Experimental investigation of the effects of oil asphaltene content on CO_(2) foam stability in the presence of nanoparticles and sodium dodecyl sulfate

Foam stability tests were performed using sodium dodecyl sulfate(SDS)surfactant and SiO2 nanoparticles as foaming system at different asphaltene concentrations,and the half-life of CO_(2) foam was measured.The mechanism of foam stability reduction in the presence of asphaltene was analyzed by scanning electron microscope(SEM),UV adsorption spectrophotometric concentration measurement and Zeta potential measurement.When the mass ratio of synthetic oil to foam-formation suspension was 1:9 and the asphaltene mass fraction increased from 0 to 15%,the half-life of SDS-stabilized foams decreased from 751 s to 239 s,and the half-life of SDS/silica-stabilized foams decreased from 912 s to 298 s.When the mass ratio of synthetic oil to foam-formation suspension was 2:8 and the asphaltene mass fraction increased from 0 to 15%,the half-life of SDS-stabilized foams decreased from 526 s to 171 s,and the half-life of SDS/silica-stabilized foams decreased from 660 s to 205 s.In addition,due to asphaltene-SDS/silica interaction in the aqueous phase,the absolute value of Zeta potential decreases,and the surface charges of particles reduce,leading to the reduction of repulsive forces between two interfaces of thin liquid film,which in turn,damages the foam stability.

Sodium dodecyl sulfate (SDS) as an effective corrosion inhibitor for Mg-8Li-3Al alloy in aqueous NaCl: A combined experimental and theoretical investigation

The corrosion inhibition behavior of Mg-8Li-3Al alloy in NaCl solution with sodium dodecyl sulfate(SDS)was investigated by hydrogen analysis,scanning electron microscopy(SEM),electrochemical test,scanning Kelvin probe force microscopy(SKPFM)and computational methods.Results showed that the corrosion resistance of Mg-8Li-3Al alloy in NaCl solution was effectively improved with SDS.The SEM and SKPFM results confirmed a dense,200 nm-thick SDS-adsorbed layer had formed on the alloy surface.The separation energy ΔE_(gap) and adsorption energy E_(ads) of SDS on the Mg surface were calculated by density functional theory and molecular dynamics simulations,respectively.And the corrosion inhibition mechanism was hypothesized and described.

Determination of Trace Amounts of Zinc, Iron and Copper by Flame Atomic Absorption after Their Preconcentration Using Sodium Dodecyl Sulfate (SDS) Coated Alumina Nanoparticles Modified with 3-Mercapto-D-Valin from Environmental Samples

A sensitive and simple solid phase extraction method for the simultaneous determination of trace and toxic metals in environmental samples has been reported. The method is based on the adsorption of Zinc, Iron and Copper on SDS-coated alumina nanoparticles, which is also modified with 3-mercapto-D-valine. The retained analyte ions on modified solid phase were eluted using 5 mL of 4 mol·L﹣1 HNO3. The analyte determination was carried out by flame atomic absorption spectrometry. The influences of some metal ion and anions on the recoveries of understudy analyte ion were investigated. The influences of the analytical parameters including pH, ligand and SDS amount, eluting solution (type and concentrations) and sample volume on metal ions recoveries were investigated. The extraction efficiency was > 98% with relative standard deviation lower than 3% the method has been successfully applied for the extraction and determination of these ions content in some real samples. Prepared adsorbent was characterized by SEM and FT-IR measurements.

Adsorption of Cr(III) from an Aqueous Solution by Chitosan Beads Modified with Sodium Dodecyl Sulfate (SDS)

This study is to prepare chitosan beads modified with sodium dodecyl sulfate (SDS) to effectively remove Cr(III) from an aqueous solution. The characterizations of SDS-chitosan by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), Fourier transform-infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) proved the successful synthesis of the adsorbent. The adsorption of Cr(III) on the SDS material was investigated by varying experimental conditions such as pH, contact time and adsorbent dosage. The maximum adsorption capacity of SDS-chitosan for Cr(III) was estimated to be 3.42 mg?g-1. The results of adsorption kinetics and isothermal models show that the adsorption process conforms to the pseudo-second-order and Langmuir isotherm models, indicating that the adsorption is single-layer chemical adsorption. Thermodynamic analyses indicate that the adsorption of Cr(III) is an endothermic reaction. These results show that the new adsorbent has obvious application prospect to eliminate Cr(III).

