Polymer/surfactant interactions

Polyelectrolytes and oppositely charged surfactants form precipitation complexes which, in many cases, can be completely resolubilized by excess surfactant. In general, maximum precipitation appears to correspond to a single layer of surfactant adsorbed on the polymer, and the resolubilized form to a double layer of surfactant. Prior to formation of the latter, the complexes are highly surface active. An analysis of the solubility diagrams of a cationic hydroxyethyl cellulose derivative, and a homologous series of sodium alkyl sulfates, has provided a value of the adsorption energy, Φ, of these surfactants into the first layer. The value of Φ, viz., 1.1 kT per CH₂ group, is somewhat higher than the corresponding value for micelle formation. Studies with a number of surfactants show that polymer/surfactant interaction is most favorable (a) the longer the hydrocarbon chain of the surfactant, (b) the straighter the chain, and (c) when the head group is terminal to the chain. Departures from these conditions reduce the extent of interaction and render difficult resolubilization of the complex. From results on a range of polymers, it is concluded that resolubilization of the precipitated complex is also difficult if the charge density of the polymer is too high.     

Nonionic surfactant polarity index determination by inverse gas chromatography

Polyglycol nonionic surfactants are widely used in industrial and consumer products. Two classes of these surfactants, made from selected combinations of 1,2-butylene oxide, propylene oxide and ethylene oxide, were compared to alcohol ethoxylate (AE) and nonyl phenol ethoxylate nonionic surfactants in this study. Polyglycol copolymers consisted of either a polypropylene glycol (PPG) or polybutylene glycol (PBG) central hydrophobe. Ethoxylation of the hydrophobes produced polyethylene glycol hydrophilic blocks. Differences in hydrophobe polarity were determined by inverse gas chromatography (IGC). IGC is a useful analytical method by which the physical and chemical characteristics of a material are studied. The stationary surfactant material under study was coated onto an inert support and used as the packing for the column. A probe mixture, containing simple organic molecules of varying polarity, was injected, and the retention characteristics were measured. The retention characteristics of the standard probe mixture were used to reveal relative polarity information about the stationary surfactant coatings. Polarities of the four hydrophobes were (in decreasing order): PPG, PBG, nonyl phenyl and fatty alkyl. Comparisons were then made between the calculated hydrophile-lipophile balance values and polarity indices of the hydrophobes and their ethoxylates. The effects of hydroxyl groups on polarity were also studied and quantified.     

降低表面活性剂吸附的研究进展

综述了目前学者在吸附机理和吸附的影响因素上的研究成果,并总结了现有的降低表面活性剂吸附的方法,着重介绍了牺牲剂的使用,这是目前降低表面活性剂吸附最高效的方法。牺牲剂种类繁杂,国外对高分子牺牲剂的研究众多,这很可能成为国内牺牲剂研究的下一个重点,以及牺牲剂在国内外现场的应用以木质素类为主,寻求这种廉价、易得的牺牲剂仍然是降低表面活性剂吸附的主要方向之一。     

A reduced adsorption isotherm for surfactant mixtures

The adsorption of surfactants of similar structure on mineral oxide surfaces can be described by a single adsorption isotherm when plotted against reduced concentration. The total adsorption of mixtures of these surfactants and the adsorption of each individual surfactant in the mixture can be estimated from this reduced adsorption isotherm. No mixture data are required for this calculation. The method of calculating the reduced concentration for pure surfactants and surfactant mixtures is discussed. Adsorption data of three isomerically pure alkylbenzene sulfonates and binary mixtures of these surfactants on alumina and kaolinite is used to illustrate this correlation.     

