Synergistic effect between cationic gemini surfactant and chloride ion for the corrosion inhibition of steel in sulphuric acid

Corrosion inhibition of cold rolled steel in 0.5 mol L⁻¹ sulphuric acid by a quaternary ammonium gemini surfactant, l,3-propane-bis(dimethyl dodecylammonium bromide) (designated as 12-3-12), in the absence and presence of chloride ions was investigated at different temperatures. The results revealed significant synergistic effect between gemini 12-3-12 and chloride ions for the corrosion protection of cold rolled steel in sulphuric acid, and that the novel composite inhibitor system containing cationic gemini surfactant and chloride ions was efficient and low-cost for steel corrosion inhibition in sulphuric acid medium, even when concentration of 12-3-12 was as low as 1 × 10⁻⁶ mol L⁻¹. By fitting the obtained experimental data with Langmuir adsorption model and Arrhenius equation, some thermodynamic and kinetic parameters such as adsorption free energy, the apparent activation energy, and the pre-exponential factor were estimated. The adsorption mechanism of the gemini surfactant onto steel surface in acid medium in the absence and presence of chloride ions was also discussed, respectively.     

Impedance spectroscopic study of corrosion inhibition of copper by surfactants in the acidic solutions

The inhibitive action of the four surfactants, cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate, sodium oleate and polyoxyethylene sorbitan monooleate (TWEEN-80), on the corrosion behavior of copper was investigated in aerated 0.5 mol dm⁻³ H₂SO₄ solutions, by means of electrochemical impedance spectroscopy. These surfactants acted as the mixed-type inhibitors and lowered the corrosion reactions by blocking the copper surface through electrostatic adsorption or chemisorption. The inhibitor effectiveness increased with the exposure time to aggressive solutions, reached a maximum and then decreased, which implies the orientation change of adsorbed surfactant molecules on the surface. CTAB inhibited most effectively the copper corrosion among the four surfactants. The copper surface was determined to be positively charged in sulfuric acid solutions at the corrosion potential, which is unfavourable for electrostatic adsorption of cationic surfactant, CTAB. The reason why CTAB gave the highest inhibition efficiency was attributed to the synergistic effect between bromide anions and positive quaternary ammonium ions. C₁₆H₃₃N(CH₃)₄⁺ ions may electrostatically adsorbed on the copper surface covered with primarily adsorbed bromide ions. On the basis of the variation of impedance behaviors of copper in the surfactant-containing solutions with the immersion time, the adsorption model of the surfactants on the copper surface was proposed.     

CTAB-TBP-Au(CN)_2-萃合物水分子数的测定

添加表面活性剂后,碱性氰化液中的金被高效萃取,水分子在萃合物结构中提供氢键。以十六烷基三甲基溴化铵(CTAB)为表面活性剂,磷酸三丁酯(TBP)为萃取剂的体系具有很好的萃金效率,用~(198)Au示踪活化、微库仑水分测定(卡尔-费休法)和红外光谱法对该体系进行了分析,并用线性拟合的方式研究有机相中水和金的定量关系。结果表明,萃合物中水浓度与金浓度线性相关,摩尔比约为4;红外光谱分析结果显示,有机相中的金、氰根和水的含量有固定比例,萃合物具有稳定的化学组成。     

Solid-phase extraction of trace Au(III) with SDG and determination by the catalytic spectrophotometric method

The new catalytic kinetic spectrophotometric method for Au(III) determination was developed and validated. It was based on the catalytic effect of gold on the oxidation of sudan red III by ammonium peroxodisulfate ((NH₄)₂S₂O₈) with nitrilo triacetic acid as an activator in microemulsion and H₂SO₄ medium. Under optimum conditions, there was the linearity of the calibration curve in the concentration range from 0 to 20 μg/L Au(III) at 520 nm. The relative standard deviation was 3.0% with a correlation coefficient of 0.9986. The detection limit achieved was 9.75 × 10⁻⁵ μg/mL. A new method using a column packed with sulfhydryl dextrose gel (SDG) as a solid-phase extractant has been developed for the preconcentration and separation of Au(III) ions. The method has been applied to the determination of trace gold with satisfactory results.     