Curing of the Bacillus subtilis Plasmid Using Sodium Dodecyl Sulfate

Curing of Bacillus subtilis plasmid using sodium dodecyl sulfate (SDS)was studied in order to obtain a host strain. An overnight culture of Bacillus subtilis 24/pMX45 was used to inoculate fresh LB containing SDS (0-0.008%). No growth of 24/pMX45 was observed when LB contained an SDS concentration of 0.006% or greater, and the sublethal concentration (w/v) of SDS was 0.005% with a killing rate of 99%. Samples were diluted and plated on LB agar, individual colonies were randomly picked to a selective agar medium by tooth to screen for loss of plasmid-encoded erythomycin resistance. CsCl-EtBr gradient centrifugation and plasmid DNA profile demonstrated that plasmid-cured derivative A7 has completely lost its plasmid. A7 had a shorter lag, and its cell concentration was consistently higher than that of the 24/pMX45. Elimination of the plasmid was first observed after 24/pMX45 had been treated with SDS for 8 h. The percent elimination then continued to increase until about 22 h, after which the fraction of cured cell in the population remained constant. Plasmid cured cell numbers were measured in a separate control culture of 24/pMX45 untreated by SDS. No spontaneous loss of pMX45 was observed after 24/pMX45 were incubated for 24 h and 48 h with shaking at 37 ℃.These results suggested that SDS can be used as curing agent to eliminate the plasmid of Bacillus subtilis.

基于SDS临界胶束浓度调控BiOBr合成及其光催化降解头孢拉定研究

以十二烷基硫酸钠(sodium dodecyl sulfate,SDS)为模板剂,采用沉淀法制备了不同胶束浓度条件下的BiOBr光催化剂(SBr-1、SBr-2、SBr-3、SBr-4).通过XRD、SEM、BET表征BiOBr晶体结构、形貌和比表面积,结果表明在SDS为临界胶束浓度(8.0×10^(-3)mol/L)时制备的SBr-2具有较好的结晶度、特殊的形貌和最大的比表面积;运用UV-vis DRS吸收光谱、PL光谱、EIS电化学抗阻谱等表征BiOBr光电特性,结果证明SBr-2具有良好的可见光吸收能力和电子空穴分离效率.在可见光照射(λ≥420 nm)下,选用头孢拉定(cefradine,CFD)为目标污染物研究光催化活性,结果表明SBr-2具有最好的光催化活性,150 min内降解率达到98%.此外,通过自由基捕获试验,发现该光催化过程超氧自由基和空穴为主要活性物种.本研究为表面活性剂调控改善BiOBr结构、形貌和晶相提升其光催化活性提供了理论参考.

乳及乳制品中乳铁蛋白含量的快速SDS-PAGE荧光检测方法

该研究采用新型的Chromeo P503(P503)染料替代考马斯亮蓝染色方法,以克服脱色染色步骤繁琐、耗时长(≥5 h)的不足,建立一种乳及乳制品中乳铁蛋白的快速简便十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis,SDS-PAGE)检测方法。P503染料标记蛋白产生强烈的红色荧光发射,在30 min内一步操作即可完成,并且进行脱铁处理后消除乳铁蛋白铁饱和度对于荧光信号的干扰,保证定量的准确性。根据凝胶成像图中78 ku蛋白条带是否存在及其灰度值的大小,实现乳铁蛋白的定性与定量检测。在优化的实验条件下,线性范围为15~75μg/mL,检出限为5.11μg/mL,加标回收率在75.79%~108.09%之间,表明该方法具有较高的灵敏度和准确性。SDS-PAGE和P503结合无需进行肝素亲和柱前处理,便可直接应用于乳及乳制品中乳铁蛋白快速简便的准确定量检测,P503染料标记还可以用于其它乳蛋白的SDS-PAGE快速低成本定量检测,从而为乳品质量控制和营养评价及加工工艺研究提供有力工具。