Effect of polarity on the adsorption of dichlorobenzene isomers

The influence of reference vapor polarity on the characterization of microporous carbon adsorbents using the Dubinin equations was investigated. Polarity may be an important parameter for reference vapor selection due to the influence of electrostatic forces on the adsorption of polar vapors. Adsorbate polarity was investigated by evaluating the adsorption isotherms and characteristic curves for the three isomers of dichlorobenzene and the heats of adsorption for the two liquid isomers. The three isomers are very similar in terms of molecular weight, vapor pressure, density, and electronic polarizations. The major difference is the range of dipole moments: 1,2-dichlorobenzene, 2.50 D; 1,3-dichlorobenzene, 1.72 D; and 1,4-dichlorobenzene, 0.00 D. If adsorbate polarity has a major influence on adsorption, the three characteristic curves should have different slopes. The slopes of the three curves were not statistically different at the 95% level, and no difference in the heats of adsorption was observed. It was concluded, therefore, that electrostatic forces do not have a major influence on vapor adsorption when adsorbate polarities are between 0 and 2.50 D. Therefore, a single reference vapor may be adequate for characterization of microporous carbon adsorbents.     

Effect of cotton substrate characteristics upon surfactant adsorption

It is shown that the reported differences in anionic surfactant adsorption on cotton can be largely attributed to the presence of variable amounts of natural wax on the fiber surface. High adsorption values with peaks near critical micelle concentration (cmc) result from surfactant adsorption on the wax surface. Wax-free surfaces fail either to show the same high maxima or the same relative magnitude of adsorption. At surfactant cmc the adsorption relationship for waxy cotton (millimoles/g. of cotton) cationic: nonionic: anionic was roughly 66 to 17 to 74. For dewaxed cotton, this became 40 to 10 to nil. Confirming the findings of others, no adsorption by cotton of sodium tripolyphosphate occurs either with waxy or wax-free cotton. Also addition of tripolyphosphate decreased the adsorption of several anionic surfactants. At concentrations greater than cmc and at sufficiently-high solution temperature, anionic surfactants can solubilize cotton wax, leaving a less waxy substrate upon which adsorption is then reduced.     

The energetics of surfactant adsorption at the air-water interface

The standard free energy, enthalpy, and entropy changes (ΔG, ΔH, and ΔS, respectively) for the adsorption at the air-water interface of a commercial ethylene oxide (EO) adduct of straight chain nonylphenol from monomer solution at the critical micelle concentration (CMC) have been calculated from surface tension-concentration data at 21C–45C using the Gibbs equation, the standard free energy change equation ΔG=−RT (In interfacial monomer concentration/CMC), and the Gibbs-Helmholtz equation which gave ΔH directly from the slope of the (ΔG/T) vs (1/T) function. The CMC and surface tension at the CMC (γCMC) decreased, and −ΔG and molecular area increased slightly, with increasing temperature. The ΔH and ΔS values were positive, and appear explainable by the postulations applied to micellization. At ambient temperature (28C) an increase in the (EO) mol ratio of straight chain nonylphenol and C₁₃ secondary alcohol ethoxylates resulted in increases of CMC, γCMC, and molecular area, and slight decreases in −ΔG. A comparison of the 9 (EO) mol ratio adducts of C₁₃ straight chain primary and secondary alcohols showed that the CMC and molecular area of the secondary alcohol ethoxylate were larger, and the γCMC and −ΔG smaller, than the corresponding values of the primary alcohol ethoxylate.     

木质素结构以及表面活性剂对木质素吸附纤维素酶的影响

引言随着世界经济的快速发展和人口的增加,石油以及其他不可再生资源已经濒临枯竭。出于经济发展、国家安全以及环境保护等各个方面的需要,各个国家都在寻找石油的代替能源。生物乙醇这一新     

Mechanism and behavior of surfactant adsorption onto resins with different matrices

The recovery of surfactant from wastewater utilizing polymeric adsorbent is important not only in the protection of the environment from pollution, but also in the effective use of raw materials. Mechanism and behavior of surfactant (linear dodecyl-benzene sulfonate, LAS) adsorption onto styrene resin XAD-4 and acrylic ester resin was studied in high concentration solution (several thousand mg/L). For comparison, a series of acrylic ester resins had been prepared, characterized and used along with commercial resins XAD-7 and HP2MG. Y-50 resin, one of the resins, exhibits better adsorption capacity than the other acrylic ester resins in this study. The experimental equilibrium data were fitted to Langmuir model, and the model was found to provide very good fits for all of acrylic ester resins over the temperature range, whereas fitted results for the styrene resin XAD-4 were less accurate. Adsorption kinetics and elution processes were also investigated to study different mechanism and behavior of surfactant adsorption onto resins. The observation indicates that the cooperation of hydrophobic interactions and electrostatic attraction impels the adsorption process as well as the formation of monolayer and bi-layer.     

