阳离子交换容量和烷基链链数对有机蒙脱石性能的影响

已有研究表明影响有机蒙脱石性能的因素很多,除了有机改性剂的特性外,蒙脱石的晶体化学特征也是不容忽视的因素。为了探讨烷基链链数和阳离子交换容量与有机蒙脱石性能之间的关系,本文选择3种不同阳离子交换容量的蒙脱石为主体,4种季铵盐阳离子改性剂十八烷基三甲基溴化铵(S18)、双-十八烷基二甲基溴化铵(D18)、十二烷基三甲基溴化铵(S12)和双-十二烷基二甲基溴化铵(D12)为客体,在不同添加量条件下(0.2、0.5、1.0、1.5、2.0、2.5、3.0、4.0CEC)制备了多个系列的有机蒙脱石,并用XRD、TG-DTG等手段对产物进行表征。实验结果表明,阳离子交换容量与层间柱撑高度之间不存在明显的相关性,但对表面活性剂在蒙脱石上的吸附量有显著的影响,吸附量随着阳离子交换容量的增加而增加。双链表面活性剂对蒙脱石层的撑开能力比单链更强,在层间具有更复杂的自组装过程,导致其热分解过程更为复杂。     

干、湿态单/双链表面活性剂柱撑蒙脱石层间微结构及分子环境比较

以含不同烷基碳链长度(8、12或16个碳原子)的单/双链阳离子表面活性剂对内蒙蒙脱石样品进行了柱撑改性。用XRD和FTIR方法研究了柱撑改性后干、湿样品的层间微结构和分子环境。单链柱撑样品中,烷基链长度增加,柱撑高度也增大。湿样的柱撑高度大多高于干样品,衍射图峰形更为规整,柱撑结构更为均一;双链柱撑样品也是柱撑高度与烷基链长度正相关,但其湿样品的底面间距反而小于干样品。同时,亚甲基伸缩振动的变化趋势与层间距的变化趋势基本一致,即当烷基链长度或数目增加时,有机蒙脱石层间有机相分子的环境更接近于似固态。     

TDTMA+-柱撑蒙脱石吸附硝基苯的实验研究

以阳离子表面活性剂(十四烷基三甲基溴化铵,TDTMBA)为柱撑剂,在不同浓度条件下(0.2 CEC～2.5 CEC)制备了一系列柱撑蒙脱石,并通过XRD对有机蒙脱石进行表征,研究季铵盐离子在层间的排列结构.同时针对TDTMA -柱撑蒙脱石对硝基苯的吸附进行研究.实验结果表明,吸附去除率受硝基苯的初始浓度、反应时间等因素的影响,而与pH值没有太大的关系.经过柱撑改性后,粘土对硝基苯的吸附能力较原土有了明显的提高.随着层间柱撑浓度的增大,柱撑蒙脱石对硝基苯的吸附量也增大.另外钙基蒙脱石和平卧双层,倾斜单层以及倾斜双层的结构的TDTMA -柱撑蒙脱石对硝基苯的吸附等温线符Freundlich和Langmuir等温方程,假三层结构的TDTMA -柱撑蒙脱石对硝基苯的吸附等温线符合Linear等温方程,这表明前者是以表面吸附为主,后者是以分配作用为主.     

不同层间堆垛密度的HDTMA^＋柱撑蒙脱石对对硝基苯酚的吸附实验研究

本文以阳离子表面活性剂(十六烷基三甲基溴化铵,HDTMAB)为柱撑剂,在不同浓度条件下(0.5～2.5CEC)制备了层间季铵盐离子呈单层平卧、双层平卧和倾斜双层排列的HDTMA 柱撑蒙脱石,并研究了具有不同层间结构的HDTMA 柱撑蒙脱石对对硝基苯酚的吸附能力以及溶液pH值、温度、对硝基苯酚初始浓度等因素对HDTMA 柱撑蒙脱石吸附性能的影响。实验结果表明,HDTMA 柱撑蒙脱石对对硝基苯酚的吸附能力随着介质溶液pH值的升高而升高,这主要受对硝基苯酚在不同pH条件下的离子化程度影响;HDTMA 柱撑蒙脱石对对硝基苯酚的吸附能力随着介质溶液温度的升高而降低,说明吸附反应是一个放热过程。同时,从单层平卧→双层平卧→倾斜双层,HDTMA 柱撑蒙脱石对对硝基苯酚的吸附能力明显提高。钠基蒙脱石和低堆垛密度(单层平卧、双层平卧)的HDTMA 柱撑蒙脱石对对硝基苯酚的吸附等温线呈S型,而高堆垛密度(倾斜双层)的HDTMA 柱撑蒙脱石对对硝基苯酚的吸附等温线呈Linear型,表明前者以表面吸附为主,后者以分配作用为主。     

