Simulation of steady-state radical concentration and reaction kinetics of MC-LR degradation by UV/hypochlorous acid based on kintecus model
FAN Yongjie1,2,, ZHENG Yuyi1,2,3,4, WANG Feifeng1,2,3,4, WU Chunshan1,2,3,4, SUN Qiyuan1,2,3,4,, 1.College of Environmental Science and Engineering, Fujian Normal University, Fuzhou 350007, China 2.Institute of Environmental Science, Fujian Normal University, Fuzhou 350007, China 3.Fujian Key Laboratory of Pollution Control and Resource Reuse, Fuzhou 350007, China 4.Research Center of Urban Waste Resource Recycling Technology and Management Engineering in Universities of Fujian Province, Fuzhou 350007, China
Abstract:Microcystin-LR (MC-LR) produced by the metabolism of cyanobacteria will contaminate drinking water sources and threaten the human health. UV/Hypochlorous acid technology can generate strong oxidizing substances such as chlorine radicals (Cl·) and hydroxyl radicals (HO·) to degrade MC-LR. However, the optimal parameters of this technology have not yet been known, and the reported experimental results can only provide some parameters. Thus, numerical simulation is urgently needed to determine more important parameters. Therefore, the kintecus chemical kinetic model was used to simulate the previously reported experimental data and predict the unreported data. The results showed that the predicted values of the model were consistent with the experimental values, and the errors were within 1.5 times. When the pH was 6, the UV/hypochlorous acid technology had the best performance on MC-LR degradation, and the degradation rate could reach 90% within 7 minutes. The steady-state concentrations of HO· and Cl· were 6.59×10?14 mol·L?1 and 1.22×10?14 mol·L?1, respectively, which were in accordance with the experimental results of the original literatures (7.89×10?14 mol·L?1, 0.93×10?14 mol·L?1). After the concentration of hypochlorous acid exceeded 40 μmol·L?1, the degradation rate remained constant. When the wavelength of ultraviolet light increased from 257.7 nm to 301.2 nm, the apparent degradation rate constant of MC-LR decreased from 5.07×10?3 s?1 to 4.69×10?3 s?1, a decrease of 7.5%. When the wavelength was 257.7 nm and the pH increased from 6 to 8, the apparent degradation rate dropped from 5.07×10?3 s?1 to 3.84×10?3 s?1 with a decrease rate of 24%. Therefore, the effect of pH on the degradation efficiency was greater than that of ultraviolet light wavelength. Key words:kintecus model/ ultraviolet/hypochlorous acid/ microcystin-LR/ steady-state concentration/ kinetics.
图1pH对HO·和Cl·稳态浓度的影响 Figure1.Effect of pH on HO· and Cl· steady-state concentrations
图7光源波长对体系内HClO组分光解速率常数及自由基稳态浓度的影响 Figure7.Influence of the wavelength of the light source on the photolysis rate constant of the HClO component in the system and the steady-state concentration of radicals
下载: 导出CSV 表4不同HClO投加量下HO·和Cl·稳态浓度的变化 Table4.Changes of HO· and Cl· steady-state concentrations at different chlorine doses
HClO投加量/ (μmol·L?1)
自由基稳态浓度/(mol·L?1)
HClO投加量/ (μmol·L?1)
自由基稳态浓度/(mol·L?1)
HO·
Cl·
HO·
Cl·
1
3.41×10?17
2.00×10?17
20
1.06×10?14
2.30×10?15
2
1.32×10?16
6.92×10?17
30
1.62×10?14
3.45×10?15
