有机分子偶氮苯在高岭石表面吸附研究

利用Gaussian 98软件,采用量子化学从头算计算方法,研究有机分子偶氮苯在高岭石表面的吸附作用.不同位置的吸附结果比较表明,吸附后体系稳定性强弱及电子发生转移的可能性大小依次是平行于硅氧烷表面、平行(010)面、平行[AlO4]八面体表面.芳香环上的π键和硅氧烷表面的O原子均相互作用,电子从偶氮苯上的C和N原子流向高岭石表面的O原子.对吸附复合物进行了X射线粉末衍射(XRD)、红外光谱(FTIR)测试及结构分析,结果表明,偶氮苯吸附到高岭石的硅氧烷表面.     

甲基对硫磷和西维因在粘土矿物表面的吸附解吸特性

研究了甲基对硫磷和西维因在蒙脱石、高岭石和针铁矿表面的吸附 解吸特征。结果表明,Langmuir方程能较好的描述甲基对硫磷和西维因在３种矿物表面的等温吸附过程,且蒙脱石对农药的最大吸附量大于高岭石和针铁矿。用动力学方程对2种农药的吸附过程进行拟合,Elovich方程、双常数方程和一级动力学方程均得到较好的结果,其中Elovich方程为最佳模型,相关系数（R²）在0.93～0.98之间,说明该吸附为非均相扩散过程。3种矿物对甲基对硫磷和西维因的吸附强度均为蒙脱石＞高岭石＞针铁矿。     

苯分子与Si_6O_18H_12和Al_6O_24H_30团簇模型相互作用的理论研究(英文)

粘土矿已经被广泛用来去除有机物,修复和净化被石油碳氢化合物污染的土壤和地下水.我们选择高岭石作为研究对象,构造了Si6O18H12和Al6O24H30两个团簇模型分别代表高岭石的硅氧层表面和铝氧层表面,在MP2/6-31G(d,p)//B3LYP/6-31G(d,p)的理论水平上系统地研究了气态下苯分子和高岭石团簇模型的相互作用.并进一步分析了苯分子和高岭石表面相互作用的各种气态性质,比如:优化的几何构型、结构参数、吸附能、自然键轨道电荷分布、振动频率变化、静电势、电子密度性质(次级氢键的电子密度和拉普拉斯算符值)和电子密度差分等.优化的几何构型表明苯分子吸附在高岭石表面的本质可能是次级氢键的形成.其他性质的结果进一步验证了次级氢键的存在,并指出苯更倾向于吸附在高岭石的铝氧层表面,且苯环和铝氧层表面形成近似90°的夹角.     

恶臭假单胞菌与土壤矿物的界面反应及其对甲基对硫磷降解影响

研究了恶臭假单胞菌在蒙脱石、高岭石和针铁矿表面的吸附特征,探讨了细菌在不同粘粒矿物存在下的生长代谢活性,及对甲基对硫磷的降解动力学.结果表明, 三种矿物对细菌的吸附强度为针铁矿>高岭石>蒙脱石.当甲基对硫磷浓度较低时(10 mg/L), 游离菌的降解能力始终比固定菌强;在高浓度(20～40 mg/L)下, 固定菌对农药的降解能力起初(前9 h)高于游离菌, 随后渐渐低于游离菌.不同矿物固定的细菌, 其降解能力为蒙脱石>高岭石>针铁矿.蒙脱石对细菌的亲和力最弱, 但它对细菌的代谢活性有促进作用, 有利于农药的生物降解; 而针铁矿与细菌的结合强度最大, 细菌活性受到抑制, 不利于农药的降解.     

