Volume 46, Issue 5

The separation efficiency of micellar solutions in thin layer chromatography of hydrophilic vitamins (B 1 , B 9 , B 12 and C) has been examined using silica gel as stationary phase. The best results were obtained with mixed micelles (aqueous solution of anionic SDS (0.5%) plus non-ionic Triton X-100 (0.5%) surfactants) and butanol (9:1 v/v) as mobile phase. The proposed method is applicable to the identification and separation of vitamins (B 1 , B 9 and C) present in drug samples (Becosule and Celin). The separation 1 μg of vitamin C from milligram quantities (up to 0.50 mg) of vitamin B 1 has been successfully realized. Effect of metal ions as impurities on the separation of B 1 , B 9 and vitamin C and limit of detection of these vitamins have been examined.

A series of nonionic surfactants containing different chains of polyethylene oxide monomethyl ether [–O(CH 2 CH 2 O) x CH 3 , x = 7, 12, 16, 44 and 112] based on castor oil were synthesized. Their structures were confirmed using FTIR, 1 H-NMR and 13 C-NMR spectra. Structural effects of the synthesized surfactants on surface tension (γ), critical micelle concentration (cmc) and hydrophile lipophile balance (HLB) were investigated. The effect of structural features on their surface behavior is analyzed through changes in surface properties, including effectiveness (π cmc ) and efficiency (PC 20 ) of adsorption, the surface excess concentration (Γ max ) and the area per surfactant molecule at the air/water interface at surface saturation (A min ). Thermodynamic properties, adsorption and micellezation of the prepared surfactant in addition to their biodegradability were investigated.

Polysorbates – which are commercially available under the name Tween – are complex mixtures of different functionalities. Molar mass distribution and chemical composition of various Tween samples (20, 40, 60 and 65) were determined using size exclusion chromatography (SEC) with dual detection. A separation of different functionalities was achieved using liquid chromatography under critical conditions (LCCC) on typical reversed phase columns with methanol – water and acetone – water as mobile phase. The size of the hydrophilic part was determined after microwave-assisted methanolysis, which allowed also the identification of the fatty acids bound to the hydrophilic core.

Using Tetrabutyl titanate (TBOT) as titanium source, the nanocrystal TiO 2 was synthesized via hydrolysis deposition processing in cationic surfactant system at room temperature. The synthesized products were characterized by TEM and XRD. Photocatalytic degrade to NPE-10, phenol and DBS in solar irradiating were studied, respectively. The TiO 2 powder showed excellent photocatalytic property. It was different to degrade three substances. NPE-10 was degraded nearly 70% in 2 hours, phenol was degraded nearly 95% in 8 hours, DBS was degraded nearly 82% in 8 hours.

Dodecyl tetramethyl guanidine (DTMG) were synthesized and characterized, and its reversible performance was studied. The results showed that DTMG could form bicarbonate ionic adduct after exposed to CO 2 , so it could be used as CO 2 switchable surfactants. By bubbling CO 2 through DTMG solution or heating CO 2 saturated DTMG solution, the alkali and surface active properties of solution was changed reversibly. Emulsion and foam stabilized by DTMG could be controlled between stable and unstable state by CO 2 . In addition, the state of DTMG solution was easy to be distinguished by naked eye through a simple indicator, phenolphthalein. Pink indicated it was inactive, and colorless indicated it was active.

The influence of chain length on the composition of mixed micelles in binary mixtures of N,N-dimethyldodecylamine oxide (DDAO) and sodium decyl-, sodium dodecyl- and sodium tetradecylsulfate (abbreviated as SDeS, SDS and STS, respectively) has been determined at 30°C. From the surface tension measurements, the critical micelle concentration (cmc) data were measured as a function of mixing composition. Cmc-values were then analyzed according to regular solution model. The composition of mixed micelles, the interaction parameter (β) and the activity coefficients were evaluated from the regular solution model for the all anionic-amphoteric mixed systems. The interaction parameter values indicated a synergistic interaction between DDAO and the three anionic surfactants at all mole fractions to be due to an overall attractive interaction in the mixed micelles. The strength of the interaction between the amphoteric surfactant and the sodium alkyl sulfate in three mixed systems obeys the following order: SDeS/DDAO > SDS/DDAO > STS/DDAO suggesting that the decrease in the length of anionic surfactant alkyl chain results in a stronger interaction with DDAO. On the other hand, the viscosity data reveals a viscosity increasing trend of STS/DDAO > SDS/DDAO > SDeS/DDAO.

The phase behavior and the influencing factors of middle phase microemulsions prepared from surfactant-like ionic liquid 1-alkyl-3-methylimidazolium bromide (C 12 mimBr, C 14 mimBr and C 16 mimBr) were studied systematically with Winsor-type phase diagrams. The minimum alcohol content needed to form the middle phase microemulsion, the alcohol width (the range of the alcohol concentrations from forming to disappearing of the middle-phase microemulsion) and the percent volume of the optimal middle phase at the midpoint of the middle phase region were obtained from the phase diagrams. It was found that with the increase in the carbon chain length of C n mimBr molecules, the minimum alcohol content and the alcohol width decrease, and the solubilization ability (the percent volume of the middle phase microemulsion) increases. With the increase in C n mimBr content, the minimum alcohol content increases, and the alcohol width increases at first and then decreases, and the solubilization ability of the microemulsion systems increases. The minimum alcohol content, the alcohol width and the solubilization ability are also influenced by alcohols, oils and brine. The minimum alcohol content and the alcohol width decrease, and the solubilization ability increases, with the increase in the carbon chain length of the alcohols, the decrease in the carbon chain length of the oils, and the increase in NaCl contents.

In the present investigation, a series of alkyl polyglycosides with alkyl chain length of C 8, 9, 10, 12 and 14 were synthesized using transacetalization method. Purity of the products was investigated using high performance liquid chromatography. Surface parameters particularly Effectiveness π cmc , Efficiency Pc 20 , maximum surface excess Γ max , minimum surface area Amin and HLB values are investigated, in addition to thermodynamic parameters (ΔG ads and ΔG mic ). Resistance to hydrolysis for the prepared compounds was investigated. The synthesized compounds were tested for their biodegradability in Nile river water according to Die-away test method and their antimicrobial activity against different strains of bacteria, yeast and fungi was investigated.