Raman and infrared study of phyllosilicates containing heavy metals (Sb,Bi): bismutoferrite and chapmanite

The kaolinite‐like phyllosilicate minerals bismutoferrite BiFe³⁺₂Si₂O₈(OH) and chapmanite SbFe³⁺₂Si₂O₈(OH) have been studied by Raman spectroscopy and complemented with infrared spectra. Tentatively interpreted spectra were related to their molecular structure. The antisymmetric and symmetric stretching vibrations of the Si O Si bridges, δ SiOSi and δ OSiO bending vibrations, ν (Si O_terminal)⁻ stretching vibrations, ν OH stretching vibrations of hydroxyl ions, and δ OH bending vibrations were attributed to the observed bands. Infrared bands in the range 3289–3470 cm⁻¹ and Raman bands in the range 1590–1667 cm⁻¹ were assigned to adsorbed water. O H···O hydrogen‐bond lengths were calculated from the Raman and infrared spectra. Copyright © 2009 John Wiley & Sons, Ltd.     

高岭土磁性复合材料表面印迹聚合物选择性吸附分离环丙沙星

以氨基改性的磁性高岭土为基质材料,利用电子转移产生催化剂的原子转移自由基聚合法制备磁性高岭土表面印迹聚合物（MMIPs）。通过FTIR、TEM、TGA、XRD和VSM等方法对其物理化学性质进行表征,其比表面积112 m²·g^-1,且具有较好的热稳定性、超顺磁性（M_s=13.365 emu·g^-1）。吸附性能研究表明,准二级动力学模型能较好地描述MMIPs对环丙沙星（CIP）吸附动力学行为,Langmuir等温模型能较好地拟合MMIPs对CIP的吸附平衡数据,25℃时MMIPs的单分子层吸附容量为89.36 mg·g^-1。选择性实验研究表明,MMIPs对CIP具有较好地选择识别性。结合高效液相色谱分析技术,MMIPs已成功应用于鲜鱼样品中痕量CIP的分离、富集和回收,CIP的回收率为92.15%。     

Thermoanalytical Investigations on Intercalated Kaolinites

The thermal behaviour of ordered kaolinites from Hungary and Australia intercalated with potassium acetate, cesium acetate and urea has been investigated by simultaneous TG-DTG-DTA, TG-MS, Raman microscopy and XRD. Remarkable changes in the thermal decomposition pattern of the intercalates were obtained as a function of the nature of the intercalating re-agents. Replacing the potassium cation to cesium leads to a change in the OH environments resulting in a more complicated dehydroxylation pattern. The urea intercalates can be decomposed completely without dehydroxylating the mineral, although further treatments are necessary to restore the original d-spacing. This revised version was published online in July 2006 with corrections to the Cover Date.     

高岭土负载SO42-/ZrO2-TiO2催化剂的制备及其在缩酮合成中的应用

以经H2SO4处理焙烧的高岭土为载体,制备了以其负载的SO2-4/ZrO2-TiO2固体酸催化剂。 用FT-IR、XRD和NH3-TPD等测试技术表征了催化剂的微观结构及酸强度,考察了对环己酮乙二醇缩酮反应的催化活性及稳定性。 结果表明,酸化处理使高岭土表面酸量增加,但酸强度变化不大,而其负载SO2-4/ZrO2-TiO2后,经500 ℃焙烧3 h其酸量及酸强度显著升高。 环己酮用量为0.2 mol、乙二醇0.24 mol、催化剂1.2 g、带水剂环己烷15 mL,回流反应70 min后,缩酮收率可达96.8%,催化剂重复使用5次收率保持在90%以上。     

蒙脱土和高岭土对Pb2+的吸附

选择带结构负电荷的蒙脱土和带微量结构负电荷的高岭土,研究了其对Pb2+的吸附性能,并探讨了吸附机理。 研究表明,蒙脱土和高岭土吸附Pb2+的动力学曲线符合准二级动力学方程,吸附等温线符合Langmuir方程。 Pb2+同时以内层络合和外层配合形式吸附,其相对量与pH值有关。 在pH值小于4和大于8的范围内,以内层配合物为主;而pH值在4～8范围内外层配合物比例增大。 Pb2+能进入蒙脱土的层间,而不能进入高岭土的层间;部分Pb2+可进入黏土颗粒的微孔中被固定。 蒙脱土对Pb2+的吸附能力和饱和吸附量明显高于高岭土。     

