焙烧镁铝水滑石吸附脱硫废水中高浓度Cl~-的基础研究
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摘要
为制备镁铝摩尔比为4∶1的镁铝水滑石(LDH),实验采用共沉淀直接法,即在450℃温度下焙烧LDH 3 h,得到焙烧镁铝水滑石(CLHD)。取CLDH吸附剂于250 m L锥形瓶中,在一定条件下对5 000～20 000 mg/L高浓度Cl~-模拟溶液及实际脱硫废水进行脱氯吸附实验和CLDH再生及重复使用性实验。探究了不同反应时间、初始浓度、反应温度、溶液的初始pH及CLDH的投加量对氯离子的脱除效果的影响,采用BET,XRD,FT-IR探究吸附机理。实验结果表明,CLHD吸附Cl~-是由于层间阴离子可交换性("结构记忆"),对Cl~-吸附符合一级动力学模型,吸附量及脱氯率随反应时间的增大呈现出先快速增加后缓慢增加的趋势,吸附平衡后发生缓慢脱附反应;吸附等温线符合Freundlich方程模型,吸附量随Cl~-初始浓度的增加而增大,最佳脱氯效果参数为Cl~-浓度5 000 mg/L,之后随着氯离子浓度增大,由于吸附点位数量一定,脱氯率降低; CLDH对吸附Cl~-的脱除率及吸附量随着温度的增加而增加,当反应温度为65℃时,脱氯率及吸附量最大,当温度继续升高,CLDH对Cl~-的吸附效果大幅下降;改变pH值,CLDH对Cl~-的吸附效果差别较小,但当pH=8时达到脱氯率及吸附量的最大值;随着CLDH投加量的增加,脱氯率逐渐变小,最佳投加量为8 g/L。65℃、pH=8时的实际脱硫废水脱氯实验中,CLDH脱氯率可达50.90%,一次煅烧再生CLDH脱氯率稍降,二次煅烧再生CLDH脱氯率降低约50%,CLDH对脱硫废水脱氯具可再生重复使用性。
In order to obtian the magnesium aluminum hydrotalcite( LDH) with a molar ratio of 4:1( magnesium:aluminum),the direct method of coprecipitation was used to calcine LDH at 450 ℃ for 3 h to obtain the calcined magnesium aluminum hydrotalcite( CLHD).The CLDH adsorbent was taken in a 250 m L Erlenmeyer flask.Under certain conditions,dechlorination adsorption experiments and CLDH regeneration and reusability experiments were carried out on 5 000-20 000 mg/L high concentration Cl~-simulation solution and actual desulfurization wastewater.The effects of different reaction times,initial concentration,reaction temperature,initial pH of solution and dosage of CLDH on the removal of chloride ions were investigated. The adsorption mechanism was investigated by BET,XRD and FT-IR. The experimental results show that CLHD adsorbs Cl~-due to interlayer anion exchangeability( "structural memory"),and Cl~-adsorption conforms to the first-order kinetic model.The adsorption amount and dechlorination rate increase rapidly with the increase of reaction time.After the slow increase trend,the slow desorption reaction occurs after the adsorption equilibrium; the adsorption isotherm conforms to the Freundlich equation model,and the adsorption amount increases with the increase of the initial concentration of Cl~-. The optimal dechlorination effect parameter is Cl~-concentration5 000 mg/L,then with the increase of chloride ion concentration,the dechlorination rate decreases due to the certain number of adsorption sites; the removal rate and adsorption capacity of CLDH for the adsorption of Cl~-increase with the increase of temperature,when the reaction temperature is 65 ℃.The dechlorination rate and the adsorption amount are the largest.When the temperature continues to increase,the adsorption effect of CLDH on Cl~-is greatly reduced.When the pH value is changed,the adsorption effect of CLDH on Cl~-is small,but when the pH is 8,the dechlorination rate and the maximum amount of adsorption are reached. With the increase of CLDH dosage,the dechlorination rate gradually becomes smaller,and the optimal dosage is 8 g/L.In the dechlorination experiment of actual desulfurization wastewater at 65 ℃ and pH = 8,the dechlorination rate of CLDH can reach 50.90%,the dechlorination rate of CLDH in one calcination is slightly decreased,and the dechlorination rate of CLDH in second calcination is reduced by about50%.Desulfurization wastewater dechlorination has a reproducible reusability.
