Preparation of a novel bentonite intercalation composite by changing the chemical state of aluminum

A new environment-friendly bentonite intercalation composite was successfully obtained from alumina sol intercalation. This process used industrial grade pseudo boehmite as the aluminum source and provided with the advantage of zero emission of acidic wastewater. The bentonite intercalation composite was investigated by XRF, ICP, XRD, FT-IR, BET, and pyridine-FTIR. Results indicated that the basal spacing was enlarged from 14.72 to 15.60 Å; the specific surface area increased by 128%; and the total acid content increased from 65.32 to 245.76 μmol/g. The catalytic activity of this composite was tested by alkylation of aromatics with olefins. The results show that the weak Lewis acid generated by extra-framework aluminum and specific surface area play a decisive role, while weak Brønsted acid site is not the active site for this alkylation reaction.     

An Electrochemical Sensor Fabricated by Sonochemical Approach for Determination of the Antipsychotic Drug Haloperidol

A nanocomposite (Ho₂O₃NPs/BNT) was synthesized by decorating holmium(III)oxide nanoparticles (H₂O₃NPs) on bentonite (BNT) through a realizable sonochemical approach for the electrochemical detection of haloperidol (Hlp). A glassy carbon electrode was modified with this nanocomposite. The Ho₂O₃NPs/BNT modified electrode outperformed bare and other modified electrodes in terms of electrochemical performance for Hlp detection in a pH 8.0 phosphate buffer. The proposed electrochemical platform showed a wide linear range (0.01 μM–24 μM), low detection limit (2.4 nM), and high sensitivity by square wave voltammetry. In addition, the proposed electrochemical sensor met the clinical criteria in terms of stability, selectivity, and repeatability.     

Effect of Direct yellow 50 removal from an aqueous solution using nano bentonite; adsorption isotherm,kinetic analysis and also thermodynamic behavior

The developing countries are suffering from the toxicity of different industrial effluents, especially dyes that contaminate water systems. This study successfully explained the preparation and characterization of nano bentonite to extract Direct Yellow Fifty (DY50). Direct Yellow 50 is an organic contaminant that may affect the quality of water. The characterization of prepared nanoparticles was done using Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared (FTIR). The impact of different operating conditions was studied using different pH, dose, temperature, contact time, and initial DY50 concentrations. The obtained results indicated that nano bentonite could adsorb about 94 % at initial concentrations of 40 mg/L, respectively. The optimum removal conditions were observed at an acidic pH (pH 3) using a sorbent material dosage of 0.05 g for 4 h at 30 °C. The adsorption isotherm, kinetic analysis, and thermodynamic behavior were studied using linear equation form, and the adjusted R² was compared to detect the preferred models. The adsorption behavior pseudo-second order kinetics, and fitted Langmuir isotherm model, respectively, showed the chemisorption interactions between adsorbed and sorbed molecules. Thermodynamic behavior indicated that the reaction was exothermic. Finally, this study strongly recommended using nano bentonite for DY50 removal from an aqueous solution.     

Effects of NAPL Contaminants on the Permeability of a Soil‐Bentonite Slurry Wall Material

Soilbentonite slurry walls are designed to inhibit the subsurface movement of contaminants from hazardous waste sites. Although it is generally accepted that high concentrations of organic compounds will adversely affect soilbentonite slurry walls and clay liners, previous research investigating the effects of NAPLs on the conductivity of clay wall materials has been inconclusive. In this study the effects of various organics (benzene, aniline, trichloroethylene, ethylene dichloride, methylene chloride) on the effective conductivity of a typical soilbentonite slurry wall material were studied under two effective stress conditions, 200 and 52kPa. The hydraulic conductivity for the soilbentonite material permeated with water averaged 1.52×10^-8cms^-1. Compared to water, there was little change in conductivity when the sample was permeated with a solution containing a NAPL compound at its solubility limit, except for aniline. However, there was a one to two order of magnitude decrease in conductivity when the sample was permeated with a pure NAPL for all NAPLs tested. When the soilbentonite material was permeated with a water/NAPL/water/NAPL sequence, the conductivity decreased one to two orders of magnitude when a NAPL was introduced following water; however, when water was reintroduced after the NAPL, the conductivity increased to the initial hydraulic conductivity. The conductivity again decreased one to two orders of magnitude when the NAPL was reintroduced. This trend occurred for all NAPLs tested, and the fluid properties of the NAPL compounds alone did not account for the decrease in conductivity compared to water.     

2种天然絮凝剂对薄荷水提液的絮凝研究和比较

为了克服传统中药提取工艺中有效成分损失率高、生产成本高、工艺复杂等缺点,采用天然无毒的高分子絮凝剂壳聚糖和矿物絮凝剂膨润土对薄荷水提液进行净化除杂.利用间歇试验方法,以絮凝率和总黄酮损失率作为指标,考察了絮凝剂用量、温度、搅拌速度等因素对絮凝效果的影响,并利用正交试验确定了薄荷水提液的最佳絮凝条件.结果表明,壳聚糖絮凝效果优于膨润土,当壳聚糖投加量为0.741g·L-1,絮凝温度30℃,搅拌速度40r·min-1时,絮凝率可达到92.75%,总黄酮损失率为10.75%.在此基础上,通过絮凝前后粒径比较及絮体形态分析,对中药絮凝机理进行了深入探讨.     