Enhancing the leaching effect of an ion-absorbed rare earth ore by ameliorating the seepage effect with sodium dodecyl sulfate surfactant

Ameliorating the problem of low leaching efficiency,long leaching period,and high agent consumption should be studied to efficiently exploit ion-absorbed rare earth ore resources.In this study,the surfactant sodium dodecyl sulfate(SDS) is used to enhance the leaching effect of an ion-absorbed rare earth ore by ameliorating the seepage effect for the first time.The effects of surfactant concentration,leaching agent dosage,solution flow velocity,and solution pH on the leaching rate were explored,and the mechanism of SDS was discussed.Under the optimum conditions,the addition of a small amount of SDS(mass fraction0.04%) can increase the leaching rate by about 5%,shorten the leaching period,and reduce the consumption of the leaching agent.SDS significantly ameliorates the seepage effect of the ore body by reducing the surface tension of the leaching agent and ameliorating the wettability of the mineral surface.This effect is the main factor that improves the leaching efficiency.DFT(density functional theory) calculation results show that SDS can react with rare earth ions,which reduces the adsorption strength on clay mineral surfaces.Hence,rare earth ions are easily exchanged by ammonium ions,and mass transfer is enhanced.

Intermolecular Interactions in Self-Assembly Process of Sodium Dodecyl Sulfate by Vertically Polarized Raman Spectra

Molecular self-assembly is extremely important in many fields, but the characterization of their corresponding intermolecular interactions is still lacking. The C-H stretching Raman band can reflect the hydrophobic interactions during the self-assembly process of sodium dodecyl sulfate （SDS） in aqueous solutions. However, the Raman spectra in this region are seriously overlapped by the OH stretching band of water. In this work, vertically polarized Raman spectra were used to improve the detection sensitivity of spectra of C-H region for the first time. The spectral results showed that the first critical micelle concentration and the second critical micelle concentration of SDS in water were 8.5 and 69 mmol/L, respectively, which were consistent with the results given by surface tension measurements. Because of the high sensitivity of vertically polarized Raman spectra, the critical micelle concentration of SDS in a relatively high concentration of salt solution could be obtained in our experiment. The two critical concentrations of SDS in 100 mmol/L NaCl solution were recorded to be 1.8 and 16.5 mmol/L, respectively. Through comparing the spectra and surface tension of SDS in water and in NaCl solution, the self-assembly process in bulk phase and at interface were discussed. The interactions among salt ions, SDS and water molecules were also analyzed. These results demonstrated the vertically polarized Raman spectra could be employed to study the self-assembly process of SDS in water.

采用SDS研究泥蚶血红蛋白(Tg-Hb)Ⅱ具有过氧化物酶及抗菌活性的结构基础

泥蚶血红蛋白(Tg-Hb)Ⅱ除了具有携氧功能外,还具有过氧化物酶活性和抗菌活性。本文采用分光光度法、光谱法和分子对接等技术研究了十二烷基硫酸钠(SDS)对Tg-HbⅡ的结构、过氧化物酶活性及抗菌活性的影响,以探讨Tg-HbⅡ具有过氧化物酶活性及抗菌活性的结构基础。研究结果显示,SDS的疏水烷基长链可嵌入到Tg-HbⅡ血红素口袋内部,与近端His104形成氢键,断裂血红素铁与His104的配位键,使Tg-HbⅡ的Soret带吸收峰降低并发生位移;此外,SDS还可与血红素口袋中的氨基酸形成疏水相互作用,改变血红素口袋原有结构,使得部分疏水氨基酸暴露,导致外源荧光强度增强,最大发射波长红移。SDS可以抑制Tg-HbⅡ的过氧化物酶活性,当SDS浓度为2 mmol·L^(-1)时,Tg-HbⅡ的酶活性仅为原来的20%,在琼脂扩散实验中失去对枯草芽孢杆菌的抗菌活性。以上结果表明,SDS通过破坏血红素口袋的内部结构抑制Tg-HbⅡ的过氧化物酶活性,使其失去抗菌活性,血红素疏水口袋是Tg-HbⅡ具有过氧化物酶活性和抗菌活性的关键结构。本研究为进一步研究Tg-HbⅡ的抗菌机理奠定基础。

