高效沥青质沉积抑制剂的筛选评价

原油中的沥青质、胶质等重有机质会在岩石和油管表面形成有机垢,给油田生产带来诸多麻烦,而预先注入化学抑制剂来保持沥青质稳定是一种有效的防沥青质沉积方法。通过沥青质溶液吸光度的变化对聚醚多元醇、烷基苯磺酸和阳离子表活剂等沥青质沉积抑制剂进行了评价。结果表明,抑制剂加量为250mg/L时,聚醚多元醇抑制剂JHIA1～4的抑制率均在50%以下,抑制效果不理想;烷基苯磺酸抑制剂JHIA5的抑制率在60%以上,抑制效果较好;而阳离子表活剂抑制剂JHIA6和JHIA7的抑制率均在75%以上,抑制效果显著。JHIA7在加量为300mg/L时,抑制率高达90%以上,且对于不同的稠油沥青质也有很好的抑制效果,说明具有强碱性的抑制剂抑制效果优于其他类型的抑制剂,并且随抑制剂加量的增大而增大。

Comparative studies on flotation of aluminosilicate minerals with Gemini cationic surfactants BDDA and EDDA

Gemini quaternary ammonium salt surfactants, butane-a, co-bis（dimethyl dodeculammonium bromide） （BDDA） ethane-a, fl-bis（dimethyl dodeculammonium bromide） （EDDA） were adopted to comparatively study the flotation behaviors of kaolinite, pyrophyllite and illite. It was found that three silicate minerals all exhibited good floatability with Gemini cationic surfactants as collectors over a wide pH range, while BDDA showed a stronger collecting power than EDDA. FTIR spectra and zeta potential analysis indicated that the mechanism of adsorption of Gemini collector molecules on three silicate minerals surfaces was almost identical for the electronic attraction and hydrogen bonds effect. The theoretically obtained results of density functional theory （DFT） at B3LYP/6-31G （d） level demonstrated the stronger collecting power of BDDA presented in the floatation test and zeta potential measurement.

Effect of cetyltrimethylammonium bromide on morphology and porous structure of mesoporous hydroxyapatite

The mesoporous hydroxyapatite （HA） was synthesized by hydrothermal method utilizing cationic surfactant cetyltrimethylammonium bromide （CTAB） as template. The crystalline phase, morphology and porous structure were characterized respectively by different detecting techniques. The results reveal that the particles are highly crystalline hydroxyapatite phase. The surfactant has little influence on the morphology of the crystals, but affects the porous structure obviously. The sample without CTAB has a low surface area not exceeding 33 m^2/g, and no distinct pores can be observed by TEM. While the samples obtained with the surfactant get better parameters. Numerous open-ended pores centered at 2-7 nm spread unequally on the surface of the hydroxyapatite nanorods. The N2 adsorption-desorption experiments show type IV isotherms with distinct hysteresis loops, illustrating the presence of mesoporous structure. When the mole ratio of CTAB to HA is 1：2, the sample has the largest surface area of 97.1 m^2/g and pore volume of 0.466 cm^3/g.

Hydrothermal Synthesis and Formation Mechanism of Micrometer-sized MoO_2 Hollow Spheres

Micrometer-sized MoO2 hollow spheres were synthesized hydrothermally with ammonium heptamolybdate tetrahydrate as molybdenum source, Cetyltrimethylammonium bromide as structure-directing agent and C2H5OH as reducing agent, respectively. The products were investigated by X-ray diffraction, thermo gravimetry and differential thermal analysis, scanning electron microscopy, transmission electron micraseopy and X-ray photoelectron spectroscopy. A morphology transition of ＂blocks-solid spheres-hollow spheres＂ during the growth procfess was observed and the possible mechanism for the formation of MoO2 samples was proposed to be through a microscale Kirkendall effcct.

Adsorption of Metsulfuron and Bensulfuron on a Cationic Surfactant-Modified Paddy Soil

Adsorption isotherms of metsulfuron and bensulfuron on a hexadecyltrimethylammonium （HDTMA） bromide-modified paddy soil under different ionic strengths, with divalent cation Cu^2＋, or having different pH were studied to describe their adsorptive behavior, and to try to explain the adsorption process of a sulfonylurea compound with a carbamoylsulfamoyl group in the modified soil environment. All the adsorption isotherms fitted the Freundlich equation well, and the HDTMA treatment of paddy soil dramatically enhanced adsorption capacity of metsulfuron or bensulfuron. Also, an increase of ionic strength and the addition of divalent heavy metal cation Cu^2＋ on the HDTMA-modified paddy soil increased the adsorption of metsulfuron or bensulfuron. Additionally, for metsulfuron and bensulfuron in the aqueous phase, adsorption capacity of the HDTMA-modified paddy soft gradually increased with decreasing pH.

