Tetraiodophenolsulfonphthalein as a spectral substitute to characterize the complexation between cationic and anionic surfactant

The complexation of cetyltrimethylammonium bromide (CTAB) with sodium dodecyl sulfate (SDS) with sodium dodecyl benzene sulfonate (SDBS), with tetraiodophenolsulfonphthalein (TIPST) as a spectral substitute was investigated at pH 5.89 and 8.30 by the microsurface adsorption--spectral correction (MSASC) technique. The aggregations of TIPST, SDS, and SDBS on CTAB obeyed the Langmuir isothermal adsorption. The aggregates TIPST-CTAB, TIPST2-CTAB3, SDS3-CTAB2, and SDBS3-CTAB2 were formed at 20 degrees C and the binding constants of all the aggregates were determined. The replacement of TIPST-binding CTAB monomer with SDS or SDBS at pH 5.89 was applied to the quantitative determination of anionic detergent (AD) in water with satisfactory recovery.     

锌电极有机复配缓蚀剂的性能研究

应用极化曲线、表面张力、放电实验和SEM等测试方法,研究了阴离子表面活性剂十二烷基苯磺酸钠(简称SDBS)和非离子表面活性剂吐温-20(简称Tween)之复配体系(简称ST)在碱性介质中对锌电极电化学性能的影响及其作用机理.实验表明,复配缓蚀剂ST具有比单一添加SDBS或Tween更高的缓蚀效率,并且二者具有明显的协同作用,Tween在复配体系中的作用是使活性物质于锌电极表面的临界胶团浓度显著降低,吸附分布更加均匀.从而可更有效的抑制锌电极腐蚀,改善锌电极的表观形貌,达到延迟钝化的效果,使活性物质利用率得到显著提高.     

Adsorption of sodium dodecylbenzenesulfonate on activated carbons: effects of solution chemistry and presence of bacteria

The objective of the present investigation was to determine the effectiveness of activated carbon in removing sodium dodecylbenzenesulfonate (SDBS) and to analyze the chemical and textural characteristics of the activated carbons that are involved in the adsorption process. Studies were also performed on the influence of operational variables (pH, ionic strength, and presence of microorganisms) and on the kinetics and interactions involved in the adsorption of this pollutant on activated carbon. The kinetics study of SDBS adsorption revealed no problems in its diffusion on any of the activated carbons studied, and Weisz-Prater coefficient (C WP) values were considerably lower than unity for all activated carbons studied. SDBS adsorption isotherms on these activated carbons showed that: (i) adsorption capacity of activated carbons was very high (260-470 mg/g) and increased with larger surface area; and (ii) dispersive interactions between SDBS and carbon surface were largely responsible for the adsorption of this pollutant. SDBS adsorption was not significantly affected by the solution pH, indicating that electrostatic adsorbent-adsorbate interactions do not play an important role in this process. The presence of electrolytes (NaCl) in the medium favors SDBS adsorption, accelerating the process and increasing adsorption capacity. Under the working conditions used, SDBS is not degraded by bacteria; however, the presence of bacteria during the process accelerates and increases SDBS adsorption on the activated carbon. Microorganism adsorption on the activated carbon surface increases its hydrophobicity, explaining the results observed.     

十二烷基苯磺酸钠在AZ31镁合金表面的吸附及其缓蚀作用

采用电化学阻抗谱(EIS)和极化曲线研究十二烷基苯磺酸钠(SDBS)对AZ31镁合金在3.5%(w, 质量分数)NaCl腐蚀介质中的吸附行为及缓蚀作用. 结果表明: SDBS可有效抑制AZ31镁合金在NaCl介质中的腐蚀, 其浓度为0.008 mol·L-1时缓蚀效率可达90%以上; 升高温度并不利于提高SDBS的缓蚀效率. SDBS在AZ31镁合金表面主要发生物理吸附, 吸附过程为放热、熵增的自发过程, 近似符合Langmuir单分子层吸附模型; SDBS为混合抑制型缓蚀剂, 但主要抑制阳极反应.     

