Volume 57, Issue 2

Microorganisms have the remarkable capacity to develop resistance to antimicrobial agents. This is of particular concern for fungal pathogens which cause devastating invasive infections with limited treatment options. Thus the need for new antifungal agents is undeniable. This work presents the antifungal properties of four surfactant groups, namely two groups of sulfobetaines and two groups of quaternary ammonium compounds, all morpholine and piperidine derivatives, against drug susceptible or drug resistant Candida albicans and Cryptococcus neoformans . The values of minimum inhibitory and fungicidal concentrations were determined. As follows from the results, the activities of the obtained compounds differed, however the most active agents from each homologous series of compounds, such as P16S3, P16S4 and C16S3, were pointed out.

In this study synergistic effect of the biosurfactants saponin and rhamnolipid on the removal of the heavy metals such as vanadium, nickel and chromium from contaminated soil was investigated. Washing solutions were prepared by using different concentrations of two biosurfactants. In this work, the optimum HLB value of the extraction process of about 10.5 was obtained for the mixture of 62.5 % rhamnolipid and 37.5 % saponin. According to our results, at the optimal HLB value, a maximum removal was obtained for Ni of 87 %, Cr of 71 % and Va of 70 %. Our results also showed that the efficiency of heavy metals decreased with increasing the pH value of system. The optimum pH value of heavy metals removal was 5. According to the results of this research saponin and rhamnolipid have the synergistic effect on the heavy metals removal and it seems to be a good alternative to chemical surfactants for environmental applications.

Modern science and technology promote synthesis routes which are eco-friendly, chemicals which are promoted as “green” and solvents which are less toxic. A convenient method for the synthesis of ether by the reaction of 4-hydroxy benzoic acid and benzyl chloride using a surfactant as catalyst has been developed. The targeted ether is completely immiscible in water but in association with the interface active surfactants, the production of such a hydrophobic organic compound in water has been made possible. Micelles produce a pseudo-cellular organic environment to isolate species from the bulk solvent and favour the compartmentalization of reagents as well. Thus, the enhancement of the local concentration takes place and consequently the reactivity increases. The interaction of such unique chemo-, regio- and stereo-selectivity of surfactants made this reaction feasible. Organic species added to a micellar media are distributed between bulk water and micelles depending on their polarity, charge and dimension. This novel chemistry describes a set of green methods for carrying out this new generation Williamson reaction which can also be used for selective O-alkylation.

In order to expand the application range of surfactants, octadecyl trimethyl ammonium chloride (OTAC) and polyacrylic acid (PAA) were used as raw materials to synthesize octadecyl trimethyl ammonium polyacrylic (OTAP). The molar ratios of OTAC to polyacrylic acid monomer were 1:1, 1:2 and 1:3. The synthesized compounds were named as OTAP-1, OTAP-2, OTAP-3. The obtained research results show that the best foaming ability was achieved with OTAP-1, and the best foam stability with OTAP-2. When the concentration was 2.0 g/L, the order of the emulsifying ability was: OTAP-1 > OTAP-2 > OTAP-3; when the concentration was 4.0 g/L, the emulsifying ability order was OTAP-2 > OTAP-3 > OTAP-1. OTAP-1 had a corrosion inhibition capacity of up to 85.11 %, and OTAP-2 and OTAP-3 had a sustained release rate of 81.06 % and 72.82 %, respectively. OTAP-3 had a good effect on scale inhibition, and the scale inhibition rate was 65.01 %.

The Fischer-Tropsch synthesis can be used to achieve a high content of α-olefin (C 5 –C 11 ) products using Fe-based catalysts. Herein, C 6 and C 8 α-olefins have been selected as examples for the alkylation of benzene catalyzed by using an acidic ionic liquid (Et 3 NHCl-AlCl 3 ) to obtain a variety of intermediates used to prepare surfactants. A series of alkylbenzenes were synthesized by controlling the reaction conditions and their corresponding alkylbenzene sulfonates were successfully obtained by sulfonation and neutralization. It was found that the single chain alkylbenzene sulfonate derivatives did not display typical surfactant properties due to their short hydrophobic chain length. However, double chain alkylbenzene sulfonates exhibit excellent surfactant properties, and decrease the water surface tension compared to commercially available sodium dodecylbenzene sulfonates. A γ cmc (mN m −1 ) value of 32.70 was observed for sodium di-hexylbenzene sulfonates, 29.98 for sodium di-octylbenzene sulfonates, and 36.0 for sodium dodecylbenzene sulfonates. In addition, double chain alkylbenzene sulfonates show an improved emulsifying and wettability performance compared to sodium dodecylbenzene sulfonate. This demonstrates that the capability of alkylbenzene sulfonate to decrease the surface tension are closely related to the total carbon number of side chain-alkyl groups connected to the benzene ring.

The composition and solubilization of the optimum microemulsion systems containing Triton X-100/pentan-1-ol/aliphatic hydrocarbon/water were studied with the ∊-β fishlike phase diagram method. The solubilities of the alkanol ( S A ), the mass fractions of the alkanol in the interfacial layer ( A S ) and the optimum solubilization parameters ( SP∗ ) of the microemulsion systems with different aqueous phases (salt, acid, alkali) and with different α values were obtained and discussed. The SP ∗ values increase significantly with the cation radius of the chlorides (NaCl, KCl, CsCl), but decrease slightly with the anion radius of the sodium halides (NaCl, NaBr, NaI). However, SP∗ values decrease with the increased salinities and NaOH contents. The trend was reversed for the acid systems. When the oil-water ratio (α) increases, the S A and A S values significantly increase, while the SP∗ values increase slowly. As the length of the carbon chain of the alkane molecules increases, both the S A and A S values increase, while the SP ∗ values decrease significantly.