5
1.12×10?15
3.31×10?16
42
2.24×10?14
4.94×10?15
12
4.26×10?15
1.07×10?15
60
3.05×10?14
7.43×10?15
HClO投加量/ (μmol·L?1)
自由基稳态浓度/(mol·L?1)
HClO投加量/ (μmol·L?1)
自由基稳态浓度/(mol·L?1)
HO·
Cl·
HO·
Cl·
1
3.41×10?17
2.00×10?17
20
1.06×10?14
2.30×10?15
2
1.32×10?16
6.92×10?17
30
1.62×10?14
3.45×10?15
5
1.12×10?15
3.31×10?16
42
2.24×10?14
4.94×10?15
12
4.26×10?15
1.07×10?15
60
3.05×10?14
7.43×10?15
下载: 导出CSV 表5不同波长光源下HClO/ClO?的量子产率和摩尔吸收系数[24] Table5.Quantum yield and molar absorption coefficient of HClO/ClO? under different wavelength light sources
BULLERJAHN G S, MCKAY R M, DAVIS T W, et al. Global solutions to regional problems: Collecting global expertise to address the problem of harmful cyanobacterial blooms: A lake erie case study[J]. Harmful Algae, 2016, 54: 223-238. doi: 10.1016/j.hal.2016.01.003
[2]
CATHERINE Q, SUSANNA W, ISIDORA E S, et al. A review of current knowledge on toxic benthic freshwater cyanobacteria: Ecology, toxin production and risk management[J]. Water Research, 2013, 47(15): 5464-5479. doi: 10.1016/j.watres.2013.06.042
[3]
HARKE M J, STEFFEN M M, GOBLER C J, et al. A review of the global ecology, genomics, and biogeography of the toxic cyanobacterium, microcystis spp[J]. Harmful Algae, 2016, 54: 4-20. doi: 10.1016/j.hal.2015.12.007
[4]
LIAO C H, KANG S F, WU F A. Hydroxyl radical scavenging role of chloride and bicarbonate ions in the H2O2/UV process[J]. Chemosphere, 2001, 44: 1193-1200. doi: 10.1016/S0045-6535(00)00278-2
[5]
FANG J Y, FU Y, SHANG C. The roles of reactive species in micropollutant degradation in the UV/free chlorine system[J]. Environmental Science and Technology, 2014, 48(3): 1859-1868. doi: 10.1021/es4036094
[6]
WATTS M J, HOFMANN R, RCDSENFELDT E J. Low-pressure UV/Cl2 for advanced oxidation of taste and odor[J]. Journal American Water Works Association, 2012, 104(1): 58-65. doi: 10.5942/jawwa.2012.104.0006
[7]
REMUCAL C K, MANLEY D. Emerging investigators series: The efficacy of chlorine photolysis as an advanced oxidation process for drinking water treatment[J]. Environmental Science: Water Research and Technology, 2016, 2(4): 565-579. doi: 10.1039/C6EW00029K
[8]
WANG A Q, LIN Y L, XU B, et al. Kinetics and modeling of iodoform degradation during UV/chlorine advanced oxidation process[J]. Chemical Engineering Journal, 2017, 323: 312-319. doi: 10.1016/j.cej.2017.04.061
[9]
ZHANG X R, HE J, LEI Y, et al. Combining solar irradiation with chlorination enhances the photochemical decomposition of microcystin-LR[J]. Water Research, 2019, 159: 324-332. doi: 10.1016/j.watres.2019.05.030
[10]
NOWELL L, HOIGNé J. Photolysis of aqueous chlorine at sunlight and ultraviolet wavelengths: II. hydroxyl radical production[J]. Water Research, 1992, 26(5): 599-605. doi: 10.1016/0043-1354(92)90233-T
[11]
WATTS M J, LINDEN K G. Chlorine photolysis and subsequent OH radical production during UV treatment of chlorinated water[J]. Water Research, 2007, 41(13): 2871-2878. doi: 10.1016/j.watres.2007.03.032
[12]
KL?NING U K, WOLFF T. Laser flash photolysis of HCIO, CIO-, HBrO, and BrO- in aqueous solution[J]. Berichte der Bunsengesellschaft für Physikalische Chemie, 1985, 89(3): 243-245.