有机蒙脱石层间微结构的分子模拟

采用分子动力学模拟方法,对舍烷基长链阳离子表面活性剂改性有机蒙脱石的层间域内分子环境及烷基长链排列状况进行模拟研究,并考察改性剂负载量与层间域含水量的改变对烷基链排列方式和活动性以及表面活性剂离子中N,C原子的分布状况的影响.1.0倍阳离子交换容量改性的有机蒙脱石在含少量水的情况下(干态),N,C原子均呈双层分布,表明烷基长链为双层平卧排列.含水量的提高(湿态)会导致烷基链从双层分布向在层闻域内均匀分布转变.2.0倍阳离子交换容量改性的有机蒙脱石在舍少量水的情况下(干态),烷基链呈双层倾斜分布于层间域内,烷基链的头部靠近四面体片层.含水量的提高(湿态)对烷基链在层间域内分布状态影响有限,但会导致烷基链整体向层间域中心平面移动,水分子优先占据靠近四面体片层的位置.     

交换液酸碱度对OTAC在蒙脱石中吸附及复合物凝胶粘度影响

在蒙脱石有机改性体系中,交换液酸碱度对蒙脱石荷电性以及十八烷基三甲基氯化铵(OTAC)的电离度影响很大,进而影响OTAC在蒙脱石中的吸附以及制备复合物的凝胶粘度。研究发现,在pH=3的强酸性交换体系中,蒙脱石端面可变电荷为正电荷,OTAC阳离子和蒙脱石之间静电斥力的存在不利于OTAC在蒙脱石上的吸附,吸附量和吸附率分别是0.943CEC和85.7%,制备复合物的凝胶粘度最低,分别是μ0min为45.67Pa·s,μ30min为16.52Pa·s;在pH=10的弱碱性交换体系中,由于蒙脱石层面和端面均带有负电荷,静电引力更有利于OTAC阳离子在蒙脱石层间交换及表面吸附,其吸附量和吸附率最高,分别为1.097CEC和99.71%,制备复合物的凝胶粘度也较高,分别是μ0min为95.93Pa·s,μ30min为37.67Pa·s;在强碱性交换体系中,当pH=11和13时,蒙脱石对OTAC的吸附量和吸附率降低明显,吸附量分别为1.08CEC和1.058CEC,吸附率分别降到98.20%和96.18%,对应复合物的μ0min分别为96.52Pa·s和93.52Pa·s,μ30min分别为36.57Pa·s和36.53Pa·s,究其原因由于交换液中OTAC阳离子和高浓度的钠离子在蒙脱石层间和表面存在竞争吸附导致蒙脱石层间钠离子的交换难度加大。     

镍铝基柱撑蒙脱石的制备及孔道结构研究

以钠基蒙脱石为原料,采用共聚法合成镍铝柱化剂,利用离子交换法制备镍铝基柱撑蒙脱石。通过研究不同镍铝物质的量比例和不同NaOH的量对柱撑蒙脱石制备的影响,并对其孔道结构进行探讨。XRD结果表明,当镍铝物质的量比为1∶6、加入75mlNaOH时,可得到(001)面网层间距达1.8940nm的镍铝基柱撑蒙脱石。FT-IR显示,镍铝基聚合羟基阳离子进入蒙脱石层间,柱撑蒙脱石的基本结构并未发生改变。对柱撑前后蒙脱石的比表面积和孔径结构进行分析,发现镍铝基柱撑蒙脱石比表面积为169.68m2/g,平均孔径为4.120nm,说明镍铝基柱撑蒙脱石具有较大的比表面积,较小且均匀的孔径分布,是一种合适的催化和吸附材料。     

不同链长烷基季铵离子在蒙脱石层间域内排列方式的对比

选用含不同烷基长链的三种季铵盐——十二烷基三甲基溴化铵(DDTMAB)、十四烷基三甲基溴化铵(TDTMAB)、十六烷基三甲基溴化铵(HDTMAB)，对河北钠交换蒙脱石进行了有机柱撑实验，以X射线衍射分析方法对实验产物进行了对比研究。结果表明，由于烷基链中所含的碳原子数目不同，三种长链季铵离子对蒙脱石的柱撑效果不同，DDTMA^ 在蒙脱石层间域内可形成平卧单层、平卧双层和假三层三种不同排列方式；TDTMA^ 与DDTMA^ 在低浓度条件下形成的前两种排列方式相同，而第三种则不同，为倾斜单层排列；HDTMA^ 有机柱撑产物中除了具有前两者的排列方式外，还具有倾斜双层排列方式。不同排列方式的复合产物可以多相共存。此外，随着柱撑剂浓度的增加，三种长链烷基季铵离子在蒙脱石层间域内的排列方式及其演化是不同的。     

