Zn系LDHs负载改性石英砂和沸石对Cr(VI)吸附效果对比及其作用机理研究
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摘要
为提升人工湿地常用填料对受污染水体中Cr(VI)的吸附性能,采用水热-共沉淀法在碱性条件下制备了Zn系LDHs涂层负载改性沸石和石英砂填料,并运用场发射扫描电子显微镜(SEM)、能谱分析仪(EDS)和BET等手段对改性前后填料的表面形态和化学成分进行了表征.最后,通过等温吸附试验、动力学吸附试验、吸附热力学试验对Zn系LDHs改性填料和天然填料的Cr(VI)吸附效果及其作用机理进行了对比研究.结果表明,通过Zn系LDHs涂层负载,沸石和石英砂对Cr(VI)的吸附类型由以物理吸附为主的多分子层吸附向以化学吸附为主的单分子层吸附转换,有利于吸附水中的Cr(VI);热力学相关参数ΔS~0<0,ΔG~0<0,ΔH~0<0,表明对Cr(VI)的吸附是自发放热过程.相比于天然沸石和石英砂,Zn系LDHs负载改性沸石和石英砂的表面物化性状发生明显变化,最大饱和吸附容量明显提高,尤其是石英砂的最大饱和吸附容量从21 mg·kg~(-1)提升到125 mg·kg~(-1).改性同种天然填料时,ZnAl-LDHs负载改性的效果更佳;而相对于天然沸石的改性,Zn系LDHs负载改性能更有效地提高石英砂对Cr(VI)的吸附能力.因此,本实验中ZnAl-LDHs负载改性石英砂可推荐用于实际人工湿地中Cr(VI)的去除.
In order to improve the adsorption performance of Cr(VI) by zeolites and quartz sand(QS), which are commonly used in constructed wetlands(CWs), Zn-LDHs-modified zeolites and QS were prepared by co-precipitation method under alkaline condition. The scanning electron microscope, energy dispersive spectrometer and BET were used to characterize the surface morphology and chemical composition of the substrates before and after modification. adsorption kinetics, isotherme and thermodynamic tests were conducted to explore the Cr(VI) adsorption mechanisms of Zn-LDHs-modified and natural substrates. The results revealed that Cr(VI) adsorption behavior of natural zeolites and QS were mainly due to the multilayer adsorption, which was mainly physical process. After Zn-LDHs coating, the Cr(VI) adsorption by Zn-LDHs-modified zeolites and QS were then transformed to monolayer and chemical adsorption, which was beneficial to adsorption of Cr(VI) in water body. Thermodynamic relevant parameters(ΔS~0<0, ΔG~0<0, ΔH~0<0) indicated that the adsorption process was a spontaneous exothermic process. After Zn-LDHs modification, the physical and chemical properties of the adsorbant were changed significantly, including the surface and the maximum adsorption capacity. In particular, the maximum adsorption capacity of QS was enhanced from 21 to 125 mg·kg~(-1). The performance of ZnAl-LDHs coating modification was better than that of ZnFe-LDHs coating, and Zn-LDHs coating modification could more significantly improve Cr(VI) adsorption capacity of QS compared with natural zeolite. Therefore, ZnAl-LDHs coating QS can be recommended for Cr(VI) removal in actual CWs.
In order to improve the adsorption performance of Cr(VI) by zeolites and quartz sand(QS), which are commonly used in constructed wetlands(CWs), Zn-LDHs-modified zeolites and QS were prepared by co-precipitation method under alkaline condition. The scanning electron microscope, energy dispersive spectrometer and BET were used to characterize the surface morphology and chemical composition of the substrates before and after modification. adsorption kinetics, isotherme and thermodynamic tests were conducted to explore the Cr(VI) adsorption mechanisms of Zn-LDHs-modified and natural substrates. The results revealed that Cr(VI) adsorption behavior of natural zeolites and QS were mainly due to the multilayer adsorption, which was mainly physical process. After Zn-LDHs coating, the Cr(VI) adsorption by Zn-LDHs-modified zeolites and QS were then transformed to monolayer and chemical adsorption, which was beneficial to adsorption of Cr(VI) in water body. Thermodynamic relevant parameters(ΔS~0<0, ΔG~0<0, ΔH~0<0) indicated that the adsorption process was a spontaneous exothermic process. After Zn-LDHs modification, the physical and chemical properties of the adsorbant were changed significantly, including the surface and the maximum adsorption capacity. In particular, the maximum adsorption capacity of QS was enhanced from 21 to 125 mg·kg~(-1). The performance of ZnAl-LDHs coating modification was better than that of ZnFe-LDHs coating, and Zn-LDHs coating modification could more significantly improve Cr(VI) adsorption capacity of QS compared with natural zeolite. Therefore, ZnAl-LDHs coating QS can be recommended for Cr(VI) removal in actual CWs.
