Degradation Of Nonylphenol Polyethoxylates Research Articles

Heterogeneous catalytic degradation of nonylphenol using persulphate activated by natural pyrite: response surface methodology modelling and optimisation

ABSTRACT The degradation of nonylphenol polyethoxylates (NPEOs) was investigated by persulphate (PS) activated using naturally pyrite semi-conductor mineral (NP-SCM) in aqueous solutions. The effects of various factors including solution pH, NP-SCM dosage, NPEOs and PS concentration were examined through response surface methodology (RSM) and Box-Behnken design (BBD) technique. The properties of NP-SCM were characterised by FESEM, BET, XRD and EDX analyses. The results showed that the RSM model had a well correlation (R2 > 0.99) between the predicted data and the experimental findings of NPEOs degradation. In addition, under the optimum conditions (PS = 5.85 mM, pH = 3.0, NP-SCM = 0.85 g/L and NPEOs = 10 µM), the removal efficiency of NPEOs reached more than 99%. The maximum removal efficiency of COD and TOC was obtained 87% and 80% at 90 min reaction time, respectively. The negative effect of various competing ions on the removal of NPEOs was as phosphate>bicarbonate>copper>nitrate>calcium>ammonium. After five successive catalyst cycles reuse, the degradation efficiency was insignificantly decreased from 99.6% to 90.5%, which indicated the excellent potential reusability of NP-SCM catalyst. It can be concluded that NP-SCM along with PS, due to the generation of highly reactive oxidising species (SO4 ●-), its simplicity and easy separation of the catalyst, has a great potential for the degradation of NPEOs from aqueous solutions.

Nonylphenol causes shifts in microbial communities and nitrogen mineralization in soil microcosms

The aims of this work was to investigate, in soil microcosms, the effects on soil microbial community structure and function of increasing concentrations of 4-Nonylphenol (NP). The lasts is a product of degradation of NPEOs (Nonylphenol polyethoxylates) with a known toxic and estrogenic capacity able to disrupt animal's hormonal systems.The effect of increasing concentrations of NP (0, 10, 30, 90, and 270 mg NP kg−1 of dry soil) in soil microcosms in three sampling dates (28, 56, and 112 days) over soil microbial activity and function were assessed. Soil microbial activity was estimated by microbial ATP content, and both bacterial and fungal communities composition were estimated using the terminal restriction fragment length polymorphism technique (T-RFLP). Abundance of ammonia-oxidizing bacteria (AOB) was estimated by qPCR of gene encoding for the bacterial ammonia-monoxygenase (amoA). Changes in biologically mediated soil properties were also assessed, namely water-soluble NH+4, NO−2 and NO−3 content, the two last allowing the assessment of mineralization rates.NP-spiking had some unexpected impacts on microbial community structure and functions, since (i) impacted both bacterial and fungal communities structure at the highest NP concentration tested, bacterial communities were resistant to lower concentrations, while fungal communities were increasingly impacted until the end of the incubation at day 112; (ii) no community structure resilience was observed in bacteria at the highest NP concentration nor for fungi at any concentration; (iii) microbial activity decreased with NP after 28 and 56 d, but increased in the last sampling at the highest concentrations tests, coupled to an enrichment in AOB taxa after 56 and 112 days, that at least partly explain also explain the observed speed up of nitrification rates.

Degradation of nonylphenol polyethoxylates by functionalized Fe3O4 nanoparticle-immobilized Sphingomonas sp. Y2

In this study, the efficiency of the nonylphenol polyethoxylates (NPEOs)-degrading bacterium Sphingomonas sp. strain Y2 was evaluated, which was immobilized by a novel system composed of polydopamine (PD)-coated Fe3O4 iron nanoparticles (IONPs). The PD-IONPs, with a distinct core-shell structure, relatively uniform size, and high saturation magnetization, were prepared for Y2 immobilization. The performance of Y2 was unaffected by this novel immobilization method, exhibiting 79.5% and 99.9% of NPEOs (500ppm) degradation efficiency at day 1 and 2, respectively. Furthermore, separation and recycling were more readily achieved for immobilized cells as compared to free cells. Immobilized cells retained over 70% of the original degradation activity after 6cycles of utilization. These results suggest that Y2-PD-IONPs can be potentially used for NPEOs-contaminated wastewater bioremediation. CapsuleImmobilization of Sphingomonas sp. Y2 by functionalized PD-IONPs with easy separation, recycling utilization and high efficiency.