Φ42 mm腔体高岭石-白云石质传压密封介质金刚石合成扩大试验

 高岭石具有良好的流动密封、固体传压及机械加工等物理性能,是传统传压密封介质原料叶蜡石的替代品。采用比纯高岭石更适合作为传压密封介质原料的某地高岭石矿物,经过配料、混料、装模、压制成型以及焙烧等工序,制成了高岭石-白云石质传压密封介质,并对其进行金刚石合成扩大试验。试验结果表明：高岭石-白云石质传压密封介质能够达到与叶蜡石质传压密封介质相当的效果;合成金刚石的单产为19 g,抗压强度不小于160 N的晶粒占32%,晶粒尺寸大于或等于0.30 mm的占82%,合成1 g金刚石的顶锤消耗小于0.5 g,合成过程稳定。     

高岭土相转变的非等温动力学

<正>高岭土为三斜晶系,一般为无色至白色的细小鳞片,单晶呈假六方板状或书册状,平行连生的集合体往往呈蠕虫状或手风琴状,是造纸、陶瓷、化工、涂料、医药和国防等几十个行业中必须的矿物     

Preparation of Organophilic Nanohybrid Kaolinite and Application to the Electrochemical Detection of Organic Pesticide

Novel organophilic nanohybrid materials (K‐TDD) were obtained by the grafting of 1,2‐tetradecanediol (TDD) onto the surface of kaolinite (K). XRD, IR, TGA‐DTG, and SEM characterization showed that TDD grafting results in a partial exfoliation of kaolinite layers. This material was used to modify a glassy carbon electrode (GCE/K‐TDD) and applied for the trace analysis of methyl parathion (MP). The signal of MP recorded on GCE/K‐TDD was more intense compared to the unmodified GCE or to one modified with a film of natural kaolinite. Several parameters that can affect the stripping response were systematically investigated to optimize the sensitivity of the organokaolinite‐modified electrode. A linear calibration curve for MP was obtained in the concentration range from 2×10⁻⁶ to 14×10⁻⁶ mol .L⁻¹ in acetate buffer (pH 6), giving a detection limit of 9×10⁻⁸ mol .L⁻¹. The sensitivity of the method was found to be 2.42 μA/μM for the range of concentrations that gives a linear calibration curve. The electrode was shown to be very stable, with the electrochemical response of MP decreasing by only 1.5 % after a series of nine measurements. The interference of various inorganic ions and organic compounds likely to influence the stripping determination of the MP were also examined. The results showed that the GCE/K‐TDD electrode was effective in solutions containing interfering species and could be applied for the quantification of MP pesticide in natural water.     

Aluminium ions at polyelectrolyte interfaces. III. Role in polyacrylic acid/aluminium oxide and humic acid/kaolinite aggregate cohesion

Understanding the formation and breakup of humic acids and clays agglomerates is a difficult challenge owing to their complex nature. Thus, to progress in the study of the stability of such systems, attempts were made to replace the humic acid/kaolinite natural system by the polyacrylic acid/aluminium oxide synthetic system. Since the present investigation was dedicated to determine some characteristics of acidic soils which contain traces of aluminium ions, these ions were added to the adsorbent/polyacid systems as trace constituents. Initial and short-term phenomena related to the adsorption of humic and polyacrylic acids on aluminium oxide and kaolinite clay have been presented elsewhere. Here we present long-term phenomena regarding the formation and cohesion of oxide and clay aggregates formed in the presence of polyacrylic and humic acids, respectively. The results of electrophoretic mobility measurements demonstrated the amphipathic character of polymeric layers adsorbed on aluminium oxide and the amphoteric character of humic acid layers adsorbed on kaolinite. The long-term stability of the two colloidal systems was determined to evolve similarly despite the existence of the these typical characteristics. Received: 24 July 2000 Accepted: 20 December 2000