引文
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陈云,于永鲜,张金利,等.2011.铁氧化物改性黏土对Cr(VI) 的吸附性能研究[J].环境科学学报,31(5):905-911
Evans D G,Duan X.2006.Preparation of layered double hydroxides and their applications as additives in polymers,as precursors to magnetic materials and in biology and medicine[J].Chemical Communications,5:485-496
Fang D A,Liao X,Zhang X F,et al.2018.A novel resource utilization of the calcium-based semi-dry flue gas desulfurization ash:As a reductant to remove chromium and vanadium from vanadium industrial wastewater[J].Journal of Hazardous Materials,342:436-445
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Fang C J,Zhang X L,Lei Y,et al.2018.Nitrogen removal via core-shell bio-ceramic/Zn-layer double hydroxides synthesized with different composites for domestic wastewater treatment[J].Journal of Cleaner Production,181:618-630
郭露,张翔凌,陈巧珍,等.2015.人工湿地常用生物陶粒基质LDHs覆膜改性及其除磷效果研究[J].环境科学学报,35(9):2840-2849
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Hernandez-Montoya V,Perez-Cruz M A,Mendoza-Castillo D I,et al.2013.Competitive adsorption of dyes and heavy metals on zeolitic strutures[J].Journal of Environmental Management,116:213-221
Jiang C,Jia L Y,Zhang B.et al.2014.Comparison of quartz sand,anthracite,shale and biological ceramsite for adsorptive removal of phosphorus from aqueous solution[J].Journal of Environmental Sciences,26:466-477
Koilraj P,Takaki Y,Sasaki K.2016.Adsorption characteristics of arsenate on colloidal nanosheets of layered double hydroxide[J].Applied Clay Science,134:110-119
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Li Y,Yue Q Y,Gao B Y.2010.Effect of humic acid on the Cr(VI) adsorption onto Kaolin[J].Applied Clay Science,48:481-484
Langmuir I.1918.The adsorption of gases on plane surfaces of glass,mica and platinum[J].Journal of the American Chemical Society,40(9):1361-1403
Prasanna S V,Vishnu Kamath P.2009.Synthesis and characterization of arsenate-intercalated layered double hydroxides(LDHs):Prospects for arsenic mineralization[J].Journal of Colloid and Interface Science,331:439-445
Sinha V,Manikandan N A,Pakshirajan K,et al.2017.Continuous removal of Cr(VI) from wastewater by phytoextraction using Tradescantia pallida plant based vertical subsurface flow constructed wetland system[J].International Biodeterioration & Biodegradation,119:96-103
Sankararamakrishan N,Dixit A,Iyengar L,et al.2006.Removal of hexavalent chromium using a novel cross linked xanthated chitosan[J].Bioresource Technology,97:2377-2382
Sheng G D,Hu J,Li H,et al.2016.Enhanced sequestration of Cr(VI) by nanoscale zero-valent iron supported on layered double hydroxide by batch and XAFS study[J].Chemosphere,148:227-232.