Gamma radiation/H2O2 treatment of a nonylphenol ethoxylates: Degradation, cytotoxicity, and mutagenicity evaluation

Gamma radiation/H2O2 treatment of nonylphenol polyethoxylates (NPEO) was performed and treatment effect was evaluated on the basis of degradation, chemical oxygen demand (COD) and total organic carbon (TOC), and toxicity reduction efficiencies. The radiolytic by-products were determined by Fourier Transform Infrared Spectroscopy (FTIR), High-Performance Liquid Chromatography (HPLC), and Gas Chromatography–Mass Spectrometry (GC–MS) techniques. Low mass carboxylic acids, aldehyde, ketone, and acetic acid were identified as the by-products of the NPEO degradation. NPEO sample irradiated to the absorbed dose of 15kGy/4.58% H2O2 showed more than 90% degradation. Allium cepa (A. cepa), brine shrimp, heamolytic tests were used for cytotoxicity study, while mutagenicity was evaluated through Ames test (TA98 and TA100 strains) of treated and un-treated NPEO. The reductions in COD and TOC were greater than 70% and 50%, respectively. Gamma radiation/H2O2 treatment revealed a considerable reduction in cytotoxicity and mutagenicity. A. cepa, heamolytic and shrimp assays showed cytotoxicity reduction up to 68.65%, 77%, and 94%, respectively. The mutagenicity reduced up to 62%, 74%, and 79% (TA98) and 68%, 78%, and 82% (TA100), respectively of NPEO-6, NPEO-9, and NPEO-30 irradiated to the absorbed dose of 15kGy/4.58% H2O2. NPEO-6 detoxified more efficiently versus NPEO-9 and NPEO-30 and results showed that Gamma radiation/H2O2 treatment has the potential to mineralize and detoxify NPEO.

Biodegradation and utilization of 4-n-nonylphenol by Aspergillus versicolor as a sole carbon and energy source

4-n-Nonylphenol (4-n-NP) is an environmental pollutant with endocrine-disrupting activities that is formed during the degradation of nonylphenol polyethoxylates, which are widely used as surfactants. Utilization of 4-n-NP by the filamentous fungus Aspergillus versicolor as the sole carbon and energy source was investigated. By means of gas chromatography–mass spectrometry, we showed that in the absence of any carbon source other than 4-n-NP in the medium, A. versicolor completely removed the xenobiotic (100mgL−1) after 3 d of cultivation. Moreover, mass spectrometric analysis of intracellular extracts led to the identification of eight intermediates. The mineralization of the xenobiotic in cultures supplemented with 4-n-NP [ring-14C(U)] as a growth substrate was also assessed. After 3 d of incubation, approximately 50% of the initially applied radioactivity was recovered in the form of 14CO2, proving that this xenobiotic was completely metabolized and utilized by A. versicolor as a carbon source. Based on microscopic analysis, A. versicolor is capable of germinating spores under such conditions. To confirm these observations, a microcalorimetric method was used. The results show that even the highest amount of 4-n-NP initiates heat production in the fungal samples, proving that metabolic processes were affected by the use of 4-n-NP as an energetic substrate.

Degradation of Nonylphenol Polyethoxylates and its Microflora Structure in an Anoxic-Oxic Activated Sludge Process

An anoxic-oxic activated sludge process (AOASP) was carried out to degrade nonylphenol polyethoxylates (NPEOs). The carbon source in influent was replaced stepwise by a mixture of nonylphenol decaethoxylate (M-NP10EO). The 2nd-derivative UV-spectrometry was applied to determine the total amount of M-NP10EO in water samples. Chemical oxygen demand (COD) removal efficiency achieves about 85% under the highest M-NP10EO loading rate, and M-NP10EO removal efficiency is about 80%. Denaturing gradient gel electrophoresis (DGGE) results of activated sludges show that the microbe species decrease but gradually stabilize with the increase of M-NP10EO concentration in influent. Fluorescence in situ hybridization (FISH) results of activated sludges showe that the dominant microflora under the highest M-NP10EO loading rate is β-Proteobacteria (35%), followed by α-Proteobacteria (15%), γ-Proteobacteria (5%) and Actinobateria (4%).

