Band 50, Heft 2

The aim of this study is to investigate the interaction of a cationic surfactant tetradecyltrimethyl ammonium bromide (TTAB) on the electronic absorption spectra of azo dye Reactive Orange 16 (RO16) and to observe the effects of the kind and concentration of electrolytes on these interactions by means of UV-Vis spectroscopy in submicellar and micellar concentration range at a certain temperature (303 K). TTAB affects the electronic absorption spectra of dye solution that is dye-surfactant interaction results into formation of complex and therefore, a decrease in maximum absorption spectra (1.577 at 494 nm). The electrolyte anions cause an increase on the absorbance of TTAB–RO16 ion-pair complex in the following order: Br– > Cl– > SO42– > NO3– > CN– and also for cations; Na+ > K+ > NH4+ > Mg2+. The increase or decrease on absorption spectra of RO16-TTAB solution depends on concentration range of the electrolyte added.

The physicochemical and colloid-chemical characteristics of a developed detergent were studied. Due to synergism of surfactants of different nature the wetting and emulsifying ability as Well as the detergency of the developed detergent are very high.

Oxidation of organic molecule by metal is very important. Selective oxidants require non aqueous media, which is toxic and hazardous. L-methionine is oxidized to industrially important methyl thiol in micellar media by chromic acid. The overall reaction follows a first order dependency on substrate and hexavalent chromium and second order dependency on hydrogen ion. Here, reverse micelle formation is observed. TX-100 increases the rate where as SDS retards the rate of oxidation.

In this work, detersive power (soil removal) was studied after washing a soiled wool fabric with addition of a non-toxic solvent microemulsion to conventional washing detergent formulations with the aim of improving the performance of the conventional washing. The non-toxic solvent used was dimethyl sulfoxide micro-dispersed with an amphoteric surfactant as emulsifier. The fabric was washed with biodegradable non-ionic surfactants such as an alcohol ethoxylate (AE) with 7 m E. O. and an alkyl polyglucoside with 1.4 glucoside groups (APG). The fabric used was EMPA 107 wool (soiled with standard impurities). The non-ionic surfactants were used separately and in mixture in varying proportions for the washes. Given the large amount of impurities in the wool fabric, sodium carbonate and sodium chloride were used to attain a suitable pH to avoid damaging the wool. The fabric was washed at low temperature with water of different hardness (20 °hf, 30 °hf and 40 °hf). In addition, the sequestering agent DTPMP was used to obtain an improvement of detersive power at the hardness of 40 °hf.

Adsorptive removal of Ni 2+ from aqueous solution by low cost cellulosic adsorbent was investigated with respect to adsorption kinetics and adsorption isotherm. Adsorbent was characterized by BET surface area, SEM, EDX, FTIR and Zeta potential technique and reported earlier. The surfaces contain carbonyl and hydroxyl functional groups, which act as binding sites for Ni 2+ ion. Adsorption kinetics of Ni 2+ was tested by first order, Elovich, parabolic diffusion and Bangham kinetic equations. Thermodynamic parameters like Δ H ≠ , Δ S ≠ and Δ G ≠ were calculated from the kinetic data. The rate of adsorption was high at high adsorption temperature. Positive values of Δ S ≠ reflect some structural exchange among the active site of the adsorbent and metal ion. Freundlich, Langmuir, Temkin isotherms and distribution coefficient were found fit to the adsorption isotherm data.

Microemulsions (O/W, W/O and B.C.) formed in Tween80/ethanol/ethyl butyrate/water system were identified by phase diagram determination and conductivity measurement at 25 °C. Comparative studies were made, by means of dynamic light scattering, viscosity and UV measurements, on (1) the difference of viscosity and particle size between β-carotene solubilized and empty microemulsions; (2) the effects of sunlight and temperature on the stability of β-carotene both in microemulsion and in ethyl butyrate solution. It is shown that in β-carotene loaded systems, the mean particle diameter is 82.13 nm and the size distributions were quite broad (PDI = 0.35). Smaller particles (31.75 nm) and narrower particle size distribution of droplets (PDI = 0.14) were obtained in empty microemulsion. The sizes of droplets of both β-carotene loaded and empty ones get shrunk sharply in the first 3 days, then keep remarkable stability even for a month. β-carotene solubilized in microemulsion is much more stable than that solubilized in ethyl butyrate solution.

Critical Micelle Concentration is a fundamental property on studying behaviour of surfactants. In general terms it depends on temperature, pressure and on the existence and concentration of other surface-active substances and electrolytes. In this work it is presented a model based on Artificial Neural Networks to obtain predictive values of Critical Micelle Concentration (CMC) of some non-ionic surfactants. ANN model works using topological descriptors of the molecules involved together with already known CMC values and provides predictive values for new cases. It is proposed a specific architecture for ANN consisting of an input layer with seven neurons, one intermediate layer with fourteen neurons and one neuron in the output layer. This ANN model seems to be a good method for forecast CMC.

Liquid phase oxidation of alcohol to corresponding aldehyde and ketone in solvent free condition with molecular oxygen, at mild temperature and pressure was studied in a self-designed three necked batch reactor, using iron supported on zirconia as a catalyst. The catalyst was prepared by incipient wetness technique, reduced in hydrogen flow and characterized by X-ray Diffractometry, Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, Thermo Gravimetric and Differential Thermal Analysis, Fourier Transform Infrared Spectroscopy, particle size analyzer, surface area and pore size analyzer. Effects of different parameters such as temperature and time on the rate of reaction were studied. It was observed that the reduced catalyst showed higher catalytic activity and selectivity than the unreduced catalyst for the liquid phase oxidation of alcohols to corresponding aldehydes and ketones.

Biosurfactants are gaining importance due their large potential for industrial applications and their eco-friendly nature. The properties of biosurfactants can vary with their structure which is dependent upon strain, cultivation conditions and carbon source. A mannosylerythritol lipid (MEL) is one of the simplest biosurfactants with a well-defined structure produced by Pseudozyma antarctica (ATCC 32657). The study includes the surfactant properties of MEL produced on soybean oil with sucrose as substrate. MEL showed surface activity at very low concentrations. The various properties were explained on the basis of the structural similarity between MEL and Gemini surfactant. The performance properties of SLS like foaming, emulsification and wetting were improved when SLS was partially substituted (5–20 %) by MEL. Based on the study, MEL can be used in various cosmetic products like shaving creams, skin creams and lotions, where MEL will not only enhance foaming property but also provide moisturizing and healing properties on skin.

The aim of the present study was to optimise the production of a biosurfactant by a new strain of Pseudomonas cepacia CCT6659 with aid of a combination of central composite rotatable design (CCRD) and response surface methodology (RSM). The factors selected for optimisation of the growth conditions were canola waste frying oil, corn steep liquor and NaNO3 substrate concentrations. Surface tension was chosen as the response variable. All factors studied were important within the ranges investigated. The empirical forecast model developed through RSM regarding effective nutritional factors was adequate for explaining 89 % of the variation observed in biosurfactant production. Maximal reduction in surface tension of 26 mN m–1 was obtained under the optimal conditions of 2 % waste frying oil, 3 % corn steep liquor and 0.2 % NaNO3. The accumulation of isolated biosurfactant increased from 2 g L–1 to 8.0 g L–1 under these conditions, demonstrating that the factorial design is adequate for identifying the optimal conditions for biosurfactant production.