沈志强,牟锐,李元志,等.2016.人工湿地生物沸石快速吸附-再生性能与再生机理研究[J].环境科学学报,36(4):1242-1247
石隽隽,程丹丹,王晓红,等.2013.石英砂负载β-FeOOH(ACS)吸附除Cr(VI) 的机理分析[J].环境科学学报,33(7):1892-1897
汤显强.2014.水位调控下沉积物的磷吸附解吸特征研究[A]//科技创新与水利改革—中国水利学会2014学术年会论文集(上册)[C].天津:中国水利学会.297-306
Uysal M,Ar I.2007.Removal of Cr(VI) from industrial wastewaters by adsorption Part I:determination of optimum conditions[J].Journal of Hazardous Materials,149:482-491
Von Oepen B,Kordel W,Klein W.1991.Sorption of nonpolar and polar compounds to soils:processes,measurements and experience with the applicability of the modified OECD-guideline 106[J].Chemosphere,22:285-304
伍清新,刘杰,游少鸿,等.2014.李氏禾湿地系统净化Cr(VI) 污染水体的机理研究[J].环境科学学报,34(9):2306-2312
吴真,梁霞,杨连珍,等.2013.微波辅助氢氧化钠改性竹炭对水溶液中铜离子的吸附[J].环境科学学报,33(2):424-430
Wang Z,Dong J,Liu L,et al.2013.Screening of phosphate-removing substrates for use in constructed wetlands treating swine wastewater[J].Ecological Engineering,54:57-65
Wu X L,Tan X L,Yang S T,et al.2013.Coexistence of adsorption and coagulation processes of both arsenate and NOM from contaminated groundwater by nanocrystallined Mg/Al layered double hydroxides[J].Water Research,47:4159-4168
Xu C H,Shi J J,Zhou W Z,et al.2012.Bromate removal from aqueous solutions by nano crystalline akaganeite(β-FeOOH)-coated quartz sand(CACQS)[J].Chemical Engineering Journal,187:63-68
张文豪.2011.LDH和Mg/Al/Fe-Mt对水中磷、铬的吸附效果研究[D].郑州:河南农业大学
张传光,张乃明,于秀芳.2013.热改性斜发沸石对富营养化水体的脱氮除磷效果[J].环境工程学报,7(5):1665-1670
张翔凌,陈俊杰,郭露,等.2014.垂直流人工湿地LDHs覆膜改性沸石基质强化除磷效果及其机制[J].环境科学,35(12):4553-4559
Zhang X L,Lei Y,Yuan Y,et al.2018.Enhanced removal performance of Cr(VI) by the core-shell zeolites/layered double hydroxides(LDHs)synthesized from different metal compounds in constructed rapid infiltration systems[J].Environmental Science and Pollution Research,25:9759-9770
Zhang X L,Guo L,Huang H L,et al.2016.Removal of phosphorus by the core-shell bio-ceramic/Zn-layered double hydroxides(LDHs)composites for municipal wastewater treatment in constructed rapid infiltration system[J].Water Research,96:280-291
张帆,李菁,谭建华,等.2013.吸附法处理重金属废水的研究进展[J].化工进展,32(11):2749-2756
甄豪波,胡勇有,程建华.2011.壳聚糖交联沸石小球对Cu2+、Ni2+及Cd2+的吸附特性[J].环境科学学报,31(7):1369-1376
Arfaoui S,Frini-Srasra N,Srasra E.2008.Modeling of the adsorption of the chromium ion by modified clays[J].Desalination,222:474-481
陈云,于永鲜,张金利,等.2011.铁氧化物改性黏土对Cr(VI) 的吸附性能研究[J].环境科学学报,31(5):905-911
Evans D G,Duan X.2006.Preparation of layered double hydroxides and their applications as additives in polymers,as precursors to magnetic materials and in biology and medicine[J].Chemical Communications,5:485-496
Fang D A,Liao X,Zhang X F,et al.2018.A novel resource utilization of the calcium-based semi-dry flue gas desulfurization ash:As a reductant to remove chromium and vanadium from vanadium industrial wastewater[J].Journal of Hazardous Materials,342:436-445
Fibbi D,Doumett S,Lepri L,et al.2012.Distribution and mass balance of hexavalent and trivalent chromium in a subsurface,horizontal flow(SF-h) constructed wetland operating as post-treatment of textile wastewater for water reuse[J].Journal of Hazardous Materials,199-200:209-216
Fang C J,Zhang X L,Lei Y,et al.2018.Nitrogen removal via core-shell bio-ceramic/Zn-layer double hydroxides synthesized with different composites for domestic wastewater treatment[J].Journal of Cleaner Production,181:618-630
郭露,张翔凌,陈巧珍,等.2015.人工湿地常用生物陶粒基质LDHs覆膜改性及其除磷效果研究[J].环境科学学报,35(9):2840-2849
Garg U K,Kaur M P,Garg V K,et al.2007.Removal of hexavalent chromium from aqueous solution by agricultural waste biomass[J].Journal of Hazardous Materials,140:60-68
国家环境保护总局.2002.水和废水监测分析方法[M].北京:中国环境科学出版
Hernandez-Montoya V,Perez-Cruz M A,Mendoza-Castillo D I,et al.2013.Competitive adsorption of dyes and heavy metals on zeolitic strutures[J].Journal of Environmental Management,116:213-221
Jiang C,Jia L Y,Zhang B.et al.2014.Comparison of quartz sand,anthracite,shale and biological ceramsite for adsorptive removal of phosphorus from aqueous solution[J].Journal of Environmental Sciences,26:466-477
Koilraj P,Takaki Y,Sasaki K.2016.Adsorption characteristics of arsenate on colloidal nanosheets of layered double hydroxide[J].Applied Clay Science,134:110-119
Li Y,Xu X J,Liu J X,et al.2008.The hazard of chromium exposure to neonates in Guiyu of China[J].Science of the Total Environment,403:99-104
Li Y,Yue Q Y,Gao B Y.2010.Effect of humic acid on the Cr(VI) adsorption onto Kaolin[J].Applied Clay Science,48:481-484
Langmuir I.1918.The adsorption of gases on plane surfaces of glass,mica and platinum[J].Journal of the American Chemical Society,40(9):1361-1403
Prasanna S V,Vishnu Kamath P.2009.Synthesis and characterization of arsenate-intercalated layered double hydroxides(LDHs):Prospects for arsenic mineralization[J].Journal of Colloid and Interface Science,331:439-445
Sinha V,Manikandan N A,Pakshirajan K,et al.2017.Continuous removal of Cr(VI) from wastewater by phytoextraction using Tradescantia pallida plant based vertical subsurface flow constructed wetland system[J].International Biodeterioration & Biodegradation,119:96-103
Sankararamakrishan N,Dixit A,Iyengar L,et al.2006.Removal of hexavalent chromium using a novel cross linked xanthated chitosan[J].Bioresource Technology,97:2377-2382
Sheng G D,Hu J,Li H,et al.2016.Enhanced sequestration of Cr(VI) by nanoscale zero-valent iron supported on layered double hydroxide by batch and XAFS study[J].Chemosphere,148:227-232.
