十二胺聚甘油醚表面活性剂的合成及光谱表征

十二胺与缩水甘油在碱催化下合成了不同聚合度的十二胺聚甘油醚表面活性剂,并以FTIR、ESI-MS、13CNMR进行了合成产品的光谱表征。用吊环法测定了该表面活性剂水溶液在25℃时的表面张力,考察了不同聚合度对其表面性质的影响。结果表明,十二胺二聚甘油醚、四聚甘油醚、六聚甘油醚水溶液的临界胶束浓度CMC（mmol/L）分别为0.32、0.055和0.20,先减小而后增大;最低表面张力γCMC（mN/m）分别为28.46、29.41和34.02,逐渐增大。     

Effect of pH Value on the Adsorption Behavior and Inhibition Mechanism of Dodecylamine on Carbon Steel

The effect of pH value on the adsorption behavior and inhibition mechanism of dodecylamine for carbon dioxide corrosion of carbon steel was investigated by electrochemical methods and scanning electron microscopy (SEM). The results indicated that the pH value of the solution played the crucial role to the adsorption behavior and inhibition mechanism of dodecylamine. The inhibition performance of dodecylamine on carbon steel was dependent on the pH value and the inhibition efficiency increased with the increase of pH value. At pH 4.9, dodecylamine mainly inhibited the cathode process of the corrosion. The adsorption energy of dodecylamine on the metal surface was lower. The adsorption of dodecylamine on the metal surface was not stable and an anode desorption phenomenon could be observed. Hence, dodecylamine did not provide effective inhibition to the corrosion. While at pH 6.9, it had much higher adsorption energy. Dodecylamine adsorbed on the metal surface tightly and formed the effective diffusion barrier which inhibited both the cathode and anode processes effectively.     

AFM探针刮擦诱导金属加速溶解行为及缓蚀剂抑制效果研究

应用原子力显微镜(AFM)探针刮伤技术研究缓蚀剂对探针诱导铜镍合金加速溶解作用的影响.实验表明,在1.5 mol/L NaC l和0.01 mol/L HC l溶液中,使用AFM探针在750 nN的力负载条件下以接触模式对铜镍合金表面持续扫描,会加速样品的溶解,并在探针刮擦区域形成蚀坑.将有机缓蚀剂十二胺及无机缓蚀剂铬酸钠添加到腐蚀介质中后,由于在合金表面形成了吸附膜和钝化膜,从而抑制探针刮擦引起的铜镍合金的加速溶解.     

pH值对十二胺在碳钢表面的吸附行为及缓蚀机理的影响

采用电化学方法和扫描电镜技术, 研究了pH值对十二胺在碳钢表面的吸附以及对碳钢CO2腐蚀缓蚀机理的影响. 研究结果表明, 溶液的pH值对十二胺的吸附和缓蚀机理起决定性作用. 十二胺对碳钢的缓蚀作用随溶液pH值的增加而增强. pH值为4.9时, 十二胺主要抑制腐蚀的阴极过程. 缓蚀剂分子在金属表面上的吸附能比较低, 缓蚀剂容易发生脱附, 因此不能有效抑制腐蚀反应的进行. pH值为6.9时, 缓蚀剂的吸附能较高, 能够牢固地吸附在金属表面, 形成有效的扩散阻挡层, 同时抑制腐蚀的阴、阳极过程, 从而有效地抑制腐蚀反应的进行.     

Thermodynamic properties and conductivities of some dodecylsurfactants in water

Densities, heat capacities, enthalpies of dilution, osmotic coefficients and conductivities are reported for dodecylamine hydrochloride, dodecyldimethylammonium and dodecyltrimethylammonium chloride in water over a wide range of concentration. The last two properties were also measured for dodecyltrimethylammonium bromide. From the thermodynamic data partial molar volumes, heat capacities and relative enthalpies and nonideal free energies and entropies were derived as a function of the surfactant concentration. The cmc's and degree of counterion dissociation were also calculated from the transport properties. It is shown that the trends of volumes, enthalpies, free energies and entropies are quite regular whereas heat capacities present maxima and minima at concentrations which depend on the nature of surfactants. Corresponding changes were observed in the osmotic coefficients and specific conductivities. The thermodynamic functions of micellization were evaluated on the basis of the pseudo-phase transition model. Finally, the effects of the introduction of methyl groups in the hydrophilic moiety of the surfactant and of the nature of the counterion on the thermodynamic properties of monomers and micelles are examined.     

