A study of the catalytic behavior of phosphotungstic acid-modified Janus particles in a heterogeneous oil/water pickering emulsion system

An emulsion interface materialization method was used to obtain amphiphilic silica Janus nanoparticles. Reducing the photosynthesis of aquatic organisms after water pollution. PW₁₂O₄₀³⁻ was introduced onto Janus particles by ion exchange, and an amphiphilic particle emulsion catalyst (PWO-J) was prepared. Hydrogen peroxide was used as the oxygen source, and the amphiphilicty of the catalyst was used to assemble the catalyst at the Pickering emulsion interface. The PWO-J catalyst was found to exhibit very high catalytic activity toward the oxidation of oleic acid in water-in-oil systems. The results showed that PWO-J catalysis of oxidation had similar results as CTAB and phosphotungstic acid (control system) under the same conditions. The azelaic acid recovery rate was 86.7%, and PWO-J could be reused 4 times. A reaction mechanism was proposed, and the constructed model was used to calculate a reaction rate constant of 15.32 × 10⁻⁵L•mol⁻¹•s⁻¹ for the PWO-J system. The PWO-J system had a lower activation energy than the control system, showing that the catalytic oxidation of oleic acid into azelaic acid was more likely to occur in the PWO-J system.     

晶种导向下干胶法合成ZSM-5分子筛

以廉价水玻璃为硅源,在晶种替代有机模板剂的条件下采用干胶法合成了ZSM-5分子筛。利用XRD、SEM、TEM、FTIR、N₂吸附-脱附和NH₃-TPD等分析方法对合成样品进行了表征和测试,考察了合成条件对ZSM-5分子筛晶化过程的影响。结果表明,在硅铝比（n/n）为30~70,钠硅比（n/n）为0.12~0.20时都可以得到结晶度良好的ZSM-5分子筛。研究发现,干胶法合成ZSM-5,在不引入外加水的情况下也可以得到ZSM-5样品,外加水的引入能够有效地提高晶化速率;与水热法合成ZSM-5分子筛相比,干胶法可以显著地缩短晶化时间,同时,合成样品的晶体尺寸也有所减小。     

Effect of Octadecanol on the Interfacial Dilational Properties of Surfactant/Polymer Systems

The effect of octadecanol on dilational properties of 4,5-diheptyl-2-propylbenzene sulfonate and partly hydrolyzed polyacrylamide at the decane-water interface has been examined by means of longitudinal method. The octadecanol plays different roles in influencing the structure of adsorbed layers at different bulk concentration. A small quantity of octadecanol may enhance the dilational modulus by forming densely packed mixed-adsorption layer with surfactant molecules through hydrophobic interaction, which leads to the increase of dilational modulus. However, due to the weakening of the “entanglement” among long alkyl chains in surfactant molecules by the intercalation of octadecanol, the superfluous addition of octadecanol could decrease the dilational modulus. In the case of polymer/octadecanol system, the addition of the polymer may enhance the dilational modulus due to the slow diffusion-exchange process of the polymer.     

Synthesis and Properties of Aromatic Side Chained N‐Acyltaurate Surfactants

A series of anionic N‐acyltaurate surfactants, side chain containing aromatic nucleus (abbreviated as SAATT), were synthesized via Williamson reaction, hydrolyzation, and acylation. Krafft temperatures and surface properties of these surfactants at 30°C, that is, critical micelle concentration, cmc, surface excess concentration, Γ_max, surface area demand per molecule, A _min, efficiency in surface tension reduction, pC₂₀, effectiveness in surface tension reduction, π_cmc, and cmc/C₂₀ parameter were determined. It was shown that these surfactants exhibit good solubility which was confirmed by measuring Krafft temperature. The cmc of SAATT was much smaller than that of conventional surfactants with similar effective carbon numbers, and shifted to lower concentration with increasing hydrocarbon chain length. In addition, the γ_cmc decreased with decrease in Γ_max. The pC₂₀ and the cmc/C₂₀ got larger with the increase in hydrocarbon chain length. From the fluorescence intensity ratios of I ₁ (373 nm) and I ₃ (384 nm) using pyrene as a probe, it was indicated that the molecules of SAATT formed loose micelles with a broad size distribution.     

Effect of Demulsifiers on Dilatational Properties of Crude Oil–Water Interfaces

The dilatational properties of polyether demulsifiers PEA, PEB, PEC, PED, PEF, and PEG at the decane-water interface were investigated. Meanwhile, the effect of demulsifiers with different structures on interfacial dilatational modulus of diluted crude oil also was explored. The properties of demulsifiers are compared and analyzed in combine with the dilatational parameters at decane-water interface and at 5% crude oil-water interface. The results show that interfacial dilatational viscoelasticity could characterize the interfacial behavior of demulsifiers. The demulsifiers, which have different kinds or structures, have different effects on destroying the interfacial film of crude oil with increasing bulk concentration. Therefore, the dosage of demulsifier is a very important role in controlling nature of crude oil film.     