不同表面活性剂修饰TiO2柱撑粘土的制备及其光催化活性研究

本文分别采用阴离子、非离子、阳离子三种不同类型的表面活性剂对河北蒙脱石进行改性修饰,并以酞酸丁酯和盐酸分别为前驱物和酸催化剂,采用溶胶-凝胶法（Sol-gel）制备了不同表面活性剂修饰TiO2柱撑粘土催化剂.用X射线粉末衍射（XRD）和场发射扫描电子显微镜（SEM）等手段表征了催化剂的微观结构,以2,4,6-三氯苯酚（2,4,6-trichlorophenol, TCP）和甲基橙染料的吸附、降解为模型反应,考察了改变溶胶和表面活性剂的不同添加顺序对阳离子表面活性剂所修饰的催化剂性质的影响,以及不同类型的表面活性剂修饰所得的催化剂的光催化活性.实验结果表明,通过添加不同的表面活性剂能够不同程度地改变柱撑粘土的BET比表面积,并使其对不同目标污染物具有不同的吸附能力和光催化活性.阴离子表面活性剂十二烷基苯磺酸钠（DBS）修饰的TiO2柱撑粘土具有较好的光催化活性,其次是非离子表面活性剂聚乙烯醇（PVA）修饰的TiO2柱撑粘土,而阳离子表面活性剂十六烷基三甲基溴化铵（CTMAB）修饰的柱撑粘土光催化活性较差.     

无机—有机柱撑蒙脱石对苯酚的吸附

分别用无机－有机改性柱撑蒙脱石对苯酚进行吸附试验,研究它们吸附苯酚的适宜条件圾吸附等温线（２５℃）,结果表明,用表面活性剂改性的柱撑蒙脱石,能大幅度提高对苯酚的吸附能力,柱撑蒙脱石对苯酚的吸附能力主要取决于改性粘土吸附剂的微孔结构和表面组分,而不仅仅依赖于表面积,经５００℃高温灼烧后柱撑蒙脱石柱结构及层间距（１．８３ｎｍ）稳定,因而柱撑蒙脱石可再生循环使用,是一种潜在的吸附环境污染物的物质。     

表面活性剂改性粉土抗剪强度特性的研究

表面活性剂随着工业、农业、日常生活等各种活动进入到土体及地下水中,不仅会带来环境污染的风险,还会改变土体的结构等从而影响土体的工程性质。为了合理评估表面活性剂污染土体的工程适宜性,采用阴离子表面活性剂十二烷基苯磺酸钠(SDBS)和阳离子表面活性剂三甲基十六烷基溴化铵(CTAB)对粉土进行改性,通过直剪试验研究其对粉土强度特性的影响。结果表明,表面活性剂改性后的粉土内摩擦角减小,随着表面活性剂浓度的增大,内摩擦角减小的幅值越大,当表面活性剂浓度达2%时,粉土内摩擦角减小23.9%;SDBS改性后的粉土黏聚力大大减小,SDBS浓度为2%时,黏聚力减小91.8%,CTAB改性后粉土黏聚力增大,最大增幅达41.8%;改性粉土中加入不同pH的表面活性剂时,内摩擦角变化很小,表明表面活性剂的酸碱程度对土样内摩擦角影响较小,随着表面活性剂溶液pH的增大,改性粉土的黏聚力呈现出下降的趋势,pH改变了土壤的电荷的分配,改变了土粒间的静电作用,从而引起土体黏聚力的变化。     

Adsorption of hydroxamate siderophores and EDTA on goethite in the presence of the surfactant sodium dodecyl sulfate