[13]
NETA P, HUIE R, ROSS A B. Rate constants for reactions of inorganic radicals in aqueous solution[J]. Physical and Chemical Reference Data, 1988, 17(3): 1027-1284. doi: 10.1063/1.555808
[14]
JAYSON G G, PARSONS B J, SWALLOW A J. Some simple, highly reactive, inorganic chlorine derivatives in aqueous solution[J]. Journal of the Chemical Society-Faraday Transactions 1: Physical Chemistry in Condensed Phases, 1973, 69: 1597-1607.
[15]
HUANG K, MACKAY A A. Microcystin-LR degradation kinetics during chlorination: Role of water quality conditions[J]. Water Research, 2020, 185: 116305. doi: 10.1016/j.watres.2020.116305
[16]
CHINTALAPATI P, MOHSENI M. Degradation of cyanotoxin microcystin-LR in synthetic and natural waters by chemical-free UV/VUV radiation[J]. Journal of Hazardous Materials, 2020, 381(5): 120921.
[17]
BUXTON G V, GREENSTOCK C L, HELMAN W P, et al. Critical review of rate constants for reactions of hydrated electrons, hydrogen atoms and hydroxyl radicals (OH·/O·-) in aqueous solution[J]. Journal of Physical and Chemical Reference Data, 1988, 17(2): 513. doi: 10.1063/1.555805
[18]
BULMAN D M, MEZYK S P, REMUCAL C K. The impact of pH and irradiation wavelength on the production of reactive oxidants during chlorine photolysis[J]. Environmental Science and Technology, 2019, 53(8): 4450-4459. doi: 10.1021/acs.est.8b07225
[19]
ACERO J L, RODRIGUEZ E, MERILUOTO J. Kinetics of reactions between chlorine and the cyanobacterial toxins microcystins[J]. Water Research, 2005, 39(8): 1628-1638. doi: 10.1016/j.watres.2005.01.022
[20]
CHUANG Y H, CHEN S, CHINN C J, et al. Comparing the UV/monochloramine and UV/free chlorine advanced oxidation processes (AOPs) to the UV/hydrogen peroxide AOP under scenarios relevant to potable reuse[J]. Environmental Science and Technology, 2017, 51(23): 13859-13868. doi: 10.1021/acs.est.7b03570
[21]
CARRELL M J. The acid ionization constant of HOCl from 5 to 35°[J]. Journal of Physical Chemistry, 1966, 70(12): 3798-3805. doi: 10.1021/j100884a007
[22]
KWON M, YOON Y, KIM S, et al. Removal of sulfamethoxazole, ibuprofen and nitrobenzene by UV and UV/chlorine processes: A comparative evaluation of 275nm LED-UV and 254nm LP-UV[J]. Science of the Total Environment, 2018, 637-638: 1351-1357. doi: 10.1016/j.scitotenv.2018.05.080
[23]
FENG Y G, SMITH D W, BOLTON J R. Photolysis of aqueous free chlorine species (HOCl and OCl-) with 254 nm ultraviolet light[J]. Journal of Environmental Engineering and Science, 2007, 6(3): 277-284. doi: 10.1139/s06-052
[24]
YIN R, LING L, SHANG C. Wavelength-dependent chlorine photolysis and subsequent radical production using UV-LEDs as light sources[J]. Water Research, 2018, 142: 452-458. doi: 10.1016/j.watres.2018.06.018
[25]
BUXTON G V, SUBHANI M S. Radiation chemistry and photochemistry of oxychlorine ions. Part 2. Photodecomposition of aqueous solutions of hypochlorite ions[J]. Journal of the Chemical Society-Faraday Transactions 1: Physical Chemistry in Condensed Phases, 1972, 68: 958-969.
