Alkylbenzene Sulphonate Research Articles

A regime map for stages in high shear mixer agglomeration using ultra-high viscosity binders

Abstract The porosities and saturation levels of high shear mixer agglomerates, containing zeolite powder bound with a highly viscous surfactant paste [linear alkylbenzene sulphonate (LAS)], were determined as a function of mixing time by performing a series of simple liquid immersion experiments. The results validated, to a certain extent, the use of the secondary break point ( P 2) obtained from a logarithmic tapping analysis of the bulk material as a measure of the individual granule plastic yield during tapping. The bulk material tapping parameter P 2 was also used to represent the dynamic yield stress ( Y g) of the granules. This enabled the determination of the Stokes deformation number (St def = p gU b c/2Y g) for the granules, which was employed on an agglomeration regime map as described by Iveson et al. Powder Technol. 117, 83-97 (2001). It was found that the variation in granule morphology with time was reflected accurately by the parameter trajectory on the regime map. The results were in accord with the previously reported agglomeration mechanism for this system.

Influence of Process Parameters on the Tapping Characteristics of High Shear Mixer Agglomerates Made with Ultra-High Viscosity Binders

Agglomeration by high-shear mixing of linear alkylbenzene sulphonate (LAS) paste and zeolite powder is investigated in terms of the initial temperature of the paste (and hence its apparent viscosity), impeller speed and volume ratio of paste to powder. Variations in these parameters chiefly affect the rate of development of the different regimes in the agglomeration process. The regimes are quantitatively described by the bulk granular aerated and tapped densities, which are determined using an automated tapping technique. The bulk tapping data are analysed using the Kawakita equation and a logarithmic compaction approach. A number of bulk compaction parameters (including the Hausner ratio) are obtained, and their variation with mixing time is discussed. Comparison of the tapping parameters, along with optical micrographs and granule size distribution data, confirmed that similar agglomeration mechanisms are occurring for each system studied. The agglomeration process features two main mechanisms, namely binder distribution followed by granule consolidation and coalescence. The results indicate that it is possible to assign scaling factors to predict the mixing time required to obtain a designated regime. The scaling factors employed for the variation in paste apparent viscosity, impeller speed and paste amount are explained physically in terms of power law functions, Froude numbers and adsorption/ viscous energy dissipation mechanisms respectively.

Effect of linear alkylbenzene sulphonate (LAS) on non-specific defence mechanisms in rainbow trout ( Oncorhynchus mykiss)

Linear alkylbenzene sulphonate (LAS) is among the most widely disseminated xenobiotics to enter waste streams and the aquatic environment. In the present investigation, we present a novel approach to evaluate in toxicity of LAS. The effects of sublethal levels (0.2 and 0.4 mg/l) of LAS on non-specific immune system, phagocytosis, respiratory burst and lyzosyme activity, and specific growth rate in the rainbow trout, Oncorhynchus mykiss, during a 54-day exposure were examined by a static bioassay test procedure. The phagocytic activity of leukocytes from fish exposed to 0.4 mg/l LAS statistically decreased compared with the control fish values. No significant reductions were observed in the extra-intracellular respiratory burst and lysozyme activities after exposure to LAS at any of the concentrations tested. The final body weight in fish groups exposed to the LAS were found to be significantly lower than in the control. The specific growth rate results also supported the result above. The results of this study showed sublethal doses (0.2–0.4 mg/l) of LAS caused to statistically insignificant supression of non-specific immune system mechanisms excluding phagocytosis in fish at laboratory conditions. These doses of LAS may produce potential synergism on immune system when presented with other environmental pollutants.

Inhibition effects of LAB and LABS on iron corrosion in chlorine solutions at different temperatures

In this study, the corrosion of iron is studied using gravimetric and potentiodynamic polarization method at different temperatures and at pH 9 level in 0.1 M NaCl solutions containing different concentrations of linear alkyl benzene (LAB) and linear alkyl benzene sulphonate (LABS). Potentiodynamic polarization experiments show that corrosion rate in presence and absence of LAB and LABS increases with increasing temperature from 303 to 338 K. The corresponding activation energies are determined. Moreover, the protective film formation on metal surface is investigated by means of FTIR. It has been concluded from the results that LABS is more effective in preventing iron corrosion than LAB.