Stability and Drag Reduction in Transient Channel Flow of Fibre Suspension

Drag reduction features in the transition regime of channel flow with fibre suspension were analyzed in terms of the linear stability theory. The modified stability equation was obtained based on the slender-body theory and natural closure approximation. Results of the stability analysis show attenuating effects of fibre additives to the flow instability. For the cases leading to transition, drag reduction rate increases with the characteristic parameter H of fibres. The mechanism of drag reduction by fibres is revealed through the variation of velocity profile and the decrease of wall shear stress. The theoretical results are qualitatively consistent with some typical experiments.

Extraction of Theanine from Waste Liquid of Tea Polyphenol Production in Aqueous Two-phase Systems with Cationic and Anionic Surfactants

Extraction of theanine from waste liquid of tea polyphenol production was studied in aqueous surfactanttwo-phase system （ASTP） with cationic surfactant （CTAB） and anionic surfactant （SDS）. Results indicate that the region of ASTP is narrow and there is only a two-phase region of cationic surfactant. The increase in concentrations of NaBr and Na2SO4 are beneficial to the formation of ASTP. Theanine concentration in the bottom phase increases with increasing concentration of theanine, whereas the Partition coefficient and extraction rate only change a littlewhen the concentration of theanine is above 0.2 g.L-＇. With the increase of SDS concentration, the phase ratio and the partition coefficient decrease, while the extraction efficiency of theanine increases and the concentration of theanine changes a little in the range from 2.4/7.5 to 2.8/7.2 for SDS/CTAB ratio. The temperature has a notable ef- fect on the concentration of theanine in the bottom phase, partition coefficient and extraction rate of theanine. The increase of waste liquid decreases the phase ratio, increases the concentration and extraction rate of theanine in the bottom ohase, since the orotein and the saccharide enter the bottom nhase with theanine.

Adsorption of sulfate in aqueous solutions by organo-nano-clay:Adsorption equilibrium and kinetic studies

The adsorption of sulfate in aqueous solutions onto organo-nano-clay prepared by natural zeolite and cationic surfactant cetyltrimethylammonium bromide （CTAB） was studied.Parameters such as adsorbent dosage,contact time and temperature were investigated using batch adsorption studies.The results show that the uptake of sulfate increases with the increase of contact time and temperature,and decreases with the increase of dosage.The Freundlich isotherm model is fit to explain the sulfate adsorption onto organo-nano-clay.The maximum adsorption capacity is found to be 38.02 mg/g at 40 ℃.The kinetic data fit well the pseudo-second-order and Elovich models with a R2 more than 0.98.It is suggested that chemisorption is the rate-controlling step for adsorption of sulfate onto organo-nano-clay,meanwhile both intraparticle diffusion and boundary layer diffusion also contribute as well.Ion-exchange between sulfate anions and bromide ions and complexation between sulfate anions and CTAB cations are responsible for the mechanism of sulfate adsorption.Keywords：organo-nano-clay; cetyltrimethylammonium bromide （CTAB）; modification; sulfate; adsorption

Direct AFM measurements of morphology and interaction force at solid-liquid interfaces between DTAC/CTAC and mica

The adsorption of dedecyltrimethylammoium chloride(DTAC) and hexadecyltrimethylammoium chloride(CTAC) on muscovite mica substrates was examined using atomic force microscopy(AFM). Adsorption morphology images and interaction forces of cationic surfactants at solid-solution interfaces were measured in tapping mode and Pico Force mode, respectively. The images demonstrated that the adsorbed structure was varied by a variety of surfactant concentrations. The adsorbed layer on mica was monolayer at first, and then became bilayer. A striped adsorbed structure was observed in a higher concentration of CTAC,which could not be found in any other concentrations of DTAC. For force measurements, the repulsive force was exponentially decreasing with the concentration increasing till a net attractive force appeared. A largest attractive force could be observed at a certain concentration, which was close to the point of charge neutralization. The results also showed a significant impact of hydrocarbon chain length on adsorption. An adsorption simulation was established to give a clear understanding of the interaction between cationic surfactants and mica.