V2O5/SiO2催化剂的异丁烷选择氧化反应性能

 采用溶胶－凝胶法和浸渍法制备了V2O5／SiO2催化剂,并用XRD,IR,TPD和活性评价等手段对催化剂的表面构造、化学吸附性能和异丁烷选择氧化反应性能进行了研究．结果表明：催化剂表面由Lewis碱位V＝O双键的端氧和Lewis酸位V5＋构成,异丁烷分子主要通过甲基中的H双位吸附在催化剂表面的Lewis碱位上,异丁烯分子可通过甲基的H吸附在催化剂表面的Lewis碱位,也可通过C＝C双键吸附在催化剂表面的Lewis酸位上．在常压条件下,异丁烷选择氧化产物主要有异丁烯、甲基丙烯醛和甲基丙烯酸,其中深度氧化产物CO2主要由通过C＝C吸附的异丁烯继续反应生成．     

苯分子与Si6O18H12和Al6O24H30团簇模型相互作用的理论研究

粘土矿已经被广泛用来去除有机物,修复和净化被石油碳氢化合物污染的土壤和地下水. 我们选择高岭石作为研究对象,构造了Si₆O₁₈H₁₂和Al₆O₂₄H₃₀两个团簇模型分别代表高岭石的硅氧层表面和铝氧层表面,在MP2/6-31G(d,p)//B3LYP/6-31G(d,p)的理论水平上系统地研究了气态下苯分子和高岭石团簇模型的相互作用. 并进一步分析了苯分子和高岭石表面相互作用的各种气态性质,比如：优化的几何构型、结构参数、吸附能、自然键轨道电荷分布、振动频率变化、静电势、电子密度性质(次级氢键的电子密度和拉普拉斯算符值)和电子密度差分等. 优化的几何构型表明苯分子吸附在高岭石表面的本质可能是次级氢键的形成. 其他性质的结果进一步验证了次级氢键的存在,并指出苯更倾向于吸附在高岭石的铝氧层表面,且苯环和铝氧层表面形成近似90°的夹角.     

N-(2-氨乙基)-月桂酰胺浮选铝硅酸盐矿物的研究

研究了N (2 氨乙基) 月桂酰胺对高岭石、伊利石和叶腊石等铝硅酸盐矿物的浮选行为.发现该表面活性剂对叶腊石的浮选回收率最高可达97.7％，对伊利石和高岭石的回收率相对较低，一般不超过82％.矿浆pH对高岭石、伊利石和叶腊石的回收率影响较小.酸性矿浆中表面活性剂通过静电引力吸附在矿粒表面；碱性矿浆中，表面活性剂通过氢键吸附在矿粒表面.红外吸收光谱证明，三种矿物表面中均存在－OH；在一个较宽的pH范围内，三种矿物矿浆的Zeta电位均为负值，表明矿粒表面荷负电.矿粒的扫描电镜（SEM）照片（×15000）表明，叶腊石主要呈薄片状颗粒，高岭石和伊利石颗粒呈不规则形状.     

ZrO2酸碱性质的TPD表征 II. NH3和CO2共吸附研究

用NH_3和CO_2双组分并吸附TPD-MS和IR技术对ZrO_2催化剂表面酸中心和碱中心的相互关系进行了表征. 先吸附NH_3（或CO_2）对在其后吸附的CO_2（或NH_3）不仅无阻碍，反而导致后吸附CO_2（或NH_3）在最高程脱峰温区（＞510 K）的脱附量增加．这种双组分并吸附效应在IR谱图上表现为NH_3共吸附诱发生成了一种新的CO_2吸附态，即在碱中心上形成单齿碳酸根物种．同时CO_2共吸附又强化NH_3与Zr~(4＋)（Lewis酸中心）的配位键合．这表明ZrO_2表面存在相互邻接的酸中心和碱中心，它们通过表面键诱导极化而令酸－碱相互作用加强．这类双组分共吸附效应可归结为表面键诱导酸－碱相互作用．     

基质影响电喷雾离子化效率的研究

着眼于液相色谱与质谱条件的匹配问题,以酸性化合物——大黄酸,碱性化合物——青藤碱为模型化合物,系统地考察了正离子和负离子模式下,6种常见的LC-MS缓冲体系对电喷雾离子化效率的基质影响。结果表明：被分析物,采用不同的溶剂体系,离子化效率有显著差异,在实际样品分析中,应根据感兴趣的化合物选择合适的缓冲溶剂体系。     

