Andrzej Szymanski

A central fission pathway in alkylphenol ethoxylate biodegradation

A representative alkylphenol Triton X-100 (having 9.5 oxyethylene subunits) was treated over 40 days under the conditions of the continuous flow activated sludge simulation test in a plant with aeration and denitrification chambers. Treated sewage was separated by sequential extraction with ethyl acetate and chloroform. The extracts were analysed by high-performance liquid chromatography-electrospray ionisation-mass spectrometry (HPLC-ESI-MS). Single ion chromatograms of the chloroform extracts showed the presence of neutral, mono- and di-carboxylated poly(ethylene glycols). This is evidence of the central fission of alkylphenol ethoxylates (APE). Simultaneously, the APE having omega-carboxylated oxyethylene chains were identified. This is the evidence that apart from central fission, the omega-oxidation oxyethylene chain pathway also occurs.

BIODEGRADATION OF FATTY ALCOHOL ETHOXYLATES IN THE CONTINUOUS FLOW ACTIVATED SLUDGE TEST

Abstract Biodegradation of two fatty alcohol ethoxylates: surfactant C12E10 (C 12 with an average 10 oxyethylene subunits (EO)) and Marlipal 1618/25 (C 16–18 with an average 25 EO) were tested under the continuous flow activated sludge conditions of the classical Husmann plant and a plant having a denitrifying chamber. Primary biodegradation and concentration of metabolites: free fatty alcohol (FFA) and poly(ethylene glycols) (PEG) were measured. PEG were divided into two fractions: short-chained (1–3 EO) and long-chained PEG (>3 EO). Tensammetric methods were used for analysis. High primary biodegradation was found (96.8±0.5% for surfactant C12E10 (C12E10) and 99.6±0.1% for Marlipal 1618/25 (Marlipal)), though with a high concentration of metabolites: FFA and PEG. FFA concentration corresponded to 30–100% of theoretically predicted concentration (presuming central fission) and dependent on the chemical structure of surfactant and type of plant used for testing. Total PEG concentration was about 20% of that predicted on the basis of central fission, while the ratio of short-chained PEG in the total PEG varied from 20 to 70% and depended on the chemical structure of surfactant and type of plant used for testing.

Tensammetry with accumulation on the hanging mercury drop electrode: Part 6. Errors of determination caused by adsorption of non-ionic surfactants on the material of the measuring cell

Abstract The adosorptive loss of oxyethylated alkylphenols (Triton X-100 and Rokafenol N-3), oxyethylated alcohols (Brij-35, Marlipal 1618/40 and surfactant 18-10) and poly(ethylene glycol) of MW 9000 on cells constructed from quartz, glass, glassy carbon, PTFE, polyethylene, polypropylene, polystyrene and aluminium during the measuring process was investigated. In all instances very substantial losses were found, which completely changed the results of the determination. Apart from the vessel itself, very important losses on the ceramic frit located at the end of the salt bridge were found. The loss of all the surfactants tested on the quartz vessel is not very substantial and, after protection of the ceramic frit, a cell with such a construction gives minimum losses. The glass cell is very sensitivie to the manner of preparation of its surface. Cells constructed from PTFE and glassy carbon adsorb more specifically than others and can be used for the determination of oxyethylated alcohols but not for the determination of oxyethylated alkylphenols. Other materials used gave substantial losses of almost all the surfactants tested. Particularly bad results were obtained with polystyrene and aluminium cells.

Application of an indirect tensammetric method for the determination of non-ionic surfactants in surface water

Abstract Three alternative procedures for the determination of non-ionic surfactants (NS) in surface water have been developed. The simplest one consists of the filtration of water samples, the extraction of NS with ethyl acetate, the evaporation of the solvent and the determination of NS using an indirect tensammetric method (ITM). The detection limit is 15 μg l −1 . The procedure using gas-stripping separation of NS shows a detection limit of 1.5 μg l −1 . Chlorophyll extracted from water plants causes a serious interference. Therefore the sample must be filtered before extraction. The extractive procedure shows good precision and recovery of spiked surfactants from river water samples. Comparative studies of the newly developed and the classical BiAS procedures were performed. The ITM procedure shows a detection limit of two orders of magnitude better than the BiAS procedure. Therefore the required volume of water sample is reduced from 5000 to 100 ml. Due to the simpler separation procedure the ITM is substantially less time-consuming, cheaper and requires no sophisticated equipment or well-trained staff. An additional advantage of the ITM compared with the BiAS procedure is the lower sensitivity to the choice of standard surfactant and the broader “spectrum” of NS that can be determined. The results of a half year current analysis of NS in river water have been included.

DETERMINATION OF SHORT-CHAINED POLY(ETHYLENE GLYCOLS) AND ETHYLENE GLYCOL IN ENVIRONMENTAL SAMPLES

A method for the determination of ethylene glycol (EG), di(ethylene glycol) (E2) and tri(ethylene glycol) (E3) in environmental samples (raw and treated sewage, river water) has been developed. These substances are important by-products in the biotransformation of non-ionic surfactants (NS). The method is based on sequential liquid-liquid extraction with ethyl acetate and chloroform (resulting in the separation of poly(ethylene glycols) (PEG) and EG from the water matrix), precipitation of long-chained PEG (PEGlch) with Dragendorff reagent, extraction of short-chained PEG (PEGsh) (EG, E2 and E3) from a filtrate with chloroform and the final determination using alternating current voltammetry. The precision of the method is 7.3%, the recovery 95% and a detection limit of 1.5 microg in the sample, i.e. 10 microg l(-1) was achieved. As evidenced by F and t tests, the developed method is equivalent to the indirect PEGsh determination by the difference approach where concentration of PEGsh is determined by the difference of the total PEG and PEGlch. The PEGsh fraction was found to be present in considerable concentrations in raw and treated sewage, river water, as well as being a major biotransformation by-product in the continuous flow activated sludge testing of fatty alcohol ethoxylates.

