Influence of Foam Apparent Viscosity and Viscoelasticity of Liquid Films on Foam Stability

The objective of this research work was to study the relationship among the apparent viscosity of bulk foam, the viscoelasticity of liquid films, and foam stability. Bulk foam tests showed that the drainage half-life of AOS foam was higher than that of sodium dodecyl sulfate (SDS) and hexadecyltrimethyl ammonium bromide (CTAB) foams. The results of foam apparent viscosity revealed that the foam apparent viscosity was related to foam quality rather than foam stability. Higher film viscoelasticity modulus could be assigned for α -olefin sulfonate (AOS) films than those for SDS and CTAB ones. The film conductivity tests indicated that AOS liquid films, compared with SDS and CTAB liquid films, could delay the liquid drainage speed under dynamic conditions. Compared with foam apparent viscosity, the viscoelasticity of liquid films appeared to be a key factor in foam stability.     

Comparative Study of Extensional Viscoelasticity Properties of Liquid Films and Stability of Bulk Foams

The extensional viscoelasticity modulus and conductivity of liquid films and stability of bulk foams were investigated respectively. The effects of sinusoidal exciting frequency, polymer type, and polymer concentration on liquid film viscoelasticity modulus were systematically discussed. Higher film viscoelasticity modulus could be assigned for FS01/MPAM film systems than for FS01/HPAM ones. The film conductivity result showed that FS01/HPAM or FS01/MPAM liquid film systems could delay the liquid drainage speed under dynamic conditions compared with FS01 ones. Bulk foam test based on Waring Blender method indicated that FS01/HPAM foam was more stable than FS01/MPAM. Compared with static bulk foam test, the extensional viscoelasticity and conductivity method could reflect the dynamic behavior of liquid films.     

Experimental Validation of the Temperature-Resistant and Salt-Tolerant Xanthan Enhanced Foam for Enhancing Oil Recovery

Xanthan enhanced foam (XGF) is a newly developed chemical agent for enhanced oil recovery in high-temperature and high-salinity reservoirs. In this paper, laboratory experiments were performed to characterize the morphology and foam properties of XGF, to study its performance under different temperature and different salinity conditions, respectively. Based on simulate reservoir formation conditions of Xidaliya field, a series of research on XGF were conducted. The experimental results showed that the scanning electron microscopy of XGF reflected a more viscoelastic and stable nature of the foam system. High temperature had a great adverse impact upon the stability of XGF, and the increase of salinity in the solution helped to improve the stability of foam. The foam stability increased remarkably when XG4 is added, and an increase in ambient pressure made enhancement of foam stability became more noticeable. In the presence of crude oil, Xanthan could enhance the stability of emulsions and was more favorable to stabilize foam. XG4 enhanced foam had dramatic properties for mobility controlling and oil displacement in the porous media.     

Foam and Wetting Films from Aqueous Cetyltrimethylammonium Bromide Solutions: Electrostatic Stability1

Foam films and wetting films on quartz formed from aqueous solutions of cetyltrimethylammonium bromide (CTAB) are investigated in a wide range of surfactant concentrations in the presence of background electrolyte (5 × 10^–4 mol dm^–3 NaCl). Foam and wetting films are convenient models for the study of symmetric (free thin liquid films) and asymmetric (thin liquid films on solid substrate) films with the same air/solution interface. Microinterferometric methods of assessment of foam and wetting films are used which allow precise determination of the film thickness. Determined are the values of the potential ₀ of the diffuse electrical layer at the solution/air interface (applying the method of equilibrium foam films) and the potential ₁ at the solution/quartz interface (applying the method of capillary electrokinetics). These values are used to analyze the stability of the films studied in terms of the DLVO theory. A conclusion drawn is that both kinds of films studied are stabilized by electrostatic interaction forces. It is shown that with increasing CTAB concentration, a charge reversal occurs at both the solution/air and solution/quartz interfaces which determines the stability/instability conditions of the foam and wetting films. Concentration ranges where both kinds of films produce stable (equilibrium) films are found. There are also concentration ranges where the films either rupture or are metastable (quasi-equilibrium). The CTAB concentration ranges, which provide the formation of unstable (rupturing and metastable) and stable films, are different for symmetric (foam) and asymmetric (wetting) thin liquid films. It is only at high CTAB concentrations (higher that >2 × 10^–4 mol dm^–3) that both cases render formation of stable equilibrium films. These studies give direct experimental indications that the electrostatic interactions between identical or different interfaces can differ when the surfactant concentration is varied.     