Preparation of silver nanostructure from silver(I) coordination polymer and fabrication of nano silver(I) bromide by reverse micelles technique

A new one-dimensional silver(I) coordination polymer, [Ag(μ-bpfb)(NO₃)]_n (1); bpfb = N,N′-bis(4-pyridylformamide)-1,4-benzene, has been synthesized and characterized by IR, ¹H NMR and ¹³C NMR spectroscopy. The single crystal X-ray data show that the silver(I) 1D coordination polymer grows into a three-dimensional network by hydrogen bonding and π–π stacking interactions. Compound 1 with nanorod morphology was also prepared by sonochemical method. The cetyltrimethylammonium bromide (CTAB) as a cationic surfactant was used in reverse micelles technique to obtain spongy silver(I) bromide nanoparticles from compound 1. Also, different silver nanoparticles have been prepared via direct calcination at 673 K and thermal decomposition in oleic acid from compound 1. The nanostructures of [Ag(μ-bpfb)(NO₃)]_n (1), silver and silver(I) bromide were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray (EDAX) analysis. Thermal stability of compound 1 in both bulk and nano-sized form was studied by thermal gravimetric (TG) and differential thermal (DT) analyses.     

In situ synthesis of palladium nanoparticles on multi-walled carbon nanotubes and their electroactivity for ethanol oxidation

Pd nanoparticles(Pd-NPs)were prepared and directly anchored on the surface of multi-walled carbon nanotubes(MWCNTs)in the absence of chemical reduction agent,where MWCNTs were used as both the chemical reduction agent and the support substrate of Pd-NPs.Effect of various surfactants on the in situ deposition of PdNPs on MWCNTs was investigated.When MWCNTs were modified with a cationic surfactant(hexadecyl trimethyl ammonium bromide,CTAB),the amount of the Pd-NPs(Pd-NP/CTAB-MWCNT)generated by such an in situ deposition method gets a notable increase,and the size of the as-synthesized Pd-NPs becomes smaller,compared with those in the absence of any surfactant(Pd-NP/MWCNT)or in the presence of an anionic surfactant SDS(Pd-NP/SDS-MWCNT)and a neutral surfactant OP(PdNP/OP-MWCNT).Results show that the MWCNTs modified with CTAB are propitious to the in situ reduction of Pd2?.Among the prepared catalysts,Pd-NP/CTABMWCNT displays the highest electroactivity for ethanol oxidation in alkaline media.     

Application of bifunctional ionic liquids for extraction and separation of Eu3+ from chloride medium

The extraction of Eu³⁺ from chloride medium using bifunctional ionic liquid extractants (Bif-ILEs) tri-n-octylmethyl ammonium bis(2-ethyl hexyl) phosphate ([A336][D2EHP]) and trihexyltetradecyl phosphonium bis(2-ethylhexyl) phosphate ([P₆₆₆₁₄][D2EHP]) in kerosene was studied to develop environmentally friendly extraction process. The extraction behavior of Eu³⁺ was examined by varying key process parameters. The extraction behavior indicates that ammonium-based ionic liquid [A336][D2EHP] shows better extraction efficiency of Eu³⁺ than that of phosphonium-based ionic liquid [P₆₆₆₁₄][D2EHP]. Quantitative extraction of Eu³⁺ is obtained with 0.05 mol/L [A336][D2EHP], whereas, 0.1 mol/L of [P₆₆₆₁₄][D2EHP] is required to achieve the same extraction rate of Eu³⁺. The extraction process is endothermic with respect to [A336][D2EHP]. Stripping experiments indicate that 100% of Eu³⁺ can be back extracted from both the loaded ionic liquids using 20 vol.% HNO₃. The highest separation factor (β_Y/Eu) of 653.59 is reported at pH of 3.2, and the separation factor of Eu³⁺ over La³⁺ is 30.6 at the same pH. From the leach liquors of waste tube light powder, 99.98% of Eu and 99.99% Y are recovered using 0.2 mol/L [A336][D2EHP] in 2-stage cross current extraction with aqueous to organcic ratio (O/A) of 1:1 and 1:2.     