Acute toxicity and genotoxicity of five selected anionic and nonionic surfactants

The results of four toxicity bioassays of selected anionic and nonionic surface active agents were presented. Three widely used anionic surfactants that belong to alkyl sulphates (AS), alkylbenzene sulphonates (LAS) and alkylpolyoxyethylene sulphates (AES) as well as nonionic surfactants: polyoxyethylene alkyl ethers (AE) and polyoxylethylene alkylphenyl ethers (APE) were tested. Three different toxicity assays to aquatic organisms: Physa acuta Draparnaud, Artemia salina and Raphidocelis subcapitata were applied. Additionally, the genotoxicity test with Bacillus subtilis M45 Rec− and H17 Rec+ strains was performed. The obtained results showed that none of the surfactants studied was genotoxic at the concentration 1000 mg l −1. On the basis of toxicity tests to aquatic organisms all tested anionic surfactants were harmful (LC50 between 10 and 100 mg l −1), whereas nonionic ones were toxic (LC50 between 1 and 10 mg l −1) or even highly toxic (LC50 below 1 mg l −1). Moreover, the bigger was the molecular weight of the tested compound, the higher toxicity was observed.

Sublethal effects of linear alkylbenzene sulphonate on larvae of the seabream (Sparus aurata): histological approach.

Neonate (< 24 h) larvae of the seabream, Sparus aurata, were exposed to sublethal concentrations (0.1-1.0 mg x L(-1)) of the anionic surfactant Linear Alkyl-benzene Sulphonate (LAS) for 72 h under laboratory conditions. The first histopathological changes, such as peri-yolk sac edema, were observed at concentrations of 0.2 mg x L(-1). Higher exposure concentrations provoked disorganisation of the nervous system, trunk musculature and trophoblastic sincitium as well as in the digestive epithelium. Immunohystochemical CYP1A analysis, however, was not shown to be an adequate indicator of sublethal effects produced by exposure to this type of anionic surfactant

Modelling the degradation of low concentration pollutants in membrane bioreactors

This paper deals with the development of a description of membrane bioreactor systems, focussing on wastewater treatment and removal of specific low concentration persistent organic pollutants (e.g. persistent polar pollutants--P3 compounds). In the present work we offer a basic model, adapted to Membrane Bioreactor (MBR) conditions, which reflects the biodegradation of recalcitrant (organic) substances. We put a particular focus on organic aromatic pollutants and demonstrate a model parameter estimation approach, with experiments carried out for linear alkylbenzene sulphonates (LAS).

Linear sulphonate detergents as pour point depressants

AbstractOil‐soluble metallic sulphonate detergents have been extensively used in automobile lubricants to keep engines clean and to extend their useful life. Calcium alkylbenzene sulphonate is widely used in the lubricant industry as a detergent. However, the authors have discovered that, uniquely, linear sulphonate detergents can play another role in lubricants, namely to depress the pour point of mineral oils. The authors have studied the relationship between the molecular structures of sulphonate detergents and pour point depression, and it has been found that, in order for a sulphonate detergent to be a pour point depressant (PPD), it must have a linear hydrocarbon tail. Other factors, such as the metal type, e.g., Ca or Mg, and the degree of overbasing, are not critical for pour point depression activity. A model is proposed to explain why sulphonate detergents with linear hydrocarbon tails can function as pour point depressants.

Potential of coacervation processes for the extraction of amphiphiles (linear alkyl benzenesulphonates) from sewage sludge samples prior to liquid chromatography

A new approach was developed for the monitoring of linear alkyl (C10–C13) benzenesulphonates (LASs) in sewage sludge. It was based on their extraction with the anionic surfactant sodium dodecanesulphonate (SDoS) that undergoes coacervation under acid conditions. The target compounds formed mixed aggregates with SDoS by ideal hydrophobic interactions which made possible the breakdown of LAS–sludge interactions and provided high extraction yields. Variables affecting extraction were optimised using a fortified dehydrated sludge. Recoveries for LASs were found independent on the length of alkyl chain. Liquid chromatography–fluorimetry was used for separation and detection of LAS homologues. Detection limit for LAS in the sludge was 5mg/kg. Concentration levels of total LASs in activated and dehydrated sludge collected from two different sewage treatment plants were in the range 0.26–0.56g/kg with LAS homologues ranging from 29 to 223mg/kg. The method did not require clean-up or preconcentration steps.

