Volume 56, Issue 3

Anionic dimeric surfactants have attracted much interest compared to the conventional monomeric surfactants. These surfactants have low critical micellar concentrations and an excellent ability in reducing the surface tension of water than conventional surfactants. Therewith, they also show better solubilizing and foaming properties, and a magnificent mildness to the skin. These special features may make them potentially attractive in several applications, for example, laundry detergents, cosmetics and personal care. This article describes the micellization and mixed micellization properties, performance properties, application and biodegradability of anionic dimeric surfactants.

Surfactants, which are the basic ingredients in washing cosmetics, can cause skin irritation. In the case of washing cosmetics intended for children, it is necessary to select the composition in such a way as to ensure maximum reduction or even elimination of the irritant effect of the final product. The paper attempts to improve the safety of bath cosmetics for children by introducing: collagen amino acids (150 Da), hydrolysed collagen (12000 Da) and soluble collagen (300 000 Da). Zein value, bovine albumin, and human keratinocyte cell line studies have shown a significant decrease in the irritant potential of the compositions following the introduction of the proposed additives, which is more pronounced with the increase in the molecular weight of marine collagen. An important part of this work is a mechanism proposed by the authors, according to which the addition of the proposed additives can increase safety of the application of cosmetics for children.

The sorption of Remazol Black B (RBB) by dried anaerobic sludge granules (ASG) was examined in this study. The biosorption process was monitored based on the statistical optimization data of the batch reactor studies. In the factorial tests, 36 different tests were established by considering the variables such as temperature (25°C, 50°C), pH (1, 3, 5), dye concentration (100, 150, 200 mg/L) and cationic surfactant concentration (0, 0.5 mM). Also, it was intended to investigate the effect of cationic surfactant dodecyl trimethylammonium bromide (DTAB) on decolorization of the anionic dye RBB by ASG. The sorption isotherms and kinetics were determined for RBB removal. The biosorption of RBB was fitted with Langmuir isotherm and pseudo-second-order kinetic models. The oppositely charged dye and surfactant molecules interacted electrostatically. These electrostatic interactions improved the dye biosorption properties of ASG. Our results indicate that a surfactant can be used as an inducer in the treatment of dye-contaminated water. This is the first paper combining factorial experiment design and surfactant-accelerated decolorization to achieve more effective biosorption conditions.

A novel environmentally friendly type of corrosion and scale inhibitor, maleic anhydride-allylpolyethoxy carboxylate copolymer (ML10), was synthesized and characterized by FT-IR and 1 H-NMR spectroscopic techniques. The anti-scale property of ML10 in seawater was also studied by static tests for scale and the scale deposits were analyzed by X-ray diffraction (XRD) and SEM, respectively. The results showed that the scale deposits surface morphology and size were changed in the presence of ML10. The performance of the synthesized copolymer as corrosion inhibitor for mild steel corrosion was evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) technique. The experimental results indicate that ML10 has a good corrosion inhibition performance and the inhibition efficiency increases with the increase of the ML10 concentration. The adsorption of ML10 obeys Langmuir adsorption isotherm with relatively high value of free energy of adsorption ΔG ads θ . Scanning electron microscopy (SEM) indicated that the corrosion inhibition is due to the formation of a chemisorbed film on the mild steel.

Three Schiff' bases (SB) were synthesized, characterized and evaluated as corrosion inhibitor for aluminum in 1.0 M HCl using chemical (weight loss) and electrochemical (open circuit potential, potentiodynamic polarization, and electrochemical impedance) techniques. The influence of temperature and concentration was investigated. It has been shown that the efficiency of corrosion inhibition increases with the inhibitor concentration and decreases with increasing temperature. The addition of the inhibitor molecules to the corrosive medium shifts the corrosion potential (E corr ) to the nobler direction. It has been found that the adsorption of the used compounds obeys the Langmuir adsorption isotherm.

The surface tension of the two mixed systems had been investigated in 0.1 M NaCl solution at 298.15 K respectively, including the surface tension of the anionic surfactant N-lauroyl-N-methyl taurine sodium (SDMT) and of the cationic surfactant dodecyltrimethylammonium chloride (DTAC), and zwitterionic surfactant dodecyl betaine (BS-12). The chemical surface properties of the two mixed systems were studied and the regular solution theory was applied to the two mixed systems. The results showed that the binary surfactant mixtures of SDMT/DTAC and SDMT/BS-12 exhibited synergism in surface tension reduction effectiveness, surface tension reduction efficiency and the mixed micelle formation according to β values. It was also found that the results calculated by this theory agreed well with the experimental values.