In order to obtian the magnesium aluminum hydrotalcite( LDH) with a molar ratio of 4:1( magnesium:aluminum),the direct method of coprecipitation was used to calcine LDH at 450 ℃ for 3 h to obtain the calcined magnesium aluminum hydrotalcite( CLHD).The CLDH adsorbent was taken in a 250 m L Erlenmeyer flask.Under certain conditions,dechlorination adsorption experiments and CLDH regeneration and reusability experiments were carried out on 5 000-20 000 mg/L high concentration Cl~-simulation solution and actual desulfurization wastewater.The effects of different reaction times,initial concentration,reaction temperature,initial pH of solution and dosage of CLDH on the removal of chloride ions were investigated. The adsorption mechanism was investigated by BET,XRD and FT-IR. The experimental results show that CLHD adsorbs Cl~-due to interlayer anion exchangeability( "structural memory"),and Cl~-adsorption conforms to the first-order kinetic model.The adsorption amount and dechlorination rate increase rapidly with the increase of reaction time.After the slow increase trend,the slow desorption reaction occurs after the adsorption equilibrium; the adsorption isotherm conforms to the Freundlich equation model,and the adsorption amount increases with the increase of the initial concentration of Cl~-. The optimal dechlorination effect parameter is Cl~-concentration5 000 mg/L,then with the increase of chloride ion concentration,the dechlorination rate decreases due to the certain number of adsorption sites; the removal rate and adsorption capacity of CLDH for the adsorption of Cl~-increase with the increase of temperature,when the reaction temperature is 65 ℃.The dechlorination rate and the adsorption amount are the largest.When the temperature continues to increase,the adsorption effect of CLDH on Cl~-is greatly reduced.When the pH value is changed,the adsorption effect of CLDH on Cl~-is small,but when the pH is 8,the dechlorination rate and the maximum amount of adsorption are reached. With the increase of CLDH dosage,the dechlorination rate gradually becomes smaller,and the optimal dosage is 8 g/L.In the dechlorination experiment of actual desulfurization wastewater at 65 ℃ and pH = 8,the dechlorination rate of CLDH can reach 50.90%,the dechlorination rate of CLDH in one calcination is slightly decreased,and the dechlorination rate of CLDH in second calcination is reduced by about50%.Desulfurization wastewater dechlorination has a reproducible reusability.
引文
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[13]吕亮.层状双金属(氢)氧化物对卤离子的吸附和离子交换性能研究[D].北京:北京化工大学,2005.LLiang.Adsorption and ion-exehange behavior of layered double hydroxides in the uptake of halide anions from aqueous solution[D].Beijing:Beijing University of Chemical Technology,2005.
[14]李春艳,蒋云福,赵俊,等.焙烧镁铝水滑石的制备及其对水中Cl-和SO24-的吸附特性[J].环境工程学报,2016,10(4):1719-1726.LI Chunyan,JIANG Yunfu,ZHAO Jun,et al. Synthesis of calcinations modified Mg-Al hydrotalcite and its adsorption properties for Cl-and SO24-in water[J].Chinese Journal of Environmental Engineering,2016,10(4):1719-1726.
[15] AHMED I M,GASSER M S. Adsorption study of anionic reactive dye from aqueous solution to Mg-Fe-CO3layered double hydroxide(LDH)[J]. Applied Surface Science,2012,259(42):650-656.
[16] KAMEDA T,OBA J,YOSHIOKA T. Recyclable Mg-Al layered double hydroxides for fluoride removal:Kinetic and equilibrium studies[J].Journal of Hazardous Materials,2015(300):475-482.
[17] MA W,LT,SONG X,et al. Characteristics of selective fluoride adsorption by biocarbon-Mg/Al layered double hydroxides composites from protein solutions:Kinetics and equilibrium isotherms study[J].Journal of Hazardous Materials,2014(268):166-176.
[18] KAMEDA T,OBA J,YOSHIOKA T.New treatment method for boron in aqueous solutions using Mg-Al layered double hydroxide:Kinetics and equilibrium studies[J]. Journal of Hazardous Materials,2015(293):54-63.
[19] MANDAL S,TRIPATHY S,PADHI T,et al,Removal efficiency of fluoride by novel Mg-Cr-Cl layered double hydroxide by batch process from water[J]. Environmental. Science,2013(25):993-1000.
[20]近藤精一,石川达雄,安部郁夫,等.吸附科学[M].北京:化学工业出版社,2006.
[21]王军锋,李子荣,郭雨.Mg/Al型水滑石及其焙烧产物对水溶液中Cl-的吸附[J].西安工程大学学报,2008,22(2):171-174.WANG Junfeng,LI Zirong,GUO Yu. Adsorption of chloride anion by Mg/Al hydrotalcite and its calcined product[J]. Journal of Xi’an Polytechnic University.2008,22(2):171-174.
[22] OGAWA M,KAUHO H. Homogeneous precipitation of uniform hydrotalcite particles[J].Langmuir,2002,18(11):4240-4242.