Studies of Interfacial Activities of Four Kinds of Surfactants at Oil/Water Interface

This article aims to compare the interfacial activities of different kinds of surfactants in the same oil/water system. The anionic surfactants of alkylbenzene sulfonates, the polyoxyethylenated nonionic surfactants, the cationic surfactants of alkyl trimethyl ammonium chlorides, and the zwitterionic surfactants of alkyl hydroxyl sulfobetaines were used, and the interfacial tensions of the surfactant solutions against kerosene at different NaCl concentrations were measured. It is found that the interfacial activities of the alkylbenzene sulfonates are high and ultralow interfacial tensions (<0.01 mN/m) can be obtained at proper salinities. While, the nonionic surfactants have relatively low interfacial activities and the minimum tensions are around 0.01 mN/ms. The salinity scanning curves of the alkylbenzene sulfonates and nonionic surfactants decrease first, then increase, showing their interfacial activities can be changed by the salinity effectively. The cationic and zwitterionic surfactants have very low interfacial activities, of which all the tensions are higher than 0.1 mN/ms and are hard to be changed by the salinity. The experimental results may have important reference values for enhanced oil recovery.     

Mechanism of Electrical Percolation of w/o Microemulsions Formed by Nonionic Surfactants

A study was carried out on the mechanism of electrical conductivity percolation of H₂O/C₁₆EO₂₀/n-butanol/heptane microemulsions. Electrical conductivity, UV-vis spectroscopy and FTIR spectra were used to study the diluted “dry” microemulsions with the mass ratio of C₁₆EO₂₀/n-butanol/heptane = 3:3:4. The results of electrical conductivity showed that the percolation occurred around φ_w = 20 wt% and the transition of w/o microemulsions to bicontinueous microemulsions happened when φ_w = 45 wt%. From the UV-vis absorption spectra, it was found that the absorption of methyl orange (MO) in microemulsions shifted red than that of in oil phase, but the maximal absorption peak (λ_max) remained unchanged when φ_w > 20 wt%. It implied that the position of MO solubilized in microemulsions was unvaried after free water appeared in the core. FTIR spectra revealed that the OH band of water in microemulsions moved to high frequency at low φ_w (< 20 wt%) and became broader at high φ_w. It indicated that the added water only caused the hydration of EO at low φ_w, the hydration completed when φ_w > 20 wt% and then the residual water entered into the core with properties similar to bulk water. The presence of free water as ions exchange medium will cause the electrical conductance increased. The percolation appeared after the hydration of EO completed.     

Studies of Synergism in Binary Alkylbenzene Sulfonate Mixtures for Producing Low Interfacial Tensions at Oil/Water Interface

In order to study the synergism between alkybenzene sulfonate and alkybenzene sulfonate, five di-n-alkylbenzene sulfonates were used and the interfacial tensions of single sulfonates and their binary mixtures against a series of alkane homologues were measured. The effects of hydrophilic-lipophilic abilities of sulfonates and mixing ratio on synergism were discussed. It is revealed that the synergistic mechanism derives from the amelioration of the hydrophilic-lipophilic ability of the surfactant system, and the method to achieve synergism is adding the hydrophilic alkybenzene sulfonate to the lipophilic alkylbenzene sulfonate, and ultralow interfacial tensions can be obtained in proper mixing ratios. The results are useful for enhanced oil recovery.      

Salinity Selection for a Low Salinity Water-Low Salinity Surfactant Process

A laboratory selection of salinity for a low salinity water-low salinity surfactant (LS-LSS) process is presented in this paper with systematical investigation on surfactant phase behavior, interfacial tension (IFT), and dynamic retention in porous media with IOS2024 and isoamyl alcohol (IAA) as surfactant system. The results show that 0.4 wt% IOS2024 with 1 wt% IAA can provide ultra-low IFT of 10^?3 mN/m at around 3000–4000 mg/L total dissolved solids, but at that salinity range the surfactant retention is very high. The search for an optimum surfactant formulation has to consider solution properties and retention in addition to the low IFT. The salinity for a LS-LSS process should thus not be focused on either optimal salinity or ultra-low IFT, but instead the best choice could be a compromise between the properties in question. The three-phase region, where ultra-low IFT are found, is also associated with high retention values. However, we show that as salinity is increased from a two-phase region with oil solubilized in a water continuous microemulsion, there is a region close to the three-phase boundary which has potential. This region does not give ultra-low, but fairly low (10^?2 mN/m in this case) interfacial tensions, and also significantly lower retention.      

基于多肽的电化学传感器在蛋白质检测中应用的研究进展

生物体内的细胞通常会分泌各种各样的蛋白质,这些蛋白质在生物体中发挥着重要作用,尤其是可被用于诊断各种疾病的发生和发展。多肽具有良好选择性、空间适应能力和识别灵活的特点,可与不同类型的蛋白分子形成非共价键,用于蛋白质的生物检测。将多肽与电化学生物传感器结合用于蛋白质的广谱检测具有良好的发展前景。本文介绍了多肽修饰的电化学传感器在不同蛋白质检测方面的研究进展,分析了待测蛋白质的不同对多肽修饰的电化学传感器分类的影响及其优缺点,提出了基于多肽的电化学传感器在不同蛋白质检测中存在的问题,并展望了其未来发展。