Methyl Tert-butyl Ether Degradation Research Articles

Stenotrophomonas maltophilia isolated from gasoline-contaminated soil is capable of degrading methyl tert-butyl ether

Background: Methyl tert-butyl ether (MTBE) is a pollutant that causes deleterious effects on human and environmental health. Certain microbial cultures have shown the ability to degrade MTBE, suggesting that a novel bacterial species capable of degrading MTBE could be recovered. The goal of this study was to isolate, identify and characterize the members of a bacterial consortium capable of degrading MTBE. Results: The IPN-120526 bacterial consortium was obtained through batch enrichment using MTBE as the sole carbon and energy source. The cultivable fraction of the consortium was identified; of the isolates, only Stenotrophomonas maltophilia IPN-TD and Sphingopyxis sp. IPN-TE were capable of degrading MTBE. To the best of our knowledge, this report is the first demonstrating that S. maltophilia and Sphingopyxis sp. are capable of degrading MTBE. The degradation kinetics of MTBE demonstrated that S. maltophilia IPN-TD had a significantly higher overall MTBE degradation efficiency and rate (48.39 ± 3.18% and 1.56 ± 0.12 mg L -1 h -1 , respectively) than the IPN-120526 consortium (38.59 ± 2.17% and 1.25 ± 0.087 mg L -1 h -1 , respectively). The kinetics of MTBE removal by both cultures fit first-order and pseudo-first-order reaction models. Conclusions: These findings suggest that S. maltophilia IPN-TD in axenic culture has considerable potential for the detoxification of MTBE-contaminated water. Normal 0 21 false false false ES-TRAD JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:Tabla normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:Cambria,serif; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin; mso-ansi-language:ES-TRAD;}

Enhanced cometabolic degradation of methyl tert-butyl ether by a Pseudomonas sp. strain grown on n-pentane

When methyl tert-butyl ether (MTBE) is added as oxygenates it increases the octane number and decreases the release of nitric oxide from the incomplete combustion of reformulated gasoline. The extensive use of MTBE allowed it to be detectable as a pollutant in both ground-level and underground water worldwide. The present study focuses on the isolation and characterization of MTB-degrading microorganisms by cometabolism based on the results of growth on different carbon sources. It also focuses on the kinetic analysis and the continuous degradation of MTBE. A bacterial strain WL1 that can grow on both n-alkanes (C5-C8) and aromatics was isolated and named Pseudomonas sp. WL1 according to the 16S rDNA sequencing analysis. Strain WL1 could cometabolically degrade MTBE in the presence of n-alkanes with a desirable degradation rate. Diverse n-alkanes with different lengths of carbon chains showed significant influence on the degradation rate of MTBE and accumulation of tert-butyl alcohol (TBA). When strain WL1 cometabolically degraded MTBE in the presence of n-pentane, higher MTBE-degrading rate and lower TBA-accumulation were observed (Vmax = 38.1 nmol/min/mgprotei, Ks = 6.8 mmol/L). In the continuous degrading experiment, the removal efficiency of MTBE by Pseudomonas sp. WL1 did not show any obvious decrease after five subsequent additions.

Effect of benzene and ethylbenzene on the transcription of methyl-tert-butyl ether degradation genes of Methylibium petroleiphilum PM1.

Methyl-tert-butyl ether (MTBE) and its degradation by-product, tert-butyl alcohol (TBA), are widespread contaminants detected frequently in groundwater in California. Since MTBE was used as a fuel oxygenate for almost two decades, leaking underground fuel storage tanks are an important source of contamination. Gasoline components such as BTEX (benzene, toluene, ethylbenzene and xylenes) are often present in mixtures with MTBE and TBA. Investigations of interactions between BTEX and MTBE degradation have not yielded consistent trends, and the molecular mechanisms of BTEX compounds' impact on MTBE degradation are not well understood. We investigated trends in transcription of biodegradation genes in the MTBE-degrading bacterium, Methylibium petroleiphilum PM1 upon exposure to MTBE, TBA, ethylbenzene and benzene as individual compounds or in mixtures. We designed real-time quantitative PCR assays to target functional genes of strain PM1 and provide evidence for induction of genes mdpA (MTBE monooxygenase), mdpJ (TBA hydroxylase) and bmoA (benzene monooxygenase) in response to MTBE, TBA and benzene, respectively. Delayed induction of mdpA and mdpJ transcription occurred with mixtures of benzene and MTBE or TBA, respectively. bmoA transcription was similar in the presence of MTBE or TBA with benzene as in their absence. Our results also indicate that ethylbenzene, previously proposed as an inhibitor of MTBE degradation in some bacteria, inhibits transcription of mdpA, mdpJ and bmoAgenes in strain PM1.

