particular, the t1/2 in the Paranapanema River is estimated at 7 to 8 days.
Collapse
Affiliation(s)
- Arlen Mabel Lastre-Acosta
- Research Group in Advanced Oxidation Processes (AdOx), Chemical Systems Engineering Center, Department of Chemical Engineering, University of São Paulo, Av. Prof. Luciano Gualberto, tr. 3, 380, São Paulo, SP, Brazil.
| | - Carolina Mendes Rocha
- Research Group in Advanced Oxidation Processes (AdOx), Chemical Systems Engineering Center, Department of Chemical Engineering, University of São Paulo, Av. Prof. Luciano Gualberto, tr. 3, 380, São Paulo, SP, Brazil
| | - Maria Anita Mendes
- Dempster MS Lab, Chemical Systems Engineering Center, Department of Chemical Engineering, University of Sao Paulo, Av. Prof. Luciano Gualberto, tr. 3, 380, São Paulo, SP, Brazil
| | - Antonio Carlos Silva Costa Teixeira
- Research Group in Advanced Oxidation Processes (AdOx), Chemical Systems Engineering Center, Department of Chemical Engineering, University of São Paulo, Av. Prof. Luciano Gualberto, tr. 3, 380, São Paulo, SP, Brazil
| | - Claudio Augusto Oller do Nascimento
- Dempster MS Lab, Chemical Systems Engineering Center, Department of Chemical Engineering, University of Sao Paulo, Av. Prof. Luciano Gualberto, tr. 3, 380, São Paulo, SP, Brazil
| |
Collapse
|
2
|
Huang C, Zeng Y, Luo X, Ren Z, Tian Y, Mai B. Comprehensive exploration of the ultraviolet degradation of polychlorinated biphenyls in different media. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 755:142590. [PMID: 33059143 DOI: 10.1016/j.scitotenv.2020.142590] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 09/21/2020] [Accepted: 09/22/2020] [Indexed: 06/11/2023]
Abstract
As one of the most important natural transformation processes, photodegradation deserves more attention and research. In the current work, we comprehensively explored the photochemical behaviors of polychlorinated biphenyls (PCBs) in n-hexane (Hex), methanol/water, and silica gel under UV-irradiation. Photodegradation rates were found to be faster in methanol/water than in Hex. All of the three photochemical systems generated sigmatropic rearrangement products. The dominant photodegradation pathways were dechlorination, dechlorination/methoxylation/hydroxylation, and hydroxylation in Hex, methanol/water, and silica gel systems, respectively. Furthermore, some new photodegradation products, such as polychlorinated biphenyl ethers, polychlorinated dibenzofurans, polychlorinated biphenylenes, and methylated polychlorinated biphenyls, are reported for the first time. These findings would provide deeper insight into the phototransformation behaviors of PCBs.
Collapse
Affiliation(s)
- Chenchen Huang
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yanhong Zeng
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
| | - Xiaojun Luo
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Zihe Ren
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yankuan Tian
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Bixian Mai
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| |
Collapse
|
3
|
Jalili-Jahani N, Fatehi A, Zeraatkar E. PLS and N-PLS based MIA-QSPR modeling of the photodegradation half-lives for polychlorinated biphenyl congeners. RSC Adv 2020; 10:33753-33761. [PMID: 35519039 PMCID: PMC9056733 DOI: 10.1039/d0ra05231k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Accepted: 07/27/2020] [Indexed: 11/21/2022] Open
Abstract
Multivariate image analysis as a useful tool in environmental risk assessment studies.
Collapse
Affiliation(s)
| | - Azadeh Fatehi
- Green Land Shiraz Eksir Chemical and Agricultural Industries Company
- Shiraz
- Iran
| | | |
Collapse
|
4
|
Karaca G, Cindoruk SS, Tasdemir Y. Migration of polycyclic aromatic hydrocarbons (PAHs) in urban treatment sludge to the air during PAH removal applications. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION (1995) 2014; 64:568-577. [PMID: 24941705 DOI: 10.1080/10962247.2013.874380] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In the present study, the amounts of polycylic aromatic hydrocarbons (PAHs) penetrating into air during PAH removal applications from the urban treatment sludge were investigated. The effects of the temperature, photocatalyst type, and dose on the PAH removal efficiencies and PAH evaporation were explained. The sludge samples were taken from an urban wastewater treatment plant located in the city of Bursa, with 585,000 equivalent population. The ultraviolet C (UV-C) light of 254 nm wavelength was used within the UV applications performed on a specially designed setup. Internal air of the setup was vacuumed through polyurethane foam (PUF) columns in order to collect the evaporated PAHs from the sludge during the PAH removal applications. All experiments were performed with three repetitions. The PAH concentrations were measured by gas chromatography-mass spectrometry (GC-MS). It was observed that the amounts of PAHs penetrating into the air were increased with increase of temperature, and more than 80% of PAHs migrated to the air consisted of 3-ring compounds during the UV and UV-diethylamine (DEA) experiments at 38 and 53 degrees C. It was determined that 40% decrease was ensured in sigma12 (total of 12) PAH amounts with UV application and 13% of PAHs in sludge penetrated into the air. In the UV-TiO2 applications, a maximum 80% of sigma12 PAH removal was obtained by adding 0.5% TiO2 of dry weight of sludge. The quantity of PAH penetrating into air did not exceed 15%. UV-TiO2 applications ensured high levels of PAH removal in the sludge and also reduced the quantity of PAH penetrating into the air. Within the scope of the samples added with DEA, there was no increase in PAH removal efficiencies and the penetration of PAHs into air was not decreased. In light of these data, it was concluded that UV-TiO2 application is the most suitable PAH removal alternative that restricts the convection of PAH pollution.