CO2和CH3OH直接合成碳酸二甲酯用Cu-Ni/ZrO2-SiO2催化剂

 采用表面反应改性法制备了ZrO2－SiO2（ZrSiO）表面复合物,用等体积浸渍法制备了ZrSiO担载的Cu－Ni双金属催化剂,并用IR,TPD,TPSR和微反技术考察了CO2和CH3OH在催化剂表面上的化学吸附及反应性能．实验结果表明：在Cu－Ni／ZrSiO催化剂上存在着Cu－Ni金属位M,Lewis酸位Zrn＋和Lewis碱位Zr－O－三类活性中心;CO2在金属位和Lewis酸位的协同作用下可形成CO2卧式吸附态,此吸附态在142℃左右可解离成M－CO和Zr－O－;CH3OH在Lewis酸位和Lewis碱位的协同作用下可形成解离吸附态Zr－OCH3和Zr－OH;CO2和CH3OH在Cu－Ni／ZrSiO催化剂表面上的主要反应产物为碳酸二甲酯（选择性在85％以上）,另有少量的CH2O,CO和H2O．     

The Adsorption of Herbicides and Pesticides on Clay Minerals and Soils. Part 1. Isoproturon

The adsorption of isoproturon and two model compounds, N,N-dimethylurea and4-isopropylaniline, on clay minerals (bentonite,montmorillonite and kaolinite), organic matter (humic acid) and soil (with and without organic matter) has been studied using FT-infrared spectroscopy (IR), thermogravimetric analysis (TGA), high pressure liquid chromatography (HPLC) and X-ray diffraction (XRD).N,N-dimethylurea interacted with bentonite and montmorillonite by the coordination of the carbonyl group, directly or indirectly through water molecules, with exchangeable cations. Adsorption on humic acid was due to hydrogen bonding with the active sites of the adsorbent. The amino group ofN,N-dimethylurea appears tobe relatively inactive during adsorption. The mechanisms involved in the adsorption of 4-isopropylaniline were hydrogen bonding and protonation. No adsorption of 4-isopropylaniline was observed on kaolinite. The investigation of isoproturon suggested that both the carbonyl and amino groups of isoproturon were involved in interactions with the active sites of the adsorbents. Both the clay minerals and organic matter of soil contribute to the adsorption of organic compounds on soil but the clay minerals bentonite and montmorillonite play a major role in their adsorption on soil.     

Effects of low-molecular-weight organic ligands and phosphate on DNA adsorption by soil colloids and minerals

Adsorption of DNA on montmorillonite, kaolinite, goethite and soil clays from an Alfisol in the presence of citrate, tartrate and phosphate was studied. A marked decrease in DNA adsorption was observed on montmorillonite and kaolinite with increasing anion concentrations from 0 to 5 mM. However, the amount of DNA adsorbed by montmorillonite and kaolinite was enhanced when ligand concentration was higher than 5 mM. In the system of soil colloids and goethite, with the increase of anion concentrations, a steady decrease was found and the ability of ligands in depressing DNA adsorption followed the sequence: phosphate > citrate > tartrate. Compared to H2O2-treated clays (inorganic clays), a sharp decrease in DNA adsorption was observed on goethite and organo-mineral complexes (organic clays) with increasing ligand concentrations. The results suggest that the influence of anions on DNA adsorption varies with the type and concentration of anion as well as the surface properties of soil components. Introduction of DNA into the system before the addition of ligands had the greatest amount of DNA adsorption on soil colloids and goethite. Organic and inorganic ligands promoted DNA adsorption on montmorillonite and kaolinite when ligands were introduced into the system before the addition of DNA. The results obtained in this study have important implications for the understanding of the persistence and fate of DNA in soil environments especially rhizosphere soil where various organic and inorganic ligands are active.     