An extractive membrane biofilm reactor as alternative technology for the treatment of methyl tert-butyl ether contaminated water.

Among the strategies developed for contaminated groundwater bioremediation, those based on the use of bacteria adhering to inert supports and establishing biofilms have gained great importance in this field. Extractive membrane biofilm reactor (EMBFR) technology offers productive solutions for the removal of volatile and semi-volatile compounds. EMBFR technology is based on the use of extractive semipermeable membranes through which contaminants migrate to the biological compartment in which microorganisms with pollutant biotransformation and/or mineralization capacities can grow, forming an active biofilm on the membrane surface. The objective of this study was to assess the use of three bacterial strains (Paenibacillus sp. SH7 CECT 8558, Agrobacterium sp. MS2 CECT 8557, and Rhodococcus ruber EE6 CECT 8612), as inoculum in a lab-scale EMBFR running for 28 days under aerobic conditions to eliminate methyl tert-butyl ether (MTBE) from water samples. Three different hydraulic retention times (1, 6, and 12 h) were employed. MTBE degradation values were determined daily by a gas GC-MS technique, as well as suspended bacterial growth. The biofilm established by the bacterial strains on the semipermeable membrane was detected by Field-Emission Scanning Electron Microscopy (FESEM) at the end of each experiment. The acute toxicity of the treated effluents and biomedium was determined by Microtox© assay (EC50 ).The results achieved from the MTBE degradation, biofilm formation, and toxicity analysis indicated that bacterial strains MS2 and EE6 were the best options as selective inoculum, although further research is needed, particularly with regard to their possible use as a mixed culture. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1238-1245, 2016.

Removal of methyl tert‐butyl ether as a water pollutant by photodegradation over a new type of poly(methyl methacrylate)/TiO2 nanocomposite

Methyl tert‐butyl ether (MTBE), as a common oxygenate additive in gasoline, not only can enhance the octane number but also reduce exhaust emissions. Unfortunately, MTBE is a highly water soluble reagent and resistant to biodegradation. One of the most important methods for treatment of the MTBE contaminated is photodegradation over TiO2. In this research work, the immobilized TiO2 nanoparticles in poly(methyl methacrylate) PMMA nanocomposite films, which prepared by ionic liquid‐based microemulsion method, have been evaluated to conduct MTBE photodegradation under visible light irradiation. The objective of this study was to find out the best TiO2 content in nanocomposite and pH value for relatively complete degradation of MTBE in aqueous solution. The obtained results demonstrated that the 0.01 wt% of TiO2 in PMMA thin film and pH value of 7 show the best performance in MTBE photodegradation. Another highlighting of this work is looking to forward the behavior of nanocomposite surface after photodegradation of MTBE pollutant. For this purpose and to confirm the stability of the nanocomposite films for long‐term operations, the XPS and FESEM‐EDX characterization methods were used. POLYM. COMPOS., 39:1248–1254, 2018. © 2016 Society of Plastics Engineers

Anaerobic biodegradation of MTBE in a field site above the Israeli Coastal Aquifer: evidence from δ13C compound‐specific isotope analysis

AbstractBACKGROUNDThe fuel additive, methyl tert‐butyl ether (MTBE), is one of the most frequently occurring groundwater pollutants worldwide. The present study focused on assessing microbial degradation of MTBE in groundwater below a gasoline station situated above the Israeli Coastal Aquifer. Groundwater was monitored in six monitoring wells over a time period of 2.5 years.RESULTSThe site water geochemistry indicated that anaerobic conditions prevailed in two of the most contaminated wells. During a year MTBE concentrations declined from 81 to 4.2 mg L−1, concurrently, with a significant change in δ13C from −31.4 to −11.8 ‰ in a source area monitoring well. MTBE biodegradation during microcosm experiments under sulfate reducing and methanogenic conditions resulted in carbon isotopic enrichment factors (ε) of −17.2 ± 1.1 ‰.CONCLUSIONSignificant decrease in MTBE concentrations, along with pronounced changes in carbon isotope composition, indicates in situ degradation of MTBE occurring at the site. This evidence was supported by a microcosm experiment with indigenous microbial cultures. The estimated rate of biodegradation is 0.7 year−1, which is about 70% of the total natural attenuation (NA) processes. © 2016 Society of Chemical Industry

Identification of a Ruminococcaceae Species as the Methyl tert-Butyl Ether (MTBE) Degrading Bacterium in a Methanogenic Consortium.

