凹凸棒石黏土-腐植酸复合吸附剂吸附Cr(Ⅵ)的性能研究
|
摘要
为促进凹凸棒石黏土-腐植酸复合吸附剂在水处理中的应用,用酸改性的甘肃靖远凹凸棒石黏土和天祝褐煤提取的腐植酸制备出凹凸棒石黏土-腐植酸复合吸附剂,通过SEM、XRD、FT-IR等分析方法对复合吸附剂的结构进行了表征,考察了物料配比及吸附时间、pH值、温度、投加量和初始浓度对Cr(Ⅵ)吸附率的影响。结果表明:靖远凹凸棒石黏土最佳酸改性条件为盐酸5 mol/L,酸化时间120 min,酸用量固液比为1∶10。当Cr(Ⅵ)的起始浓度为0.1 g/L,体积为50 m L,复合吸附剂用量为1.2 g,吸附时间为6 h,p H值为6,温度25℃,酸改性的凹凸棒石黏土与腐植酸的最佳复合比为1∶3时,复合吸附剂对Cr(Ⅵ)的吸附率达到91.7%。复合吸附剂对Cr(Ⅵ)的吸附满足Freundlich模型。在25～45℃条件下,吸附过程ΔG <0、ΔS=87.46 J/(mol·K)、ΔH=-21.2 kJ/mol,表明该吸附是一个自发、熵增、放热的过程。
The attapulgite clay-humic acid composite adsorbent was prepared by acid-modified Ganjing Jingyuan attapulgite clay and humic acid extracted from Tianzhu brown coal. The composite adsorbent was analyzed by SEM,XRD and FT-IR to character the structure. The effects of material ratio,adsorption time,pH value,temperature,dosage and initial concentration on the adsorption rate of Cr( Ⅵ) were investigated.Results showed that the optimum acid modification condition of Jingyuan attapulgite clay was hydrochloric acid concentration of 5 mol/L,acidification time of 120 min,and acid-to-liquid ratio of 1 ∶ 10. The adsorption efficiency of Cr( Ⅵ) by the composite adsorbent reached91.7% when the conditions were as follows: the initial concentration of Cr(Ⅵ) of 0.1 g/L,the amount of composite adsorbent of 1.2 g,the adsorption time of 6 h,the p H value of 6,the temperature of 25 ℃,and the ratio of acid-modified attapulgite clay and humic acid complex of 1 ∶ 3. The adsorption of Cr(Ⅵ) ions by the composite adsorbent met the Freundlich model. At 25-45 ℃,the adsorption process ΔG<0,ΔS =87.46 J/( mol·K),ΔH =-21.2 k J/mol,indicating that the adsorption was a spontaneous,entropic-increasing and exothermic process.
The attapulgite clay-humic acid composite adsorbent was prepared by acid-modified Ganjing Jingyuan attapulgite clay and humic acid extracted from Tianzhu brown coal. The composite adsorbent was analyzed by SEM,XRD and FT-IR to character the structure. The effects of material ratio,adsorption time,pH value,temperature,dosage and initial concentration on the adsorption rate of Cr( Ⅵ) were investigated.Results showed that the optimum acid modification condition of Jingyuan attapulgite clay was hydrochloric acid concentration of 5 mol/L,acidification time of 120 min,and acid-to-liquid ratio of 1 ∶ 10. The adsorption efficiency of Cr( Ⅵ) by the composite adsorbent reached91.7% when the conditions were as follows: the initial concentration of Cr(Ⅵ) of 0.1 g/L,the amount of composite adsorbent of 1.2 g,the adsorption time of 6 h,the p H value of 6,the temperature of 25 ℃,and the ratio of acid-modified attapulgite clay and humic acid complex of 1 ∶ 3. The adsorption of Cr(Ⅵ) ions by the composite adsorbent met the Freundlich model. At 25-45 ℃,the adsorption process ΔG<0,ΔS =87.46 J/( mol·K),ΔH =-21.2 k J/mol,indicating that the adsorption was a spontaneous,entropic-increasing and exothermic process.