Toxicity Testing of Wastewater and Sewage Sludge by Biosensors, Bioassays and Chemical Analysis

AbstractFor Abstract see ChemInform Abstract in Full Text.

Biogeochemistry of Aromatic Surfactants in Microtidal Estuaries

This paper summarizes several studies on input, distribution, and fate of two different types of aromatic surfactants, the anionic linear alkylbenzene sulphonates (LAS) and nonionic alkylphenol polyethoxylates (APnEO), in a karstic estuary characterized by sharp salinity gradients. A combination of reversed-phase and normal-phase HPLC analysis followed by spectrofluorimetric detection allowed detailed characterization of homologue and oligomer compositions of aromatic surfactants in wastewater and estuarine waters. The distribution patterns of homologues and/or oligomers in the wastewater plume reveal a significant alteration of the original composition of both surfactants by biotransformation and physico-chemical partitioning. The vertical distribution of surfactant residues in the estuarine water column is characterized by pronounced maxima at the air–brackish water and brackish water–sea water interface. The brackish water–sea water interface is a very efficient barrier, which prevents spreading of surfactants into the deeper layers. In addition, the interface seems to be a site of high biological activity, including biotransformation of surfactant residues. As a consequence, this layer can contain enhanced levels of lipophilic metabolites of APnEO. Biotransformation is the main mechanism for the removal of both surfactant classes from the water column. However, our studies suggest that a significant percentage of surfactant residues discharged into the stratified estuaries reaches the coastal sea due to the incomplete removal in the estuary. This situation is a consequence of a rather fast flushing of the brackish layer and a very slow biotransformation kinetics in the saline layer, especially in the winter period.

Technical, occupational health and environmental aspects of metal degreasing with aqueous cleaners.

Aqueous cleaners used for metal degreasing are detergent formulations containing surfactants (such as linear alkylbenzene sulphonates, alkylphenol ethoxylates or alcohol ethoxylates), builders (such as hydroxides, phosphates or silicates), sequestrants (such as EDTA or NTA), anti-corrosive agents (such as ethanolamines), solvents (such as glycol ethers or d-limonene) and other specialty additives. Generally sold as concentrates, they are typically diluted between 3 and 20 times in water, leading to solutions containing only a few per cent active products. The cleaning efficiency depends on physicochemical phenomena such as wetting, solubilization, emulsification, dispersion, sequestration and saponification, and is enhanced by thermal and mechanical energy. Cleaning equipment is based on spraying or immersion of the parts and may include drying and rinsing steps. Because of the complexity and variability of the mixtures, the occupational health and environmental evaluation of aqueous cleaners is based on the study of their components. Aqueous cleaners are generally believed to present a low risk to workers' health and to the environment. However, some anionic surfactants and strong alkalis are skin and eye irritants, ethanolamines are allergenic and several glycol ethers of the ethylene glycol family are proven systemic toxicants that are easily absorbed through the skin. Although most components of aqueous cleaners are biodegradable and of low ecotoxicity, alkylphenol ethoxylates degrade into persistent and toxic compounds. Phosphates, if released directly into the environment, may cause eutrophication of rivers and lakes. Waste recycling or treatment by specialized facilities is usually required for spent solutions containing contaminants such as oils and heavy metals. From a technical, toxicological and environmental standpoint, aqueous cleaners can be used successfully to replace traditional organic solvents used in metal degreasing.

Tapping characterisation of high shear mixer agglomerates made with ultra-high viscosity binders

The time-dependent consistency regimes produced during high shear mixing of zeolite powder and an ultra-high viscosity binder (linear alkylbenzene sulphonate (LAS) paste) were quantitatively described by the bulk aerated and tapped densities, which were determined using both hand and automated tapping techniques. The Hausner ratio was calculated, providing information on the inter-granular friction and cohesivity of the granular bulk as a function of mixing time. An agglomeration mechanism is proposed based upon the trend in Hausner ratio, which was confirmed by optical micrographs and granule size distribution data. The suggested mechanism comprises layering of zeolite particles onto an LAS paste core, breakage of powder-coated paste granules, micro-mixing of the granules, granule growth via coalescence, and finally granule consolidation.The bulk tapping data were analysed using the Kawakita equation and a logarithmic compaction approach. Three distinct compaction regions were identified with the latter analysis, the first of which was related to weak agglomerate break up, and the second and third to granule movement involving elastic and plastic granule deformations respectively during rearrangement. A variety of bulk compaction parameters were obtained, and their variation with mixing time is discussed. At least 10 times as many automated taps were required to reach the final tapped density in comparison to the hand-tapping procedure, and the final density was always lower than that obtained via hand-tapping. When the automated tapping data were scaled in terms of total number of taps and analysed, the parameters describing the bulk compressibility showed similar trends to those obtained from the hand-tapping procedure.