聚苯撑苯并二噻唑(PBT)的耐热性和液晶性研究

PBT溶于甲基磺酸(MSA)和多聚磷酸(PPA)等强酸溶剂中时能形成液晶。用TGA法测定了PBT在氮气和空气中的热分解温度,分别高达690℃和585℃。计算了PBT在氮气中的分解活化能为161 kJ/mol。测定了PBT-MSA体系液晶的退偏振光强度-温度谱和浓度-温度二元液晶区域相图,并发现8％的PBT-PPA体系表现出特殊的退偏光强度-温度特性。液晶和PBT固体的X-衍射图表明液晶状态下沉积的薄膜保持了液晶态的结构,固体小角光散射的H_v图表明非液晶态下沉积的PBT薄膜有球晶结构。     

Influence of the type of foam films and the type of surfactant on foam stability

The behaviour and the life time ( _p) of different types of foam films (thin liquid films, for which DLVO-theory is valid; common black films, Newton black films) have been studied as a function of external pressure (P), applied in the Plateau-Gibbs-borders of the foam. The foam stability and the course of thep/P-dependence are determined mainly by the type of the foam films. A criterion for estimation of foam stability is proposed on the base of the obtained experimental results.     

Foaming in aqueous solutions of zwitterionic surfactant: Effects of oil and salts

This paper reports a study on the stability of foams generated from the aqueous solutions of the zwitterionic surfactant, N-Dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate, in presence of NaCl, CaCl₂ and AlCl₃. The effect of oil (i.e. n-hexane) on foam was also studied. The surface and interfacial tensions were measured. These tensions and the CMC decreased upon salt addition, signifying an increased adsorption of the surfactant molecules at the interface. The quantity of salt required for reducing the surface tension and CMC was in the sequence: NaCl > CaCl₂ > AlCl₃. The salts had a pronounced effect on the foaming characteristics, i.e. they reduced the initial foam volume. The effectiveness of salts in reducing the foam stability followed the sequence: AlCl₃ > CaCl₂ > NaCl. However, the foam collapse rate was reduced in the presence of salt. The presence of oil decreased the foam volume and reduced its stability. The entering, bridging, and spreading coefficients were calculated, which explained the stability of foams in presence of oil.     

新型含氟聚醚链修饰的咪唑离子液体的合成及其热稳定性

含氟聚醚链修饰的咪唑与碘代烷烃经季铵化反应高产率地制备了4个新型的含氟聚醚链修饰的咪唑碘盐(3a ～3d);通过3的复分解反应合成了一系列新型的含氟聚醚链修饰的咪唑离子液体盐(4a ～4d,5a～5d),其结构经1 H NMR,19F NMR,IR和元素分析确证.热重分析研究表明,4和5具有较高的热稳定性.     

Solvent-free Synthesis, Crystal Structure and Thermal Stability of Ionic Liquid 1-Hexadecyl-3-methylimidazolium Bromide

Ionic liquid 1-hexadecyl-3-methylimidazolium bromide [C16mim]Br was synthesized by solvent-free alkylation of N-methylimidzole with hexadecyl bromide. A large transparent single crystal of 1-hexadecyl-3-methylimidazolium bromide monohydrate （[C16mim]Br·H2O）, 4 mm in length, was firstly obtained in the water-trichloromethane-toluene growth system （Vwater＇Vtrichloromethane＇Vtoluene = 0.1：1：2）. The crystal structure was determined by single-crystal X-ray diffraction method. It crystallizes in the triclinic system, space group P1, with a = 5.4962（15）, b = 7.839（2）, c = 27.279（8） A, α = 94.375, β = 91.500, γ = 101.999°, Z = 2, V = 1145.2（5） A3, C20H41BrN2O, Mr = 405.46, Dc = 1.176 Mg/m3, μ = 1.804 mm^-1, F（000） = 436, the final R = 0.0523 and wR = 0.1345. The 3D supramolecular structure is constructed through weak interactions between imidazolium cations, Br- anions and lattice water molecules. The long alkyl chain to the imidazolium ring and lattice water molecules play an important role in the self-assembly process. Moreover, it is proposed that [C16mim]Br in water has aggregation behavior and the possible self-assembled structure is the interdigitated pattern. Finally, thermal stability of [C16mim][Br]·H2O was also studied by DSC and TGA analysis.     

1-Methyl-3-octylimidazolium Polyoxomolybdate Ionic Liquid with Low Melting Point and High Stability:Preparation and Photocatalytic Activity

The polyoxometalate(POM)-imidazole ionic liquid(IL) [C8mim]2[Mo6O19](C8mim=1-methyl-3-octylimi- dazolium) with a low melting point of 82.6 °C was successfully prepared and characterized by FTIR, XPS, NMR, TG and so on. The polyoxomolybdate-based IL has high stability, and its decomposing temperature reaches 321 °C, which is higher than that of 1-alkyl-3-methylimidazolium halides IL. Further photocatalytic performances of the IL were measured via degrading dye rhodamine B(RB) in aqueous solution under the UV...     