Siderophore-promoted iron acquisition by microorganisms usually occurs in the presence of other organic molecules, including biosurfactants. We have investigated the influence of the anionic surfactant sodium dodecyl sulfate (SDS) on the adsorption of the siderophores DFOB (cationic) and DFOD (neutral) and the ligand EDTA (anionic) onto goethite (α-FeOOH) at pH 6. We also studied the adsorption of the corresponding 1:1 Fe(III)-ligand complexes, which are products of the dissolution process. Adsorption of the two free siderophores increased in a similar fashion with increasing SDS concentration, despite their difference in molecule charge. In contrast, SDS had little effect on the adsorption of EDTA. Adsorption of the Fe-DFOB and Fe-DFOD complexes also increased with increasing SDS concentrations, while adsorption of Fe-EDTA decreased. Our results suggest that hydrophobic interactions between adsorbed surfactants and siderophores are more important than electrostatic interactions. However, for strongly hydrophilic molecules, such as EDTA and its iron complex, the influence of SDS on their adsorption seems to depend on their tendency to form inner-sphere or outer-sphere surface complexes. Our results demonstrate that surfactants have a strong influence on the adsorption of siderophores to Fe oxides, which has important implications for siderophore-promoted dissolution of iron oxides and biological iron acquisition.     

Precipitate flotation of copper as the sulfide,using recyclable amphoteric surfactants

An experimental study was made to identify surfactants which are effective for removal of copper from dilute aqueous solution (100–500 ppm) by precipitate flotation as the sulfide, and which at the same time can be recovered from the CuS product for recycle. Batch flotation experiments confirmed that a cationic surfactant was necessary for flotation of CuS from such dilute suspensions; however, no satisfactory way could be found for recovering cationic surfactants from the CuS. This led to consideration of amphoteric surfactants, which are cationic at low pH and anionic at high pH. It was found that a change to negative, rather than simply neutral, charge was required for efficient surfactant recovery. It was further found, through the assistance of experiments in which the CuS suspension was agitated with solvents, that certain functional groups which interact chemically with the CuS surface should also be absent from the surfactant molecule. Following this logic, Amphoterge K-2 (Lonza Chemical Co.) was identified as a suitable surfactant, provided CuS was precipitated with S^2? in excess. Tests established that 95% of adsorbed Amphoterge K-2 could be recovered by raising the pH to 11 and boiling the suspension for one hour, followed by decanting. Surfactant thus recovered was effective in a second flotation test. Foamate solids settled rapidly; such behavior would help reduce the consumption of chemicals for the pH change.Column flotation studies were made using Amphoterge K-2 for removal of Cu²⁺ present at 100 ppm and pH = 2. High removals of CuS could be obtained at concentrations of surfactant above about 25 ppm, for which conditions a substantial fraction of the surfactant remains in solution rather than being adsorbed onto the CuS. The recovery of CuS would be improved by introducing the surfactant in a separate feed, below the feed of CuS suspension. Adding some surfactant in the CuS feed, as well as in a lower feed, gave an even better recovery of CuS (99.8%) at sufficiently high surfactant loadings.     

New Organic Montmorillonite Preparation: Anion-Nonionic Surfactants Modified Montmorillonites

Montmorillonites (MMT) was modified with nonionic surfactant Trion X-100 (OP-10) and anionic surfactants sodium stearate (SSTA) and sodium dodecyl benzene sulfonate (SDBS) respectively. In this study, the effects of anionic surfactant types and MMT types on modification montmorillonite were investigated. XRD analysis results showed that SSTA/OP-10/MMT and SDBS/OP-10/MMT were successfully obtained. The basal spacing of SSTA/OP-10/MMT reached 5.07nm and the SSTA intercalation reaction was relatively stable. Different types of MMT (Xinjiang natural sodium montmorillonite(MMT-1), Jianping sodium montmorillonite (MMT-2) and artificial sodium montmorillonite(MMT-3)) were modified with SSTA/OP-10. XRD test results showed that MMT-1, MMT-2 and MMT-3 can be modified by SSTA/OP-10. Anion-nonionic organic montmorillonite (SSTA/OP-10/MMT-1, SSTA/OP-10/MMT-2 and SSTA/OP-10/MMT-3 were successfully obtained respectively. The higher expansion capacity was found to be beneficial to organic modification.     

