【作者】 李效红；

【导师】 朱琨； 赵保卫；

【作者基本信息】 兰州交通大学 ， 环境工程， 2012， 博士

【摘要】 论文依据不同的改性机理和方法,以β-环糊精作为改性剂,对天然沸石进行改性,制备了两种具有特殊结构与性能的改性沸石。采用FTIR光谱、元素分析、扫描电镜以及X射线能量色散谱仪等现代分析测试手段对改性沸石进行了表征。研究了改性沸石分别吸附处理水中有机污染物、重金属和复合污染物的能力,初步探讨了改性沸石吸附污染物的作用机理,为拓展沸石的功能与应用提供了理论依据,为改性沸石在水处理中的应用提供了技术基础,也为安全、无毒、环保的高效吸附剂的开发提供了信息。主要研究内容和结论归纳如下：提出了利用β-环糊精改性沸石的新方法。以2,3-环氧丙基三甲基氯化铵(ETMAC)和β-环糊精合成的阳离子化β-环糊精对沸石进行改性,制得改性沸石CCDMZ;利用环氧氯丙烷(EPI)作为交联剂,通过醚化作用,使β-环糊精固载到沸石表面,制得改性沸石ECDMZ。以吸附量(qe)为指标,分别考察了两种改性沸石的制备条件对所得产物吸附污染物量的影响,确定了两种改性沸石的最佳制备条件。结果表明,阳离子化β-环糊精的制备条件(初始β-环糊精的浓度、合成溶液的pH值、摩尔比METMAC:Mβ-CD)、天然沸石的预处理、阳离子化β-环糊精的浓度、改性时间等制备条件均对CCDMZ及附污染物的qe产生影响,其中尤以阳离子化β-环糊精的制备条件影响最大；天然沸石的预处理、摩尔比MEPI:Mβ-CD、改性时间、溶液的pH值以及溶液中NaOH百分含量等均对ECDMZ吸附污染物的qe产生影响。对两种改性沸石分别进行FTIR光谱、元素分析、扫描电镜以及X射线能量色散谱等方面的表征,结果显示β-环糊精可以较稳定地固载于沸石表面,形成具有优良吸附性能的新型吸附剂。研究了改性沸石对水中硝基苯酚(NPs)、重金属离子和对-硝基苯酚(p-NP)-重金属离子复合污染物体系的吸附能力。结果表明,CCDMZ和ECDMZ吸附NPs、重金属离子时,qe受粒径、吸附时间、溶液初始浓度和溶液pH值等的影响。在粒径0.45～0.9mm范围内,CCDMZ和ECDMZ对NPs和重金属离子均具有较高的qe。CCDMZ和ECDMZ吸附NPs的平衡时间分别为60min和100min、Cu2+的吸附平衡时间均为120min、Ni2+的吸附平衡时间分别为120min和140min。NPs和重金属离子初始浓度的升高有利于CCDMZ和ECDMZ对NPs和重金属离子的吸附。当NPs浓度为300mg/L时,CCDMZ吸附p-NP、间-硝基苯酚(m-NP)和邻-硝基苯酚(o-NP)的qe分别为335、220和324μg/g；ECDMZ对p-NP、m-NP和o-NP的qe分别为902、766和855μg/g。当Cu2+和Ni2+的浓度为100mg/L时,CCDMZ和ECDMZ对Cu2+和Ni2+的qe分别为1267、1148μg/g和3751、3811μg/g。溶液pH值对CCDMZ和ECDMZ的qe影响非常明显,因为pH值的变化不但影响了NPs、Cu2+和Ni2+在溶液中的形态,同时也影响了CCDMZ和ECDMZ表面的荷电性。对比ECDMZ、CCDMZ和NZ对NPs和重金属离子的吸附,其吸附效果是ECDMZ>CCDMZ>NZ。吸附动力学和等温线研究表明,CCDMZ和ECDMZ吸附NPs、Cu2+和Ni2+的过程符合二级动力学模型,吸附等温线符合Langmuir型,说明吸附过程是以单分子层吸附为主,既存在化学吸附又存在物理吸附,且吸附过程的主控速率是化学吸附。Freundlich型吸附等温线拟合结果n值表明CCDMZ和ECDMZ对NPs、Cu2+和Ni2+的吸附均为优先吸附。低浓度下的高分离因子(r)值表明CCDMZ和ECDMZ对NPs、Cu2+和Ni2+的吸附更适合于微污染水处理。如：对100mg/L的NPs、CCDMZ和ECDMZ对p-NP、o-NP和m-NP的qe分别较NZ提高了8、5、13和23、14、37倍。吸附热力学研究表明对NPs的吸附是自发的放热过程,吸附过程是焓推动作用,而对Cu2+和Ni2+的吸附过程是自发的吸热过程,吸附过程是熵推动作用。对于p-NP和重金属离子复合污染物体系的研究表明,CCDMZ和ECDMZ因共存污染物的相互影响而使得qe下降。更多还原

