Enhanced soil washing of phenanthrene by mixed solutions of TX100 and SDBS

Increased desorption of hydrophobic organic compounds (HOCs) from soils and sediments is a key to the remediation of contaminated soils and groundwater. In this study, phenanthrene desorption from a contaminated soil by mixed solutions of a nonionic surfactant(octylphenol polyethoxylate, TX100) and an anionic surfactant (sodium dodecylbenzenesulfonate, SDBS) was investigated. Phenanthrene desorption depended on not only aqueous surfactant concentrations and phenanthrene solubility enhancement but also the soil-sorbed surfactant amount and the corresponding sorption capacity of sorbed surfactants. The added surfactant critical desorption concentrations (CDCs) for phenanthrene from soil depended on both sorbed concentrations of surfactants and their critical micelle concentrations (CMCs). Phenanthrene desorption by mixed solutions was more efficient than individual surfactants due to the low sorption loss of mixed surfactants to soil. Among the tested surfactant systems, mixed TX100 and SDBS with a 1:9 mass ratio exhibited the highest phenanthrene desorption. Mixed micelle formation, showing negative deviation of CMCs from the ones predicted by the ideal mixing theory, was primarily responsible for the significant reduction of soil-sorbed amounts of TX100 and SDBS in their mixed systems. Therefore, mixed anionic-nonionic surfactants had great potential in the area of enhanced soil and groundwater remediation.     

Influence of the nonionic surfactant Brij 35 on the bioavailability of solid and sorbed dibenzofuran

The effect of the nonionic surfactant Brij 35 on the bioavailability of solid and Teflon-sorbed dibenzofuran for Sphingomonas sp. strain HH19k was studied in simple model systems. Growth with dibenzofuran and dibenzofuran-specific oxygen uptake in surfactant-free media and with Brij 35 above the critical micelle concentration (cmc) were compared with dissolution and desorption in the absence of bacteria. Brij 35 accelerated dissolution and biodegradation of solid dibenzofuran by a factor of 2. It also enhanced the initial desorption rate of dibenzofuran from Teflon by this factor. Continuously decreasing desorption rates were attributed to slow diffusion of dibenzofuran inside Teflon, leading to depletion of dibenzofuran in the exterior of the Teflon particles. Surprisingly, Brij 35 slowed the initial biodegradation of desorbing dibenzofuran. We propose two processes that led to low bioavailability of sorbed dibenzofuran in the presence of surfactant. First, desorbing dibenzofuran rapidly accumulated in surfactant micelles, leading to reduced truly water-dissolved dibenzofuran concentration as the factor controlling the biodegradation rate. Second, Brij 35 suppressed the contact between bacteria and Teflon. This increased the average diffusion distance of dibenzofuran to the bacteria, which in turn flattened the gradient of the dissolved dibenzofuran concentration between the sorbent and the cells as the driving force for desorption.     

烷基糖苷水溶液的表面活性以及电解质的影响

烷基糖苷APGs作为新一代绿色表面活性剂,以其优异的表面特性在各个领域的应用开发受到了广泛的关注。文章深入研究了不同链长的烷基糖苷水溶液的表面张力、胶束化行为以及电解质的加入对其的影响。结果表明,APGs溶液的CMC主要取决于其分子疏水端的结构。随着疏水链的增长,APGs溶液的CMC随之减小。相对离子型表面活性剂而言,硫酸钠的加入对溶液的影响较小,主要是通过对疏水链的盐析作用来实现的。在强碱体系下,APGs分子亲水端部分去质子化使得所形成的胶束带负电性,从而导致氢氧化钠的盐析效应相对较弱。     

The relationship between the interfacial properties of surfactants and their toxicity to aquatic organisms