Toxicity testing of wastewater and sewage sludge by biosensors, bioassays and chemical analysis

Toxicity testing has grown steadily in recent years, being a useful tool in environmental risk assessment. This review highlights different bioassays and recently developed biosensors based on acute toxicity measurements. Emphasis is placed on the use of combined approaches involving chemical analysis for the characterization and identification of complex toxic wastewater effluents and sewage sludge. Fractionation schemes that combine sample preparation and chemical analysis with biological measurements are presented and reviewed. Bioassay-directed chemical-analysis protocols involve solid phase extraction (SPE), followed by chromatographic techniques, such as liquid chromatography-mass spectrometry (LC-MS) or gas chromatography-mass spectrometry (GC-MS). Toxicity testing is carried out by either bioluminescence inhibition methods or a whole-cell bacterial biosensor. Other biological toxicity tests are also reviewed. Examples of using different bacterial acute toxicity assays are presented for phenols, polyethoxylate surfactants, linear alkyl benzene sulphonates (LASs), naphthalene and benzene sulphonates, polycyclic aromatic hydrocarbons (PAHs), pesticides and pharmaceutical drugs.

In vitro acute toxicity of anionic surfactant linear alkylbenzene sulphonate (LAS) on the motility of gilthead (Sparus aurata L.) sperm.

This paper describes the acute toxicity of a known anionic surfactant, Linear Alkylbenzene Sulphonate (LAS), on the quality of gilthead Sparus aurata L. sperm. The parameter used to judge exposure effectiveness was sperm motility as well as its fertilizing ability after being combined with unexposed gilthead eggs. Preincubation of sperm suspensions with concentrations of LAS of 0.1, 0.5, 1, 2 and 4 mg/L caused decrease in sperm motility and fertilizing ability. In this respect, percentages of motile sperm were respectively 89.8+/-9.8, 81.7+/-16.3, 69.5+/-21.3, 57.1+/-19.1 and 21.2+/-10.9%. With regard to the percentage of fertilization success, the results were 85.7+/-8.1, 75.1+/-20.2, 62.9+/-19.7, 52.7+/-19.2 and 14.2+/-7.9% respectively. At concentrations of LAS of 0.5 mg/L or higher, the differences in both percentage of motility and fertilizing ability with controls were significant (p<5%). Although extrapolation from the laboratory to the field requires caution, the results of this work demonstrated that low-level surfactant pollution may impact directly on reproduction of the free gametes (sperm) released into water. It may lead to a long-term decline and eventual extinction of gilthead populations in nature when they are located close to effluents that are either untreated or receive inadequate secondary treatment. It is also quite important because this species constitutes an important link in the food chain and its death via exposure to surfactants may imbalance the littoral ecosystem.

Assessment of bioconcentration and secondary poisoning of surfactants

The relevance of the bioconcentration behaviour of surfactants for the secondary poisoning assessment and for the risk characterisation in the bird and mammalian food chain has been investigated. The approach used is described in the recently revised EU Technical Guidance Document for the Risk Assessment of Substances. The results demonstrate that, based on experimentally derived bioconcentration factors, environmental concentrations and effects in animals, there is a clear level of safety for both linear alkylbenzene sulphonate (LAS) and alcohol ethoxylates (AE), the most important surfactants by volume.To assess other surfactants used in detergents, a bioconcentration factor that would need to be attained for secondary poisoning to be of concern has been estimated from predicted environmental concentrations and known long-term effects data in animals. Based on the known structural similarity of these surfactants to LAS and AE and the ubiquitous nature of the enzymatic systems that are present in biotransformation processes in organisms, it is concluded that bioconcentration of these surfactants to these levels is highly unlikely. Therefore the potential for secondary poisoning effects of these surfactants is extremely low.

Combination ecotoxicity and testing of common chemical discharges to sewer using the Vibrio fischeri luminescence bioassay.