Electrochemical behaviour of carbon steel in acid chloride solution in the presence of dodecyl cysteine hydrochloride self-assembled on gold nanoparticles

In this work, the dodecyl cysteine hydrochloride surfactant was synthesized. The surface properties of this surfactant were studied using surface tension technique. The nanostructure of this surfactant with the prepared gold nanoparticles was investigated using TEM technique. The synthesized surfactant and its nanostructure with the prepared gold nanoparticles were examined as non-toxic corrosion inhibitors for carbon steel in 2 M HCl solution using potentiodynamic polarization and electrochemical impedance spectroscopy techniques. The results show that the percentage inhibition efficiency (η%) for each inhibitor increases with increasing concentration until critical micelle concentration (CMC) is reached. The maximum inhibition efficiency approached 76.6% in the presence of 175 ppm of dodecyl cysteine and 90.8% in the presence of the same concentration of dodecyl cysteine hydrochloride self-assembled on gold nanoparticles. Polarization data indicate that the selected additives act as mixed type inhibitors. The slopes of the cathodic and anodic Tafel lines (β_c and β_a) are approximately constant and independent of the inhibitor concentration. Analysis of the impedance spectra indicates that the charge transfer process mainly controls the corrosion process of carbon steel in 2 M HCl solution both in the absence and presence of the inhibitors. Adsorption of these inhibitors on carbon steel surface is found to obey the Langmuir adsorption isotherm. From the adsorption isotherms the values of adsorption equilibrium constants (K_ads) were calculated. The relatively high value of (K_ads) in case of dodecyl cysteine hydrochloride self-assembled on gold nanoparticles reveals a strong interaction between the inhibitor molecules and the metal surface.     

预分散溶剂萃取法处理Cr(Ⅲ)废水(英文)

以2-乙基己基膦酸单2-乙基己基酯(HEHPEHE)为萃取剂,以及与其它萃取剂形成酸加酸、酸加碱、酸加中性混合萃取剂,通过考察萃取剂对废液中的Cr3+萃取分配比的影响,筛选出萃取Cr3+的适宜萃取剂HEHPEHE;采用预分散溶剂萃取技术对含Cr3+废液进行分离研究,以煤油为稀释剂,HEHPEHE为萃取剂,十二烷基苯磺酸钠(SDBS)为水性表面活性剂,吐温20(Tween-20)为油性表面活性剂,制备胶质液体泡沫CLAs。同时,为了研究预分散溶剂萃取技术萃取Cr3+废液的效果,考察了废液中的Cr3+浓度、胶质气体泡沫CGAs体积、萃取剂浓度、相比、阳离子表面活性剂十六烷基三甲基溴化铵(HTAB)浓度、阴离子表面活性剂SDBS浓度、表面活性剂Tween20浓度以及Cr3+废液的pH值等影响因素对Cr3+的萃取率影响,得到了萃取Cr3+的适宜条件;并用实际的含Cr3+废液进行检验,结果表明,在获得的适宜工艺条件下,经过二级萃取后,废水可以直接排放,Cr3+的萃取率超过99.9%。     

Investigation of the Corrosion Inhibition of CTAB and SDS on Carbon Steel Using an Experimental Design Strategy

The corrosion inhibition performance of sodium dodecyl sulfate (SDS) and cetyltrimethyl ammonium bromide (CTAB) on carbon steel was investigated in sodium chloride solutions. Using an experimental design strategy pH, chloride concentration, SDS/CTAB concentrations, and temperature were optimized by conducting only 30 experiments. The optimum value of each factor was obtained from the designed matrix of the experiments based on the lowest log I _corr value calculated for each experimental condition. The 3D surface plots of the electrochemical response (log I _corr) against each factor were constructed. The optimum conditions in which the lowest log I _corr can be achieved were found as follows: pH 12, [Cl^?] ≈ 1 M, [SDS] ≈ 200 ppm, [CTAB] ≈ 20 ppm, and T ≈ 10 °C.     

A Porosity Test for Electrodeposits on Zinc-Base Die-Castings

A new method of determining the porosity of metal coatings on zinc-base die-castings has been developed. It uses a test solution consisting of ammonium chloride and potassium ferrocyanide. The ammonium chloride corrodes the zinc at the bottom of pores and keeps the zinc in solution; the ferrocyanide forms a white, insoluble compound with the dissolved zinc.

Irregularly shaped articles are first given a thin coat of shellac and are then completely immersed in the test solution; white spots grow on the sites of pores in the coating. For testing flat, cylindrical or conical surfaces, the solution may be applied by means of absorbent paper. The white compound shows up well on black paper; alternatively, if the compound is converted to suitably coloured salts (e.g., ferric, cupric), white paper can be used.     

Preparation of organo-soluble polyanilines in ionic liquid

A method for preparation of organo-soluble polyaniline (PANI) is described. Oxidative coupling polymerization of anilium chloride with ammonium persulfate in a new ionic liquid, 2-hydroxyethyl ammonium formate (HAF), gives organo-soluble polyaniline with appreciable molecular weights (M_w = 86,400). Interestingly polyaniline (PANI) prepared by this method is highly soluble in many organic solvents such as acetone, tetrahydrofurane, dioxane, dimethyformamide and N-methyl, 2-pyrrolidinone. Thin films of PANI prepared at 0 °C (by solvent casting) show reasonable conductivities (up to 37.0 S cm⁻¹) when doped with p-toluene sulfonic acid.     