In previous work, the toxicity of several anionic and nonionic surfactants to rotifer (Brachionus calyciflorus) was shown to be highly correlated with interfacial activity. In this study, the relationship between interfacial properties of surfactants and their effects on aquatic organisms is extended to include the toxicity of the cationic surfactant class (homologues of alkyl trimethylammonium chloride and alkyl hydroxyethyl dimethylammonium chloride) to green algae (Selenastrum capricornutum) and the bioconcentration of linear alkylbenzene sulfonate (LAS) isomers and homologues by fish (Pimephales promelas and Ictalurus punctatus). In each case, the interfacial activity is expressed by the physicochemical parameter, delta G0ad/Amin, where delta G0ad is the standard free energy of adsorption of the surfactant at the air/solution interface and Amin is the minimum cross sectional area of the surfactant, or the analogous parameter, delta 1sG0ad/1sAmin, at the solid/liquid interface, where the solid is an immobilized artificial membrane (IAM) that mimics a biological cell membrane. The general nature of the relationship between interfacial activity of surfactants and their biological effects in aquatic systems indicates that sorption to biological membranes is a critical parameter for predicting and understanding environmental effects. While specific interactions probably occur once a surfactant has penetrated a membrane bilayer, nonspecific hydrophobic interactions appear to be driving the sorption process.     

Evaluation of component characteristics of soil-surfactant-herbicide system that affect enhanced desorption of linuron and atrazine preadsorbed by soils

The aim of the present work was to evaluate the surfactant-enhanced desorption of atrazine and linuron preadsorbed by soils and to study the effect of different characteristics of the components of soil-surfactant-herbicide systems on the efficiency of desorption. Two soils with organic matter contents of 3.16% and 7.28% and 11 surfactants, three of them anionic (SDS, LAS, and SDOSS) and 8 of them nonionic (Tween 80, Tween 20, Triton X-100, Triton X-114, Brij 35, Brij 30, Tergitol NP-10, and Tergitol 15S12), at concentrations 1.5 and 10 times the critical micellar concentration (cmc) were used. Adsorption-desorption studies were performed using a batch system, and the Freundlich model was applied to the isotherms except for some cases in which this was not possible. The desorption isotherms of both pesticides in aqueous medium pointed to the existence of hysteresis. The values of the hysteresis coefficients of the adsorption isotherms in water decreased in some cases while in others they increased in the presence of the surfactants, depending on the structure of these and on their concentration in water, on the organic matter content of the soil, and on the K(ow) of the herbicide. Parallel to the decrease in hysteresis, the percentage of herbicide desorption and desorption efficiency coefficient (E; ratio between the percentages of herbicide desorption in the presence of surfactant and those found in aqueous medium) increased. For a 10 cmc surfactant concentration, a linear relationship was seen between the E values and the absolute values of the cmc of the surfactants. Also, for the same surfactant, a linear relationship was seen between log E and the log of the absolute concentrations of surfactant in solution. The results obtained are of practical interest for the choice of surfactants for concrete problems involved in the recovery of pesticide-polluted waters using the surfactant-enhanced desorption pumping technique.     

Gemini表面活性剂(一)

Gemini表面活性剂由于其独特的结构,而具有优异的表面活性.其临界胶束浓度（CMC）较传统表面活性剂低数百倍,不仅应用浓度可大幅降低,而且具有传统表面活性剂不具备的性能.文中介绍了Gemini表面活性剂的研发现状,分子结构特点及表面行为,以及其优良性能.根据Gemini表面活性剂的性能,可将其分为阳离子型、阴离子型、非离子型和两性离子型,并详细阐述了合成、性能和应用.     

新型表面活性剂的表面张力和电导率性能研究

合成了三种孪连型阳离子季铵盐表面活性剂16-4-16,2Br-1、14-4-14,2Br-1、18-2-18,2Br-1,对三者的性能进行评定,分别通过表面张力和电导率测得临界胶束浓度(CMC)、表面活性剂在气-液界面的吸附量、单个分子的面积和胶束电离度α。结果表明:首先,相对于单头基单尾链的表面活性剂,三种孪连表面活性剂的表面活性更强,CMC值更低;其次,三种表面活性剂都有其各自的特性,16-4-16,2Br-1的粘弹性能较好,而14-4-14,2Br-1、18-2-18,2Br-1表面张力很低。实验表明,通过调节孪连表面活性剂联结基和疏水链的长度会对产品的性能有很大的影响。     

Sorption of ionic surfactants to estuarine sediment and their influence on the sequestration of phenanthrene