Size effect in thiol and amine binding to small Pt nanoparticles

A study was carried out to compare the binding affinities of 1-dodecanethiol and dodecylamine for small Pt nanoparticles. The results showed that the affinity of thiol for Pt nanoparticles increases with increasing particle size whereas the affinity of amine for Pt nanoparticles decreases. The divergence in binding affinities has resulted in differences in catalytic activities of thiol- and amine-protected Pt nanoparticles in the room temperature electro-oxidation of methanol (a fuel cell reaction). It was therefore possible for the larger Pt nanoparticles to be catalytically more active than the smaller Pt nanoparticles up to a certain critical size, before the surface area effects of nanoparticles become noticeable.     

DDA在碱酸介质中的存在状态与缓蚀行为的关系

利用电化学方法、物理检测技术及表面分析技术，针对十二烷基胺（ＤＤＡ）作用于ＦｅＮｉＳｉＢ非晶合金表面时，在不同浓度范围内，缓蚀效率与缓蚀剂２在不同的对应关系的现象、探讨了ＤＤＡ的存在状态与其缓蚀行为的关系，利用物理测量技术对临界浓度前后ＤＤＡ的存在状态进行了分析，利用扫描隧道显微镜捕获了高浓度时ＤＤＡ在非晶合金表面的典型结构，详细阐述了ＤＤＡ对非晶合金的微观缓蚀机制。     

缓蚀剂吸附行为的电化学及AFM力曲线研究

结合极化曲线,微分电容曲线测试和AFM力曲线技术研究了直链十二胺对氯化钠溶液中铜镍合金的缓蚀行为以及吸附机理。结果表明:十二胺在合金表面形成单分子层吸附膜而起到缓蚀作用。十二胺浓度越大,吸附膜越致密,缓蚀率越高,力曲线上测得的粘附力值也越大。质子化的十二胺在荷负电的合金表面的吸附使电极零电荷电位正移,电荷屏蔽作用使得AFM力曲线上探针与试样之间的长程静电斥力减小。     

Enhanced spore detection using dipicolinate extraction techniques

We have developed a method for bacterial endospore detection based on the presence dipicolinic acid (dpa), a substance unique to endospores. Since the sensitivity of this technique correlates directly with the amount of dpa extracted from the spores, we examined several types of extraction techniques for their dpa extraction efficiency. The three main categories investigated are physical, germination, and chemical methods for liberation of dpa from B. subtilis endospores. Attention is concentrated on the speed, efficiency, and simplicity of the extraction techniques for optimization of endospore detection using terbium-dipicolinate photoluminescence. Although methods from all categories succeeded in extracting dpa, the technique utilizing heated dodecylamine (dda) extracted the majority of the available dpa in less than 3 min. Application of the dda extraction procedure to the terbium-dipicolinate photoluminescence method in conjunction with an increased detection capability resulted in a two-order of magnitude improvement in endospore detection. This combination of methods resulted the lowest reported limit of detection (LOD) (1000 CFU/ml) for a terbium-dipicolinate photoluminescence method in the shortest reported time (5-7 min) for the total procedure.     

DDA在硫酸介质中的存在状态与缓蚀行为的关系

利用电化学方法、物理检测技术及表面分析技术，针对十二烷基胺（DDA）作用于FeNiSiB非晶合金表面时，在不同浓度范围内，缓蚀效率与缓蚀剂浓度存在不同的对应关系的现象，探讨了DDA的存在状态与其缓烛行为的关系．利用物理测量技术对临界浓度前后DDA的存在状态进行了分析，利用扫描隧道显微镜捕获了高浓度时DDA在非晶合金表面的典型结构，详细阐述了DDA对非晶合金的微观缓蚀机制．