吸附树脂极性的高效液相色谱法测定及表征

建立了测定及表征吸附树脂极性的高效液相色谱法。DA-201极性树脂、AB-8弱极性树脂和D-101非极性树脂分别填充高效液相色谱柱,以去离子水为流动相,葡聚糖为示踪剂,流速1.0 mL/min,柱温30℃,测定树脂的极性。结果表明,正丁醇、乙醇均可作为单一探针分子,流出顺序可定性表征吸附树脂极性:DA-201极性树脂AB-8弱极性树脂D-101非极性树脂;采用乙醇/甲醇作为探针分子组,通过相对极性法计算,得到3种吸附树脂的定量极性值:DA-201极性树脂极性值100,AB-8弱极性树脂极性值18,D-101非极性树脂极性值0,相对标准偏差(RSD)均小于1.50%。方法稳定可靠,可以有效表达吸附树脂的极性。     

Polymer/surfactant interaction—Its relevance to detergent systems

The field of polymer/surfactant interaction is reviewed in this work. Results from two investigative methods,viz., dialysis and surface tension, are discussed, illustrating the main behavioral patterns and outlining the principles of the interactions. Next, aspects of the interaction phenomena that appear to have relevance to detergent formulation are presented. These include solution rheology, solubility control and surface conditioning. Lastly, the importance of surface activity of the polymer itself is stressed, culminating in a discussion of the properties of hydrophobically modified water-soluble polymers (“polymeric surfactants”), both alone and in the presence of conventional surfactants. Based on the Samuel Rosen Memorial Award lecture, given at the AOCS Annual Meeting, Anaheim, CA, April 1993.     

The adsorption of calcium ions to surfactant films on Graphon

Previously, the adsorption mechanisms of sodium dodecyl sulfate (NaDS) and of sodium dodecylbenzene sulfonate (NaDBS) onto Graphon (a high area, graphitized carbon black) had been determined. Calorimetric heats of adsorption of the surfactants were also measured using a plastic calorimeter designed to avoid contamination by calcium ions. This work has now been extended to learn the effects of calcium on the Graphon/solution interface. Radiocalcium adsorption measurements showed that the adsorbed NaDS takes up limiting amounts of one calcium for two DS ions and the chains extend directly from the surface in close-packed array. (In the absence of calcium, the NaDS takes up one of two arrangements with two different lengths of the hydrocarbon chain lying on the Graphon surface). Several lines of evidence indicate that the calcium is tightly bound at the interface. Above the cmc, the micelles compete for the calcium ions. For NaDBS, the arrangement on the Graphon is not altered by the calcium but other results are similar. Trace amounts of calcium strongly enhance the flocculation of the Graphon. This finding suggested that deposition of the surfactant-coated Graphon onto cotton should be followed as a function of added calcium. It was found that traces of calcium greatly increased the deposition apparently by bridging surfactant on the Graphon to surfactant on the cotton.     

The correlation of washability with the rate of surfactant adsorption

A relation between the rate of adsorption of surfactant molecules at a gas-liquid interface and the soil removal ability of the surfactant solution is presented. The relation is of the form SR=A+Bk+Ck² where SR is the percentage soil removed, A, B, and C are constants, and k is the first order rate constant for the adsorption process. The relation is empirical and as yet has not been coupled with a fundamental explanation of the detergency process on a molecular scale. The maximum soil removal does not always occur at the highest rate constant but may reach a maximum at an intermediate value. The soil removal process seems to be different above the CMC than below it. For the different surfactants studied, the soil removal is higher for the surfactant with larger rate constants. The rate of surfactant adsorption was obtained from dynamic surface tension measurements made with the oscillating jet technique. Soil removal information was obtained from laboratory tests using a Terg-O-Tometer and reflectance measurements on standard cloth swatches. Cationic, nonionic, and anionic surfactants were studied. Specifically, the surfactants were Triton X-100 (an octyl phenol with 8 or 9 ethylene oxide units), NaDBS (sodium dodecylbenzene sulfonate), and CTAB (cetyl trimethylammonium bromide). The surface tension time range of 5 to 60 milliseconds and soil removal ability of these surfactants was investigated over the temperature range of 20 to 60C, and the concentration range of 0.0003 to 0.009 M.     