探针体耐尔蓝(NB)与DNA结合反应研究

应用微相吸附-光谱修正(MPASC)新技术研究DNA与耐尔蓝(NB)探针分子间的相互作用,分析生物大分子内静电场的形成与Langmuir吸附的关联性,测定了结合产物结合比、平衡常数等.通过在pH=10.38介质中对DNA-NB反应的光谱分析,结果表明产物结合比NB∶ DNA-P=3∶ 1、平衡常数K=3.33×105,摩尔吸收系数ε660 nm=4.81×103 L/mol cm.样品分析表明DNA回收率95.6%～108%,相对标准偏差RSD=2.8%.     

Polychlorinated Biphenyls-contaminated Soil Washing with Mixed Surfactants Enhanced by Electrokinetics

On the basis of comparing the adsorption loss of different surfactants[single nonionic surfactant sorbitanmonooleatepolyoxyethylene ether(Tween 80), anionic surfactant sodium dodecyl benzene sulfonate(SDBS), and mixed surfactants Tween 80/SDBS(3:2), Tween 80/SDBS(4:1)] and their performance in the enhancement of polychlorinated biphenyls(PCBs) desorption from soil, the impact of electric field intensity on the desorption of PCBs and the transport of surfactants in washing resulted solution were investigated in this study. With regard to the remediation cost, 1000 mg/L mixed Tween 80/SDBS(3:2) was recognized as an optimum concentration in the remediation of PCBs-contaminated soil, because Tween 80/SDBS(3:2) had the highest washing capacity and relatively low adsorption loss onto soil. Electrokinetics can enhance the washing efficiency of PCBs-contaminated soil by Tween 80/SDBS(3:2) effectively and safely at an electric field intensity of 1.5 V/cm for 10 d, for the desorption of PCBs was 1.57 times more than that without electrokinetics, and the most of organic residue in washing resulted solution was removed in an electrical field to avoid the possible secondary contamination risk.     

Entropic nature of the adsorption of sodium dodecylbenzenesulfonate on nanoparticles of aluminum and iron oxides in aqueous medium

The adsorption of anionic surfactant sodium dodecylbenzenesulfonate (SDBS) from aqueous solution on the hydrophilic surfaces of aluminum oxide and iron oxide nanoparticles is studied via UV spectrophotometry, electrophoretic light scattering, and isothermal microcalorimetry. It is shown that the isotherms of the adsorption of SDBS on the surfaces of both oxides in the area of concentrations up to 0.6 mmol/L is linear. It is found that the positive zeta potential of the surfaces of the particles falls to zero and shifts toward the range of negative values due to adsorption. The adsorption of SDBS is characterized by positive enthalpy values over the investigated range of concentrations, while the loss of energy during adsorption indicates it is of an entropic nature. It is concluded that the probable cause of the increase in entropy is the dehydration of SDBS molecules during on surface adsorption. The obtained results are discussed in terms of the formation of hemimicelles of surfactant on the hydrophilic surfaces of metal oxide nanoparticles in an aqueous medium.     

Mixed adsorption of poly(vinylpyrrolidone) and sodium dodecylbenzenesulfonate on kaolinite

The mixed adsorption of the nonionic polymer poly(vinylpyrrolidone) (PVP) and the anionic surfactant sodium dodecylbenzenesulfonate (SDBS) on kaolinite has been studied. Both components adsorb from their mixture onto the clay mineral. The overall adsorption process is sensitive to the pH, the electrolyte concentration, and the amounts of polymer and surfactant. Interpretation of the experimental data addresses also the patchwise heterogeneous nature of the clay surface. In the absence of PVP, SDBS adsorbs on kaolinite by electrostatic and hydrophobic interactions. However, when PVP is present, surfactant adsorption at 10(-2) M NaCl is mainly driven by charge compensation of the edges. The adsorption of PVP from the mixture shows similar behavior under different conditions. Three regions can be distinguished based on the changing charge of polymer-surfactant complexes in solutions with increasing SDBS concentration. At low surfactant content, PVP adsorbs by hydrogen bonding and hydrophobic interactions, whereas electrostatic interactions dominate at higher surfactant concentrations. Over the entire surfactant concentration range, polymer-surfactant aggregates are present at the edges. The composition of these surface complexes differs from that in solution and is controlled by the surface charge.     

