Linear Alkylbenzene Sulfonate Solution Research Articles

Surfactant Linear Alkylbenzene Sulfonate Effect on Soil Cd Fractions and Cd Distribution in Soybean Plants in a Pot Experiment

A pot experiment was conducted to study the effect of an anionic surfactant linear alkylbenzene sulfonate (LAS) application on cadmium (Cd) fractions in soils and Cd distribution in different tissues of soybean ( Glycine max)plants as well as soil pH. Soil samples were treated with three levels of Cd (0, 5, and 10 mg kg −1) and five levels of LAS (0, 5, 15, 50, and 100 mg L −1). Results indicated that compared to the control soils (no Cd and no LAS treatment), soil pH increased and available Cd decreased in the soil treated with external Cd and watered with LAS solutions. Meanwhile, soil exchangeable Cd and Cd bound to carbonates decreased; Cd bound to amorphous iron and manganese oxides and Cd bound to organic matter increased. In addition, LAS application could reduce enrichment of Cd in soybean plants, resulting in decreased Cd in the soybean plants. Thus, suitable LAS application could decrease bioavailability and mobility of soil Cd.

Combined Photochemical and Biological Processes for the Treatment of Linear Alkylbenzene Sulfonate in Water

In this study, the effects of photochemical pre-treatment (pilot-plant UV/H2O2 process) of linear alkylbenzene sulfonate (LAS) on its subsequent biological treatment were examined. It was observed that the photochemical pre-treatment of the LAS solution did not increase its biodegradability. Moreover, the effects of acclimated microorganisms on the biodegradability of the LAS solution were also studied. It was observed that the acclimated activated sludge increased the biodegradation of the LAS solution. However, due to the presence of some intermediates in the effluent of the photoreactor, the biodegradability of this effluent was less than the biodegradability of the untreated LAS solution with the same concentration of the LAS in the effluent of the photoreactor.

Photocatalytic Treatment of Linear Alkylbenzene Sulfonate (LAS) in Water

The photocatalytic degradation of aqueous linear alkylbenzene sulfonate (LAS) was studied. Two different photocatalysts, Degussa P25 TiO2 and Hombikat UV 100 TiO2, were used to degrade aqueous linear alkylbenzene sulfonate in slurry batch photoreactors. For a 100 mg/L LAS solution based on first–order rate constants, the optimum photocatalyst loading for Degussa P25 TiO2 was 4.0 g/L, while for Hombikat UV 100 TiO2 it was 2.0 g/L. The photoactivity of Degussa P25 TiO2 it was higher than that of Hombikat UV 100 TiO2 for the treatment of LAS. A mixture of both photocatalysts did not improve the LAS degradation rates in batch experiments. Combination of Degussa P25 TiO2 and 600 mg/L H2O2 along with irradiation with UV light at either 254 or 365 nm did not improve the LAS degradation rates over the photocatalytic or photolytic processes individually.

Effects of pilot‐plant photochemical pre‐treatment (UV/H2O2) on the biodegradability of aqueous linear alkylbenzene sulfonate (LAS)

The effects of the photochemical pre‐treatment by using a pilot‐plant UV/H2O2 process on the biodegradability of aqueous linear alkylbenzene sulfonate (LAS) were studied. It was observed that the photochemical pre‐treatment of the LAS solutions by UV‐254/H2O2 increased the biodegradability of LAS solutions. Aqueous solutions with higher concentrations of LAS (> 100 mg/L) were non‐biodegradable. The ratio of BOD5/COD of the pre‐treated LAS solutions was increased, indicating that the pre‐treated LAS solutions were more biodegradable. This ratio was improved as the LAS solutions were more pre‐treated. Also, the biodegradability factor for the pre‐treated LAS solutions was increased as the time of the photochemical pre‐treatment was increased.

