金属氧化物纳米颗粒在水环境中的团聚与沉降
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摘要
采用吸光度动态分析、动态光散射(DLS)及电泳淌度等技术,对比了100 mg/L CuO、ZnO、SiO_2纳米颗粒(NPs)在:(1)无机盐(离子强度IS=18 mmol/L)模拟溶液;(2)天然有机质(NOM,TOC=8.96 mg/L)模拟溶液;(3)无机盐(IS=18 mmol/L)-NOM(TOC=8.96mg/L)模拟溶液;(4)太湖水(IS=4.5 mmol/L,TOC=2.42 mg/L)等介质中的48 h沉降动力学、水力学直径分布及Zeta电位。结果表明,NPs在水环境中的团聚与沉降不但取决于水化学因素,同时取决于NPs自身的化学性质。CuO NPs在太湖水与NOM模拟溶液中呈现类似的团聚与沉降现象,主要受NOM与表面Cu_(2+)的螯合作用主导。ZnO NPs的团聚与沉降主要受IS控制,因而在太湖水与IS模拟溶液中展现相似的行为。Si O2NPs具有对NOM较低的吸附能力和较小的Hamaker常数等内在特性,其在太湖水与模拟溶液中具有独特的团聚与沉降行为,并不取决于NOM或IS等水环境条件。在水环境中,这3种NPs都将通过团聚与沉降快速迁移至底泥,对水生生态造成潜在风险。
Via time-resolved optical absorbency,dynamic light scattering(DLS),as well as electrophoretic mobility analysis,the 48-h sedimentation kinetics,the distributions of hydrodynamic diameters,and the Zeta potentials of respective100 mg/L CuO,ZnO and SiO_2nanoparticles(NPs)in simulative waters containing inorganic salts with ionic strength(IS)as18 mmol/L,natural organic matter(NOM,TOC=8.96 mg/L),or mixed IS(18 mmol/L) and NOM(8.96 mg/L TOC),were determined and compared with those in Lake Taihu water(IS=4.5 mmol/L,TOC=2.42 mg/L). The results indicate that aggregation and sedimentation of NPs depended not only on the water chemistry but also on their chemical properties of the NPs. The similar observations in Lake Taihu and NOM-containing simulative waters suggested that NOM controlled the aggregation and sedimentation of CuO NPs,probably through chelation of NOM with surface Cu~(2+). ZnO NPs were aggregated and sedimented with the presence of IS,hence similar performances in Lake Taihu water and simulative waters with IS were exhibited. The peculiar behaviors of SiO_2 NPs in Lake Taihu and simulative waters manifested the predominance of its intrinsic properties over the aquatic factors(eg.,NOM and IS)in controlling the aggregation and sedimentation of SiO_2 NPs.This may be attributable to low NOM adsorption capacity by the NPs and their small Hamaker constant. The three NPs will be largely transferred to the sediment compartment of water bodies via aggregation and sedimentation,and pose potential risks to aquatic ecosystem.
Via time-resolved optical absorbency,dynamic light scattering(DLS),as well as electrophoretic mobility analysis,the 48-h sedimentation kinetics,the distributions of hydrodynamic diameters,and the Zeta potentials of respective100 mg/L CuO,ZnO and SiO_2nanoparticles(NPs)in simulative waters containing inorganic salts with ionic strength(IS)as18 mmol/L,natural organic matter(NOM,TOC=8.96 mg/L),or mixed IS(18 mmol/L) and NOM(8.96 mg/L TOC),were determined and compared with those in Lake Taihu water(IS=4.5 mmol/L,TOC=2.42 mg/L). The results indicate that aggregation and sedimentation of NPs depended not only on the water chemistry but also on their chemical properties of the NPs. The similar observations in Lake Taihu and NOM-containing simulative waters suggested that NOM controlled the aggregation and sedimentation of CuO NPs,probably through chelation of NOM with surface Cu~(2+). ZnO NPs were aggregated and sedimented with the presence of IS,hence similar performances in Lake Taihu water and simulative waters with IS were exhibited. The peculiar behaviors of SiO_2 NPs in Lake Taihu and simulative waters manifested the predominance of its intrinsic properties over the aquatic factors(eg.,NOM and IS)in controlling the aggregation and sedimentation of SiO_2 NPs.This may be attributable to low NOM adsorption capacity by the NPs and their small Hamaker constant. The three NPs will be largely transferred to the sediment compartment of water bodies via aggregation and sedimentation,and pose potential risks to aquatic ecosystem.
引文
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[14]Li X N,Song H L,Li W,et al.An integrated ecological floating-bed employing plant,freshwater clam and biofilm carrier for purification of eutrophic water[J].Ecological Engineering,2010,36(4):382-390.