Adsorption of SDBS and Its Effect on Rheology of Preformed Particle Gels

The adsorption of anionic surfactant sodium dodecylbenzenesulfonate (SDBS) onto preformed particle gels (PPGs) and the effect of SDBS on the swelling ratio and rheology of PPGs were investigated. SDBS molecules can adsorb onto PPGs because of the hydrophobic association with the chain of PPGs at low concentration and the association of the SDBS micelles with the chains of PPGs at high concentration. PPGs contract and the shear stress of PPGs decreases after adsorption of SDBS. In addition, the storage modulus decreases first and then increases with increasing SDBS concentration.     

BSA和SDBS在水溶液与空气界面的相互作用

表面活性剂与蛋白质在界面处的相互作用在许多应用里都会遇到．如去污、药品或生物制剂的制备和提纯、某些开科手术等等[1]这常常涉及到表面活性剂与蛋白质在界面的吸附，蛋白质大分子在界面吸附层的取向和构象．对于这两种物质在界面处可能发生的相互作用的性质，是表面活性剂     

Chitosan-based aerogels with high adsorption performance

New natural polymer-based aerogels, cross-linked chitosan aerogels, were prepared by the sol-gel route with glutaradehyde, glyoxal, and formaldehyde as cross-linkers. The alcogels were dried by supercritical carbon dioxide (CO2) fluid extraction. The resulting materials were characterized using scanning electron microscopy (SEM), nitrogen adsorption/desorption analysis, and Fourier transform infrared (FT-IR) spectroscopy. Furthermore, the adsorption of the anionic surfactant sodium dodecylbenzene-sulfonate (SDBS) from aqueous solution by the materials was investigated. The aerogels exhibit high adsorption capability, can remove SDBS from acidic aqueous solutions, and have potential applications in controlling SDBS pollution.     

Determination of bovine serum albumin using resonance light scattering technique with sodium dodecylbenzene sulphonate-cetyltrimethylammonium bromide probe

In this paper, the anionic surfactant sodium dodecylbenzene sulphonate (SDBS) and cationic surfactant cetyltrimethylammonium bromide (CTMAB) were used as resonance light scattering (RLS) probe to determine bovine serum albumin (BSA). Based on the weak RLS intensity of SDBS-CTMAB probe and the enhancement of RLS intensity of BSA in the presence of the probe, a simple assay for BSA was developed. The experimental results showed that the formation of three component complex BSA-SDBS-CTMAB is the main reason for the enhancement of RLS intensity of BSA, in which SDBS as a bridge can interact with both BSA and CTMAB. The effects of pH value, incubation time, concentrations of SDBS and CTMAB on the enhanced RLS intensity of BSA were investigated. Under the optimum conditions, the enhanced RLS intensity is proportional to the concentration of BSA in the range from 2.5 x 10(-8) to 2.0 x 10(-6)mol L(-1). The detection limit is 9.7 x 10(-9) mol L(-1) for BSA. The study of foreign substance effect on the determination of BSA indicated that most of metal ions have little effect on the determination of BSA. The results of assay for BSA in synthetic samples were satisfactory.     