沈志强,牟锐,李元志,等.2016.人工湿地生物沸石快速吸附-再生性能与再生机理研究[J].环境科学学报,36(4):1242-1247
石隽隽,程丹丹,王晓红,等.2013.石英砂负载β-FeOOH(ACS)吸附除Cr(VI) 的机理分析[J].环境科学学报,33(7):1892-1897
汤显强.2014.水位调控下沉积物的磷吸附解吸特征研究[A]//科技创新与水利改革—中国水利学会2014学术年会论文集(上册)[C].天津:中国水利学会.297-306
Uysal M,Ar I.2007.Removal of Cr(VI) from industrial wastewaters by adsorption Part I:determination of optimum conditions[J].Journal of Hazardous Materials,149:482-491
Von Oepen B,Kordel W,Klein W.1991.Sorption of nonpolar and polar compounds to soils:processes,measurements and experience with the applicability of the modified OECD-guideline 106[J].Chemosphere,22:285-304
伍清新,刘杰,游少鸿,等.2014.李氏禾湿地系统净化Cr(VI) 污染水体的机理研究[J].环境科学学报,34(9):2306-2312
吴真,梁霞,杨连珍,等.2013.微波辅助氢氧化钠改性竹炭对水溶液中铜离子的吸附[J].环境科学学报,33(2):424-430
Wang Z,Dong J,Liu L,et al.2013.Screening of phosphate-removing substrates for use in constructed wetlands treating swine wastewater[J].Ecological Engineering,54:57-65
Wu X L,Tan X L,Yang S T,et al.2013.Coexistence of adsorption and coagulation processes of both arsenate and NOM from contaminated groundwater by nanocrystallined Mg/Al layered double hydroxides[J].Water Research,47:4159-4168
Xu C H,Shi J J,Zhou W Z,et al.2012.Bromate removal from aqueous solutions by nano crystalline akaganeite(β-FeOOH)-coated quartz sand(CACQS)[J].Chemical Engineering Journal,187:63-68
张文豪.2011.LDH和Mg/Al/Fe-Mt对水中磷、铬的吸附效果研究[D].郑州:河南农业大学
张传光,张乃明,于秀芳.2013.热改性斜发沸石对富营养化水体的脱氮除磷效果[J].环境工程学报,7(5):1665-1670
张翔凌,陈俊杰,郭露,等.2014.垂直流人工湿地LDHs覆膜改性沸石基质强化除磷效果及其机制[J].环境科学,35(12):4553-4559
Zhang X L,Lei Y,Yuan Y,et al.2018.Enhanced removal performance of Cr(VI) by the core-shell zeolites/layered double hydroxides(LDHs)synthesized from different metal compounds in constructed rapid infiltration systems[J].Environmental Science and Pollution Research,25:9759-9770
Zhang X L,Guo L,Huang H L,et al.2016.Removal of phosphorus by the core-shell bio-ceramic/Zn-layered double hydroxides(LDHs)composites for municipal wastewater treatment in constructed rapid infiltration system[J].Water Research,96:280-291
张帆,李菁,谭建华,等.2013.吸附法处理重金属废水的研究进展[J].化工进展,32(11):2749-2756
甄豪波,胡勇有,程建华.2011.壳聚糖交联沸石小球对Cu2+、Ni2+及Cd2+的吸附特性[J].环境科学学报,31(7):1369-1376