Interaction of ciprofloxacin hydrochloride with sodium dodecyl sulfate in aqueous/electrolytes solution at different temperatures and compositions

Interactions of ciprofloxacin hydrochloride(CPFH)with sodium dodecyl sulfate(SDS)were investigated by conductivity measurement in H2O/electrolyte solutions(NaCl,Na2SO4&Na3PO4)over 298.15–318.15 K temperature range(with 5 K interval)considering the human body temperature.In all cases,two critical micelle concentrations(c*)were observed which are increased in the presence of drug and decreased in the presence of salts enunciating the presence of interaction amongst the studied components.For(CPFH+SDS)system in the presence of salt,the c*values at 303.15 K and I=0.50 mmol·kg^-1 followed the order:CNaCl>CNa2SO4>CNa3PO4.TheΔG1,m0 andΔG2,m0values are found to be negative for all systems that show that the micellization process is thermodynamically spontaneous.For(CPFH+SDS)system in water,theΔHm0&ΔSm0 values reveal that the micellization processes is both entropy dominated in almost all cases.In the occurrence of electrolytes,ΔHm0 andΔSm0 values indicate that micellization processes are both entropy&enthalpy restricted at upper temperature but it becomes totally entropy dependent at higher temperature.The higher positiveΔSm0 values indicate the enhanced hydrophobic interaction in presence of salts.The enthalpy-entropy compensation was determined from the linear relationship betweenΔHm0 andΔSm0 values in every state.Different transfer energies as well as compensation temperature and intrinsic enthalpy were also evaluated and the behaviors were comparable to other biological system.

Phase Behavior of Sodium Dodecyl Sulfate-n-Butanol-Kerosene-Water Microemulsion System

Experiments were carried out to investigate the influences of cation from electrolytes and acidity/alkalinity on the phase behavior of sodium dodecyl sulfate-n-butanol-organics-water （with electrolytes） microemulsion sys-tem. The organics used is commercial kerosene. The volume ratio of water to organics is 1︰1. The results show that the type and valence of electrolyte cations are important factors influencing the microemulsion behavior. Biva-lent Ca2＋is more effective than monovalent K＋and Na＋for the formation of Winsor type III and II microemulsion. For electrolytes with the same monovalent cation Na＋, i.e. NaCl and Na2CO3, anions in the electrolyte have some effect. Bivalent anion 23CO - leads to a lower activity of cation Na＋than monovalent anion Cl-. NaOH （or KOH） behaves similar with NaCl （or KCl）. When HCl is used as electrolyte, its acidity plays an important role. Phase in-version of microemulsion from type III （or II） to type I is observed through precipitation of Ca2＋using Na2CO3, neutralization of HCl by NaOH, and addition of water to the system, which releases the oil from the microemulsion.

Molecular Dynamics Simulation of Effect of Salt on the Compromise of Hydrophilic and Hydrophobic Interactions in Sodium Dodecyl Sulfate Micelle Solutions

The presence of salt has a profound effect on the size,shape and structure of sodium dodecyl sulfate(SDS)micelles.There have been a great number of experiments on SDS micelles in the presence and absence of salt to study this complex problem.Unfortunately,it is not clear yet how electrolyte ions influence the structure of micelles.By describing the compromise between dominant mechanisms,a simplified atomic model of SDS in presence of salt has been developed and the molecular dynamics(MD)simulations of two series of systems with different concentrations of salt and charges of ion have been performed.Polydispersity of micelle size is founded at relatively high concentration of SDS and low charge of cation.Although the counter-ion pairs with head groups are formed,the transition of micelle shape is not observed because the charge of cation is not enough to neutralize the polar of micelle surface.