引文
[1] Duranoglu D,TROCHIMCZUK A W,BEKER U. Kinetics and Thermodynamics of Hexavalent Chromium Adsorption onto Activated Carbon Derived from Acrylonitrile-divinylbenzene Copolymer[J]. Chem Engine J,2012,187:193-202.
[2] CHO D W,CHON C M,KIM Y,et al. Adsorption of Nitrate and Cr(Ⅵ)by Ccationic Polymer-modified Granular Activated Carbon[J]. Chem Engine J,2011,175:298-305.
[3] LI L L,FAN L L,SUN M,et al. Adsorbent for Chromium Move Based Ongraphene Oxide Functionalized with Magnetic Cyclodextrin-chitosan[J]. Colloids Surf B,2013,107:76-83.
[4]王爱勤,王文波,郑易安,等.凹凸棒石棒晶束解离及其纳米功能复合材料[M].北京:科学出版社,2014:106-107.
[5]王爱勤,王文波,郑易安,等.凹凸棒石黏土应用研究[M].北京:科学出版社,2007:60-61.
[6]何为红,李福春,吴志强,等.重金属离子在胡敏酸-高岭石复合体上的吸附[J].岩石矿物学杂志,2007,26(4):359-365.
[7]王意锟,郝秀珍,王玉军,等.凹凸棒土-腐植酸复合体对Pb(II)的吸附特性及机理研究[J].农业环境科学学报2009,28(11):2 324-2 327
[8] ZHANG J H,ZHANG L L,ZHOU S Y. Magnetically Separable Attapulgite-TiO 2-FexOyComposites with Superior Activity towards Photodegradation of Methyl Orange under Visible Light Radiation[J]. Journal of Industrial and Engineering Chemistry,2014,20:3 884-3 889.
[9]李凤,李涛海. H0.8Ni0.4Ti1.6O4/TiO 2纳米复合材料的合成及光催化性质[J].湘潭大学自然科学学报,2009(2):96-98.
[10]李静萍,郑李纯,陈峰,等.提取腐植酸后的残渣对Cu2+的吸附性能研究[J].化学通报,2010,73(8):719-723.
[2] CHO D W,CHON C M,KIM Y,et al. Adsorption of Nitrate and Cr(Ⅵ)by Ccationic Polymer-modified Granular Activated Carbon[J]. Chem Engine J,2011,175:298-305.
[3] LI L L,FAN L L,SUN M,et al. Adsorbent for Chromium Move Based Ongraphene Oxide Functionalized with Magnetic Cyclodextrin-chitosan[J]. Colloids Surf B,2013,107:76-83.
[4]王爱勤,王文波,郑易安,等.凹凸棒石棒晶束解离及其纳米功能复合材料[M].北京:科学出版社,2014:106-107.
[5]王爱勤,王文波,郑易安,等.凹凸棒石黏土应用研究[M].北京:科学出版社,2007:60-61.
[6]何为红,李福春,吴志强,等.重金属离子在胡敏酸-高岭石复合体上的吸附[J].岩石矿物学杂志,2007,26(4):359-365.
[7]王意锟,郝秀珍,王玉军,等.凹凸棒土-腐植酸复合体对Pb(II)的吸附特性及机理研究[J].农业环境科学学报2009,28(11):2 324-2 327
[8] ZHANG J H,ZHANG L L,ZHOU S Y. Magnetically Separable Attapulgite-TiO 2-FexOyComposites with Superior Activity towards Photodegradation of Methyl Orange under Visible Light Radiation[J]. Journal of Industrial and Engineering Chemistry,2014,20:3 884-3 889.
[9]李凤,李涛海. H0.8Ni0.4Ti1.6O4/TiO 2纳米复合材料的合成及光催化性质[J].湘潭大学自然科学学报,2009(2):96-98.
[10]李静萍,郑李纯,陈峰,等.提取腐植酸后的残渣对Cu2+的吸附性能研究[J].化学通报,2010,73(8):719-723.