真空紫外光解SO_3~(2-)高效还原降解全氟辛烷磺酸
|
摘要
为消除全氟辛烷磺酸(PFOS)对环境水体带来的不利影响,采用真空紫外(VUV)光解SO_3~(2-)产生水合电子(e_(aq))还原降解PFOS。结果表明,在溶液初始pH为10.59,PFOS为20.0μmol/L,SO_3~(2-)为10.0mmol/L的条件下,反应180min,PFOS的脱氟率为53.5%,高于相同条件下紫外光解SO_3~(2-)体系(40.2%),通过刃天青探针实验证实与体系e_(aq)的生成量有关。动力学分析表明,PFOS脱氟满足平行指数动力学(PEK)模型,其快反应与慢反应分别对应于PFOS支链与直链异构体的降解。液相色谱—串联质谱(LC—MS/MS)监测发现,PFOS降解主要中间产物为短链全氟羧酸(PFCAs),且全氟丙酸(PFPrA)和全氟丁酸(PFBA)浓度较高,表明PFOS在e_(aq)的进攻下除了直接脱除α位氟原子及发生端基断裂外,还能通过中间碳碳键断裂的方式进行降解。
Degradation of perfluorooctane sulfonate(PFOS)in aqueous solution by hydrated electrons(e-aq)mediated reduction was researched in vacuum ultraviolet(VUV)/sulfite(SO_3~(2-))system for eliminating its adverse effect.Under the conditions of pH 10.59,20.0μmol/L PFOS and 10.0 mmol/L SO_3~(2-),the defluorination efficiency of PFOS was 53.5%,which was higher than that in UV/SO_3~(2-) system.The e-aqproduction had strong effect on PFOS defluorination confirmed by a fluorogenic reaction using resazurin as probe.Experimental results demonstrated that the defluorination of PFOS followed the parallel exponential kinetics(PEK)model.The fast and slow exponential processes were assigned to the degradation of branched PFOS and linear PFOS,respectively.Accompanying the reduction of PFOS,short-chain perfluorocarboxylic acids especially pentafluoropropionic acid(PFPrA)and heptafluorobutyric acid(PFBA)were detected.It indicated that e-aqinduced degradation pathway of PFOS involved defluorination,desulfonation,and centermost C—C bond scission in a SO_3~(2-)-mediated VUV photolysis system.
Degradation of perfluorooctane sulfonate(PFOS)in aqueous solution by hydrated electrons(e-aq)mediated reduction was researched in vacuum ultraviolet(VUV)/sulfite(SO_3~(2-))system for eliminating its adverse effect.Under the conditions of pH 10.59,20.0μmol/L PFOS and 10.0 mmol/L SO_3~(2-),the defluorination efficiency of PFOS was 53.5%,which was higher than that in UV/SO_3~(2-) system.The e-aqproduction had strong effect on PFOS defluorination confirmed by a fluorogenic reaction using resazurin as probe.Experimental results demonstrated that the defluorination of PFOS followed the parallel exponential kinetics(PEK)model.The fast and slow exponential processes were assigned to the degradation of branched PFOS and linear PFOS,respectively.Accompanying the reduction of PFOS,short-chain perfluorocarboxylic acids especially pentafluoropropionic acid(PFPrA)and heptafluorobutyric acid(PFBA)were detected.It indicated that e-aqinduced degradation pathway of PFOS involved defluorination,desulfonation,and centermost C—C bond scission in a SO_3~(2-)-mediated VUV photolysis system.
引文
[1]OLSEN G W,BURRIS J M,MANDEL J H,et al.Serum perfluorooctane sulfonate and hepatic and lipid clinical chemistry tests in fluorochamical production employees[J].Journal of Occupational and Environmental Medicine,1999,41(9):799-806.
[2]VECITIS C D,PARK H,CHENG J,et al.Treatment technologies for aqueous perfluorooctanesulfonate(PFOS)and perfluorooctanoate(PFOA)[J].Frontiers of Environmental Science&Engineering in China,2009,3(2):129-151.
[3]HIGGINS C P,FIELD J A,CRIDDLE C S,et al.Quantitative determination of perfluorochemicals in sediments and domestic sludge[J].Environmental Science&Technology,2005,39(11):3946-3956.
[4]张峰振,吴超飞,胡芸,等.卤代有机污染物的光化学降解[J].化学进展,2014,26(6):1079-1098.
[5]JIN L,ZHANG P Y,SHAO T,et al.Ferric ion mediated photodecomposition of aqueous perfluorooctane sulfonate(PFOS)under UV irradiation and its mechanism[J].Journal of Hazardous Materials,2014,271:9-15.
[6]HORI H,NAGAOKA Y,YAMAMOTO A,et al.Efficient decomposition of environmentally persistent perfluorooctanesulfonate and related fluorochemicals using zerovalent iron in subcritical water[J].Environmental Science&Technology,2006,40(3):1049-1054.
[7]YAMAMOTO T,NOMA Y,SAKAI S I,et al.Photodegradation of perfluorooctane sulfonate by UV irradiation in water and alkaline 2-propanol[J].Environmental Science&Technology,2007,41(16):5660-5665.
[8]OCHOA HERRERA V,SIERRA ALVAREZ R,SOMOGYI A A,et al.Reductive defluorination of perfluorooctane sulfonate[J].Environmental Science&Technology,2008,42(9):3260-3264.
[9]SONG Z,TANG H Q,WANG N,et al.Reductive defluorination of perfluorooctanoic acid by hydrated electrons in a sulfitemediated UV photochemical system[J].Journal of Hazardous Materials,2013,262:332-338.