纳米氧化锌和SDS促进二氧化碳水合物生成特性实验研究

水合物法捕集和封存二氧化碳(CO_(2))具有储气量高和成本低等优点,但生成CO_(2)水合物(简称“水合物”)的诱导时间长、生成速率缓慢限制了该方法的应用。为促进水合物的生成,采用恒容法研究了纳米氧化锌(ZnO)和十二烷基硫酸钠(SDS)对水合物生成的影响。结果表明,在一定条件下增大初始压力和引入机械搅拌可以促进水合物生成,并且单独添加纳米ZnO或SDS均能显著缩短诱导时间。其中,在ZnO质量分数为0.06%和275.65 K的条件下,确定了初始压力和搅拌速率的最优值分别为4.5 MPa和500 r/min。在3.5 MPa、275.65 K和300 r/min的条件下,加入质量分数为0.10%、粒径为50 nm的纳米ZnO(ZnO-50)体系的诱导时间为41.6 min,较纯水体系的诱导时间(487.4 min)缩短了91.5%。体系中ZnO-50的质量分数为0.06%时,气体消耗总量为0.903 mol,较纯水体系的气体消耗总量(0.444 mol)提高了103.4%。提高SDS的质量分数对气体消耗总量的促进效果逐渐增强,当体系中SDS的质量分数为0.10%时,气体消耗总量达到最大(1.027 mol),比纯水体系的气体消耗总量提高了131.3%。以质量分数为0.10%的SDS与质量分数为0.02%的ZnO-50构建协同体系,其气体消耗总量(1.045 mol)受相平衡压力的影响变化不大,但可以显著加快水合物生成速率,实验半程(反应5 h)的气体消耗量可达0.924 mol,占实验全程(反应10 h)气体消耗总量的88.4%,明显高于单独使用质量分数为0.02%的ZnO-50和质量分数为0.10%的SDS体系的相应数据(分别为63.7%和48.5%)。相关研究结果可为应用水合物技术进行CO_(2)捕集和封存提供一定的理论指导。

Molecular dynamics simulations of the effects of sodium dodecyl sulfate on lipid bilayer

Molecular dynamics simulations have been performed on the fully hydrated lipid bilayer with different concentrations of sodium dodecyl sulfate （SDS）. SDS can readily penetrate into the membrane. The insertion of SDS causes a decrease in the bilayer area and increases in the bilayer thickness and lipid tail order, when the fraction of SDS is less than 28%. Through calculating the binding energy, we confirm that the presence of SDS strengthens the interactions among the DPPC lipids, while SDS molecules act as intermedia. Both the strong hydrophilic interactions between sulfate and phosphocholine groups and the hydrophobic interactions between SDS and DPPC hydrocarbon chains contribute to the tight packing and ordered alignment of the lipids. These results are in good agreement with the experimental observations and provide atomic level information that complements the experiments.

The Electrooxidation of Tetracycline at Acetylene Black Electrode in the Presence of Sodium Dodecyl Sulfate

The electrooxidation of tetracycline (TC) at acetylene black electrode has been studied in the presence of sodium dodecyl sulfate (SDS). Tetracycline (TC) exhibited very sensitive oxidation peak in this system. The peak current was proportional to TC concentration, and the detection limit was 1.2×10-8 mol/L. The system was used to the determination of TC in Pharmaceuticals.

Effect of β-Cyclodextrin Upon the Sol-gel Transition of Methylcellulose Solutions in the Presence of Sodium Dodecyl Sulfate