Dye–surfactant interaction: solubilization of styryl pyridinium dyes of varying alkyl chain in alfa-olefinic sulfonate and linear alkyl benzene sulfonate solutions

Cationic dyes, like alkyl styryl pyridinium dyes, are found to interact with anionic surfactant systems differently according to their structural differences. The absorption and emission spectral data of the dyes in various organic solvents and in a wide range of surfactant concentration reveal a variation in the solubilization pattern of the dyes with varying alkyl chain at the pyridinium end. The existence of monomer and H/J-stacked dimers in aqueous medium as well as in surfactant media gets evidence from the spectral data. The difference in binding constant of the dyes with the surfactant aggregates is rationalized through the change in hydrophobicity of the dye due to change in alkyl chain.

Anaerobic biodegradation of linear alkylbenzene sulfonate (LAS) in upflow anaerobic sludge blanket (UASB) reactors.

The anaerobic biodegradation of Linear Alkylbenzene Sulfonate (LAS) was studied in Upflow Anaerobic Sludge Blanket Reactors (UASB). One reactor was fed with easily degradable substrates and commercial LAS solution during a period of 3 months (Reactor 1), meanwhile a second reactor was fed with a commercial LAS solution without co-substrate (Reactor 2) during 4 months. Both reactors were operated with an organic loading rate of 4-5 mg-LAS/l x day and a hydraulic retention time of one day. The LAS biodegradation was determined by full mass balance. LAS was analysed by HPLC in the liquid phase (influent and effluent streams of the reactors) as well as in the solid phase (granular sludge used as biomass). The results indicate a high level of removal (primary biodegradation: 64-85%). Biodegradation was higher in the absence of external co-substrates than in the presence of additional sources of carbon. This indicates that the surfactant can be partially used as carbon and energy source by anaerobic bacteria. Under the operating conditions used, inhibition of the methanogenic activity or any other negative effects on the biomass due to the presence of LAS were not observed. The methanogenic activity remained high and stable throughout the experiment.

Wet Air Oxidation of Aqueous Solutions of Linear Alkylbenzene Sulfonates

The semibatch wet air oxidation of aqueous solutions of linear alkylbenzene sulfonate (LAS), an anionic surfactant, has been investigated at temperatures of 453 and 473 K, total pressures of 2.8 and 3.3 MPa, and reaction times varying from 40 to 390 min. The concentration of total organic carbon, chemical oxygen demand, and active detergent were followed throughout the reaction, the main intermediates formed were identified by means of electrospray-MS and high-performance liquid chromatography, and a mechanism describing LAS oxidation was proposed. It was found that LAS could easily be oxidized at 473 K to yield a group of molecules with short alkyl chains that do not behave as active detergents. The segments of alkyl chains broken off the reaction intermediates appear primarily as short-chain organic acids that are resistant to total oxidation. Oxidation experiments were also performed at 473 K with solutions of 4-hydroxybenzene sulfonic acid, an intermediate formed during the oxidation of LAS. It was fo...

Effect of Calcium Ions on Detergency III

The gradual precipitation of surfactant calcium salts was observed from solutions of linear alkylbenzene sulfonate (LAS) and α-sulfohexadecanoic acid methyl ester (SFM) where either was the sole surfactant in the presence of calcium ions. When LAS and SFM were present in the same solution, their precipitation was retarded and detergency enhanced. In the present study, an investigation was made of interactions between LAS and SFM. Based on thermodynamic considerations, the influence of SFM on the alkyl distribution of LAS as monomer was predicted. It was considered that, should a mixed aggregate of LAS and SFM be formed in the presence of calcium ions, the surfactant with the lower alkyl chain of LAS would constitute the greater part of the monomer. The alkyl length distribution of monomeric LAS was determined from the initial permeation rate of each LAS constituent in solution in a semipermeable tube, this rate being assumed proportional to monomer concentration. LAS monomer was measured in various solutions with and without calcium ions or SFM. Experimental data confirmed the formation of mixed aggregates of LAS and SFM which we concluded to be responsible for preventing the precipitation of LAS and SFM in solution containing calcium ions.