在NaCl溶液中CTAB、SDS和钨酸钠对印刷电路板缓蚀作用研究

采用电化学阻抗和极化曲线法,研究了在NaCl溶液中,钨酸钠、十六烷基三甲基溴化铵(CTAB)及十二烷基硫酸钠(SDS)的单一配方以及其复配对印刷电路板的缓蚀作用.结果表明:CTAB、SDS和钨酸钠各自的单一配方对印刷电路板(PCB)均具有一定的缓蚀作用,其中CTAB浓度为1.0×10-4mol/L,SDS浓度为5.0×10-3mol/L及350 me,/L钨酸钠表现出最佳的缓蚀效率;SDS和钨酸钠属于阳极型缓蚀剂,CTAB为混合型缓蚀剂;当二者复配使用时,浓度为250 ms/L钨酸钠和1.0 x 10-4moL/L CTAB以及300 mg/L钨酸钠和5.0×10-3～moL/L SDS的复配缓蚀剂的缓蚀效果最佳,复配缓蚀剂具有协同效应,并且对印刷电路板的缝隙腐蚀有一定的抑制作用.     

盐酸溶液中阳离子Gemini表面活性剂在碳钢表面的吸附与缓蚀性能研究

 合成并用元素分析和核磁共振(1H-NMR)表征了阳离子Gemini表面活性剂1,2-双亚甲基-双(十烷基二甲基溴化铵)和1,2-双亚甲基-双(十二烷基二甲基溴化铵)(分别简写为10-2-10和12-2-12)，并用失重法研究了1M盐酸溶液中该类表面活性剂在碳钢表面的吸附行为及其缓蚀性能.实验结果表明，其缓蚀机理为表面活性剂在钢铁表面的吸附形成单分子膜，从而阻碍了盐酸对钢铁的侵蚀，其缓蚀效率随着表面活性剂浓度的增加而增加，当表面活性剂浓度接近其临界胶束浓度时达到最大，理论计算表明，在研究的浓度范围内，盐酸溶液中该类Gemini表面活性剂在碳钢表面的吸附行为符合Langmuir吸附等温式.      

Inhibition of Corrosion resistant alloys in hot hydrochloric acid solutions

Weight loss measurements were performed in 20% and 28% hydrochloric acid at 90 °C on carbon steel, 22Cr5Ni duplex stainless steel, and two superaustenitic steels – 27Cr31Ni3Mo and 19Cr25Ni4Mo –, in presence of organic substances used singly or mixed. The organic substances examined were quaternary ammonium salts (1–4-pyridyl)-pyridinium chloride hydrochloride, dodecylpy-ridiniumchloride, benzyldimethylstearylammonium chloride, and (dodecyltrimethylammonium bromide), alkynols (1-octyn-3-ol, propargyl alcohol) and trans-cinnamaldehyde. The synergistic effect of potassium iodide on the inhibitive efficiency of the organic substances was studied. The variations of corrosion rate during the test time (normally six hours) were recorded by means of polarization resistance measurements. Polarization curves were also recorded. The results showed that the corrosion rates of the four steels examined can be reduced to less than 1 mg/cm² · h using ternary inhibitor mixtures containing quaternary ammonium salts, trans-cinnamaldehyde and potassium iodide (0.2% of each component). Electrochemical tests gave useful indications on the action mechanism of the inhibitors studied.     

Polythiophene/SiO2 nanocomposites prepared in the presence of surfactants and their application to glucose biosensing

Conducting polythiophene/SiO₂ (PT/SiO₂) nanocomposites were prepared in the presence of three different surfactants (anionic, cationic and non-ionic) via chemical oxidative polymerization in an anhydrous medium to create an enzyme-immobilized polymeric amperometric biosensor. An anionic surfactant, sodium dodecylbenzenesulfonate (DBSNa), a cationic surfactant, tetradecyltrimethylammonium bromide (TTAB), and a non-ionic surfactant, poly(ethylene oxide) (20) sorbitan monolaurate (Tween 20), were used as additives. The properties of the nanocomposites were investigated, as a function of surfactant type and the amount of PT contained, by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The SEM results reveal that all PT/SiO₂ samples form nanometer-dimensioned globular structures. The highest conductivity obtained was 2.7 × 10⁻² S cm⁻¹ for a PT/SiO₂-Tween 20 nanocomposite. Thermogravimetric analysis (TGA) shows that the residue decreases with increasing amount of PT. Glucose oxidase (GOX) was immobilized by crosslinking to the conducting PT/SiO₂ composites and was used for amperometric detection of glucose.     

