响应曲面分析优化改性粉煤灰漂珠对水中氟的吸附性能及机理研究
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摘要
为提升粉煤灰漂珠对水溶液中氟的吸附性能,以氧化钙为原料,采用煅烧法制备钙改性粉煤灰漂珠吸附材料.通过响应曲面分析中的Box-Behnken设计吸附氟试验,探讨各吸附因数及其交互作用对吸附效果的影响,确定最佳吸附条件.利用SEM(扫描电镜)、EDS(能量散射光谱)、XRD(X射线衍射)以及BET比表面积等手段对吸附材料进行表征,并结合吸附动力学、吸附等温试验探讨钙改性粉煤灰漂珠吸附剂的除氟机制.结果表明:①初始ρ(F-)和吸附温度对改性粉煤灰漂珠吸附水中F-的去除率有显著影响,当p H为5. 0、初始ρ(F-)为125 mg/L、吸附温度为40℃时,改性粉煤灰漂珠对水中F-的吸附效果最佳.②动力学试验显示,改性粉煤灰漂珠对水中F-的吸附过程符合准二级动力学模型,说明该吸附过程主要以化学吸附为主;与Langmuir和Freundlich吸附等温模型相比,Temkin吸附等温模型更适合于描述该吸附平衡过程.③SEM、EDS和BET比表面积分析显示,改性后的粉煤灰漂珠内部生成了具有不规则表面和多孔结构的含钙团簇物质,从而增加了BET比表面积,改善了孔隙结构. XRD分析显示,钙改性粉煤灰漂珠主要通过离子交换作用吸附去除水中的F-.研究显示,以工业废物为原料制备的钙改性粉煤灰漂珠吸附剂的最大除氟率为93. 59%,是一种具有应用潜力的低成本吸附材料.
In order to improve the adsorption efficiency of adsorbent for removal of fluoride in wastewater,the fly ash cenospheres modified with calcium were prepared by annealing method. Through the Box-Behnken response surface methodology design of adsorption fluorine experiments,the effects of adsorption factors and their interactions were investigated,and the optimal adsorption conditions were determined. Scanning electron microscope( SEM),energy dispersive spectrometer( EDS),X-ray diffraction( XRD) and specific surface area analysis( BET) were employed to characterize the physicochemical properties of the adsorbents. The mechanisms of fluoride adsorption were investigated by means of adsorption kinetics and isothermal adsorption experiments. The results suggested that:( 1) The initial F-concentration and adsorption temperature significantly affected the removal efficiency of F-; the optimal adsorption conditions were at p H of 5. 0,initial F-concentration of 125 mg/L and adsorption temperature of 40 ℃.( 2) The experimental kinetic data were well fitted by the pseudo-second-order model,which indicated that the dominant adsorption belonged to the chemisorption. The Temkin isotherm model was more suitable for describing the adsorption equilibrium than the Freundlich or Langmuir isotherm model.( 3) The SEM,EDS and BET analyses indicated that Ca-containing cluster materials with irregular surface and porous structure were formed inside the fly ash cenospheres,which led to increases in porosity and specific surface area. The XRD analysis showed that the removal of F-from water by the fly ash cenospheres was mainly via the ion-exchange. These results showed that the maximum F-adsorption rate of the fly ash cenospheres modified with calcium and prepared from industrial waste is 93. 59%,and the low-cost adsorption material has potential application.
In order to improve the adsorption efficiency of adsorbent for removal of fluoride in wastewater,the fly ash cenospheres modified with calcium were prepared by annealing method. Through the Box-Behnken response surface methodology design of adsorption fluorine experiments,the effects of adsorption factors and their interactions were investigated,and the optimal adsorption conditions were determined. Scanning electron microscope( SEM),energy dispersive spectrometer( EDS),X-ray diffraction( XRD) and specific surface area analysis( BET) were employed to characterize the physicochemical properties of the adsorbents. The mechanisms of fluoride adsorption were investigated by means of adsorption kinetics and isothermal adsorption experiments. The results suggested that:( 1) The initial F-concentration and adsorption temperature significantly affected the removal efficiency of F-; the optimal adsorption conditions were at p H of 5. 0,initial F-concentration of 125 mg/L and adsorption temperature of 40 ℃.( 2) The experimental kinetic data were well fitted by the pseudo-second-order model,which indicated that the dominant adsorption belonged to the chemisorption. The Temkin isotherm model was more suitable for describing the adsorption equilibrium than the Freundlich or Langmuir isotherm model.( 3) The SEM,EDS and BET analyses indicated that Ca-containing cluster materials with irregular surface and porous structure were formed inside the fly ash cenospheres,which led to increases in porosity and specific surface area. The XRD analysis showed that the removal of F-from water by the fly ash cenospheres was mainly via the ion-exchange. These results showed that the maximum F-adsorption rate of the fly ash cenospheres modified with calcium and prepared from industrial waste is 93. 59%,and the low-cost adsorption material has potential application.