Biochemical and Pathomorphologic Studies for Safety Evaluation of Synthetic Detergents

AbstractImmersion tests were performed with linear alkyl benzene sulfonate (LAS) for the evaluation of the consumer safety of household detergents. The test showed marked biochemical and pathomorphologic alterations in the skin of guinea pigs on exposure for 7 consecutive days for up to 90 min in 1% neutralized LAS solution. Increase in the activity of histidine decarboxylase and decrease in -SH, histamine, and lactic dehydrogenase along with hyperkeratinization and discontinuity in epidermis in the skin of the guinea pigs treated with LAS were found.

Effect of protein cationicity on inhibition of in vitro epidermis curling by alkylbenzene sulfonate

Dilute solutions of linear alkylbenzene sulfonate (LAS), an anionic detergent, caused strips of epidermis to twist and curl. Four commercially available protein hydrolysate mixtures and a synthetic peptide, when added to the LAS solution, countered this to varying degrees, from the epidermis being as distorted as the LAS control to as flat as the water control. A study to determine the contribution of these materials’ positive charge (isoionic point) to in vitro epidermis flatness demonstrated a direct linear relationship, i.e., the more positive the charge the flatter the epidermis. This effect was even discernible in a 1 to 30 ratio of a highly cationic protein to detergent. One of the protein mixtures, which was then fractionated according to charge, showed a linear regression correlation coefficient of 0.86 for this relationship. Because the twisting and curling of epidermis has been demonstrated to be related to human skin irritation, these results suggest that positively charged proteins might increase the mildness of solutions containing anionic detergents.

Study of the Effect of Linear Alkylbenzenesulfonate on Fishes

This study was undertaken to know the toxicity, distribution of sodium linear alkylbenzenesulfonate (LAS) and the histological feature of fish exposed to LAS or LAS-gluten solution. In LAS-gluten solution the apparent acute toxicity of LAS to fish was decreased. In distribution study using 14C-labeled LAS, it was found that in LAS solution the radio-activities were observed mainly in skin and gill, and in LAS-gluten solution the activities in these parts of fish were lower. But the radio activity in bile was higher in LAS-gluten solution than in LAS solution. Radio activity in whole body of fish was lower in LAS-gluten solution than in LAS solution. Histological investigation showed that gill and intestine and then kidney and liver were affected. Those histological effects of each organ occurred more faster in LAS solution than in LAS-gluten solution. The radio-active substance in the bile was detected as a metabolic product of LAS by TLC method.

Tallow alkanolamides: Preparation and effect on surfactant solutions

AbstractOxyalkylation of N‐(2‐hydroxyethyl) amides and N,N‐bis‐(2‐hydroxyethyl) amides gave products which were valuable as detergent additives and detergent intermediates. Oxyalkylation of simple amides was difficult to carry out, and the product contained large quantities of unreacted amide which had an adverse effect on surfactant properties. Amides with short oxyalkyl chains and long fatty chains were not soluble by themselves but were solubilized by aqueous detergent solutions and had characteristic “Krafft Points.” This temperature, at which the mixed solution became clear, was independent of detergent used, amide to detergent ratio up to 1.4, total concentration, and water hardness. Krafft point of poorly soluble detergents such as sodium octadecyl sulfate and disodium α‐sulfostearate was lowered by mixing with alkanolamides. N,N‐Bis‐(hydroxyethyl)‐hexadecanamide and the oxyalkylated products of N,N‐bis‐(hydroxyethyl) hexadecanamide and N,N‐bis‐(hydroxyethyl) octadecanamide increased the viscosity of solutions of linear alkylbenzene sulfonate and sodium dodecyl sulfate in the same was as the N,N‐bis‐(hydroxyethyl) amide prepared from coconut oil. Foam stabilizing properties ere observed for some of oxyethylated amides. One per cent N,N‐bis‐(2‐hydroxyethyl) oleamide and 2‐(2‐hydroxyethoxy)‐ethyloleamide formed petrolatum‐water emulsions which were stable for more than a month.