Nonylphenol Polyethoxylates Degraded by Three Different Wavelengths of UV and Their Genotoxic Change—Detected by Generation of γ‐H2AX

UV rays in sunlight are an important factor in the degradation of chemicals. In this study, we investigated the degradation of nonionic surfactants, nonylphenol polyethoxylates (NPEOs) with 10 or 70 ethylene oxide (EO) units using UVA, B and C, and their genotoxic change based on phosphorylation of histone H2AX (γ-H2AX), a marker of DNA damage. NPEOs were degraded dependent on the energy of UV, that is, UVC having the highest energy was most effective, whereas UVA having the lowest energy caused little change. The EO side chain of NPEO(70) was broken near the benzene ring by UV, producing NPEOs with a shortened EO chain (around 10 units). The generation of γ-H2AX reflected the pattern of degradation; shortening of the EO chain changed NPEO(70) into an inducer for γ-H2AX, and degradation of NPEO(10) attenuated the genotoxicity. The γ-H2AX generated by NPEO(10) and UV-degraded NPEO(70) was independent of the cell cycle. The formation of DNA double strand breaks detected by gel electrophoresis was consistent with the results for γ-H2AX. These results suggested that UV rays can make NPEOs harmless or genotoxic according to the degradation of the EO side chain, the effects being dependent on wavelength.

Photodegradation of nonylphenol polyethoxylates in aqueous solution

Environmental context. Nonylphenol polyethoxylates (NPEOs) are widely used non-ionic surfactants, and they cause environmental concern because some metabolites of NPEOs possess endocrine-disrupting activities. Photodegradation is an important pathway for NPEOs degradation, and different degradation products may lead to different environmental risks. The present paper looks at the kinetics and pathways of NPEO photodegradation in aqueous solutions, focussing on the effects of humic acid, H2O2, and FeIII. We found that the presence of different chemicals led to different degradation pathways, and a new mechanism is proposed. Abstract. To further elucidate the mechanism of photoinduced degradation of nonylphenol polyethoxylates (NPEOs) in aqueous environments, two different light systems, UVA and simulated sunlight, were used, and the effects of humic acid, H2O2, and FeIII were investigated. The 96-h degradation efficiencies of NPEOs in pure water solution were found to be 36.6 and 22.6% under UVA and SSL irradiation respectively. The presence of humic acid and FeIII in solution increased the photodegradation efficiency of NPEOs to different extents. The proportion of short-chain NPEOs in the NPEOn mixture was found to increase significantly in the solution containing FeIII, whereas this phenomenon was not observed in pure water and solutions containing H2O2 or humic acid. The result of NPEO3 photodegradation experiments indicated that FeIII in solution led to an ethoxylate-reduction pathway. Dicarboxylated formate ethoxylates were proposed as the intermediate products of NPEO photodegradation through an oxidative pathway based on the analytical results of liquid chromatography–electrospray ionisation–mass spectrometry and tandem mass spectrometry. Different mechanisms of NPEO photodegradation were elucidated.

The Impact of Process Variables on the Removal of PBDEs and NPEOs During Simulated Activated Sludge Treatment

This work illustrates that the removal of some endocrine-disrupting compounds from sewage treatment works effluent is dependent on parameters such as sludge age, influent concentrations, concentrations of co-pollutants and hydraulic retention time as well as physicochemical properties of the compound. Greater nonylphenol polyethoxylates (NPEO) and polybrominated diphenyl ether (PBDE) removal was observed at a higher sludge age, and it appeared that the enzymes required for NPEO degradation were already present. NPEO degradation was reduced in the presence of the more hydrophobic PBDE compounds as sorption of PBDEs occurred, rapidly reducing available sorption sites for NPEOs. The more hydrophobic NP and PBDEs demonstrated little degradation in comparison to longer-chain NPEO compounds. From this research, it is apparent that the principal environmental risk of PBDE contamination after wastewater treatment is via sludge-disposal routes. Treatment of wastewater containing NPEO surfactants poses environmental risks via two routes: some nonylphenolic compounds may pass through into receiving waters and degradation products such as nonylphenol and short-chain ethoxylate compounds will enter the environment via sludge disposal.