In order to investigate possible synergistic or antagonistic (more or less than additive) toxicity effects, mixtures of chemicals were tested in water using a microbial bioassay. Ten toxicants (3,4-dichloroaniline, 3,5-dichlorophenol, cadmium, chromium, copper, Lindane, linear alkylbenzene sulphonate, pentachlorophenol, toluene, zinc) were chosen on the basis of their common occurrence in industrial effluents within local waste water treatment plants. These toxicants also cover a wide range of modes of toxic action, namely, polar and non-polar narcosis, membrane disruption, respiratory disruption, uncouplers of oxidative phosphorylation, biochemical disruption and enzyme inhibition. Efficient screening for possible combination toxicity between toxicants involved testing the chemicals both singly and in triplet combinations. The triplets were based on four replicates of a balanced incomplete block design (BIB). A standardised Vibrio fischeri rapid toxicity bioluminescence assay was used. The combinations tested showed that only one mixture was found to be significantly more toxic than expected from the pure single-toxicant results. Two triplets were significantly less toxic. Further tests on the more toxic triplet showed that the effect was due to only one of the 45 pairs originally screened. It is concluded that synergistic effects in combinations of toxicants are rather rare in bioluminescence systems utilising common effluents discharged to sewer.

Biodisposition of linear alkylbenzene sulphonates and their associated sulphophenyl carboxilic acid metabolites in sea water

Abstract The present paper describes the results of the application of the biodegradation assay proposed by the United States Environmental Protection Agency “Biodegradability in sea water” Office of Prevention, Pesticides, and Toxic Substances 835.3160, in shaked flask, to linear alkylbenzene sulphonate (LAS), the synthetic surfactant with the highest consumption volume on a world-wide basis. The concentration of sulphophenyl carboxylic acids (SPCs) which are the main metabolites of LAS have also been monitored by high performance liquid chromatography. The experiment were conducted using water originating from the Bay of Cadiz (in the South West of the Iberian peninsula). The results indicate that LAS was rapidly biodegraded. SPCs were transiently produced during the process and they were biodegraded to levels below the limits of detection (136 μg / l ) after 42 days of assay. The kinetic of biodegradation of the surfactant and its biointermediates have been modeled; half-life times of 6.2 days for the primary biodegradation of LAS and of 9.6 days for the mineralization of the biointermediates were obtained.

Phthalates, nonylphenols and LAS in an alternately operated wastewater treatment plant—fate modelling based on measured concentrations in wastewater and sludge

The performance of an alternately operated activated sludge wastewater treatment plant (WWTP) has been investigated with respect to six phthalates, nonylphenol (NP) and nonylphenol diethoxylate (NPDE) and linear alkylbenzene sulphonates (LAS). Samples of raw sewage, primary and secondary sludge and treated water were collected during an 8-day period in May 1999 and analysed for dissolved and sorbed substances. To evaluate the system performance with respect to substance removal through biodegradation and sorption to sludge the measured data were applied in a model describing the different bioreactors as one single reactor, corresponding to the concepts of, e.g. SimpleTreat. The most abundant of the investigated phthalates was di-(2-ethylhexyl)-phthalate (DEHP) with a measured mean inlet flow of 240 g/ day . Two percent of this amount was found in the treated water, 70% was biodegraded and 28% was found in the sludge. For LAS the mean inlet flow was 20,300 g/ day , of which less than 1% was found in the treated water, 84% was biodegraded and 15% was found in the sludge. The mean inlet flow of NP and NPDE was 44 and 590 g/ day , of which 4% and 2% was found in the treated water, 80% was biodegraded for both substances, and 16% and 18% was found in the sludge, respectively. The WWTP removal of the investigated substances was thus high compared to other studies of conventional activated sludge WWTPs. The simple model set-up presents a strong tool for predicting substance removal and system sensitivity related to changes in the inlet conditions, such as concentrations and flow. Furthermore, it allows the inclusion of complex alternately operated WWTPs in risk assessment tools such as e.g. SimpleTreat.

Linear Alkylbenzene Sulphonates, Branched Dodecylbenzene Sulphonates and Soap Analysed in Marine Sediments from the Baltic Proper and Little Belt

Linear Alkylbenzene Sulphonates, Branched Dodecylbenzene Sulphonates and Soap Analysed in Marine Sediments from the Baltic Proper and Little Belt