Collapse
|
5
|
Izadifard M, Achari G, Langford CH. The pathway of dechlorination of PCB congener by a photochemical chain process in 2-propanol: the role of medium and quenching. CHEMOSPHERE 2008; 73:1328-1334. [PMID: 18721997 DOI: 10.1016/j.chemosphere.2008.07.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2008] [Revised: 07/01/2008] [Accepted: 07/02/2008] [Indexed: 05/26/2023]
Abstract
As part of a program aimed at developing a field process for cleanup of PCB contaminated soils using photochemistry in basic 2-propanol, additional details of the dechlorination pathway are presented. The mechanism involves a chain reaction with both homolytic photochemical C-Cl bond fission and electron transfer steps producing PCB anion radicals. Kinetics of dechlorination of various congeners show patterns of relative rates associated with the basic 2-propanol medium that are not found in other media because both electron transfer and photochemical homolysis steps determine overall rates of dechlorination and govern the pathways and relative concentrations of intermediates. The electron transfer steps display opposite structure-reactivity correlations to the photo-homolysis, C-Cl bond fission steps. Oxygen quenching is shown to differentially affect both types of steps. In contrast to the suggestion that inter system crossing can be highly efficient with reaction originating from a PCB triplet, oxygen quenching data suggest that a significant minimum of the quantum yield is non-quenchable, presumably because of a reaction path from the PCB singlet. This may help to explain why exclusion of air is not entirely necessary in practice.
Collapse
Affiliation(s)
- Maryam Izadifard
- Department of Chemistry, University of Calgary, 2500 University Dr. NW Calgary, AB, Canada T2N 1N4
| | | | | |
Collapse
|
6
|
Li X, Fang L, Huang J, Yu G. Photolysis of mono- through deca-chlorinated biphenyls by ultraviolet irradiation in n-hexane and quantitative structure-property relationship analysis. J Environ Sci (China) 2008; 20:753-759. [PMID: 18763572 DOI: 10.1016/s1001-0742(08)62123-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The photolysis of 16 polychlorinated biphenyls (PCBs) (including mono- through deca-chlorinated) in n-hexane was investigated under ultraviolet irradiation using a 500-W high-pressure mercury lamp. Photolysis of PCBs follows pseudo-first-order reaction kinetics, with photolysis rate constants ranging between 0.0011 s(-1) for PCB-52 and 0.0574 s(-1) for PCB-118. The degradation rates of PCBs by high-pressure mercury lamp irradiation were remarkably independent with respect to the degree of chlorination. Furthermore, partial least squares (PLS) models were developed to provide insight into which aspect of the molecular structure influenced PCB photolysis rate constants. It was found that the photolysis rates of PCBs increased with an increase in the net charge on the carbon atom (qc), (E(LUMO)-E(HOMO))2, and the Y-axis dipole moment (mu(y)) values, or the decrease in the energy of the second highest occupied molecular orbital (E(HOMO-1)), energy of the lowest unoccupied molecular orbital (E(LUMO)), E(LUMO) + E(HOMO), E(LUMO)--E(HOMO), most positive atomic charge (q+), and the twist angle of the chlorine atom (TA) values.
Collapse
Affiliation(s)
- Xue Li
- POPs Research Centre, Department of Environmental Science and Engineering, Tsinghua University, Beijing 100084, China.
| | | | | | | |
Collapse
|
7
|
Niu JF, Yang ZF, Shen ZY, Wang LL. QSPRs for the prediction of photodegradation half-life of PCBs in n-hexane. SAR AND QSAR IN ENVIRONMENTAL RESEARCH 2006; 17:173-82. [PMID: 16644556 DOI: 10.1080/10659360600636170] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
By partial least squares (PLS) regression analysis, a quantitative structure-property relationship (QSPR) model was developed for photodegradation half-life (t1/2) of polychlorinated biphenyls (PCBs) in n-hexane solution under UV irradiation. Quantum chemical descriptors computed by PM3 Hamiltonian were used as predictor variables. The cross-validated value for the optimal QSPR model was 0.589, indicating good predictive capability for log t1/2 values of PCBs in n-hexane. The QSPR results show that standard heat of formation (DeltaHf), total energy (TE), and molecular weight (Mw) have dominant effect on t1/2 values of PCBs in n-hexane. Increasing DeltaHf and TE values or decreasing Mw values of the PCBs leads to decrease of log t1/2 values. In addition, increasing the largest negative atomic charge on a carbon atom and dipole moment of the PCBs leads to decrease of log t1/2 values.
Collapse
Affiliation(s)
- J F Niu
- State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, P. R. China.
| | | | | | | |
Collapse
|