Distribution and dissipation pathways of nonylphenol polyethoxylates in the Yellow River: Site investigation and lab-scale studies

Spatial distribution of nonylphenol polyethoxylates (NPEOs) and nonylphenol (NP) was investigated in a field study in Lanzhou Reach of the Yellow River. NPEOs and their metabolites were found in the river, with the maximum dissolved concentrations of 6.38 nmol/L for NPEOs, 0.19 nmol/L for nonylphenol ethoxy acetic acids (NPECs) and 0.79 nmol/L for NP, respectively. The maximum concentrations in the sediment and suspended particle samples were 1.50 and 5.09 nmol/g for NPEOs and NP, respectively. The effects of particles, light and microorganism on the dissipation of NPEOs in the river water were investigated based on lab-scale experiments. When natural particles were removed, 72% and 22% degradation of NPEOs were achieved at 120 h in non-sterile and sterile conditions with light, respectively. Different concentrations of NPECs were also observed in these experiments. When suspended particle matters (SPMs) were present, about 38–50% of NPEOs were sorbed to the particulate phase in only 1 h. As a result, the degradation of NPEOs and production of NPECs were inhibited. However, the combined sorption and degradation in the presence of SPMs resulted in lower dissolved NPEO concentrations than those in the absence of SPMs. Biodegradation was the most important pathway for NPEOs degradation in the river water, while NPECs seemed to be produced through both biological and abiological pathways.

Metabolic pathway of xenoestrogenic short ethoxy chain-nonylphenol to nonylphenol by aerobic bacteria, Ensifer sp. strain AS08 and Pseudomonas sp. strain AS90

Ensifer sp. strain AS08 and Pseudomonas sp. strain AS90 degrading short ethoxy (EO) chain-nonylphenol (NP) [NPEO(av2.0) containing NP mono- approximately tetraethoxylates (NP1EO approximately NP4EO); average 2.0 EO units] were isolated by enrichment cultures. Both strains grew on NP but not on octyl- and nonylphenol polyethoxylates (NPEOs) (average 10 EO units). Growth and degradation of NPEO(av2.0) was increased with increased concentrations of yeast extract (0.02-0.5%) in a culture medium. Culture supernatants of both strains grown on NPEO(av2.0) were analyzed by high-performance liquid chromatography, showing degradation of NP4EO-NP1EO. The metabolites from nonylphenol diethoxylate (NP2EO) by resting cells of both strains were identified by gas chromatography-mass spectrometry as nonylphenoxyethoxyacetic acid, NP1EO, nonylphenoxyacetic acid (NP1EC), and NP, while those from NP1EO were identified as NP1EC and NP. Cell-free extracts from strain AS08 grown on NPEO(av2.0) dehydrogenated NPEOs, NPEO(av2.0), NP2EO, NP1EO, and PEG 400, but the extracts were inactive toward di- approximately tetraethylene glycol. Aldehydes were formed in the reaction mixture of each substrate with cell-free extracts. From these results, the aerobic metabolic pathway for short EO chain-NP is proposed: A terminal alcohol group of the EO chain is oxidized to a carboxylic acid via an aldehyde, and then one EO unit is removed. This process is repeated until NP is produced.

Degradation of Low-Ethoxylated Nonylphenols by a Stenotrophomonas Strain and Development of New Phylogenetic Probes for Stenotrophomonas spp. Detection

An aerobic bacterium (BCc6), isolated from nonylphenol polyethoxylates (NPEOs)-contaminated sludge, was shown to be capable of degrading low-ethoxylated NPEO mixtures. Sequencing of 16S rRNA gene (rDNA) showed that it clustered with Stenotrophomonas nitritireducens. Fluorescent in situ hybridization (FISH), performed on BCc6 strain and on the previously isolated Stenotrophomonas BCaL2, also involved in NPEO degradation but clustering with S. maltophilia, showed that strain BCc6 did not hybridize with the S. maltophilia-specific probe, and neither of the two strains hybridized with probes targeted to the Gammaproteobacteria site, rDNA analyses performed on the two strains evidenced two new polymorphisms, the first one at the 23S rRNA Gammaproteobacteria site, characterizing the known members of the Stenotrophomonas genus, and the other one at the 16S rRNA level, characteristic of S. nitritireducens. Two new FISH probes were designed accordingly, tested on control bacterial cultures, and employed for in situ monitoring of Stenotrophomonas representatives.

Degradation of nonylphenolic surfactants in activated sludge batch tests

The fate of nonylphenol polyethoxylate surfactants in the activated sludge wastewater treatment process is a concern due to the formation of estrogenic nonlyphenols on degradation and due to the large amounts discharged to the aquatic environment through sewage treatment works. Batch tests using activated sludge from a Husmann apparatus were used to determine the effects of these compounds physico-chemical properties and biological sludge characteristics on biodegradation. Degradation of nonylphenol polyethoxylates with up to 12 ethoxy groups was observed in unacclimated sludge with a concomitant production of nonylphenol and short chain nonylphenol polyethoxylate compounds. Degradation was determined to be a biotic process involving intracellular enzyme activity, which resulted in sludge age being an influential parameter. With increasing sludge age there is an increase in mixed liquor solids concentration in activated sludge which results in greater bacterial numbers and the potential for greater species diversity which therefore increases compound degradation. However, increased degradation of long chain compounds resulted in an accumulation of shorter chain compounds and nonylphenol, which are more resistant to degradation.