Sulfate-selective PVC membrane electrode based on a strontium Schiff's base complex

A strontium Schiff's base complex (SS) can be used as a suitable ionophore to prepare a sulfate-selective PVC-based membrane electrode. The use of oleic acid (OA) and hexadecyltrimethylammonium bromide (HTAB), as additives, and nitrobenzen (NB), dibutyl phthalate (DBP) and benzyl acetate (BA) as solvent mediators, were investigated. The best performance was observed with a membrane composition PVC: NB: SS: HTAB of 30%: 62%: 5%: 3% ratio. The resulting sensor works well over a wide concentration range (1.0 x 10(-2)-1.0 x 10(-6) M) with a Nernstian slope of -29.2 mV per decade of sulfate activity over a pH range 4.0-7.0. The limit of detection of the electrode is 5 x 10(-7) M. The proposed sensor shows excellent discriminating ability toward SO4(2-) ions with regard to many anions. It has a fast response time of about 15 s. The membrane electrode was used to the determination of zinc in zinc sulfate tablets. The sensor was also used as an indicator electrode in the potentiometric titration of SO4(2-) against barium ion.     

Adsorption of methylene blue and orange II onto unmodified and surfactant-modified zeolite

Adsorption of cationic methylene blue and anionic orange II onto unmodified and surfactant-modified zeolites was studied using a batch equilibration method. The effects of equilibrium time, solution pH, and sorption temperature were examined. The results suggested that 2% sodium dodecyl benzenesulfonate (SDBS)- and 3% sodium dodecyl sulfate (SDS)-modified zeolites had higher adsorption capacities for methylene blue than the unmodified zeolite, while 2% cetylpyridinium bromide hexadecyl (CPB)- and 2% hexadecylammonium bromide (HDTMA)-modified zeolites were the best adsorbents for orange II. The adsorption conditions were optimized, and the mechanisms of adsorption are briefly discussed.     

The surface and solution properties of dihexadecyl dimethylammonium bromide

The surface adsorption behavior and solution aggregate microstructure of the dichain cationic surfactant dihexadecyl dimethylammonium bromide (DHDAB) have been studied using small angle neutron scattering (SANS), light scattering, neutron reflectivity (NR), and surface tension (ST). Using a combination of surface tension and neutron reflectivity, the DHDAB equilibrium surface excess at saturation adsorption has been measured as 2.60 +/- 0.05 x 10 (-10) mol.cm (-2). The values obtained by both methods are in good agreement and are consistent with the values reported for other dialkyl chain surfactants. The critical aggregation concentration (CAC) values obtained from both methods (NR and ST) are also in good agreement, with a mean value for the CAC of 4 +/- 2 x 10 (-5) M. The surface equilibrium is relatively slow, and this is attributed to monomer depletion in the near surface region, as a consequence of the long monomer residence times in the surfactant aggregates. The solution aggregate morphology has been determined using a combination of SANS, dynamic light scattering (DLS), cryogenic transmission electron microscopy (CryoTEM), and ultrasmall angle neutron scattering (USANS). Within the concentration range 1.5-80 mM, the aggregates are in the form of bilamellar vesicles with a lamellar " d-spacing" of the order of 900 A. The vesicles are relatively polydisperse with a particle size in the range 2000-4000 A. Above 80 mM, the bilamellar vesicles coexist with an additional L beta lamellar phase.     

Highly efficient capture and long-term encapsulation of dye by catanionic surfactant vesicles

Vesicles formed from the cationic surfactant, cetyltrimethylammonium tosylate (CTAT) and the anionic surfactant, sodium dodecylbenzenesulfonate (SDBS), were used to sequester the anionic dye carboxyfluorescein. Carboxyfluorescein was efficiently sequestered in CTAT-rich vesicles via two mechanisms: encapsulation in the inner water pool and electrostatic adsorption to the charged bilayer. The apparent encapsulation efficiency (22%) includes both encapsulated and adsorbed fractions. Entrapment of carboxyfluorescein by SDBS-rich vesicles was not observed. Results show the permeability of the catanionic membrane is an order of magnitude lower than that of phosphatidylcholine vesicles and the loading capacity is more than 10 times greater.     