The sorption of an anionic surfactant (sodium dodecyl sulfate; SDS) and a cationic surfactant (hexadecyl trimethylammonium bromide; HDTMA) to estuarine sediment has been studied in river water and seawater. Sorption isotherms for SDS were essentially linear in both waters, suggesting a nonspecific, hydrophobic interaction between the SDS tail and particle surface. Sorption of HDTMA was considerably greater, more nonlinear, and more sensitive to water composition. These observations were attributed to a combination of both electrostatic and hydrophobic interactions between the surfactant and particle surface, the formation of admicelles, and salinity-induced structural alteration of the hydrophobic tail of the HDTMA molecule. Presence of SDS caused a reduction in the sorption of phenanthrene to estuarine sediment because of the competitive effects of the surfactant tail for hydrophobic sorption sites on the particle surface. Conversely, the presence of HDTMA caused significant enhancement in phenanthrene sequestration because of head-on sorption of surfactant molecules and a resulting, more hydrophobic particle surface. The most persistent feature of our results was an inverse dependence of unit sorption on particle concentration, and an empirical algorithm defining the effect was used to calculate the sediment-water fractionation of realistic concentrations of reactants in the estuarine water column. The results of these calculations, and the more general findings of this study, significantly improve our understanding of both the transport and fate of ionic surfactants in the estuarine environment, and the effects that these surfactants have on the partitioning of hydrophobic organic micropollutants.     

Micellar partitioning and its effects on Henry's law constants of chlorinated solvents in anionic and nonionic surfactant solutions

Micellar partitioning of volatile chlorinated hydrocarbons in surfactant solutions and its effects on vapor-liquid equilibrium is fundamental to the overall design and implementation of surfactant-enhanced aquifer remediation. Surfactant micelles greatly enhance contaminant recovery from the subsurface; however, the reduced volatility of organic compounds compromises the aboveground treatment of surfactant-laden wastewaters using air-stripping process. Batch equilibrium tests were performed to acquire micellar partition coefficients (Km) and apparent Henry's law constants (H*) of three prominent groundwater contaminants (tetrachloroethylene, trichloroethylene, cis-dichlorethylene) in the presence of two anionic surfactants (sodium dodecyl sulfate, SDS; sodium dodecylbenzene sulfonate, SDBS) and two nonionic surfactants (Triton X-100 and Tween 80). The H* values were significantly reduced in the presence of all four surfactants over their critical micelle concentrations (cmc's). On a cmc basis, the anionic surfactant SDS had the greatest effect on H*, followed by SDBS, Triton X-100, and Tween 80. Anionic surfactants decreased H* to an order of magnitude lower than nonionic surfactants, although nonionic surfactants decreased the H* at concentrations significantly lower than the anionic surfactants due to their lower cmc's. Nonionic surfactants present higher Km and molar solubilization ratio than anionic surfactants. Tetrachloroethylene has the highest Km values among three chlorinated solvents, which agrees well with the hydrophobicity (Kow) of these chemicals. An empirical correlation between log Km and log Kow is developed on the basis of data from this study and the Km values reported for a number of chlorinated and nonchlorinated hydrocarbons. Equilibrium data were also tested against three sets of models that describe the partitioning of volatile compounds in vapor-water-micelle phases. Applications of these models in experimentally determining Km from batch vapor-water equilibrium data are discussed.     

表面活性剂对T1脂肪酶活力的影响

本文研究了非离子型、阳离子型、阴离子型以及两性离子型表面活性剂对T1脂肪酶活力的影响。采用不同浓度的表面活性剂对T1脂肪酶进行处理,再以对硝基苯酚月桂酸酯作为底物,测定处理后的酶活变化。研究发现,低浓度的非离子型表面活性剂对T1都有激活作用,使其相对酶活提高50%到150%。当非离子型表面活性剂的浓度超过其临界胶束浓度,T1的活力受到不同程度的抑制,其中吐温80的抑制作用最为明显。阳离子型(CTAB)、阴离子型(N-L与SDS)和两性离子型(SB3-14)表面活性剂都对脂肪酶的酶活有强烈的抑制作用,可能是因为离子型表面活性剂的带电基团与蛋白质表面的带电氨基酸产生强烈的电荷相斥作用,导致蛋白变性而失去活力。T1脂肪酶是一类具有工业应用价值的耐热脂肪酶,研究不同类型的表面活性剂对其活力的影响,对于在不同目的下选择使用适合的表面活性剂具有重要意义。     