表面活性剂吸附对促进甲烷水合物生成效果的影响

基于表面活性剂固-液界面吸附理论,在无搅拌条件下研究了十二烷基硫酸钠（SDS（、脂肪醇聚乙烯醚硫酸钠（AES（、脂肪醇聚乙烯醚（AEO（3种表面活性剂在不锈钢反应釜中对甲烷水合物生成的促进效果。结果表明：水合物的生成形态与表面活性剂吸附金属表面形态有良好的对应关系;SDS与AES在金属表面的吸附作用可使水合物成核速率提高,成核位置增多。由于AEO不能在金属壁面发生吸附,导致对水合物生成促进效果降低,在浓度为300 mg·L^-1的SDS、AES和AEO溶液中,水合物储气密度及平均储气速率分别为131.4、128.3、12.3（体积比（和5.8、7.6、0.07 mmol·min^-1;逐步提高SDS溶液浓度（80~1200 mg·L^-1（和AES溶液浓度（60~1350 mg·L^-1（,水合物储气密度首先增大然后减小,储气速率线性增大。因此,合理选择表面活性剂种类及浓度,可显著促进水合物生成。     

Mechanisms of surfactant adsorption on non-polar, air-oxidized and ozone-treated carbon surfaces

Ozone treatment of fly ash carbon has recently been reported to inhibit the adsorption of commercial surfactants in concrete paste, thus mitigating the known negative effects of carbon on ash utilization. This paper examines the general mechanism of surfactant adsorption on carbon and its suppression by surface oxidation. Experimental results are presented for two carbon types (carbon black, fly ash carbon), both raw and surface oxidized (by ozone and molecular oxygen) and several commercial anionic and non-ionic surfactants (Darex II, SDS, Tergitol). The treated carbon surfaces were characterized with XPS, FT-IR, thermal desorption in N₂ and H₂/He, surface acidity, hygroscopic behavior, interfacial energy and its components through contact angle measurement involving standard liquid probes. Surface oxidation is found to decrease surfactant adsorption in each of the carbon/oxidant/surfactant systems examined, and its effect correlates with the amount of surface oxides by XPS. The combined results suggest that surfactant adsorption primarily occurs on non-polar carbon surface patches where it is driven by hydrophobic interactions. The main mechanism of oxidative suppression is the destruction of this non-polar surface, though micropore blockage and increased negative surface charge may also contribute for some systems.     

吸附伏安法测定阳离子表面活性剂的临界胶束浓度

以中性红为探针,用吸附伏安法测定了溴化十六烷基三甲铵的临界胶束浓度。     

分光光度法测定阳离子表面活性剂在砂岩表面的吸附

为测定阳离子表面活性剂十六烷基三甲基氯化铵(1631)在岩石表面的吸附量,利用紫外分光光度法,检测了1631溶液在岩石表面吸附前后的质量浓度,算出1631在岩石表面的吸附量。结果表明,用紫外分光光度法检测阳离子表面活性剂浓度快速准确,确定617nm为测定波长,线性回归方程为y=0 0027x-0 0058,R2=0 9991;不同砂岩表面的吸附平衡时间不同,亲水表面为10h,油表面为16h,砂表面为18h;同砂岩表面的静态饱和吸附量不同,亲水表面是0 7mg·g-1·砂,亲油表面是1 4mg·g-1·砂,油砂表面是6 7mg·g-1·砂;天然岩心动态吸附量为0 8066mg·g-1·砂。