【Abstract】 Two modification zeolites with special structure and performance were synthesized by modifying natural zeolite (NZ) using beta-cyclodextrin (β-CD) as modifying agent through the two different mechanisms and methodes. The modified zeolites were characterized with the modern analytical techniques such as fourier transform infrared spectroscopy (FTIR), elemental analysis, scanning electronic microscope (SEM), and Energy dispersive X-ray spectrometry (EDS) etc.. Through studying the adsorption capacity of modified zeolites on organic pollutant, heavy metal, and compound pollutants, the related mechanisms in adsorption of pollutants in water were investigated. This dissertation aimed to sumbit a theoretical basis in function and application of zeolites in order to provide a techno-basic in application of zeolites in water treatment, and to expend information for development of high-efficiency absorbents of safety, avirulence and environmental protection.The main contents and results were as follows:The novel modification methods of zeolites was presented using β-cyclodextrin (β-CD) as modifying agent. CCDMZ was obtained by modification zeolite using cationic β-CD (CCD) which was synthesized by2,3-expoxypropyl trimethylammonium chloride (ETMAC), and ECDMZ was obtained using epoxy chloropropane (EPI) as cross-linking agent through etherification to locate β-CD on NZ surface. The optimal preparation conditions of two modification zeolites were determined by studying the effects of preparaction condition on adsorption capacity (qe) of CCDMZ and ECDMZ, respectively. The results indicated that qe of CCDMZ was affected by the preparaction conditions of CCD (the concentration of β-CD, pH of solution, and METMAC:Mβ-CD), pretreament of NZ, concentration of CCD, and modification time etc.. The qe of ECDMZ was affected by pretreament of NZ, MEPT:Mβ-CD, reaction time, pH of solution, and percent of NaOH in solution etc.. The modern analytical techniques of FTIR, elemental analysis, SEM, and EDS were used to characterize the surface modification. The characterization results showed that β-CD could successfully be located on the surface of zeolites.The qe of CCDMZ and ECDMZ were investigated dealing with nitrophenols (NPs), heavy metals, para-nitrophenol (p-NP) and heavy metal ion of composite pollution system. The results indicated that the qe of CCDMZ and ECDMZ were affected by partical size, contact time, concentration and pH of solution etc.. The high qe of CCDMZ and ECDMZ on NPs and heavy metals was found at size fraction of0.45-0.9mm. Adsorption equilibrium times of CCDMZ and ECDMZ on NPs were60min and100min, respectively. The equilibrium times of Cu2+were120min, and that of Ni2+were120min and140min, respectively. The increas of concentration of NPs and heavy metals were favorable to the increas of qe. At an initial solute concentration of NPs of300mg/L, the qe of CCDMZ on p-NP,mid-nitrophenol (m-NP) and ortho-nitrophenol (o-NP) were335,220and324μg/g, and the qe of ECDMZ onp-NP, m-NP and o-NP were902,766and855μg/g, respectively. At an initial solute concentration of Cu2+and Ni2+of100mg/L, the qe of CCDMZ and ECDMZ on Cu2+and Ni2+were1267,1148μg/g and3751,3811μg/g, respectively. The effects of pH on qe of CCDMZ and ECDMZ were greatly visible because of the effect of changed pH on both morphological structure of NPs, Cu2+and Ni2+in solution and electrical charge structure of CCDMZ and ECDMZ. The adsorption effect of NPs and heavy metal ions on NZ, CCDMZ and ECDMZ was ECDMZ>CCDMZ>NZ. The adsorption process of CCDMZ and ECDMZ for NPs, Cu2+and Ni2+followed Langmuir isotherm and fitted with pseudo-second order. The results indicated that the adsorption process was physical absorption and chemical adsorption when the chemical adsorption mainly controlled the process. The n of Freundlich isotherm indicated that the adsorption of CCDMZ and ECDMZ for NPs, Cu2+and Ni2+were preferential, and the r of Langmuir showed that CCDMZ and ECDMZ were beneficial to treat low concentration water. For example, at an initial solute concentration of NPs of100mg/L, the qe of CCDMZ and ECDMZ on p-NP, o-NP and m-NP were increased8,5,13and23,14,37times than NZ. Thermodynamic study showed that the adsorption of NPs was a spontaneous and exothermic process, and the adsorption of Cu2+and Ni2+was a spontaneous and endothermic process. The adsorption results of mixed pollutants in the aqueous solutions indicated that the qe was decreased because of the mutual effects of β-NP and metal ions.更多还原