The widespread use of methyl tert-butyl ether (MTBE) has caused major contamination of groundwater sources and is a concern due to its taste and odor problems, as well as its toxicity. MTBE can be degraded anaerobically which makes bioremediation of contaminated aquifers a potential solution. Nevertheless, the organisms and mechanisms that are responsible for anaerobic MTBE degradation are still unknown. The aim of our research was to identify the organisms actively degrading MTBE. For this purpose we characterized an anaerobic methanogenic culture enriched with MTBE as the sole carbon source from the New Jersey Arthur Kill intertidal strait sediment. The cultures were analyzed using stable isotope probing (SIP) combined with terminal restriction fragment length polymorphism (T-RFLP), high-throughput sequencing and clone library analysis of bacterial 16S rRNA genes. The sequence data indicated that phylotypes belonging to the Ruminococcaceae in the Firmicutes were predominant in the methanogenic cultures. SIP experiments also showed sequential incorporation of the (13)C labeled MTBE by the bacterial community with a bacterium most closely related to Saccharofermentans acetigenes identified as the bacterium active in O-demethylation of MTBE. Identification of the microorganisms responsible for the activity will help us better understand anaerobic MTBE degradation processes in the field and determine biomarkers for monitoring natural attenuation.

A kinetic and mechanistic study of the degradation of 1,2-dichloroethane and methyl tert-butyl ether using alkaline-activated persulfate oxidation

Alkaline-activated persulfate accelerates the degradation of 1,2-dichloroethane (1,2-DCA) while the rate of degradation of methyl tert-butyl ether (MTBE) in alkaline-activated persulfate system is decreased.

Gene mdpC plays a regulatory role in the methyl-tert-butyl ether degradation pathway of Methylibium petroleiphilum strain PM1.

Among the few bacteria known to utilize methyl tert-butyl ether (MTBE) as a sole carbon source, Methylibium petroleiphilum PM1 is a well-characterized organism with a sequenced genome; however, knowledge of the genetic regulation of its MTBE degradation pathway is limited. We investigated the role of a putative transcriptional activator gene, mdpC, in the induction of MTBE-degradation genes mdpA (encoding MTBE monooxygenase) and mdpJ (encoding tert-butyl alcohol hydroxylase) of strain PM1 in a gene-knockout mutant mdpC(-). We also utilized quantitative reverse transcriptase PCR assays targeting genes mdpA, mdpJ and mdpC to determine the effects of the mutation on transcription of these genes. Our results indicate that gene mdpC is involved in the induction of both mdpA and mdpJ in response to MTBE and tert-butyl alcohol (TBA) exposure in PM1. An additional independent mechanism may be involved in the induction of mdpJ in the presence of TBA.

Cometabolism of methyl tert-butyl ether by a new microbial consortium ERS.

The release of methyl tert-butyl-ether (MTBE) into the environment has increased the worldwide concern about the pollution of MTBE. In this paper, a microbial consortium was isolated from the soil sample near an oil station, which can degrade MTBE directly with a low biomass yield and MTBE degrading efficiency. Further research has indicated that this consortium can degrade MTBE efficiently when grown on n-octane as the cometabolic substrate. The results of 16S rDNA based on phylogenetic analysis of the selected operating taxonomic units (OTUs) involved in the consortium revealed that one OTU was related to Pseudomonas putida GPo1, which could cometabolically degrade MTBE on the growth of n-octane. This may help explain why n-octane could be the optimal cometabolic substrate of the consortium for MTBE degradation. Furthermore, the degradation of MTBE was observed along with the consumption of n-octane. Different K s values for MTBE were observed for cells grown with or without n-octane, suggesting that different enzymes are responsible for the oxidation of MTBE in cells grown on n-octane or MTBE. The results are discussed in terms of their impacts on our understanding of MTBE biodegradation and cometabolism.

Involvement of the cytochrome P450 system EthBAD in the N-deethoxymethylation of acetochlor by Rhodococcus sp. strain T3-1.