The Role of Internal Droplet Size on Emulsion Stability and the Extraction Performance of Kraft Lignin Removal from Pulping Wastewater in Emulsion Liquid Membrane Process

It has been discovered that the size of internal droplets in primary emulsion determines emulsion dispersion and stability in emulsion liquid membrane (ELM) process for removal of lignin from pulping wastewater. Generally, primary emulsion contains kerosene, Aliquat 336, sodium bicarbonate, as well as Span 80 as diluent, carrier, internal phase, and surfactant, respectively. Hence, this study had looked into the parameters, including concentration of surfactant, carrier, and stripping agent; emulsification speed and time; as well as agitation speed and time. As a result, the diameter of the smallest droplets (1.4 µm) was formed with maximum lignin extraction (95%), minimum swelling (5%) at 3% (w/v) surfactant concentration, 12,000 rpm of emulsification within 5 minutes, 0.01 M of Aliquat 336, 0.1 M of NaHCO_3, and 250 rpm of extraction within 10 minutes.     

聚合物网络分散液晶复合膜的制备与性能研究

报道了一种新型树脂基的聚合物网络分散晶复合膜材料。研究了基体材料的组成，液晶种类，液晶含量，聚合温度，紫外光强度及聚合时间等聚合物网络分散液晶复合膜性能的影响。扫描电子显微镜观测，发现这种材料是由两个连相互穿构成了属于聚合物球型。     

泡沫浮选-固相提取分离富集三七提取液中的人参皂苷

采用泡沫浮选-固相提取联用法,分离富集三七中的R1,Rg1,Re,Rc,Rb2,Rb3,Rd和Rb1,并用液相色谱法测定其含量,检测灵敏度和选择性都有所提高.对泡沫浮选过程的载气流量、浮选时间、样品溶液pH值和固相提取柱的洗脱条件进行了优化.原人参二醉型皂苷R1,Rc,Rb2,Rb3,Rd和Rb1的回收率在85.0%9...     

Removal of Mercury by Emulsion Liquid Membranes: Studies on Emulsion Stability and Scale Up

Emulsion liquid membranes (ELM) have received significant attention in the separation of various metal ions from industrial wastewater. Still efforts are needed to get the desired level of stability to overcome the hindrance in the application of ELM at industrial scale. In this paper, the effects of various parameters such as emulsification speed, concentration of cosurfactant, surfactant, carrier and impeller speed during extraction on the stability of an emulsion liquid membrane are studied. Dispersion destabilization of w/o emulsion is checked by Turbiscan. Drop size distribution and photomicrographs of the emulsions are also analyzed to evaluate stability of the emulsion. Instability of emulsion liquid membrane during extraction process is measured in terms of membrane breakage. A stable emulsion is used for the extraction of mercury from aqueous solution in small scale as well as in large scale.     

Extraction of Priority Pollutant 4-Nitrophenol from Water by Emulsion Liquid Membrane: Emulsion Stability,Effect of Operational Conditions and Membrane Reuse

This work aims to the extraction of the priority pollutant 4-nitrophenol (4-NP) from water by emulsion liquid membrane (ELM). Liquid membrane consists of a diluent (hexane) and a surfactant (Span 80). Sodium carbonate solution was used as internal aqueous phase. Effects of important experimental conditions governing the stability of the W/O emulsion were investigated. Influence of operating parameters that affects the permeation of 4-NP such as surfactant concentration, emulsification time, sulfuric acid concentration in external phase, acid type in external phase, internal phase concentration, type of internal phase, stirring speed, volume ratio of internal phase to membrane phase, treatment ratio, 4-NP initial concentration, and diluent type was examined. This study also evaluated the effect of Na₂CO₃ concentration in the internal aqueous phase on the stripping of 4-NP. Additionally, the reuse of the recovered membrane was studied. Under most favorable conditions, practically all the 4-NP and aniline (AN) molecules present in the feed phase were extracted. The recovery of the membrane phase was total and the extraction of 4-NP was not decreased. The ELM treatment process represents a very interesting advanced separation process for the removal of 4-NP and AN from aqueous solutions.     