[15]Chang Y N,Zhang M,Xia L,et al.The toxic effects and mechanisms of Cu O and Zn O nanoparticles[J].Materials,2012,5(12):2850-2871.
[16]Diedrich T,Dybowska A,Schott J,et al.The dissolution rates of Si O2nanoparticles as a function of particle size[J].Environmental Science and Technology,2012,46(9):4909-4915.
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[19]Zhang Y,Chen Y,Westerhoff P,et al.Impact of natural organic matter and divalent cations on the stability of aqueous nanoparticles[J].Water Research,2009,43(17):4249-4257.
[20]Nowack B,Bucheli T D.Occurrenc e,behavior and effects of nanoparticles in the environment[J].Environmental Pollution,2007,150(1):5-22.
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[3]Keller A A,Lazareva A.Predicted releases of engineered nanomaterials:from global to regional to local[J].Environmental Science&Technology Letters,2014,1(1):65-70.
[4]Baun A,Hartmann N B,Grieger K,et al.Ecotoxicity of engineered nanoparticles to aquatic invertebrates:a brief review and recommendations for future toxicity testing[J].Ecotoxicology,2008,17(5):387-395.
[5]Heinlaan M,Ivask A,Blinova I,et al.Toxicity of nanosized and bulk Zn O,Cu O and Ti O2to bacteria Vibrio fischeri and crustaceans Daphnia magna and Thamnocephalus platyurus[J].Chemosphere,2008,71(7):1308-1316.
[6]Navarro E,Baun A,Behra R,et al.Environmental behavior and ecotoxicity of engineered nanoparticles to algae,plants and fungi[J].Ecotoxicology,2008,17(5):372-386.
[7]Lowry G V,Gregory K B,Apte S C,et al.Transformations of nanomaterials in the environment[J].Environmental Science&Technology,2012,46(13):6893-6899.
[8]Nowack B,Ranville J F,Diamond S,et al.Potential scenarios for nanomaterial release and subsequent alteration in the environment[J].Environmental Toxicology and Chemistry,2012,31(1):50-59.
[9]方华,沈冰冰,孙宇心,等.水中富勒烯(C60)纳米颗粒凝聚动力学研究[J].环境科学与技术,2014,37(4):11-14.
[10]Zhang Y,Chen Y,Westerhoff P,et al.Stability of commercial metal oxide nanoparticles in water[J].Water Research,2008,42(8/9):2204-2212.
[11]Keller A A,Wang H,Zhou D,et al.Stability and aggregation of metal oxide nanoparticles in natural aqueous matrices[J].Environmental Science and Technology,2010,44(6):1962-1967.
[12]Conway J R,Ade leye A S,Gardea-Torresdey J,et al.Aggregation,dissolution and transformation of copper nanoparticles in natural waters[J].Environmental Science and Technology,2015,49(5):2749-2756.
[13]Van Hoecke K,De Schamphelaere K A C,Van der Meeren P,et al.Aggregation and ecotoxicity of Ce O2nanoparticles in synthetic and natural waters with variable p H,organic matter concentration and ionic strength[J].Environmental Pollution,2011,159(4):970-976.
[14]Li X N,Song H L,Li W,et al.An integrated ecological floating-bed employing plant,freshwater clam and biofilm carrier for purification of eutrophic water[J].Ecological Engineering,2010,36(4):382-390.
[15]Chang Y N,Zhang M,Xia L,et al.The toxic effects and mechanisms of Cu O and Zn O nanoparticles[J].Materials,2012,5(12):2850-2871.
[16]Diedrich T,Dybowska A,Schott J,et al.The dissolution rates of Si O2nanoparticles as a function of particle size[J].Environmental Science and Technology,2012,46(9):4909-4915.
[17]Zhan W,Sathasivan A,Joll C,et al.Impact of NOM character on copper adsorption by trace ferric hydroxide from iron corrosion in water supply system[J].Chemical Engineering Journal,2012,200:122-132.
[18]Liu W S,Peng Y H,Shiung C E,et al.The effect of cations on the aggregation of commercial Zn O nanoparticle suspension[J].Journal of Nanoparticle Research,2012,14(12):1259.
[19]Zhang Y,Chen Y,Westerhoff P,et al.Impact of natural organic matter and divalent cations on the stability of aqueous nanoparticles[J].Water Research,2009,43(17):4249-4257.
[20]Nowack B,Bucheli T D.Occurrenc e,behavior and effects of nanoparticles in the environment[J].Environmental Pollution,2007,150(1):5-22.