[10]QU Y,ZHANG C J,LI F,et al.Photo-reductive defluorination of perfluorooctanoic acid in water[J].Water Research,2010,44(9):2939-2947.
[11]JIN L,ZHANG P Y.Photochemical decomposition of perfluorooctane sulfonate(PFOS)in an anoxic alkaline solution by185nm vacuum ultraviolet[J].Chemical Engineering Journal,2015,280:241-247.
[12]SONG Z,TANG H Q,WANG N,et al.Activation of persulfate by UV and Fe2+for the defluorination of perfluorooctanoic acid[J].Advances in Environmental Research,2014,3(3):185-197.
[13]LI Z M,ZHANG P Y,JIN L,et al.Efficient photocatalytic decomposition of perfluorooctanoic acid by indium oxide and its mechanism[J].Environmental Science&Technology,2012,46(10):5528-5534.
[14]SONG Z,DONG X L,WANG N,et al.Efficient photocatalytic defluorination of perfluorooctanoic acid over BiOCl nanosheets via a hole direct oxidation mechanism[J].Chemical Engineering Journal,2017,317:925-934.
[15]HILL C A,NORTON A J,NEWMAN G.The water vapour sorption properties of Sitka spruce determined using a dynamic vapour sorption apparatus[J].Wood Science and Technology,2010,44(3):497-514.
[16]牛夏梦,史亚利,张春晖,等.全氟辛烷磺酸和全氟辛烷羧酸异构体的高效液相色谱-串联质谱联用分析方法[J].环境化学,2015,34(8):1453-1459.
[17]LYU X J,LI W W,LAM P K,et al.Boiling significantly promotes photodegradation of perfluorooctane sulfonate[J].Chemosphere,2015,138:324-327.
[18]GU Y R,DONG W Y,LUO C,et al.Efficient reductive decomposition of perfluorooctanesulfonate in a high photo flux UV/sulfite system[J].Environmental Science&Technology,2016,50(19):10554-10561.
[2]VECITIS C D,PARK H,CHENG J,et al.Treatment technologies for aqueous perfluorooctanesulfonate(PFOS)and perfluorooctanoate(PFOA)[J].Frontiers of Environmental Science&Engineering in China,2009,3(2):129-151.
[3]HIGGINS C P,FIELD J A,CRIDDLE C S,et al.Quantitative determination of perfluorochemicals in sediments and domestic sludge[J].Environmental Science&Technology,2005,39(11):3946-3956.
[4]张峰振,吴超飞,胡芸,等.卤代有机污染物的光化学降解[J].化学进展,2014,26(6):1079-1098.
[5]JIN L,ZHANG P Y,SHAO T,et al.Ferric ion mediated photodecomposition of aqueous perfluorooctane sulfonate(PFOS)under UV irradiation and its mechanism[J].Journal of Hazardous Materials,2014,271:9-15.
[6]HORI H,NAGAOKA Y,YAMAMOTO A,et al.Efficient decomposition of environmentally persistent perfluorooctanesulfonate and related fluorochemicals using zerovalent iron in subcritical water[J].Environmental Science&Technology,2006,40(3):1049-1054.
[7]YAMAMOTO T,NOMA Y,SAKAI S I,et al.Photodegradation of perfluorooctane sulfonate by UV irradiation in water and alkaline 2-propanol[J].Environmental Science&Technology,2007,41(16):5660-5665.
[8]OCHOA HERRERA V,SIERRA ALVAREZ R,SOMOGYI A A,et al.Reductive defluorination of perfluorooctane sulfonate[J].Environmental Science&Technology,2008,42(9):3260-3264.
[9]SONG Z,TANG H Q,WANG N,et al.Reductive defluorination of perfluorooctanoic acid by hydrated electrons in a sulfitemediated UV photochemical system[J].Journal of Hazardous Materials,2013,262:332-338.
[10]QU Y,ZHANG C J,LI F,et al.Photo-reductive defluorination of perfluorooctanoic acid in water[J].Water Research,2010,44(9):2939-2947.
[11]JIN L,ZHANG P Y.Photochemical decomposition of perfluorooctane sulfonate(PFOS)in an anoxic alkaline solution by185nm vacuum ultraviolet[J].Chemical Engineering Journal,2015,280:241-247.
[12]SONG Z,TANG H Q,WANG N,et al.Activation of persulfate by UV and Fe2+for the defluorination of perfluorooctanoic acid[J].Advances in Environmental Research,2014,3(3):185-197.
[13]LI Z M,ZHANG P Y,JIN L,et al.Efficient photocatalytic decomposition of perfluorooctanoic acid by indium oxide and its mechanism[J].Environmental Science&Technology,2012,46(10):5528-5534.
[14]SONG Z,DONG X L,WANG N,et al.Efficient photocatalytic defluorination of perfluorooctanoic acid over BiOCl nanosheets via a hole direct oxidation mechanism[J].Chemical Engineering Journal,2017,317:925-934.
[15]HILL C A,NORTON A J,NEWMAN G.The water vapour sorption properties of Sitka spruce determined using a dynamic vapour sorption apparatus[J].Wood Science and Technology,2010,44(3):497-514.
[16]牛夏梦,史亚利,张春晖,等.全氟辛烷磺酸和全氟辛烷羧酸异构体的高效液相色谱-串联质谱联用分析方法[J].环境化学,2015,34(8):1453-1459.
[17]LYU X J,LI W W,LAM P K,et al.Boiling significantly promotes photodegradation of perfluorooctane sulfonate[J].Chemosphere,2015,138:324-327.
[18]GU Y R,DONG W Y,LUO C,et al.Efficient reductive decomposition of perfluorooctanesulfonate in a high photo flux UV/sulfite system[J].Environmental Science&Technology,2016,50(19):10554-10561.