Spectrophotometric assay of POE nonionic surfactants and its application to surfactant sorption isotherms

The operational range and suitability toward environmental samples of an iodine-iodide (I-I) assay for nonionic surfactants were assessed. The I-I assay provides a rapid and repeatable method for determining aqueous nonionic surfactant concentrations. Through a systematic examination of surfactant structure, the operational range of the assay was shown to be on the order of 10(-6) to 10(-3) MEO, where the concentration unit MEO is defined as the molar surfactant concentration multiplied by the number of ethylene oxide units in the surfactant molecule. For environmental samples, it was shown that the I-I assay can be applied to measurement of surfactant sorption isotherms to aquifer sands and bacteria cultures. A potential limitation of the I-I assay is interference with humic acids, with the magnitude of the interference dependent on the concentration of humic acids present. The main benefit of the I-I assay is that its high accuracy and ease of application allows measurement of low levels of surfactant sorption. Surfactant sorption to aquifer sand could be measured down to the range of 10(-9) mol/g.     

Surfactant cleaning of ultrafiltration membranes fouled by whey

A polyethersulphone ultrafiltration membrane was prepared for concentration of whey. The membrane was fouled by whey and the effect of different cleaning agents on flux recovery of the fouled membrane was studied. The optimum cleaning procedure for membrane regeneration was elucidated. The results showed that a combination of surfactants (anionic, cationic and nonionic) may be employed as the optimum cleaning agent for maximum flux recovery. The fluorescence studies revealed that the cationic surfactant interact with proteins by breaking the intra‐chain hydrophobic bonding and providing electrostatic repulsion. Changing the alkyl chain from dodecyl to hexadecyl increases the interaction of surfactant–protein. Dodecyltrimethylammonium bromide (DTAB) provided a weak interaction with whey proteins than to tetradecyltrimethylammonium bromide (TTAB) and cetyltrimethylammonium bromide (CTAB). All data obtained in this study support a surfactant–protein interaction in which hydrophobic forces play a dominant role. The nonionic surfactants poly(oxyethylene) isooctyl phenyl ether (TX‐100) and anionic surfactants SDS interact with amino acids in the inner protein structure thus denaturate tertiary protein structure and reduce hydrophobic interaction of proteins by membrane surface.     

Structural aspects of surfactant selection for the design of vegetable oil semi-synthetic metalworking fluids

This paper presents a set of surfactant-selection guidelines that can be used to design bio-based semi-synthetic metalworking fluid (MWF) microemulsions as a renewable alternative to conventional petroleum formulations. Ten surfactant classes (six anionic and four nonionic) with different head and tail structures and three vegetable base oils (canola oil, soybean oil, and a fatty acid trimethylolpropane ester) were investigated as representatives of oil and surfactant options currently under consideration in the MWF industry. All combinations of these surfactants and oils were formulated at the full range of oil to surfactant ratios and surfactant concentrations. The stability of each formulation was evaluated based on visual transparency, light transmittance, and droplet diameter. The experimental results yield the following guidelines that produce stable bio-based MWF microemulsions with minimum necessary concentrations of surfactants: (1) a combination of two surfactants, one nonionic and one water soluble co-surfactant (either nonionic or anionic) is preferred over a single surfactant; (2) the nonionic surfactant should have a carbon tail length greater than or equal to the nominal carbon chain length of the fatty acids in the oil as well as a head group that is not excessively small or large (e.g., 10-20 ethylene oxide groups for a polysorbitan ester, ethoxylated alcohol, or ethoxylated glyceryl ester); (3) the difference in tail lengths between the surfactant and the co-surfactant should be less than 6 to maximize the feasible range of oil to surfactant ratios yielding stable emulsions. These guidelines are consistent with general results of micelle solubilization theory and evidence is provided to suggest that common semi-synthetic MWF systems can be thought of as swollen micelle systems.     