Effects of Ionic Surfactants on Bacterial Luciferase and α-Amylase

In order to study the effects of ionic surfactants on bacterial luciferase,the cationic surfactant dodecyltrimethylammonium biomide (DTAB) and anionic surfactant sodium dodecylsulfate (SDS) were chosen.For comparison with bacterial luciferase,α-amylase was used since these two enzymes have similar electrostatic potential and charged active sites.After the enzymes were treated with the surfactants,the catalytic properties of bacterial luciferase andα-amylase were assayed,and fluorescence spectroscopy and circular dichroism (CD) were used to analyze the alteration of the protein structure.The results showed that when the DTAB concentration was low,the cationic surfactant DTAB enhanced the enzymatic activities of bacterial luciferase andα-amylase.On the other hand,the anionic surfactant SDS did not alter the enzymatic activity.The main interaction of cationic surfactant DTAB and the negatively charged surface of the proteins was the ionic interaction,which could alter the environment for the enzyme to work when the DTAB/enzyme molar ratio was low.However,at high cationic surfactant concentration,the ionic interaction and hydrophobic interaction might destroy the secondary and tertiary structures of the proteins,leading to the loss of enzymatic activities.

Orientation and Structure of Ionic Liquid Cation at Air/[bmim][BF4] Aqueous Solution Interface

The watermiscible room temperature ionic liquid 1butyl3methylimidazolium tetrafluorob orate （[bmim] [BF4]） is a model system for studying the interactions between ionic liquid and water molecules. In this work the orientational structure of the low concentrated aqueous solution of [bmim] [BF4] at the air/liquid interface was investigated by sum frequency gener ation vibrational spectroscopy. It has been found that at very low concentrations, the butyl chain exhibited a significant gauche defect, indicating a disordered conformation; and the cation ring oriented with a fairly small tilting angle at the surface. When the concentration increased, the cation ring tended to lie flat at the surface, and the gauche defects of the butyl chain decreased due to the intermolecular chainchain interactions and the consequent more ordered interfacial molecular arrangement. Additionally, the antisymmetric stretching mode in the PPP and SPS spectra exhibited a peak shift, showing that there exists more than one kind of orientation or chemical environment for the butyl CH3 group. These results may shed new light on understanding the surface behavior of watermiscible ionic liquids as well as the imidazolium based surfactants.

Interaction of DNA with Cationic Gemini Surfactant Trimethylene-1, 3-bis （dodecyldimethyl-ammonium bromide） and Anionic Surfactant SDS Mixed System

The interaction of DNA with cationic gemini suffactant trimethylene-1,3-bis （dodecyl dimethyl-ammonium bromide） （12-3-12） and anionic surfactant sodium dodecyl sulfate （SDS） mixed system has been investigated by measuring the fluorescence, zeta potential, UV-Vis spectrum, and circular dichroism. In the absence of SDS, owing to the electrostatic and hydrophobic interactions, 12-3-12 forms micelle-like structure on the DNA chain before the micellization in bulk phase. For the mixed system of 12-3-12 and SDS, the negative charges on SDS can compete against DNA to bind with cationic 12-3-12 because of the stronger interaction between oppositely charged surfactants, and thus, the catanionic mixed micelles are formed before the formation of DNA/12-3-12 complexes. There-after, the positive charges on the mixed micelles bind with DNA, and thus, the change of the zeta potential from negative to positive is distinctly different from the system without SDS. Meanwhile, the existence of SDS postpones the exclusion of ethidium bromide （EB） from DNA/EB complexes. The conformation of DNA undergoes a change from native B-form to chiral ψ-phase as binding with 12-3-12 process. Upon adding SDS to the DNA/12-3-12 complex solution, however, DNA is released to the bulk and the ψ-phase returns to B-form again.