Study of the spectrophotometric analysis of protein solution with p-iodochlorophosphonazo as adsorbate by the microphase adsorption-spectral correction technique

A microphase adsorption-spectral correction (MPASC) technique was established, which consists of Langmuir adsorption and the spectral correction technique. The hypothesis of a microelectric field formed in macromolecules is proposed, the existence of which results in the adsorption and aggregation of dye molecules in macromolecules. This paper describes the spectrophotometric analysis of protein solution with p-iodochlorophosphonazo (p-ICPA) dye. The results showed that the adsorption ratios of p-ICPA to proteins (bovine serum albumin, ovalbumin, myoglobin and gamma-globulin) at pH 2.56 were 54, 25, 14 and 90, respectively, their adsorption constants 2.86 x 10(5), 1.42 x 10(6), 2.38 x 10(5) and 1.09 x 10(5) and their absorptivities 8.00 x 10(5), 4.02 x 10(5), 1.77 x 10(5) and 1.15 x 10(6) l mol-1 cm-1 at 620 nm. The analysis of practical samples showed that the recovery of protein was between 92.3 and 108% and the relative standard deviation was 4.7%.     

Effect of SDBS on interfacial electron transfer at the liquid/liquid interface by thin layer method

The effect of an adsorbed anionic surfactant sodium dodecyl benzene sulfonate(SDBS) on electron transfer(ET) reaction between ferricyanide aqueous solution and decamethylferrocene(DMFc) located on the adjacent organic phase was investigated for the first time by thin layer method.The adsorption of SDBS at the interface resulted in a decay in the cathodic plateau current of bimolecular reaction with increasing concentrations of SDBS in aqueous phase.However,the rate constant of electron transfer(k_(et)) i...     

Adsorption Behavior and Mechanisms of Surfactants by Farmland Soils in Northeast China

The adsorption of two nonionic surfactants polyethylene glycol tert-octylphenyl ether Triton X-100 (TX-100), polyoxyethylene lauryl ether(Brij35) and an anionic surfactant sodium dodecyl benzene sulfonate(SDBS) by two soils(S1, S2) of different natures and their respective organic-matter-extracted samples(S3, S4) were investigated. These adsorption isotherms show different adsorption stages of different types of surfactants by soils. The data fitted Langmuir equation very well. The adsorption maximum capaci...     

Temperature-swing solid-phase extraction of heavy metals on a poly(N-isopropylacrylamide) hydrogel

The feasibility of temperature-swing adsorption of heavy metals on a thermosensitive N-isopropylacrylamide (NIPA) hydrogel was examined. We have proposed a novel temperature-swing solid-phase extraction (TS-SPE) technique. First, a metal ion in an aqueous solution is complexed with an extractant. Subsequently, the metal-extractant complexes (or micelles) are adsorbed onto the NIPA hydrogel through a hydrophobic interaction above the lower critical solution temperature (LCST). Finally, the metal-extractant complexes are desorbed from the NIPA hydrogel after it is cooled below the LCST. In a model system consisting of Cu(II) ions, sodium n-dodecylbenzenesulfonate (SDBS), and NIPA hydrogel, the proposed TS-SPE technique has been successfully conducted. The following observations can be made: the amount of adsorbed Cu(II) ions increases with the increase in temperature, the maximum adsorption is attained at a temperature above the LCST, and the hydrogel adsorbs and desorbs Cu(II) ions reversibly due to the temperature-swing between 10 and 40 degrees C. The LCSTs of poly(NIPA) in aqueous SDBS solutions with/without CuCl2 and the surface tensions of their solutions suggest that the hydrophobicity of the complex Cu(DBS)2 is greater than the hydrophobicities of SDBS and DBS. In addition to the separation of heavy metals, TS-SPE is potentially applicable to cases such as the separation of biological molecules by means of metal-ion affinity.