多种类表面活性剂临界胶束浓度定量构效关系

表面活性剂的临界胶束浓度(CMC)是个非常重要的物质特性参数, CMC在研究表面活性剂的工业应用和生物利用方面发挥着关键作用. 本工作提出了一个新的拓扑指数—扩展距离矩阵, 建立了一个稳定的构效关系模型, 并对175种表面活性剂的临界胶束浓度进行了计算预测. 结果表明, 基于新的拓扑指数建立的构效关系模型计算临界胶束浓度能给出稳定可靠的预测结果, 其预测结果相关性系数R²(training set)=0.9295, 相对标准偏差ARD(training set)=8.20%, R²(testing set)=0.9257, ARD(testing set)=6.76%. 与文献中模型预测结果的对比表明, 本工作在稳定性和可靠性上均有显著改善.     

Development of aqueous oxidative Ugi-type reactions by copper-catalyzed surfactant-promoted C(sp)–H direct functionalization in water

Direct assembly of α-amino amides from N-alkyl amines and isocyanides through oxidative Ugi-type reactions in aqueous conditions, has been achieved in a Cu(I)–TBHP–surfactant catalysis system. Various N-alkyl amines and isocyanides could be tolerated in this reaction and furnish α-amino amides in moderate yields.     

Head group specificity of novel functionalized surfactants: synthesis,self-assembly and calcium tolerance

The present work describes the synthesis, characterization and application of functionalized surfactants derived through simple organic reaction steps. These surfactants have been particularly tailor made to resist hardness due to calcium ions in water. It is unique of its kind because here the surfactants have an analogous hydrophobic chain but differ structurally in the composition of the head groups in terms of the position of attachment of the chain. The effect of this small variability in the head group on the surfactant property, adsorption, self assembly and calcium tolerance behaviour has been studied in detail. This kind of phenol–keto surfactants has not been reported before. It was also found that one of the surfactants was more tolerant towards Ca²⁺ ion than the other. The individual packing behaviour of the surfactants at the air–water interface has been projected to cause this difference which is very interesting.     

PtRuAgCoNi高熵合金纳米颗粒高效电催化氧化5-羟甲基糠醛

5-羟甲基糠醛(HMF)的电催化氧化被认为是合成2,5-呋喃二甲酸(FDCA)最环保、经济和有效的方法之一,它可作为聚呋喃二甲酸乙二醇酯(PEF)的生物基前体。在这项工作中,我们通过低温溶剂热法合成了PtRuAgCoNi高熵合金纳米颗粒,并在不改变颗粒结构和组成的情况下进行了简易的处理以去除表面活性剂。负载在碳载体上的合金纳米催化剂无论是否含有表面活性剂在HMF电催化氧化为FDCA的过程中都表现出比商业Pt/C更好的催化性能。且表面活性剂的去除可以进一步提高其电催化性能,表明高熵合金纳米粒子在电催化和绿色化学中具有广阔的应用前景。     

Investigating the generation of ferrous sulfide nanoparticles in the produced fluid after acidizing oil wells and its influence on emulsifying stability between oil and water

Studies show that after acidizing operation of oil wells using the alkali/surfactant/polymer (ASP) flooding technology, the produced fluid is emulsified. Since the produced emulsion is stable, it affects the oil–water separation performance. In order to analyze the generation of stable emulsion in the produced fluid after acidizing an oil well, innovative separation experiments were carried out on real oil wells. During the experiments, solid particles in the middle layer of the emulsifying system in the produced fluid after acidizing ASP flooding were extracted and characterized. The generation of the stable emulsifying system in the produced fluid was studied through stability experiments and molecular dynamics simulations. The results showed that the synergistic effect of ferrous sulfide nanoparticles and surfactants was the fundamental reason for the strong emulsifying stability of the produced liquid after acidizing of the ternary composite system. The generation of ferrous sulfide solid particles mainly included two steps. First, sulfate reducing bacteria in injected water by ASP flooding reacted with sulfate in formation water to form hydrogen sulfide. Then, the hydrogen sulfide reacted with iron metal in oil wells and casing of wellbore to form ferrous sulfide particles. It was found that surfactants are adsorbed on the surface of ferrous sulfide nanoparticles. Subsequently, the control ability of surfactant on oil and water phases in the liquid film was enhanced. The performed analyses demonstrate that the adsorption of solid particles to the oil phase was enhanced, while the free motion of molecules in the oil phase at the liquid film position was weakened. The strength of the interfacial film between oil and water was further increased by the synergistic effect of ferrous sulfide nanoparticles and surfactant. The present study is expected to provide a guideline for a better understanding of the efficient treatment of produced fluids in ASP flooding.     