引文
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[23] RICOU-HOEFFER P,LECUYER I,LE C P. Experimental design methodology applied to adsorption of metallic ions onto fly ash[J].Water Research,2001,35(4):965-976.
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[31] THAKRE D,RAYALU S,KAWADE R,et al. Magnesium incorporated bentonite clay for defluoridation of drinking water[J].Journal of Hazardous Materials,2010,180(1/2/3):122-130.
[32] VALVERDE J L,LUCAS A D,SNCHEZ P,et al. Cation exchanged and impregnated Ti-pillared clays for selective catalytic reduction of NOxby propylene[J]. Applied Catalysis B:Environmental,2003,43(1):43-56.
[33] WAJIMA T,RAKOVAN J F. Removal of fluoride ions using calcined paper sludge[J]. Journal of Thermal Analysis&Calorimetry,2013,113(3):1027-1035.
[34] ISLAM M,PATEL R K.Evaluation of removal efficiency of fluoride from aqueous solution using quick lime[J]. Journal of Hazardous Materials,2007,143(1/2):303-310.
[2] BHATNAGAR A,KUMAR E,SILLANPM. Fluoride removal from water by adsorption:a review[J]. Chemical Engineering Journal,2011,171(3):811-840.
[3] HARRISON P T C.Fluoride in water:a UK perspective[J].Journal of Fluorine Chemistry,2005,126(11):1448-1456.
[4] YADAV K K,GUPTA N,KUMAR V,et al. A review of emerging adsorbents and current demand for defluoridation of water:bright future in water sustainability[J]. Environment International,2017,111(2):80-108.
[5] WU Haixia,WANG Tingjie,CHEN Lin,et al.Granulation of Fe-AlCe hydroxide nano-adsorbent by immobilization in porous polyvinyl alcohol for fluoride removal in drinking water[J]. Powder Technology,2011,209(1/2/3):92-97.
[6] GUPTA A B,DUBEY S,AGARWAL M. Coagulation process for fluoride removal by comparative evaluation of alum and PACl coagulants with subsequent membrane micro-filtration[J].International Journal of Environmental Technology&Management,2018,20(3/4):200-224.
[7] LUI Xiaoji,TSUTOMU S,EINSTINE O,et al. Adsorption and coprecipitation behavior of fluoride onto Mg-bearing minerals in Si-Al-Mg mineral system at hyperalkaline conditions[J]. Clay Science,2017,16(2):49-57.
[8] WEI Fang,CAO Changyan,HUANG Peipei,et al. A new ion exchange adsorption mechanism between carbonate groups and fluoride ions of basic aluminum carbonate nanospheres[J]. Rsc Advances,2015,5(17):13256-13260.
[9] EZZEDDINE A,MEFTAH N,HANNACHI A. Removal of fluoride from an industrial wastewater by a hybrid process combining precipitation and reverse osmosis[J]. Desalination&Water Treatment,2015,55(10):2618-2625.
[10] SHARMA P P,YADAV V,MARU P D,et al.Mitigation of fluoride from brackish water via electrodialysis:an environmentally friendly process[J].Chemistryselect,2018,3(2):779-784.
[11] IMAI Y.Removing fluoride from a hot spring using an electrolysis system[J]. International Journal of Geomate,2017,12(32):101-106.
[12] GAIKWAD M S,BALOMAJUMDER C. Simultaneous rejection of chromium(Ⅵ)and fluoride(Cr(Ⅵ)and F)by nanofiltration:Membranes characterizations and estimations of membrane transport parameters by CFSK model[J].Journal of Environmental Chemical Engineering,2016,5(1):45-53.
[13] DIALLO M A,DIOP S N,DIMM M,et al. Efficiency of nanofiltration membrane TFC-SR3 and SelRo MPF-34 for partial elimination of fluoride and salinity from drinking water[J]. Journal of Water Resource&Protection,2015,7(7):457-462.
[14] IRIEL A,BRUNEEL S P,SCHENONE N,et al. The removal of fluoride from aqueous solution by a lateritic soil adsorption:kinetic and equilibrium studies[J]. Ecotoxicology Environmental Safety,2018,149:166-172.