Polyaniline microtubes synthesized via supercritical CO2 and aqueous interfacial polymerization

We report a new route to prepare polyaniline (PANI) microtubes via supercritical (SC) CO₂/aqueous interfacial polymerization. The synthesis is based on the well-known chemical oxidative polymerization of aniline in an acidic environment, with ammonium peroxydisufate (APS) as the oxidant, and sodium dodecyl sulfate (SDS) surfactant was used as the template. The main feature of this route is that the monomer (aniline) which is dissolved in SC CO₂ phase, slowly polymerized at the interface of SC CO₂ and aqueous solution to form the PANI microtubes. The morphologies, phase structure, composition and some properties of PANI microtubes were characterized by TEM, SEM, XRD, IR, XPS UV–vis and SYSTEM DM digital multimeter, respectively.     

Die Korrosion von Messing in Ammoniumchloridlösungen

Corrosion of brass in ammonium chloride solutions The corrosion behaviour of brass (Cu77Zn21A/2, with and without addition of As) has been investigated in 0.01 to 1 M ammonium chloride solution of PH 4 and 2, and in solutions 1 M in chloride ion, with variable Na⁺ and NH⁺₄ concentrations (total concentration 1 M in each case), at pH 4 and 2. While arsenium-free brass was attacked by dezincification in most cases, intercrystalline corrosion was found on As-containing brass. The latter type of corrosion is found already at As contents as low as 0.01%. In a medium 1 M in chloride ion intercrystalline corrosion is found at PH 2, irrespective of the ammonium ion concentration, while at PH 4 intercrystalline corrosion is found only at higher ammonium ion concentrations (practically 1 M). The intercrystalline corrosion was found to be due to the segregation of Zn and As respectively at the grain boundaries and to the influence of As on the stability of the CuCl^?₂ formed by the anodic reaction. The influence of the solution composition on the progress in time of the intercrystalline corrosion is explained.     

Morphology and photoluminescence of colloidal polypyrrole nanoparticles

In order to elucidate the origin of the photoluminescence (PL) of polypyrrole (PPy) colloids, several PPy colloidal samples were prepared under various emulsifying conditions and their PL properties were correlated with the particle morphologies. While highly aggregated fibril- or sheet-like PPy particles were obtained when a cationic surfactant [decyltrimethyl ammonium bromide (DeTAB)] and metal halide oxidant (CuCl₂) were used, employment of anionic surfactant and non-metallic oxidant [sodium di(2-ethyl-1-hexyl)sulfosuccinate (DEHSNa) and ammonium persulfate (APS)] afforded spherical PPy nanoparticles with more regularity. PL measurements of these samples indicated that the highest PL intensity is obtained from the less aggregated and smaller PPy nanoparticles. It was presumed that the smaller particles generate more localized excitons due to shorter π-conjugation length, thereby resulting in stronger PL intensity.     

Polyaniline by new miniemulsion polymerization and the effect of reducing agent on conductivity

A new stable miniemulsion of aniline was prepared using sodium dodecyl sulphate (SDS) as the surfactant and cetyl alcohol as the cosurfactant. The oxidative polymerization reaction was initiated by ammonium peroxy disulphate (APS). At the end of the polymerization reaction polyaniline (PAni) formed was treated with stannous chloride (SnCl₂) and finally doped with p-toluene sulphonic acid (PTSA). The monomer to oxidant and polymer to dopant mole ratio were optimized. Maximum conductivity is obtained with monomer to oxidant mole ratio1:1 and polymer to dopant mole ratio 1:0.5. There is a decrease in particle size and increase in the solubility in miniemulsion process. Dramatic increase in the conductivity is due to the treatment with SnCl_2. Part of the pernigraniline (PNB) form of PAni formed was reduced by SnCl₂ to emeraldine base (EB) form having higher conductivity. Plausible reduction mechanism with SnCl₂ is proposed. The conduction mechanism is explained using EPR measurement. The reason for difference in conductivity of different forms of PAni is explained with the help of polaron formation and hole theory.