Stability of Sulfur(IV) Solutions in the Presence of Amines and the Tendency of Sulfite Ions to Disproportionate in Stock Solutions

Abstract

Several sulfite solutions at the level of 0.050 mol.L^?1 were kept at 25°C, in polyethylene flasks, in the presence and absence of air. The concentration of sulfite was periodically checked by the iodometric method. The presence of ethanolamine, ethylenediamine or tris(hydroximethyl)aminomethane, at 0.05 - 0.20 mol.L^?1 concentration levels, showed a remarkable stabilizing effect at pH values higher than 10.5. The amine ionization was supressed by the common ion effect by using OH^?, added as NaOH. The changes in the concentration of S(IV) solutions in the presence of amine were about 1 to 3 %, during the period of 85 days. The stabilizing effect depends only on the amine group and not on the mixed function alcohol/amine. It was shown that an adduct of R-NH₂.SO₂ type is not formed in aqueous medium. In the stock S(IV) solutions kept in highly alkaline medium a slow increase in pH was observed and disproportionation of sulfite ion was evidenced by formation of thiosulfate as revealed from ion chromatographic measurements. In the presence of oxygen dithionate ion is also formed.     

Facile Preparation of an Ionic Liquid Composite Mesoporous Polymer as a Solid Phase Extraction Adsorbent for the Separation and Purification of Flavonoids from Chamaecyparis obtusa

A new ionic liquid composite mesoporous polymer (ILCMP) was synthesized by one-pot copolymerization. The obtained ILCMP with good morphology, good pore diameter distribution, and high adsorption capacity was successfully applied as the sorbent in solid-phase extraction (SPE) to extract and separate quercitrin and myricetin from Chamaecyparis obtusa. 87.8–101.8% of satisfactory recoveries were obtained with RSDs less than 6.2% and the amounts of quercitrin and myricetin in Chamaecyparis obtusa were 0.38 and 0.12 mg/g, respectively. The proposed ILCMP-SPE-HPLC method was applied for the separation, purification, and determination of flavonoids from natural products.     

Main-chain liquid crystalline copolymers: synthesis and comparative study of the mesomorphic properties and non-linear optical properties

Linear main-chain polymers (P1, P2 and P3) have been synthesised and characterised. The polymers were designed to understand the rigidity of the mesogen’s linking groups and its effect on transition temperature. The liquid crystalline behaviour of these polymers was investigated using polarised optical microscopy and differential scanning calorimetry. All polymers exhibited phase transition on heating and cooling runs. The mesophase stability decreases with the decrease of rigidity of the second mesogen (P2>P1>P3). Similarly, the enthalpy and entropy changes are dependent on the rigidity of the second mesogen (Mesogen B). Polymer P1 undergoes photoisomerisation under UV-visible light irradiation and it attains a photo-stationary state at 275 s. This provides an opportunity to investigate the third-order non-linear optical properties. The non-linear behaviour of polymer P1 in chloroform presents a distinct deviation in a different concentration, where polymer P1 also exhibits a negative non-linear refractive index. Thus, polymer P1 can be used as a potential candidate for optical device applications such as optical limiters.     

Synthesis,Structure and Thermal Stability of a Cadmium Coordination Polymer：[Cd（phen）（4,6-dimethyl-5-nitro-isophthalic Acid）]_n

One cadmium(Ⅱ)coordination polymer [Cd(phen)(4,6-dimethyl-5-nitro-isophtha-lic acid)]n(1)has been synthesized with 4,6-dimethyl-5-nitro-isophthalic acid,phen(phen = 10-phenanthroline),and cadmium nitrate in the mixture of DMSO:H2O(V:V = 2:1).Crystallogra-phic data for this complex:monoclinic,space group P21/c,with a = 11.668(2),b = 11.841(6),c = 14.446(2),β = 102.440(4)°,V = 1.9491(8)3,Dc = 1.805 g/cm3,Z = 1,F(000)= 1056,GOOF = 0.999,R = 0.0280 and wR = 0.0662.The crystal structure analysis indicates that the cadmium ion is coordinated with two nitrogen atoms of one 1,10-phenanthroline molecule and five oxygen atoms from three 4,6-dimethyl-5-nitro-isophthalic acid molecules.The curve of TGA shows that 1 is stable up to 380.0 ℃.     

聚氨酯/环氧树脂互穿网络硬质泡沫塑料反应过程和微观结构

聚氨酯／环氧树脂互穿网络(PU／EPIPN)硬泡中异氰酸根的消耗速度较纯PU硬泡高，是由于环氧树脂的固化荆同时也是异氰酸根反应的催化荆。而PU／EP IPN硬泡中环氧基的反应速度和反应程度均较纯EP网络低，归因于互穿网络对基团扩散的阻碍。在互穿网络硬泡形成过程中，存在环氧开环中所新产生的羟基与异氰酸根的反应、大分子多元醇中羟基与环氧基的反应以及异氰酸根与环氧基形成嗯唑烷酮的反应三种形成网络间的化学键的途径。同时由于PU／EPIPN硬泡高度的交联，使得IPN硬泡中两个网络具有良好的相容性。动态力学性能表明所有IPN样品都只有一个玻璃化温度。透射电镜表明IPN样品无明显的相界面。