[23] ADACHI-PAGANO M,FORANO C,BESSE J P. Synthesis of Alrich hydrotalcite-like compounds by using the urea hydrolysis reaction-control of size and morphology[J].Journal of Materials Chemistry,2003,13(8):1988-1993.
[24] LAZARIDIS N K,PANDI T A,MATIS K A.Chromium(VI)removal from aqueous solutions by Mg-Al-CO3hydrotalcite:Sorption-desorption kinetic and equilibrium studies[J]. Industrial&Engineering Chemistry Research,2004,43(9):2209-2215.
[25]夏燕,朱润良,陶奇,等.阴离子表面活性剂改性水滑石吸附硝基苯的特性研究[J].环境科学.2013,34(1):226-230.XIA Yan,ZHU Runliang,TAO Qi,et al.Sorption of nitrobenzene to anionic surfactant modified layered double hydroxides[J].Environment Science.2013,34(1):226-230.
[26] YANG Weishen,KIM Y,LIU P K T,et al.A study by in situ techniques of the thermal evolution of the structure of a Mg-Al-CO3layered double hydroxide[J].Chemical Engineering Science,2002,57(15):2945-2953.
[27]申震,唐先进,刘超,等.焙烧态镁铝水滑石处理阴离子染料废水研究[J].环境科学与技术,2006,29(3):89-91.SHEN Zhen,TANG Xianjin,LIU Chao,et al. Experimental study of treating anion dyestuff-containing wastewater by calcined layered double hydroxide[J]. Environmental Science&Technology,2006,29(3):89-91.
[28]郭亚祺,杨洋,伍新花,等.煅烧的水滑石同时去除水体中砷和氟[J].环境工程学报,2014,8(6):2485-2491.GUO Yaqi,YANG Yang,WU Xinhua,et al. Removal of arsenate and fluoride in water by calcined layered double hydroxides[J].Chinese Journal of Environmental Engineering,2014,8(6):2485-2491.
[2] DOU Weixiao,ZHOU Zhen,YE Jiongjiong,et al.Reusing effluent of flue gas desulfurization wastewater treatment process as an economical calcium source for phosphorus removal[J]. Water Science&Technology,2017,76(6):1429-1435.
[3]于伟静.脱硫废水蒸发处理系统研究[D].北京:华北电力大学,2016.YU Weijing. Study on FGD wastewater evaporation treatment[D].Beijing:North China Electric Power University,2016.
[4] DENG J J,PAN L M,CHEN D Q,et al.Numerical simulation and field test study of desulfurization wastewater evaporation treatment through flue gas[J]. Water Science&Technology,2014,70(7):1285-1291.
[5] JIANG D N,SHA H W,GONG G H,et al. Fundamental research and demonstration project of evaporation treatment of wastewater from FGD in flue gas duct[J]. Advanced Materials Research,2013(4):864-867.
[6] MA S,CHAI J,CHEN G,et al. Research on desulfurization wastewater evaporation:Present and future perspectives[J]. Renewable&Sustainable Energy Reviews,2016(58):1143-1151.
[7]公新忠,丁德馨,李广悦,等.含氟离子和氯离子酸性废水处理技术[J].环境工程学报,2012,6(9):3157-3160.GONG Xinzhong,DING Dexin,LI Guangyue,et al.A treatment method for fluorine ion and chlorine ion-containing wastewater[J]. Chinese Journal of Environmental Engineering,2012,6(9):3157-3160.
[8] THEISS F L,COUPERTHWAITE S J,AYOKO G A,et al.A review of the removal of anions and oxyanions of the halogen elements from aqueous solution by layered double hydroxides[J].Journal of Colloid&Interface Science,2014,417:356-368.
[9] LU L,HE J,WEI M,et al.Factors influencing the removal of fluoride from aqueous solution by calcined Mg-Al-CO3layered double hydroxides[J].Journal of Hazardous Materials,2006,133(1-3):119-128.
[10] CAVANI F,TrifiròF,et al.Hydrotalcite-type anionic clays:Preparation,properties and applications[J]. Catalysis Today,1991,11(2):173-301.
[11] BARRIGA C,GAITáN M,PAVLOVIC I,et al.Hydrotalcites as sorbent for 2,4,6-trinitrophenol:Influence of the layer composition and interlayer anion[J]. Journal of Material Chemistry,2002,12(4):1027-1034.
[12]胡静.焙烧镁铝碳酸根水滑石在含氯废水处理中的应用基础研究[D].杭州:浙江大学,2005.HU Jing.Basic research on the application of calcined Mg-Al-CO3layered double hydroxides in the treatment of chlorinated wastewater[D].Hangzhou:Zhejiang University,2005.