Preferential adsorption of extracellular polymeric substances from bacteria on clay minerals and iron oxide

The adsorption of extracellular polymeric substances (EPS) from Bacillus subtilis on montmorillonite, kaolinite and goethite was investigated as a function of pH and ionic strength using batch studies coupled with Fourier transform infrared (FTIR) spectroscopy. The adsorption isotherms of EPS on minerals conformed to the Langmuir equation. The amount of EPS-C and -N adsorbed followed the sequence of montmorillonite>goethite>kaolinite. However, EPS-P adsorption was in the order of goethite>montmorillonite>kaolinite. A marked decrease in the mass fraction of EPS adsorption on minerals was observed with the increase of final pH from 3.1 to 8.3. Calcium ion was more efficient than sodium ion in promoting EPS adsorption on minerals. At various pH values and ionic strength, the mass fraction of EPS-N was higher than those of EPS-C and -P on montmorillonite and kaolinite, while the mass fraction of EPS-P was the highest on goethite. These results suggest that proteinaceous constituents were adsorbed preferentially on montmorillonite and kaolinite, and phosphorylated macromolecules were absorbed preferentially on goethite. Adsorption of EPS on clay minerals resulted in obvious shifts of infrared absorption bands of adsorbed water molecules, showing the importance of hydrogen bonding in EPS adsorption. The highest K values in equilibrium adsorption and FTIR are consistent with ligand exchange of EPS phosphate groups for goethite surface. The information obtained is of fundamental significance for understanding interfacial reactions between microorganisms and minerals.     

蒙脱土/阳离子偶氮染料插层纳米复合物离子交换吸附

从有机阳离子与蒙脱土离子交换吸附原理出发,推导出吸附等温式和表面二维状态方程理论关系,给出了热失重确定吸附量的数据处理方法．选择具有光致变色功能、整个分子共轭的有机阳离子GTL作为插层剂,成功制备了一系列插层纳米复合物．GTL阳离子交换吸附实验数据符合推导出的吸附等温式,插层复合物界面压强π随其含水量增大而线性减小,在较低π下,层间GTL以平行于蒙脱土片层表面的单分子层形态排列;随着π增大,层间GTL以倾斜于蒙脱土片层表面的头尾交指型团聚体形态排列;在更大的π下,层间GTL倾向垂直于蒙脱土片层表面成双分子层排列,其尾端重叠自组装形成超分子共轭纳米结构,层间GTL热稳定性大幅度提高。     

Conformation, activity and proteolytic stability of acid phosphatase on clay minerals and soil colloids from an Alfisol

The present study was carried out to investigate the conformation, enzymatic activity and proteolytic stability of acid phosphatase on montmorillonite, kaolinite and soil colloids from an Alfisol by means of circular dichroism (CD) spectroscopy, isothermal titration microcalorimetry (ITC) and biochemical assay, respectively. The results showed that the secondary structure of phosphatase was changed from disordered type to ordered form during adsorption/desorption cycle, organic substance and 2:1-clay mineral in Brown Soil benefited the formation of ordered structure. Enzymatic activity of phosphatase was inhibited while the proteolytic stability was promoted after the interaction with active particles from permanent charge soil. The decrease of enzymatic activity and the increase of proteolytic stability resulted by montmorillonite and organic colloid were both greater than that by kaolinite and inorganic colloid, which was in consistent with the extent of structural change induced by different colloid particles. Thus, one of the most significant factors responsible for the variation of enzymatic activity and proteolytic stability might be the hiding or even damage of active sites and the irrecognition of cleavage sites in enzyme molecules induced by the formation of ordered structure. The information obtained in this study is of crucial significance for the understanding of the behavior and fate of extracellular enzymes in soils with permanent charges.     