The synthesis of MCM-41 nanomaterial from Algerian Bentonite: The effect of the mineral phase contents of clay on the structure properties of MCM-41

This study focuses on the MCM-41 material (Mobil Composition of Matter). The MCM-41 nanomaterial presents higher physical properties such as pore sizes, surface areas and pore volumes. This material is usually synthesized by using laboratory reagents as silicate sources and aluminium source. These laboratory reagents are still expensive and toxic for large scale production. The main aim of this work is to resolve this problem and to replace these expensive laboratory reagents by more cost effective ones. The volclay and Algerian bentonite low-cost mass clay materials are used as silicate and acuminate sources separately by adopting an alkaline fusion process to extract both silicon and aluminium (1 kg of silicium and aluminium from volclay and Algerian bentonite cost around 0.03 and 0.01 € whereas the same amount of silicon from ludox and aluminium from sodium aluminates cost around 350 €). The synthesis of MCM-41 from bentonite was carried out by the hydrothermal method using the supernatants of bentonite (in the form of sodium silicate and sodium aluminate). On the basis of the data obtained from powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and N₂ adsorption and desorption, the results revealed that the properties of MCM-41 synthesized from Algerian bentonite and volclay separately depend on both elemental composition and mineral phase contents of the used bentonite. Pure and highly ordered hexagonal mesoporous MCM-41 with uniform pore sizes and a high specific surface area have been successfully synthesized without any phases which exist in natural bentonite. The Algerian bentonite was chosen because of its low cost compared to volclay, another commercial clay source.     

Modified bentonite by polyhedral oligomeric silsesquioxane and quaternary ammonium salt and adsorption characteristics for dye

To remove methylene blue dye from water by adsorption, bentonites were modified by polyhedral oligomeric silsesquioxane (POSS) and three kind of quaternary ammonium surfactants (dodecyl trimethyl ammonium bromide, tetrabutyl ammonium bromide, cetyl trimethylammonium bromide) in aqueous solution. Systematic adsorption experiments were carried out, the adsorption mechanism was studied, and the factors governing the adsorption of methylene blue on modified bentonite were discussed. The adsorption capacity of methylene blue on all three modified bentonites in 1000 mg·L⁻¹ solutions quickly reached equilibrium within 2000 s, and the removal rate was basically 100%; however, the removal rate in raw bentonite samples was only 60%. The pseudo second-order kinetic model can provide satisfactory kinetic data fitting. The obtained adsorption isotherms fit well with the Dubinin-Radushkevich isotherm model. The thermodynamic results showed that the adsorption process was a spontaneous endothermic physical adsorption process. With increasing pH and KCl concentration, the removal of methylene blue increased significantly. The results of this study confirmed that the modified bentonite is a candidate material as a cationic dye adsorbent.     

Kinetics of regioselective acetolysis of epichlorohydrin

The liquid phase acetolysis of epichlorohydrin (ECH) with acetic acid was studied over bentonite clay catalysts and was found to be very active for the selective formation of 1-acetoxy-3-chloro-2-propanol. The reaction followed first order kinetics with respect to epichlorohydrin and obeyed the Langmuir-Hinshelwood mechanism.     

砂-膨润土混合屏障材料渗透性影响因素研究

建立了一个新的结构-尾流振子耦合模型. 流场近尾迹动力学特征被模化为非线性阻尼 振子，采用van der Pol方程描述. 以控制体中结构与近尾迹流体间受力互为反作 用关系来实现流固耦合. 采用该模型进行了二维结构涡激振动计算，得到了合理的 振幅随来流流速的变化规律和共振幅值，并正确地预计了共振振幅值$A_{\max}^\ast$ 随着质量阻尼参数$\left( {m^\ast + C_A } \right)\zeta $的变化规律，给出了预测$A_{\max }^\ast $值的拟合公式. 采用该模型计算了三维柔性结构在均匀来流和简谐波形来流作用下的VIV 响应. 结构在均匀来流作用下振动呈现由驻波向行波的变化过程, 并最后稳定为行波振动形态. 在简谐波形来流作用下，结构呈现混合振动形态，幅值随时间呈周期变化.     

Thermodynamic and Kinetic Studies for the Adsorption of Fe(III) and Ni(II) Ions From Aqueous Solution Using Natural Bentonite

In this study, the adsorption behavior of natural bentonite with respect to Fe(III) and Ni(II) has been studied in order to consider its application to purity metal finishing wastewaters. During the adsorption process, batch technique is used, and the effects of pH, bentoite amount, temperature, heavy metal concentration, bentonite treatment (calcinations of natural bentonite at 700°C, washing by deionized water to remove the excess salt from bentonite surface), and agitation time on adsorption efficiency are studied. The washed and calcined bentonite samples were labeled by WB and CB, respectively. The pH-dependence of Fe(III) and Ni(II) sorption on the bentonite is significantly more noticeable, indicating a major contribution of surface complexation at the edge sites. It was determined that adsorption of Fe(III) and Ni(II) is well fitted by the second order reaction kinetic. Furthermore, the sorption rate of Fe(III) was higher than the sorption rate of Ni(II). Adsorption of Fe(III) and Ni(II) on NB appeared to follow Langmuir isotherm. In addition, calculated and experimental adsorbed amounts of Fe(III) by the unit NB mass are very higher than Ni(II). The paper also discusses the thermodynamic parameters of the adsorption (the Gibbs free energy, entropy, and enthalpy). Our results demonstrate that the adsorption process was spontaneous and endothermic under natural conditions. Also the adsorption capacity of bentonite for Fe(III) Ni(II) and increases with increased bentonite dose. According to the equilibrium studies, the selectivity sequence can be given as Fe(III) > Ni(II). The adsorbed amount of Fe(III) and Ni(II) on washed bentonite (WB) were very higher compared to NB and CB. Our results show that bentonite could especially WB be considered as a potential adsorbent for Fe(III) and Ni(II) removal from aqueous solutions.