Phase Separation and Microstructure of Mixed Surfactants Solution Containing Cationic Geminis and Traditional Anionic Surfactant

The properties of aqueous two-phase system (ATPS) of mixed solution containing gemini cationic surfactant trimethylene-1,3-bis(dodecyldimethyl ammonium) bromide (12-3-12, 2Br-) and traditional anionic surfactant sodium dodecyl sulfate (SDS) with or without added salt have been studied. An ATPS is formed in a narrow region of the ternary phase diagram different from that of traditional aqueous cationic-anionic surfactant systems. In ATPS region, the lowest total concentration of surfactants varies with the mixing ratio of geminis to SDS. Photographs obtained from freeze-etching, negative-staining and transmission electron microscopy show that the microstructures of two phases are different from each other. Micelles and vesicles can coexist in a single phase. The addition of salts can change the phase diagram of ATPS. Furthermore, the added salts promote the aggregation of rod-like micelles to form coarse network structure that increase the viscosity of solutions. The negative ions of the added salts are the determining factor.

Effect of different surfactants on removal efficiency of heavy metals in sewage sludge treated by a novel method combining bio-acidification with Fenton oxidation

The aim of this work was to investigate the effect of different surfactants on the removal efficiency of heavy metals in sewage sludge treated by a method combining bio-acidification with Fenton oxidation. Four surfactants were adopted such as anionic surfactant(sodium dodecyl benzene sulfonate, SDBS), nonionic surfactants(tween-20 and tween-60) and cationic surfactant(hexadecyl trimethyl ammonium chloride, HTAC), respectively. The indigenous sulfur-oxidizing bacteria in bio-acidification phase were enriched and cultured from fresh activated sludge obtained from a wastewater treatment plant. It is shown that different surfactants exhibited distinct effect on the removal efficiency of heavy metals from sewage sludge. The nonionic surfactants,especially tween-60, promotes the solubilization of heavy metals, while the anionic and cationic surfactants hinder the removal of heavy metals. Copper is efficiently leached. The removal efficiency of cadium is relatively lower than that of Cu due to the demand for rigorous p H value. Lead is leached with a low efficiency as the formation of low soluble Pb SO4 precipitates.

Photorheologically reversible micelle composed of polymerizable cationic surfactant and 4-phenylazo benzoic acid

A photorheologically reversible micelle composed of polymerizable cationic surfactant n-cetyl dimethylallyl am- monium chloride （CDAAC） and trans-4-phenylazo benzoic acid （trans-ACA） was prepared. The effects of molar ratio of CDAAC/trans-ACA, time of UV and visible light irradiation and temperature on the rheological properties of micellar system were investigated. The results show that before UV irradiation the system with an optimum CDAAC/trans-ACA molar ratio of 1.4 forms viscoelastic micelles at 45 ℃. After 365 nm UV irradiation, the viscos- ities of micelle systems with different concentrations at fixed molar ratio of 1.4 are decreased by 85%-95%. The CDAAC/trans-ACA （14 mmol. L- 1/10 mmol. L- 1 ） micelle system exhibits shear thinning property and its viscos- ity is decreased obviously with the increases of UV irradiation time less than I h. The rheological process during LIV irradiation for CDAAC/trans-ACA （14 mmol- L- 1/10 mmol. L 1） micelle proves that viscosity, elastic modulus G＇ and viscous modulus G＂ will reduce quickly with the UV light. Furthermore, the micelle system after 1 h UV- irradiation is able to revert to its initial high viscosity with 460 nm visible light irradiation for 4 h, and the micelle can be cycled between low and high viscosity states by repetitive UV and visible light irradiations. The LIV-Vis spectra of CDAAC/trans-ACA micelle indicate that its photosensitive theological properties are related closely to photoisomerization of trans-ACA to c/s-ACA.

Biphasic Catalytic Hydroformylation of 1-Dodecene in Micellar System with Cationic Gemini Surfactants

The promotion effect of cationic gemini surfactants for the hydroformylation of 1-dodecene in the organic/aqueous biphasic catalytic system is reported. The hydroformylation reaction in the presence of gemini surfactant occurred with higher turnover frequency and higher selectivity for linear aldehyde than using conventional monomeric surfactant CTAB.