FT-IR Spectroscopic Investigation of Adsorption of Pyrimidine on Sepiolite and Montmorillonite from Anatolia

The adsorption of pyrimidine (PM) on natural montmorillonite and sepiolite from Turkey was investigated by FT-IR spectroscopy. The intercalation of PM within montmorillonite has been shown by X-ray diffraction to increase the interlayer spacing. The spectroscopic results indicate that PM molecules adsorbed on sepiolite are coordinated to Lewis acidic centers or surface hydroxyls by H-bonding interaction through one of the pyrimidine ring nitrogen lone pairs. Moreover, some of the adsorbed PM molecules may enter the interior channels of the sepiolite structure and replace zeolitic water. The intercalated PM molecules within montmorillonite are coordinated to exchangeable cations directly or indirectly through water bridges.     

Adsorption of europium(III) and americium(III) on kaolinite and montmorillonite in the presence of humic acid

Distribution of trace amount of Eu(III), or Am(III), in the aqueous/solid system containing humic acid and kaolinite, or montmorillonite, was studied by batch experiments. Humic acid was also adsorbed on the clay minerals and its adsorption isotherm can be regarded as a Langmuir type. It is shown that Eu(III), or Am(III), exists as humate complex either in the aqueous or on solid phase in the system including kaolinite, or montmorillonite. These results suggest that the organic-inorganic complex like clay minerals coated with humic substances is important as metal reservoir in the environment.     

Adsorption d'eau sur la kaolinite: Influence de la nature des sites actifs

Water adsorption on kaolinite is a specific cooperative adsorption which does not satisfy the fundamental hypothesis of the BET theory.The adsorption isotherms on different homoionic samples show the effect of the hydration energy of the active sites (exchangeable cations) on quantitative adsorption data.The corresponding calorimetric curves present a maximum which characterizes interactions in the adsorbed phase. A relationship is apparent between these interactions and the electric field or the polarizability of the fixed cation, these factors determining the nature of the bond between the surface and cation.From the experimental data, we may propose an approximative value for the number of molecules which compose the primary hydration sheath of the active sites.     

A microcalorimetric study of the interaction between water and poly(hexamethylene guanidine)-modified kaolinite surface

The isotherms and differential heats of water vapor adsorption on kaolinite modified with poly(hexamethylene guanidine) hydrochloride are measured. Modification efficiency is, to a high extent, determined by the compliance (complementarity) between the structure of the modifying agent and the chemical nature of the kaolinite surface. It is shown that the individual stages of the interaction between water and the modified sorbent comprise sorption of four or five molecules on triads of amino groups of the modifying layer, conformational changes in the layer, the formation of additional adsorption sites, partial rupture of the modifying layer, and the dispersion of kaolinite particles induced by adsorbed water. Alternative opinions are presented on the reason for the appearance of the additional adsorption sites. It is proven that not only the adsorbate, but also the adsorbent, undergoes efficient changes during the adsorption.     

Effects of low-molecular-weight organic ligands and phosphate on adsorption of Pseudomonas putida by clay minerals and iron oxide

Adsorption of Pseudomonas putida on kaolinite, montmorillonite and goethite was studied in the presence of organic ligands and phosphate. Citrate, tartrate, oxalate and phosphate showed inhibitive effect on P. putida adsorption by three minerals in a broad range of anion concentrations. The highest efficiencies of the four ligands in blocking the adsorption of P. putida on goethite, kaolinite and montmorillonite were 58–90%, 35–76% and 20–48%, respectively. The ability of organic ligands in prohibiting the binding of P. putida cells to the minerals followed the sequence of citrate > tartrate > oxalate > acetate. The significant suppressive effects on P. putida adsorption were ascribed to the increased negative charges by adsorbed ligands and the competition of ligands with bacterial surface groups for binding sites. The inhibitive effects on P. putida adsorption by organic ligands were also dependent on the steric hindrance of the molecules. Acetate presented promotive effect on P. putida adsorption by kaolinite and goethite at low anion concentrations. The results obtained in this study suggested that the adsorption of bacteria in soils especially in the rhizosphere can significantly be impacted by various organic and inorganic anions.