Biodegradation of oxo-alcohol ethoxylates in the continuous flow activated sludge simulation test.

Biodegradation of two alpha-methyl branched oxo-alcohol ethoxylates (OAE) of different polydispersity: LIAL 125/14 BRD (LIALB) (broad M.W. distribution) and LIAL 125/14 NRD (LIALN) (narrow M.W. distribution), both having an average of 14 oxyethylene subunits (EO) and a C(12-15) alkyl moiety were tested under the continuous flow activated sludge conditions of the classical Husmann plant. Primary biodegradation and concentration of metabolites: free oxo-alcohol fraction (FOA) and poly(ethylene glycols) (PEG), were measured. PEG were divided into two fractions: short-chained PEG (PEGshch) (1-4 EO) and long-chained PEG (PEGlch) (>4 EO). The indirect tensammetric technique combined with an adequate separation was used for analysis. Central fission was found to be a highly dominating pathway, as is the case with fatty alcohol ethoxylates. OAE are highly primarily biodegraded (above 95%). High concentrations of FOA and PEG are formed. Once formed the PEGlch are further fragmented into the PEGshch. Free alcohol fraction compounds are biodegraded sooner when alkyl moiety is shorter. OAE polydispersity has an influence on the kinetics of biodegradation; PEG formed from LIALN are biodegraded slower and to a lower degree than those from LIALB.

Determination of poly(ethylene glycol)s in environmental samples by the indirect tensammetric method

Poly(ethylene glycol)s (PEGs) are one of major metabolic products of the biodegradation of non-ionic surfactants (NS). Therefore, a method for the determination of PEGs in mixtures of metabolic products of the biodegradation of NS would be useful in the control of the aquatic environment. In order to solve this problem, the indirect tensammetric method (ITM) combined with an adequate separation scheme was applied. The analytical signal in the ITM reacts additively on both PEGs and NS. Therefore, NS interfere with the determination of PEGs. In order to separate NS, extraction with ethyl acetate was used. Sequential extraction of the sample with chloroform resulted in the separation of PEGs. The residue after evaporation of an aliquot or the whole chloroform phase was analysed using the ITM. The recovery and precision were checked on the example of a PEG of Mr 600. The recovery was 92 and 96% for 100 and 1000 µg spikes of PEG, respectively and the relative standard deviation was 5.6 and 3.4%, respectively. The problem of the choice of standard and the error related to this choice are discussed. The developed method was used for the determination of PEGs in mixtures formed during the testing of the biodegradation of oxyethylated alcohols under the OECD Confirmatory Test and in die-away experiments on ‘native’ NS of river water. In both cases PEGs were found to be major metabolic products. The method was also applied to the determination of PEGs in river water.

Indirect tensammetric method for the determination of non-ionic `surfactants: Part 2. Investigation and improvement of tolerance to man-made anionic surfactants

Abstract Non-ionic surfactants can be determined by means of their lowering effect on the tensammetric peak of ethyl acetate. Representative man-made anionic surfactants were investigated in order to check the tolerance to this group during the determination of non-ionic surfactants. Both the “normal” procedure (recording in the cathodic direction starting from —1.200 V) and “reverse” recording (scanning in the anodic direction starting from — 1.400 V) were used. Sodium salts of dodecylbenzene sulphonate (DBS), dodecyl sulphate (DSA), dodecyl sulphonate (DSO) and stearate (S) and the commercial products Kosulfonat 40 (KOS) and Sulforokanol L-3 (lauryl ether sulphate) (LES) were investigated. The interference of the anionic surfactants increases in the order DSA, DBS

Tensammetric studies of separation of surfactants

Abstract Precipitation of surfactants with modified Dragendorff reagent, being a part of the bismuth active substance (BiAS) standard procedure, was investigated with the use of adsorptive stripping tensammetry and an indirect tensammetric method. Triton X-100 was used as a representative surfactant. The washing step with glacial acetic acid part of the investigated procedure, was found to be a serious source of loss of precipitate and therefore the main source of error of determination in the BiAS procedure. The concentration of surfactant in the filtrate and adsorptive losses on the filter were also determined.

Tensammetric determination of non-ionic surfactants combined with BiAS separation procedure (Wickbold) 2. Optimisation of the precipitation and investigation of interferences.

The precipitation step in the developed procedure (BiAS-ITM) was optimised with the aim of achieving a lower detection limit. Losses during filtration using Triton X-100 as representative non-ionic surfactant (NS), the indirect tensammetric method (ITM) and adsorptive stripping tensammetry (AdST) for the determination of the concentration of the surfactant in the precipitate and in the filtrate were investigated. The G4 glass filter recommended up to now was found to be insufficiently effective and a source of loss. The new version of the procedure developed works within the range 2-1000 mug of NS in the sample, and thus two orders of magnitude lower than the former version of the procedure, showing satisfactory recovery and precision. The detection limit (3 x S.D.) was found to be below 1.5 mug in the sample. Interferences of anionic surfactants (ASs) e.g. sodium dodecylbenzenesulphonate and sodium lauryl sulphate, lipids, e.g. glycerol trioleate (GTO), and chlorophyll were investigated. GTO and AS show no effect on the BiAS-ITM results although strong adsorption of ASs on the glass filter as well as a slight adsorption on the precipitate was found. Chlorophyll does not interfere with the determination up to 30 mug in the sample, whereas higher concentrations produce results that are too high.