The microenvironment of water droplets of nonionic polyoxyethylene (4) lauryl ether reverse micelles was investigated with infrared and ultraviolet-visible spectroscopy, also by viscosity and dynamic light scattering measurements in the presence of biological surfactant sodium cholate as additive. Influence of concentrations of polyoxyethylene (4) lauryl ether and sodium cholate on the microstructure of mixed reverse micelles was studied. Influence of sodium cholate as additive on the ratio of free, bound and trapped water fractions was studied via deconvolution of the O-H stretching vibrational absorption spectra in the region of 3 000–3 800 cm −1 into three subpeaks with a Monte Carlo method. Several characteristic parameters of reverse microemulsions were calculated on the basis of measurements of their kinematic viscosity. A different influence of concentration of sodium cholate on the binding constant and association degree of optical probes (o-nitroaniline and methyl orange respectively) to ethylene oxide groups of nonionic surfactant was observed. It was found that the bound water fraction, the binding constants and association degrees, the relative density of water pockets, etc. change their values passing through an extremum under the influence of sodium cholate.

In this study a solvent extraction method is used to investigate the succesive removal of a binary mixture of the cationic dyes Basic Yellow-2 (BY) and Basic Blue-26 (BB) from textile effluents by the anionic surfactant sodium dodecylsulfate (SDS) and isoamyl alcohol as an organic solvent. The dye ions are encapsulated in the core of the reverse micelles which remain in the organic phase and are subsequently separated from the aqueous phase resulting in significant removal of dyes. The effects of different parameters such as the concentration of surfactant, dye concentration, pH, temperature, salt concentration etc. have also been studied in the present work. The removal efficiency of dyes increased with increasing surfactant concentration and decreasing dye concentration. UV-visible absorption spectra were analyzed to evaluate the state of the dyes in bulk water before and after extraction with reverse micelles. In addition, the dyes were recovered successively by backward extraction and then reused. TEM analyses were carried out to determine the size of reverse micelles and shape of the formed clusters.

This study is aimed to examine the quality of beauty soap bars available to the consumers in Pakistan. A range of soap bars manufactured by local small-scale manufacturers from Pakistan were analyzed for their physiochemical properties such as pH, foaming, total fatty substances, matter insoluble in alcohol, free fatty acids, total alkali and moisture contents. The quality of the Pakistani local soap brands was compared to that of imported soaps or those made by multi-national conglomerates. The products were examined following the national standards set by Pakistan standards and quality control authority (PSQCA). The results showed that pH and total alkali level in the local beauty soaps was ((9,40–9,75) ± 0,03) and ((0,100–0,120) ± 0,02). The values of other physiochemical properties were: total fat matter ((62–71) % ± 0,50) %), matter insoluble in alcohol ((15–21) % ± 0,32 %), free fatty acid ((0,05–0,275) % ± 0,01 %) and moisture content ((10–16) % ± 0,50 %). The results demonstrate that Pakistani locally made soap products showed a relatively low amount of total fatty matter as defined by PSQCA and are required to improve their quality in terms of total fat matter. The products made by multi-national companies were superior for most of the examined features.

Cationic polyacrylamide (CPAM) was prepared in aqueous solution by free radical polymerization of methacryloyloxy ethyl trimethylammonium chloride (DMC) and acrylamide (AM). A redox initiator system was used. The structure of CPAM was characterized by IR and 1 H NMR. The intrinsic viscosity and cationicity of CPAM were measured by an Ubbelohde viscometer and titration experiments, respectively. It was found that at the same concentration, the intrinsic viscosity decreases as the cationicity increases. The antistatic properties of CPAM on polyester fabric, the combability of hair, the flocculation on diatomaceous earth in a simulated sewage system and the thickening effect in solution were investigated. The results show that the higher the concentration, cationicity and intrinsic viscosity of CPAM, the better the thickening effect and the better the combability, the antistatic and flocculation properties. Therefore, the production of CPAM with high intrinsic viscosity and cationicity is important for an enhanced application performance.

A single borate ester additive sometimes fails to meet the requirements of modern working conditions, it needs two or more additives for the use. Two N-containing heterocyclic borate esters, 2-(1H-benzotriazol-1-yl) ethyl bis(2-aminoethyl) borate (BEB) and bis-(2-amionethyl) (2-benzothiazol-2-ylthio)ethyl borate (MEB) have been synthesized. Their tribological properties were studied by a four-ball tester after mixing with tricresyl phosphate (TCP) in rapeseed oil (RSO). The results show that these complex additives have strong synergistic effects on load carrying and anti-wear properties. At a mass ratio of BEB (MEB) to TCP of 0.5:0.5, the load carrying capability (P B value) of RSO can be improved by 160.6 % and 204.2 %, respectively. At the same mass ratio, the load carrying capability of the complex additive from the TMx series (MEB with TCP) was better than that of the TBx series (BEB with TCP). The anti-wear effect of TBx was better than that of TMx at high load. The friction reduction of 196 N showed little difference because of the small difference in physical adsorption capacity between TCP and BEB (MEB). The analytical results of Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS) on the worn steel ball surfaces showed that the complex additives were adsorbed on the lubricating surface and formed a stable protective film during the sliding process due to absorption and tribochemical reactions between the borate ester, TCP and metal surface which helped to improve the tribological properties of RSO.