[15] WANG Jianguo,CHEN Nan,FENG Chuanping,et al. Performance and mechanism of fluoride adsorption from groundwater by lanthanum-modified pomelo peel biochar[J]. Environmental Science&Pollution Research,2018,16(25):15326-15335.
[16] CHERUKUMILLI A K K,DELAIRE C,AMROSE S E,et al.Factors governing the performance of bauxite for fluoride remediation of groundwater[J]. Environmental Science&Technology,2017,51(4):2321-2328.
[17] TCHOMGUI-KAMGA E,ALONZO V,NANSEU-NJIKI C P,et al.Preparation and characterization of charcoals that contain dispersed aluminum oxide as adsorbents for removal of fluoride from drinking water[J].Carbon,2010,48(2):333-343.
[18] CAMACHO L M,TORRES A,SAHA D,et al. Adsorption equilibrium and kinetics of fluoride on sol-gel-derived activated alumina adsorbents.[J]. Journal of Colloid&Interface Science,2010,349(1):307-313.
[19] KAMBLE S P,DIXIT P,RAYALU S S,et al. Defluoridation of drinking water using chemically modified bentonite clay[J].Desalination,2009,249(2):687-693.
[20] ROJAS-MAYORGA C K,BONILLA-PETRICIOLET A,AGUAYOVILLARREAL I A,et al. Optimization of pyrolysis conditions and adsorption properties of bone char for fluoride removal from water[J].Journal of Analytical&Applied Pyrolysis,2013,104(11):10-18.
[21] XU Xiaotian,LI Qin,CUI Hao,et al. Adsorption of fluoride from aqueous solution on magnesia-loaded fly ash cenospheres[J].Desalination,2011,272(1/2/3):233-239.
[22]许效天,霍林,左叶颖,等.铝改性粉煤灰漂珠吸附水溶液中砷的性能研究[J].中国环境科学,2011,31(8):1300-1305.XU Xiaotian,HUO Lin,ZUO Yeying,et al.Performance research on arsenic adsorption from aqueous solution by aluminum-modified fly ash cenospheres[J]. China Environmental Science,2011,31(8):1300-1305.
[23] RICOU-HOEFFER P,LECUYER I,LE C P. Experimental design methodology applied to adsorption of metallic ions onto fly ash[J].Water Research,2001,35(4):965-976.
[24] BARTON R R. Response surface methodology[J]. Wiley Interdisciplinary Reviews Computational Statistics,1999,2(2):128-149.
[25] HO Y S,MCKAY G.A comparison of chemisorption kinetic models applied to pollutant removal on various sorbents[J].Process Safety&Environmental Protection,1998,76(4):332-340.
[26] HO Y S,MCKAY G. Pseudo-second order model for sorption processes[J].Process Biochemistry,1999,34(5):451-465.
[27] LANGMUIR I.The adsorption of gases on plane surfaces of glass,mica and platinum[J]. Journal of Chemical Physics,2015,40(12):1361-1403.
[28] EN S,GUNNAR L.Stability constants of metal-ion complexes[M].Washington:Chemical Society,1964:769-770.
[29] GILES C H,SMITH D,HUITSON A. A general treatment and classification of the solute adsorption isotherm. I. Theoretical[J].International Journal of Nanoscience,1974,10(3):391-396.
[30] KALAIARASAN E,PALVANNAN T. Removal of phenols from acidic environment by horseradish peroxidase(HRP):aqueous thermostabilization of HRP by polysaccharide additives[J].Journal of the Taiwan Institute of Chemical Engineers,2014,45(2):625-634.
[31] THAKRE D,RAYALU S,KAWADE R,et al. Magnesium incorporated bentonite clay for defluoridation of drinking water[J].Journal of Hazardous Materials,2010,180(1/2/3):122-130.
[32] VALVERDE J L,LUCAS A D,SNCHEZ P,et al. Cation exchanged and impregnated Ti-pillared clays for selective catalytic reduction of NOxby propylene[J]. Applied Catalysis B:Environmental,2003,43(1):43-56.
[33] WAJIMA T,RAKOVAN J F. Removal of fluoride ions using calcined paper sludge[J]. Journal of Thermal Analysis&Calorimetry,2013,113(3):1027-1035.
[34] ISLAM M,PATEL R K.Evaluation of removal efficiency of fluoride from aqueous solution using quick lime[J]. Journal of Hazardous Materials,2007,143(1/2):303-310.