Effect of surfactants on the survival and sorption of viruses

There is an increasing concern about the protection of groundwater from contamination by enteric viruses and the prevention of outbreaks of waterborne diseases. Knowledge of survivability and transport of viruses from their point of origin is necessary to determine their potential effects on the neighboring groundwater systems. The distribution of virus is, in turn, dependent on the physical and chemical compositions of the surrounding soil and subsurface systems. For the present study, we have determined the effects of different surfactants (cationic, anionic, nonionic, and biological) and natural organic matter (NOM) on bacteriophages. Results indicated that surfactants and NOM adversely affect phage survival in binary systems, with surfactants being the most harmful. Studies with ternary systems also showed that the presence of surfactants reduced sorption of phages on sorbents either by occupying available sorption sites on the sorbent material or by displacing the sorbed phages from the sorbent surface. Water contact angles of the selected phages and different sorbent surfaces have been measured. Experimental data demonstrated that the sorption of hydrophobic viruses was favored by hydrophobic sorbents, while the sorption of hydrophilic viruses was favored by hydrophilic sorbents.     

表面活性剂的协同作用在造纸毛毯洗涤中的应用

表面活性剂LAS、OP-10、TX-10、AEO-9等对毛毯有一定的洗涤效果。不同表面活性剂混合后会产生协同作用,其CMC值(临界胶团质量分数)和表面张力值均小于各自表面活性剂组分的CMC值和表面张力值,使毛毯的洗涤效果大大增强。研究表明:几种表面活性剂在混合后表面张力最小,协同作用最显著的是LAS与AEO-9比例为1∶4的复配溶液。     

Efficiency and usability of silicone surfactants in emulsions

The critical micelle contration (CMC) of silicone surfactants was determined to provide their optimal efficiency in emulsion systems. The lowest CMC value was found for the amphionic polysiloxane polyorganobetaine copolymer, which is undoubtedly the consequence of electrostatic repulsion preventing the aggregation of ionized molecules. Also the nonionic surfactants (polydimethyl siloxane polyethers) showed some differences: the surfactant with polyethylene oxide side chain is more effective compared to the polyethylene-polypropylene oxide side chain.
The results of miscibility testing of silicone surfactants with common components of emulsions and creams confirm that not only silicone oils, but also silicone surfactants, should be considered as both explicitly hydrophobic and non lipophilic.
The stability of emulsions containing silicone surfactants prepared by cold emulsification supported the incorporation of polyelectrolyte sodium carboxymethylcellulose, which increased viscosity of the continuous phase and prevented coalescence.
The physical stability testing of prepared emulsions confirms that the used methods - centrifugation, particle size analysis and the observation of ageing at room (20–25°C) and elevated temperature (40°C) - give comparable results.     

Sorption of perfluorinated surfactants on sediments

The sorption of anionic perfluorochemical (PFC) surfactants of varying chain lengths to sediments was investigated using natural sediments of varying iron oxide and organic carbon content. Three classes of PFC surfactants were evaluated for sorptive potential: perfluorocarboxylates, perfluorosulfonates, and perfluorooctyl sulfonamide acetic acids. PFC surfactant sorption was influenced by both sediment-specific and solution-specific parameters. Sediment organic carbon, rather than sediment iron oxide content, was the dominant sediment-parameter affecting sorption, indicating the importance of hydrophobic interactions. However, sorption also increased with increasing solution [Ca2+] and decreasing pH, suggesting that electrostatic interactions play a role. Perfluorocarbon chain length was the dominant structural feature influencing sorption, with each CF2 moiety contributing 0.50-0.60 log units to the measured distribution coefficients. The sulfonate moiety contributed an additional 0.23 log units to the measured distribution coefficient, when compared to carboxylate analogs. In addition, the perfluorooctyl sulfonamide acetic acids demonstrated substantially stronger sorption than perfluorooctane sulfonate (PFOS). These data should prove useful for modeling the environmental fate of this class of contaminants.     