Degradation of nonylphenol polyethoxylates by ultraviolet B irradiation and effects of their products on mammalian cultured cells.

Nonylphenol polyethoxylates (NPEOs) are widely used as non-ionic surfactants and their biodegradation products such as 4-n-nonylphenol are stable and have been demonstrated to be cytotoxic. In the aquatic environment, these compounds are usually exposed to sunlight, and while the correlation between the biodegradation of NPEOs and changes in cytotoxicity has been reported, the relationship between the photodegradation of NPEOs and cytotoxicity has not. In this study, we investigated the degradation of NPEO by ultraviolet (UV) irradiation, especially UVB irradiation, and the effects on mammalian cell lines. NPEO with a smaller number of ethylene oxide (EO) units showed greater cytotoxicity. Although NPEO (10) completely inhibited the proliferation of the cells, NPEO (70) showed no toxicity. UVB irradiation significantly induced a shortening of the side chain, which was due to the production of ROS. The EO side chain of NPEO (10), was gradually degradated, but that of NPEO (70) was degradated near the benzene ring. Furthermore, the degradation of the benzene ring was more effective in NPEO (70) than NPEO (10). The toxicity of NPEO (10) in cultured cells decreased following UVB irradiation, whereas that of NPEO (70) was induced after UVB irradiation at 500 J/cm2 and disappeared at 1000 J/cm2. This might be due to the production of NPEO with a short side chain and 4-n-nonylphenol by the degradation of EO and due to the degradation of the benzene ring at higher doses of UVB irradiation. This study shows the significance of UV exposure to the degradation of alkylphenol polyethoxylates in the environment.

Tracing of surfactants in the biological wastewater treatment process and the identification of their metabolites by flow injection–mass spectrometry and liquid chromatography–mass spectrometry and –tandem mass spectrometry

Results of aerobic biodegradation of alkyl ethoxylates (AEOs), of nonylphenol polyethoxylates (NPEOs), and of NPEO derivatives (sulfonates and sulfates), as well as anaerobic NPEO biodegradation monitored by flow injection analysis (FIA) or liquid chromatographic separation (LC) in combination with mass (MS) and tandem mass spectrometry (MS–MS) are presented. The application of visual pattern recognition in the FIA–MS mode showed quite different degradation pathways for C 13-AEOs, so that aldehyde compounds as metabolites could be confirmed by collision-induced dissociation for the first time. Methyl ethers of AEO compounds were found to be persistent under aerobic conditions, while NPEO degradation resulted in nonylphenol polyether carboxylates. FIA– and LC–MS proved that NPEO derivatives used as anionic surfactants were either non-biodegradable (nonylphenol diethoxy sulfonate) or were primarily degraded (nonylphenol polyethoxy sulfates) into compounds of the same molar masses yet of different retention behaviour. Anaerobic degradation of NPEOs led to the generation of nonylphenols, which was confirmed by GC–MS.

Bacterial Attack of Non-Ionic Aromatic Surfactants: Comparison of Degradative Capabilities of New Isolates from Nonylphenol Polyethoxylate Polluted Wastewaters

Nonylphenol polyethoxylates (NPEOs) are largely used in many different industrial applications. In 1987 estimated production of NPEOs in Europe was 150,000 tons, with 25,000 tons only produced in Italy (1). They represent a group of compounds which are of environmental concern because of their toxicity to biological systems. Furthermore, NPEOs and their intermediates tend to accumulate in sewage sludge during wastewater depuration or possibly in sediments once treated waters are discharged into rivers and sea. Primary degradation of NPEOs, that also means the loss of surfactant properties, easily occurs in aerobic conditions as a consequence of the progressive loss of ethylene oxide units. On the other hand, complete mineralization appears to proceed very slowly. Anyway scarce information is available about microorganisms which possibly carry out biodegradation of these compounds. The present paper reports results concerning the isolation and characterization of three different Gram negative bacteria from nonylphenol polyethoxylate contaminated sludge, that can individually attack NPEOs in axenic cultures effecting primary degradation.