Metal cation exchanged silica gel for identification of cationic and nonionic surfactants with preliminary separation by thin layer chromatography

Silica gel impregnated with 1% aqueous solutions of different metal cations （Li^＋, Mg^2＋, Zn^2＋, Cu^2＋, Co^2＋, Ni^2＋, Ba^2＋and Th^4＋） has been used for the analysis of nonionic and cationic surfaetants using simple aqueous acetone as mobile phase system. Co^2＋ was found the most suitable impregnant for the mutual separation of nonionic surfactants （Brij-35 and Brij-57） and cationic from nonionic surfactants （tetmdecyltrimethylammonium bromide and Cween-20）. Zinc sulphate impregnation （Zn^2＋-silica gel） shows identical chromatographic behavior and these layers are useful to separate nonionic surfactant （Brij-35） from cationic surfaetant （cetylpyridinium chloride）. The mutual separation of B J-35 and B J-57 is not influenced by the presence of optical brightener in the sample.

Spectrophotometric Investigation of Complex Formation of Ge（IV） with Bis（2,3,4-Trigidroksifenilazo） Benzidine in the Presence of Cationic Surfactants Active Substances

It is investigated the interaction of Ge（IV） with bis（2,3,4-trigodroksifenolazo） benzidine （R） in the presence of KSAS （cationic surface active substances）-CPCl （cetylpyridinium chloride）, CPBr （cetylpyridinium bromide） and CTMABr （cetyltrimethylammonium bromide）. It is studied the effect pH, time on the formation of ternary complexes. It is determinated of molar absorption coefficients and stability constants of germanium. Binary （Ge-R） and triple （Ge-R-CPCI, Ge-R-CPBr, Ge-R-CTMaBr） complex form at pH 4 and pH 1, respectively. The composition proportion of binar system is 1：2 and the composition proportion triple complex is 1：1：2. The concentration interval of germanium which obeying beer low in the Ge-R 0.12-2.92 mkq/mL, in the Ge-R-CPCI is 0.04-1.46 mkq/mL, in the Ge-R-CPBr is 0.00-1.00 mkq/mL and in the Ge-R-CTMaBr is 0.00-1.00 mkq/mL. Molar absorbtivities of complexes are 45,000, 57,000, 59,000 and 60,000, respectively. The effect of interfering ions and masking agents has been learned. Stability constants of complexes have been determined： lgKl = 7.21 ＋ 0.06 （Ge-R）,＇ lgK1 = 12.08 _＋ 0.05 （Ge-R-CPCI）, lgK1 = 12.12 ＋ 0.07 （Ge-R-CPBr） and lgK1 = 12.85 ＋ 0.06 （Ge-R-CTMaBr）. It is developed highly selective method of photometric determination of trace amounts of Ge（IV） in petroleum coke.

Drag-reduction of a nonionic surfactant aqueous solution and its rheological characteristics

In order to develop turbulent drag-reducing technology by using an environmentally friendly additive in a water-transporting system,the drag reducing characteristics in a non-ionic surfactant(Oleyldimethylamineoxide,ODMAO) dilute aqueous solution flowing in a circular pipe of 5 mm diameter have been experimentally investigated with an air-driven fluid resistance test device.The rheological characteristics of the solution have also been examined by a rheometer with a cone-plate flow cell.The results show that the ODMAO solutions are drag-reducing when concentration is 400 ppm or higher,that the critical Reynolds number corresponding to the maximum drag reduction rate increases with both concentration and temperature,and that the maximum drag reduction rate can reach up to 70% in the straight pipe.At low shear rates,the shear viscosity of ODMAO solutions with a relatively high drag-reduction behaves similarly to Newtonian fluids;at above a certain critical shear rate,it is firstly shear-thickening,then shear-thinning.Such shear-rate-dependent characteristics of the shear viscosity are attributed to the different transitions of micellar network structure induced by different shear rates.Relaxation of shear stress after removing an applied constant shear rate at which the solution is in the SIS(shear-induced structure) state is found to be well expressed by a 2-step Maxwell model with a tail relaxation time much shorter than that for a drag-reducing cationic surfactant,which indicates that for the ODMAO solution,a viscoelasticity as strong as a drag-reducing cationic surfactant is not needed to realize turbulent drag-reduction.

Supramolecular vesicles of cationic gemini surfactants modulated by p-sulfonatocalix[4]arene

Supramolecular binary vesicles were constructed by host-guest complex formation between p-sulfonatocalix[4]arene and three cationic gemini surfactants, which were identified by UV-vis, dynamic laser scattering, transmission electron microscopy, scanning electron microscopy, atomic force microscopy, and surface tension experiments. The critical aggregation concentration of gemini surfactants decreased pronouncedly by a factor of ca. 1000 owing to the complexation of p-sulfonato-calix[4]arene.