Effects of nonionic surfactants on bacterial transport through porous media

Nonionic surfactants of the form CxEy, where x is the number of carbons in the alkyl chain and y is the number of ethylene oxide units in the polyoxyethylene (POE) chain, were studied for their ability to alter the transport of Sphingomonas pacilimobilis through an aquifer sand. The surfactants C12E4 (Brij 30) and C12E23 (Brij 35) were the focus of this study. Through a systematic study, it was shown that these nonionic surfactants were able to enhance the transport of this bacterial culture through porous media. The magnitude of the enhancement increased with decreasing solution ionic strength and increasing POE chain length. The mechanism of this enhanced transport appears to be due to expansion of the electric double layer about the bacteria and aquifer sand through displacement of the counterions by the sorbed surfactant. This expanded electric double layer increases the electrostatic repulsion, with a resultant reduction in the collision efficiency and an increase in the Langmuirian blocking parameter. Application of the colloid filtration theory with the experimental parameters of this study shows that nonionic surfactants have the potential to significantly enhance the bacterial travel distance, especially for low ionic strength systems.     

Selective solubilization of polycyclic aromatic hydrocarbons from multicomponent nonaqueous-phase liquids into nonionic surfactant micelles

This research investigates the equilibrium solubilization behavior of naphthalene and phenanthrene from multicomponent nonaqueous-phase liquids (NAPLs) by five different polyoxyethylene nonionic surfactants. The overall goal of the study was to achieve an improved understanding of surfactant-aided dissolution of polycyclic aromatic hydrocarbons (PAHs) from multicomponent NAPLs in the context of surfactant-enhanced remediation of contaminated sites. The extent of solubilization of the PAHs in the surfactant micelles increased linearly with the PAH mole fraction in the NAPL. The solubilization extent and micelle-water equilibrium partition coefficient of the PAHs increased with the size of the polar shell region of the micelles rather than the size of the hydrophobic core of the micelle. The presence of both PAHs in the shell region of the micelles was confirmed by 1H NMR analysis. This is an important observation because it is commonly assumed that in multi-solute systems the solutes with relatively greater hydrophobicity are solubilized only in the micellar core. A comparison of the 1H NMR spectra of pure surfactant solutions and solutions contacted with various NAPLs demonstrated that the distribution of PAHs between the shell and the core changed with the concentration of PAHs in the micelles and in the NAPL. Competitive solubilization of the PAHs was observed when both PAHs were present in the NAPL. For example, in surfactant solutions of Brij 35 and Tween 80, the solubilization of phenanthrene was decreased in the presence of naphthalene as compared to systems that contained phenanthrene as the only solute. In contrast, with micellar solutions of Tergitol NP-10 and Triton X-100, phenanthrene solubilization was enhanced in the presence of naphthalene. The activity coefficients of the PAHs in the micellar phase were generally found to increase with PAH concentrations in the micelle.     

Effect of a nonionic surfactant on biodegradation of slowly desorbing PAHs in contaminated soils

The influence of the nonionic surfactant Brij 35 on biodegradation of slowly desorbing polycyclic aromatic hydrocarbons (PAHs) was determined in contaminated soils. We employed a soil originated from a creosote-polluted site, and a manufactured gas plant soil that had been treated by bioremediation. The two soils differed in their total content in five indicator 3-, 4-, and 5-ring PAHs (2923 mg kg(-1) and 183 mg kg(-1) in the creosote-polluted and bioremediated soils, respectively) but had a similar content (140 mg kg(-1) vs 156 mg kg(-1)) of slowly desorbing PAHs. The PAHs present in the bioremediated soil were highly recalcitrant. The surfactant at a concentration above its critical micelle concentration enhanced the biodegradation of slowly desorbing PAHs in suspensions of both soils, but it was especially efficient with bioremediated soil, causing a 62% loss of the total PAH content. An inhibition of biodegradation was observed with the high-molecular-weight PAHs pyrene and benzo[a]pyrene in the untreated soil, possibly due to competition effects with other solubilized PAHs present at relatively high concentrations. We suggest that nonionic surfactants may improve bioremediation performance with soils that have previously undergone extensive bioremediation to enrich for a slowly desorbing profile.