Influence of Cationic Cetyltrimethylammonium Bromide on Rate of Zn(II)-Histidine Complex and Ninhydrin

Paper analyses the influence of cationic cetyltrimethylammonium bromide on rate of Zn(II)-histidine and ninhydrin. UV-visible spectroscopy was applied to note absorbance of Zn(II)-histidine complex with ninhydrin at the end of reaction in the two systems. Rate constant, k_obs, (in aqueous) and rate constant, k_ψ, (in cetyltrimethylammonium bromide, CTAB) were determined by computer software. Reactions depict first-order in Zn(II)-histidine concentration and fractional-order in ninhydrin concentration in aqueous and micellar media. The results achieved indicate that the reactions take place principally by the same reaction mechanism in both the media. Critical micelle concentration of CTAB surfactant was calculated by recording the conductivity as a function of surfactant concentrations. Influence of various amounts of surfactant on Zn(II)-histidine complex and ninhydrin reaction was performed under different reaction conditions. Reaction was catalyzed and accelerated efficiently by surfactant medium compared to aqueous medium. The observed influence of surfactant on rate has been mentioned in details and their quantitative treatment of kinetic results have been deduced by the means of Menger and Portnoy model for micellar catalysis.

Ultra-Low Interfacial Tension of a Surfactant under a Wide Range of Temperature and Salinity Conditions for Chemical Enhanced Oil Recovery

Ultra-low interfacial tension (IFT) is an important parameter for selecting surfactants to apply in chemical enhanced oil recovery (CEOR). In this study, the IFT between the solution of the surfactant ANSM and Dagang crude oil was measured using the spinning drop method. The effects of the surfactant concentration, temperature, salt types and aging time on the IFT were investigated in detail. The results showed that ANSM effectively reduced the IFT without alkali. Ultra-low IFT was formed in a wide range of surfactant concentrations from 0.05∼ 0.5 wt.% and a wide range of temperatures from 20∼80°C. In addition, ANSM also showed great NaCl tolerance, with a maximum NaCl concentration of 130000 mg · L−1. Furthermore, 0.1 wt.% ANSM maintained an ultra-low IFT, even with 900 mg · L−1 CaCl2 or 1300 mg · L−1 MgCl2, in the presence of 10000 mg · L−1 NaCl. ANSM also had an excellent stability; the solution maintained the ultra-low IFT for 60 days at 90°C. Thus, ANSM proved itself as a potential candidate for CEOR.