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31.
《Journal of Saudi Chemical Society》2014,18(5):520-527
The effect of cationic micelles of cetyltrimethylammonium bromide (CTAB) on the interaction of dipeptide glycyl-tyrosine (Gly-Tyr) with ninhydrin under varying conditions has been studied spectrophotometrically at 70 °C and pH 5.0. The reaction followed first- and fractional-order kinetics with respect to [Gly-Tyr] and [ninhydrin], respectively. Increase in total concentration of CTAB from 0 to 70 × 10−3 mol dm−3 resulted in an increase in the pseudo-first-order rate constant (kψ) by a factor of ca. 3. Quantitative kinetic analysis of kψ − [CTAB] data was performed on the basis of pseudo-phase model of the micelles (proposed by Menger and Portnoy and developed by Bunton) and Piszkiewicz model. A possible mechanism has been proposed and the kinetic data have been used to evaluate the micellar binding constants KS (268 mol−1 dm3 for Gly-Tyr) and KN (64 mol−1 dm3 for ninhydrin). 相似文献
32.
《Arabian Journal of Chemistry》2020,13(9):6942-6948
In the present study, SiO2 nanoparticles were first hydrophobically modified and then added into anionic surfactant sodium dodecyl sulfate (SDS) stabilized water-based foam to improve the foam stability. The foam stability was experimentally evaluated by measuring surface tension, Zeta potential and half-life of the foam. The foam stabilizing mechanism was also studied from a micro perspective by molecular dynamics simulation through analyzing the equilibration configuration and MSD curve of both SDS surfactant and water molecules. The results show that foam exhibits an optimal stability when SiO2 concentration is 0.35 wt% under a specific surfactant concentration (0.5 wt%) in this work. The addition of SiO2 nanoparticles with suitable concentration could improve the adsorption between SDS molecules and nanoparticles, thus limiting the movement of SDS and restricting the movement of surrounding water molecules, which is beneficial to enhance the foam stability. 相似文献
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Surfactants and related products are closely related to the daily life of humankind and play a vital role in industrial production. In this paper, the classification, developing history and future direction of surfactants are introduced by means of anthropomorphism. In addition, it addresses the principles of related physical chemistry, so that the readers could understand the relevant theories and knowledge of surfactant chemistry with a pleasant reading experience. 相似文献
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比较了三阶段Hermit插值和二次多项式的表面张力-稀释倍数拟合曲线及其求积方式,得出由三阶段Hermit插值所得n 1个离散数据点的拟合曲线,及对其前n个离散数据点所在区间上进行求积较佳。在三阶段Hermit插值拟合及求积方式下,分析了十二烷基硫酸钠、十六烷基三甲基溴化铵、茶皂素和去菌体前后含鼠李糖脂发酵液溶液浓度与表面张力-稀释倍数积分值之间的线性回归方程F值和r值,结果显示:F值大小受积分区间、(生物)表面活性剂种类、溶液浓度与临界胶团浓度的比值大小及溶液中杂质的影响,但F值均大于F0.005。 相似文献
38.
The consequences of Ge deposition on Br-terminated Si(1 0 0) were studied with scanning tunneling microscopy at ambient temperature after annealing at 650 K. One monolayer of Br was sufficient to prevent the formation of Ge huts beyond the critical thickness of 3 ML. This is possible because Br acts as a surfactant whose presence lowered the diffusivity of Ge adatoms. Hindered mobility was manifest at low coverage through the formation of short Ge chains. Further deposition resulted in the extension and connection of the Ge chains and gave rise to the buildup of incomplete layers. The deposition of 7 ML of Ge resulted in a rough surface characterized by irregularly shaped clusters. A short 800 K anneal desorbed the Br and allowed Ge atoms to reorganize into the more energetically favorable “hut” structures produced by conventional Ge overlayer growth on Si(1 0 0). 相似文献
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An amphiphilic Lattice-Boltzmann approach is adopted to model dynamic interfacial tension due to non-ionic surfactant. In the current system, the surfactant adsorption kinetics is diffusion dominated and the interface separates two immiscible fluids. A rotational relaxation time and a diffusive/viscous relaxation time are associated with the surfactant. The model results are compared with experimental data for the dynamic interfacial tension of a pendant oil droplet in water, with oil soluble surfactant. We demonstrate how to adapt and calibrate the model to capture the adsorption timescale of the surfactant and the magnitude of interfacial tension reduction due to surfactant. A scheme to overcome numerical instabilities due to the relatively low surfactant concentration, is devised. We are able to qualitatively match the Frumkin equation of state for the interfacial tension. 相似文献
40.
Xiaomiao HouXiaoling Zhang Shutang ChenYan Fang Jilin YanNa Li Pengxu Qi 《Applied Surface Science》2011,257(11):4935-4940
A facile and novel way was reported here for the synthesis of hydrophobic Ag nanoparticles (NPs), using AgNO3, tri-n-octylphosphine (TOP) and sulfur (S) powder in process. TOP was used as solvent, reducing agent and stabilizer. S could chelate with excessive TOP to form trioctylphosphine sulfide (TOPS), which served as second capping agent. The hydrophobic Ag NPs could be transformed into hydrophilic state through ligand exchange. Furthermore, surface-enhanced Raman scattering (SERS) spectra of 4-aminothiophenol (4-ATP) were obtained on the hydrophobic and hydrophilic Ag NPs modified substrates, indicating that the as-synthesized Ag NPs had great potential for high sensitive optical detection applications. 相似文献