[13]吕亮.层状双金属(氢)氧化物对卤离子的吸附和离子交换性能研究[D].北京:北京化工大学,2005.LLiang.Adsorption and ion-exehange behavior of layered double hydroxides in the uptake of halide anions from aqueous solution[D].Beijing:Beijing University of Chemical Technology,2005.
[14]李春艳,蒋云福,赵俊,等.焙烧镁铝水滑石的制备及其对水中Cl-和SO24-的吸附特性[J].环境工程学报,2016,10(4):1719-1726.LI Chunyan,JIANG Yunfu,ZHAO Jun,et al. Synthesis of calcinations modified Mg-Al hydrotalcite and its adsorption properties for Cl-and SO24-in water[J].Chinese Journal of Environmental Engineering,2016,10(4):1719-1726.
[15] AHMED I M,GASSER M S. Adsorption study of anionic reactive dye from aqueous solution to Mg-Fe-CO3layered double hydroxide(LDH)[J]. Applied Surface Science,2012,259(42):650-656.
[16] KAMEDA T,OBA J,YOSHIOKA T. Recyclable Mg-Al layered double hydroxides for fluoride removal:Kinetic and equilibrium studies[J].Journal of Hazardous Materials,2015(300):475-482.
[17] MA W,LT,SONG X,et al. Characteristics of selective fluoride adsorption by biocarbon-Mg/Al layered double hydroxides composites from protein solutions:Kinetics and equilibrium isotherms study[J].Journal of Hazardous Materials,2014(268):166-176.
[18] KAMEDA T,OBA J,YOSHIOKA T.New treatment method for boron in aqueous solutions using Mg-Al layered double hydroxide:Kinetics and equilibrium studies[J]. Journal of Hazardous Materials,2015(293):54-63.
[19] MANDAL S,TRIPATHY S,PADHI T,et al,Removal efficiency of fluoride by novel Mg-Cr-Cl layered double hydroxide by batch process from water[J]. Environmental. Science,2013(25):993-1000.
[20]近藤精一,石川达雄,安部郁夫,等.吸附科学[M].北京:化学工业出版社,2006.
[21]王军锋,李子荣,郭雨.Mg/Al型水滑石及其焙烧产物对水溶液中Cl-的吸附[J].西安工程大学学报,2008,22(2):171-174.WANG Junfeng,LI Zirong,GUO Yu. Adsorption of chloride anion by Mg/Al hydrotalcite and its calcined product[J]. Journal of Xi’an Polytechnic University.2008,22(2):171-174.
[22] OGAWA M,KAUHO H. Homogeneous precipitation of uniform hydrotalcite particles[J].Langmuir,2002,18(11):4240-4242.
[23] ADACHI-PAGANO M,FORANO C,BESSE J P. Synthesis of Alrich hydrotalcite-like compounds by using the urea hydrolysis reaction-control of size and morphology[J].Journal of Materials Chemistry,2003,13(8):1988-1993.
[24] LAZARIDIS N K,PANDI T A,MATIS K A.Chromium(VI)removal from aqueous solutions by Mg-Al-CO3hydrotalcite:Sorption-desorption kinetic and equilibrium studies[J]. Industrial&Engineering Chemistry Research,2004,43(9):2209-2215.
[25]夏燕,朱润良,陶奇,等.阴离子表面活性剂改性水滑石吸附硝基苯的特性研究[J].环境科学.2013,34(1):226-230.XIA Yan,ZHU Runliang,TAO Qi,et al.Sorption of nitrobenzene to anionic surfactant modified layered double hydroxides[J].Environment Science.2013,34(1):226-230.
[26] YANG Weishen,KIM Y,LIU P K T,et al.A study by in situ techniques of the thermal evolution of the structure of a Mg-Al-CO3layered double hydroxide[J].Chemical Engineering Science,2002,57(15):2945-2953.
[27]申震,唐先进,刘超,等.焙烧态镁铝水滑石处理阴离子染料废水研究[J].环境科学与技术,2006,29(3):89-91.SHEN Zhen,TANG Xianjin,LIU Chao,et al. Experimental study of treating anion dyestuff-containing wastewater by calcined layered double hydroxide[J]. Environmental Science&Technology,2006,29(3):89-91.
[28]郭亚祺,杨洋,伍新花,等.煅烧的水滑石同时去除水体中砷和氟[J].环境工程学报,2014,8(6):2485-2491.GUO Yaqi,YANG Yang,WU Xinhua,et al. Removal of arsenate and fluoride in water by calcined layered double hydroxides[J].Chinese Journal of Environmental Engineering,2014,8(6):2485-2491.