Effect of heavy metals and surfactants on the adsorption of phenolic compounds on sediment

The effects of different heavy metals (copper and mercury), cationic surfactants cetylpyridinium chloride, anionic surfactant sodium dodecylbenzenesulfonate and the chemistry of the solution (pH value) on the adsorption of three selected phenolic compounds (2, 4-Dichlorophenol, 2, 4-Dinitro-phenol and 2, 4-Dimethyphenol) on sediment were studied. Results indicated that in the sediment-water system with phenolic compounds: (1) all of the data could be simulated by Freundlich equation; (2) the experiments studying pH effects showed that the adsorption capacity of 2, 4-Dichlorophenol and 2, 4-Dimethyphenol were quite potentia Hydrogenii dependent and increased with decrease in potentia Hydrogenii, while 2, 4-Dinitrophenol followed the different trend; (3) As the concentration increased from 0 to 0.2?mM for Cu²⁺, the Freundlich capacity coefficient constant varied from 62.84 to 325.1 for 2, 4-Dichlorophenol, from 13.1 to 82.179 for 2, 4-Dinitrophenol and from 29.433 to 7.976 for 2, 4-Dimethyphenol, respectively. The Freundlich capacity coefficient constant of 2, 4-Dichlorophenol, 2, 4-Dinitrophenol and 2, 4-Dimethyphenol varied from 62.84 and 421.43, 13.1 and 138.1, 29.433 and 1.381, respectively, with concentration of Hg²⁺ increased from 0 to 0.04?mM, respectively; (4) the adsorption of 2, 4-Dichlorophenol and 2, 4-Dimethyphenol were accentuated by cetylpyridinium chloride but suppressed by sodium dodecylbenzenesulfonate, whereas the adsorption of 2, 4-Dinitrophenol on sediment was enhanced by both cationic and anionic surfactants, effects that are consistent with electrostatic and hydrophobic interactions among ionic surfactants, phenolic compounds and sediment. The results are believed to provide a useful insight into describing the transport and fate of phenolic compounds in natural environments.     

The Structure of Montmorillonites Modified with Zwitterionic Surfactants and Their Sorption Ability

In the past four decades, there is a growing use of surfactant modified clay complexes in wide range of applications. The mostly used surfactants to modify the swelling clay minerals are cationic surfactants, such as quaternary ammonium, which consists of two distinct moieties, a hydrophilic head, where the positive charge is concentrated, and a hydrophobic hydrocarbon chain tail. During the surface modification, this kind of surfactant molecules attach on the inner and outer surface of clay minerals, the hydrophilic surface of raw clay minerals may changed into hydrophobic surface. The changes of organophilicity and hydrophobicity of clay minerals enable them used in more wide fields, such as adsorbents for organic contaminant, geotechnical barriers, filling of nanocomposite, etc.     

蒙脱石中性化改性实验研究

使用表面活性剂HDTMAB对含有蒙脱石等粘土矿物的膨润土进行不同程度的有机改性,并利用自由膨胀率的实验方法定量描述改性膨润土在水以及甲苯介质中的膨胀规律。对实验结果进行数学分析后发现,随着改性剂用量的加大,改性膨润土在水介质中的自由膨胀率明显降低,而在甲苯介质中的自由膨胀率显著上升,当改性剂用量约为15%时,改性膨润土在水以及甲苯介质中都没有发生剧烈膨胀。依照上述膨润土的改性方法,对胜利油田提供的岩心样品进行了有机改性,并得到了相同的规律。由此得出,严格控制改性剂用量可以实现蒙脱石的中性化改性。利用这一规律,将适量的改性剂注入地下,既能够缓解油气田储层中蒙脱石的水敏膨胀危害,又不会造成过量的油脂分子吸附于矿物表面。     

Biodegradation of anionic surfactants by isolated bacteria from activated sludge

Sodium dodecyl sulphate, (SDS) is an anionic surfactant that widely used all over the world. They will eventually end-up and accumulate in household or industrial sewage. Due to their high foaming capabilities, which can cause numerous problems in sewage treatment facilities as well as direct toxic effects on many different organisms in ecosystem; they are generally considered as serious pollutants. In this survey, two different bacteria were isolated from Tehran municipal activated sludge. Biochemical tests as well as 16S rRNA gene sequencing for identification have been applied. After experiments to optimize the pH and temperature for growth of the two bacterial isolates, the extent of SDS utilization was evaluated by HPLC method. Two bacterial isolates show which ability to rapidly and actively degrade SDS upon using it as their sole source of carbon. The identification tests have indicated the two isolates to be Acinetobacter johnsoni and Pseudomonas beteli. The Pseudomonas beteli and Acinetobacter johnsoni isolates were able to degrade 97.2% and 96.4% of the original SDS levels after 10 days of growth; respectively. Mixed culture of the two isolates did not significantly increase SDS utilization, (97.6%). In conclusion, the results of this study suggest that growth of simple bacteria such as Acinetobacter or Pseudomonas in household and industrial sewage can be cost-effective method anionic surfactants elimination.