[26]
JIN J, EL-DIN M G, BOLTON J R. Assessment of the UV/Chlorine process as an advanced oxidation process[J]. Water Research, 2011, 45(4): 1890-1896. doi: 10.1016/j.watres.2010.12.008
[27]
ZHANG X R, HE J, XIAO S, et al. Elimination kinetics and detoxification mechanisms of microcystin-LR during UV/chlorine process[J]. Chemosphere, 2019, 214: 702-709. doi: 10.1016/j.chemosphere.2018.09.162
[28]
MARíN A, TUDELA J A, GARRIDO Y, et al. Chlorinated wash water and pH regulators affect chlorine gas emission and disinfection by-products[J]. Innovative Food Science and Emerging Technologies, 2020, 66: 102533. doi: 10.1016/j.ifset.2020.102533
[29]
XIE G, HU X, DU Y, et al. Light-driven breakdown of microcystin-LR in water: A critical review[J]. Chemical Engineering Journal, 2021, 417: 129244.
[30]
WU Z, CHEN C, ZHU B Z, et al. Reactive nitrogen species are also involved in the transformation of micropollutants by the UV/monochloramine process[J]. Environmental Science and Technology, 2019, 53(19): 11142-11152. doi: 10.1021/acs.est.9b01212
[31]
YIN R, BLATCHLEY E R, SHANG C. UV photolysis of mono- and dichloramine using UV-LEDs as radiation sources: Photodecay rates and radical concentrations[J]. Environmental Science and Technology, 2020, 54(13): 8420-8429. doi: 10.1021/acs.est.0c01639
[32]
MEREL S, LEBOT B, CLEMENT M, et al. Ms identification of microcystin-LR chlorination by-products[J]. Chemosphere, 2009, 74(6): 832-839. doi: 10.1016/j.chemosphere.2008.10.024
[33]
ZHANG X R, LI J, YANG J Y, et al. Chlorine/UV process for decomposition and detoxification of microcystin-LR[J]. Environmental Science and Technology, 2016, 50(14): 7671-7678. doi: 10.1021/acs.est.6b02009
1.College of Environmental Science and Engineering, Fujian Normal University, Fuzhou 350007, China 2.Institute of Environmental Science, Fujian Normal University, Fuzhou 350007, China 3.Fujian Key Laboratory of Pollution Control and Resource Reuse, Fuzhou 350007, China 4.Research Center of Urban Waste Resource Recycling Technology and Management Engineering in Universities of Fujian Province, Fuzhou 350007, China Received Date: 2021-04-12 Accepted Date: 2021-07-01 Available Online: 2021-09-15 Keywords:kintecus model/ ultraviolet/hypochlorous acid/ microcystin-LR/ steady-state concentration/ kinetics Abstract:Microcystin-LR (MC-LR) produced by the metabolism of cyanobacteria will contaminate drinking water sources and threaten the human health. UV/Hypochlorous acid technology can generate strong oxidizing substances such as chlorine radicals (Cl·) and hydroxyl radicals (HO·) to degrade MC-LR. However, the optimal parameters of this technology have not yet been known, and the reported experimental results can only provide some parameters. Thus, numerical simulation is urgently needed to determine more important parameters. Therefore, the kintecus chemical kinetic model was used to simulate the previously reported experimental data and predict the unreported data. The results showed that the predicted values of the model were consistent with the experimental values, and the errors were within 1.5 times. When the pH was 6, the UV/hypochlorous acid technology had the best performance on MC-LR degradation, and the degradation rate could reach 90% within 7 minutes. The steady-state concentrations of HO· and Cl· were 6.59×10?14 mol·L?1 and 1.22×10?14 mol·L?1, respectively, which were in accordance with the experimental results of the original literatures (7.89×10?14 mol·L?1, 0.93×10?14 mol·L?1). After the concentration of hypochlorous acid exceeded 40 μmol·L?1, the degradation rate remained constant. When the wavelength of ultraviolet light increased from 257.7 nm to 301.2 nm, the apparent degradation rate constant of MC-LR decreased from 5.07×10?3 s?1 to 4.69×10?3 s?1, a decrease of 7.5%. When the wavelength was 257.7 nm and the pH increased from 6 to 8, the apparent degradation rate dropped from 5.07×10?3 s?1 to 3.84×10?3 s?1 with a decrease rate of 24%. Therefore, the effect of pH on the degradation efficiency was greater than that of ultraviolet light wavelength.
下载: 
点击查看大图