Catalytic effect of CTAB on the interaction of dipeptide glycyl-tyrosine (Gly-Tyr) with ninhydrin

The effect of cationic micelles of cetyltrimethylammonium bromide (CTAB) on the interaction of dipeptide glycyl-tyrosine (Gly-Tyr) with ninhydrin under varying conditions has been studied spectrophotometrically at 70 °C and pH 5.0. The reaction followed first- and fractional-order kinetics with respect to [Gly-Tyr] and [ninhydrin], respectively. Increase in total concentration of CTAB from 0 to 70 × 10⁻³ mol dm⁻³ resulted in an increase in the pseudo-first-order rate constant (k_ψ) by a factor of ca. 3. Quantitative kinetic analysis of k_ψ − [CTAB] data was performed on the basis of pseudo-phase model of the micelles (proposed by Menger and Portnoy and developed by Bunton) and Piszkiewicz model. A possible mechanism has been proposed and the kinetic data have been used to evaluate the micellar binding constants K_S (268 mol⁻¹ dm³ for Gly-Tyr) and K_N (64 mol⁻¹ dm³ for ninhydrin).     

表面活性剂辅助共沉淀法制备Ni-Mg-Al固体碱催化剂用于CH_4-CO_2重整反应

采用表面活性剂辅助共沉淀法制备了Ni-Mg-Al固体碱催化剂并用于CH4-CO2重整反应,探讨了表面活性剂对Ni(111),Ni(200)晶面的择优取向作用,在800℃下比较了不同表面活性剂制备的催化剂的催化性能,详细考察了CTAB制备的催化剂CB-LDO在不同反应温度下的催化活性和稳定性.采用红外光谱、X射线衍射、程序升温还原、X射线光电子能谱、高分辨透射电镜和程序升温氧化等表征手段分析了催化剂的活性、稳定性和失活原因.结果表明,四丙基氢氧化铵(TPAOH)促进Ni(200)的生长,而聚氧乙烯-聚氧丙烯-聚氧乙烯(P123)、聚乙烯吡咯烷酮(PVP)和十六烷基三甲基溴化铵(CTAB)抑制Ni(200)晶面的生长;Ni(200)的结晶程度对CH4的活化起到关键的作用,催化剂CB-LDO在高温下反应会发生晶型的转化,Ni(200)晶面由于反应过程中生成NiAl2O4尖晶石而得到缓慢释放,使催化剂的活性得以维持较高的水平.     

The boundary condition at the air–liquid interface and its effect on film drainage between colliding bubbles

The drainage of thin liquid films between colliding bubbles is strongly influenced by the boundary conditions at the air–liquid interface. Theoretically, the interface should not resist any tangential stress (fully mobile) in a clean water system, resulting in very fast film drainage and coalescence between bubbles within milliseconds. In reality, under most experimental and industrial conditions, the presence of impurities or surfactants can immobilize the interface and significantly hinder bubble coalescence by several orders of magnitude. In this opinion, we introduce the recent progress on understanding the boundary conditions at the air–water interface, and how they may affect the outcome of bubble collisions. The transition from mobile to immobile boundary conditions in the presence of contaminations is discussed. Despite the considerable recent progress, there are still experimental and theoretical challenges remaining on this topic, for example, finding the mechanism for hindered bubble coalescence by high salt concentrations.     

Effect of hydrophobically modified SiO2 nanoparticles on the stability of water-based SDS foam

In the present study, SiO₂ nanoparticles were first hydrophobically modified and then added into anionic surfactant sodium dodecyl sulfate (SDS) stabilized water-based foam to improve the foam stability. The foam stability was experimentally evaluated by measuring surface tension, Zeta potential and half-life of the foam. The foam stabilizing mechanism was also studied from a micro perspective by molecular dynamics simulation through analyzing the equilibration configuration and MSD curve of both SDS surfactant and water molecules. The results show that foam exhibits an optimal stability when SiO₂ concentration is 0.35 wt% under a specific surfactant concentration (0.5 wt%) in this work. The addition of SiO₂ nanoparticles with suitable concentration could improve the adsorption between SDS molecules and nanoparticles, thus limiting the movement of SDS and restricting the movement of surrounding water molecules, which is beneficial to enhance the foam stability.     

Stereocontrolled Iodolactonization of Acyclic Olefinic Amides

Acyclic olefinic amides were iodolactonized in the mixed solvent of CH₃CN and H₂O (90:10₂ v/v) under reflux to give products with trans configuration of the newly formed iodomethyl to the inherent alkyl group in high yield.