The sol-gel transition temperature of methylcellulose （MC） solution in the presence of sodium dodecyl sulfate （SDS） as well as the mixtures of SDS and β-cyclodextrin （β-CD） was mea- sured, and the effect of the two competing interactions, the hydrophobic interaction between SDS and MC and the inclusion interaction between SDS and β-CD, upon the sol-gel transition of MC solution was studied. It has been found that the inclusion interaction between SDS and β-CD is much greater than the hydrophobic interaction between SDS and MC. As a result, in the coexistence of SDS and β-CD, the sol-gel transition temperature of MC solution keeps the same value, independent of the concentration of SDS in solution on con- dition that the concentration of SDS is less than β-CD. Our experimental results not only suggest that the effect of SDS upon the sol-gel transition of MC solution can be screened by β-CD completely but also indicate the inclusion ratio of SDS to β-CD can be determined quantitatively by using rheological measurement. The inclusion ratio of SDS to β-CD is 1：1, which is in good agreement with the inclusion ratio of SDS to β-CD in the presence of poly（vincyl pyrrolidone） determined by the viscosity measurement but is critically different from the inclusion ratio of SDS to β-CD in the presence of the oppositely charged polyelec-trolyte by using the rheological measurement, mainly due to the reason that the mechanism of the interaction between SDS and MC is critically different from the mechanism of the interaction between SDS and the oppositely charged polyelectrolyte.

Effects of Sodium Dodecyl Sulfate on a Single Cavitation Bubble

Dynamics of a single cavitation bubble in sodium dodecyl sulfate（SDS） aqueous solutions is investigated experimentally and theoretically. The bubble pulsation is measured by a phase-locked integrated imaging technique,and the ambient radius is obtained by fitting the numerical calculation based on the Rayleigh–Plesset bubble dynamics model to the experimental data. The results show that, under the same driving condition, the ambient radius of the cavitation bubble decreases correspondingly with the increase of SDS concentration within the critical micelle concentration, while the compression ratio of the radius increases, which indicates that the addition of SDS decreases the internal molecular number of the cavitation bubble and increases the power capability of the cavitation bubble. In addition, bubble oscillation increases the concentration of the surfactant molecules on the bubble wall, so that the effect of SDS on a single cavitation bubble is reduced when the SDS concentration is greater than 0.8 m M.

Experimental and Quantum Chemical Studies of the Inhibition of Copper with Sodium Dodecyl Sulphate (SDS) in Acidic Medium

This work investigates the inhibitive properties of sodium dodecyl sulphate (SDS) on the corrosion of copper (Cu) in nitric acid using gasometric methods. The inhibition efficiency increases with time and concentration of SDS. The corrosion rate of copper decreases as concentration of SDS increases. Adsorption of the SDS on the surface obeyed the Langmuir adsorption isotherm. The high negative values of the kinetic parameter B suggest that the inhibitor’s effectiveness increases with temperature. The equilibrium constant and the free energy of adsorption of SDS to copper are negative and large. This observation implies that the adsorption mechanism maybe chemisorption. The quantum chemical calculation of copper dodecyl sulphate shows that the energy change in the HOMO-LUMO energy of the moiety is positive and small. This observation implies that the SDS is an efficient inhibitor. The high dipole moment obtained implies that corrosion inhibition of Cu is enhanced by adsorption of SDS and this observation correlates with the observed experimental inhibition efficiency.

Observations on the Function of Mucous Cells in the Epidermis of the Cat-fish Clarias batrachus Exposed to Sodium Dodecyl Sulfate

Response of mucous cells, in the epidermis of the catfish Clarias batrachus, to a sublethal concentration of sodium dodecyl sulfate was studied and correlated with the alteration in the status of their secretory activity after different durations of the treatment. At 4h, 8h, 24h,48h and 72h of the detergent treatment, most mucous cells attained voluminous dimensions and appeared closely approximating to or even overlapping the adjacent ones. At 12h, 36h, and 60h, in contrast, the mucous cells appeared small and slender, and seemed to be located at greater intervals. These changes in dimensions were responsible for the apparent increase or decrease in the density of mucous cells after different durations of detergent treatment. Statistically, however, no significant change was observed in the total number of the mucous cells throughout the experiment.The mucous cells appeared enlarged towards the end of the experiment signifying increased mucus production. This is considered as an adaptation, for protection, assisting the fish to adjust to the changed environment.A shift in the histochemical nature of the secretory contents at the middle and basal parts of the mucous cells, from a mixture of neutral and acid glycoproteins to neutral glycoproteins, during the early stages of the treatment suggests that acid moities could not simultaneously be synthesized as an immediate response to enhanced mucous secretion. The apical parts of the mucous cells, however, showed no histochemical change throughout the experiment.