A series of betaine-type Gemini surfactants (C s -BGS, where C is the methylene part of the spacer, s = 2, 4, 6) were synthesized from sodium 3-chloro-2-hydroxypropanesulfonate, oleamidopropyl dimethylamine and bromoalkane. The chemical structure of the prepared compounds was confirmed by 1 H NMR, 13 C NMR, IR spectra, and elemental analysis. Their critical micelle formation concentrations (CMC) in the aqueous solution at 25 °C were determined by measuring the surface tension and the electrical conductivity. As the length of the spacer increased, the values of their CMC and γ cmc also increased. The surface tension measurements of C 2 -BGS revealed that the surfactant possesses a low CMC, is very efficient in reducing the surface tension, and is very strongly adsorbed at the air-water interface. In addition, the adsorption and micellization behavior of C s -BGS was estimated from the efficiency of surface tension reduction (pC 20 ), minimum average surface area per surfactant molecule (A min ), and standard free energies of micellization and adsorption. These properties are significantly affected by the spacers and the adsorption is more favored than the micellization.

Surface chemical properties of the mixed system of sodium lauryl diphenyl ether disulfonate (C 12 -MADS, an anionic surfactant with double hydrophilic groups) and dodecyl dimethyl hydroxyethyl ammonium chloride (K 3 , a cationic quaternary ammonium surfactant) along with different proportion have been studied at 298 K and 318 K. Synergistic parameters of the mixture in the mixed micelles and the mixed adsorption layer were also calculated by using the regular solution theory. The composition of the mixed micelles and of the mixed adsorption layer was obtained. The results show that the surface chemical properties of C 12 -MADS/K 3 mixture are better than either of single system, and when the solution ratio (α 1 = [n (K 3 )/n (C 12 -MADS + K 3 )]) is 0.7 and 0.9, the surface tension curve has a double inflection point which indicates a synergistic effect between the surfactant molecules. The complex system showed a strong synergistic effect in the mixed adsorption layer and the mixed micelles. The mixed system of C 12 -MADS/K 3 has synergism in surface tension reduction effectiveness, surface tension reduction efficiency and mixed micelle formation. When α 1 is 0.67, the synergistic effect is the strongest.

In this paper, oleic acid was used as raw material to synthesize 9,10-di-hydroxystearic acid (DHSA), which contains two hydroxyl groups and one carboxyl group. DHSA was reacted with ethylene oxide (EO) to obtain a new surfactant category that is characterized by the presence of 3 hydrophilic chains: 9,10-di-hydroxystearic acid ethoxylates (DHSAE-n, n = 10, 12, 15, 18, 20 EO). FT-IR and 1 H NMR were used to characterize the molecular structure of DHSAE-n. The surface activity, adsorption and aggregation behavior in aqueous solution have been investigated by static surface tension, dynamic surface tension, contact angle and transmission electron microscopy (TEM). In addition, the application properties (wettability, emulsification, foamability and decontamination) of DHSAE-n have been systematically studied.

Lauryl phosphate monoester was synthesized from the starting materials lauryl alcohol and phosphoric acid without catalysts. Subsequently, the crude product was purified by recrystallization and characterized by Fourier transform infrared (FT-IR) and nuclear magnetic resonance ( 31 P-NMR). From the results, it was apparent that the synthesized material was the desired target product. Lauryl monoester potassium phosphate reduced the surface tension of water to 25.08 mN/m at a critical micelle concentration (CMC) of 0.569 mmol/L. It showed a low contact angle and had a low surface tension, indicating a good hydrophilicity. Lauryl monoester potassium phosphate also showed excellent antistatic properties, however its emulsifying ability was not good. The size of the aggregates of lauryl monoester calcium phosphate in aqueous solution was 220 nm and their morphology was spherical.

A series of novel polymeric nonionic surfactants based on water-soluble N,O-hydroxyethyl chitosan (N,O-HECTS) and dehydroabietyl glycidyl ether (DAGE), DAGE-g-N,O-HECTSs, were synthesized by an additive reaction between N,O-HECTS and DAGE. The structures of DAGE-g-N,O-HECTSs were characterized by FT-IR and 1 H NMR. The substitution degree of hydroxyethylation (DS HE ) of N,O-HECTS and the grafting degree (DG) of DAGE onto N,O-HECTS for DAGE-g-N,O-HECTSs were determined by elemental analysis. The surface activities of DAGE-g-N,O-HECTSs in aqueous solution were investigated by measuring the surface tension. The experimental results showed that the degree of grafting (DG) of DAGE-gN,O-HECTSs could have a significant impact on their critical micelle concentrations (CMCs) and surface tensions at the CMC (γ CMC ), but the DG of DAGE-g-N,O-HECTSs had almost no effect on the minimum of surface tensions (γ min ). When using the DAGE-g-N,O-HECTSs as emulsifier, the increase in DG had a favorable influence on the stability of an emulsion of water and benzene. At a DG greater than 40.45%, the emulsifying power of DAGE-g-N,O-HECTS exceeded that of Tween-60.