Acetochlor [2-chloro-N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl)-acetamide] is a widely applied herbicide with potential carcinogenic properties. N-Deethoxymethylation is the key step in acetochlor biodegradation. N-Deethoxymethylase is a multicomponent enzyme that catalyzes the conversion of acetochlor to 2'-methyl-6'-ethyl-2-chloroacetanilide (CMEPA). Fast detection of CMEPA by a two-enzyme (N-deethoxymethylase-amide hydrolase) system was established in this research. Based on the fast detection method, a three-component enzyme was purified from Rhodococcus sp. strain T3-1 using ammonium sulfate precipitation and hydrophobic interaction chromatography. The molecular masses of the components of the purified enzyme were estimated to be 45, 43, and 11 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Based on the results of peptide mass fingerprint analysis, acetochlor N-deethoxymethylase was identified as a cytochrome P450 system, composed of a cytochrome P450 oxygenase (43-kDa component; EthB), a ferredoxin (45 kDa; EthA), and a reductase (11 kDa; EthD), that is involved in the degradation of methyl tert-butyl ether. The gene cluster ethABCD was cloned by PCR amplification and expressed in Escherichia coli BL21(DE3). Resting cells of a recombinant E. coli strain showed deethoxymethylation activity against acetochlor. Subcloning of ethABCD showed that ethABD expressed in E. coli BL21(DE3) has the activity of acetochlor N-deethoxymethylase and is capable of converting acetochlor to CMEPA.

Removal of MTBE in Columns Filled with Modified Natural Zeolites

Methyl tert-butyl ether (MTBE) is an organic compound toxic and very soluble in water. When MTBE-contaminated water is available, it requires some method of decontamination. The Fenton method is used in environmental remediation and water treatment with low contaminant concentrations. In the search to extend the field of application of this methodology, they were begun to use catalysts in solid phase, particularly, metallic Fe nanoparticles (ZVI).In our laboratory we have prepared and characterized a supported catalyst (ZVI on a natural zeolite) that was studied for benzene degradation in experiences in batch and in fixed bed (continuous system) with interesting results. A similar set up was designed for the experiences described in this paper where aqueous solutions of MTBE with different concentrations were employed. The pH was regulated at 3.5 with a buffer.Bubble detachment was observed from the catalyst located in the bottom of the erlenmeyer demonstrating an important MTBE mineralization degree. Secondary products of degradation were detected and characterized. For experiences in batch, the MTBE removal was 45% approximately in 24hours. MTBE degradation in columns after the first hour is higher than the observed in the batch system although it raises a degradation degree in the order of 52% during the entire run.

Novel Water Treatment Processes Based on Hybrid Membrane-Ozonation Systems: A Novel Ceramic Membrane Contactor for Bubbleless Ozonation of Emerging Micropollutants

The aim of this study is the presentation of novel water treatment systems based on ozonation combined with ceramic membranes for the treatment of refractory organic compounds found in natural water sources such as groundwater. This includes, firstly, a short review of possible membrane based hybrid processes for water treatment from various sources. Several practical and theoretical aspects for the application of hybrid membrane-ozonation systems are discussed, along with theoretical background regarding the transformation of target organic pollutants by ozone. Next, a novel ceramic membrane contactor, bringing into contact the gas phase (ozone) and water phase without the creation of bubbles (bubbleless ozonation), is presented. Experimental data showing the membrane contactor efficiency for oxidation of atrazine, endosulfan, and methyl tert-butyl ether (MTBE) are shown and discussed. Almost complete endosulfan degradation was achieved with the use of the ceramic contactor, whereas atrazine degradation higher than 50% could not be achieved even after 60 min of reaction time. Single ozonation of water containing MTBE could not result in a significant MTBE degradation. MTBE mineralization by O3/H2O2combination increased at higher pH values and O3/H2O2molar ratio of 0.2 reaching a maximum of around 65%.

Study on photocatalytic activity of ZnO nanoneedles, nanorods, pyramids and hierarchical structures obtained by spray pyrolysis method

In this research, ZnO nanostructured layers with various morphology, i.e. nanoneedles, nanorods, pyramid shaped ZnO crystals, and hierarchical structures of ZnO deposited on nanorods and pyramid shaped crystals, were synthesised by pneumatic spray pyrolysis method. Hierarchical structures, a dense network of well-ordered platelets covering the side facets of the rod-like and pyramid shaped ZnO crystals, were obtained by spraying Zn(Ac)2 solution over the surface of pre-grown ZnO crystals at deposition temperature of 330°C within 5min. All ZnO layers have been characterised by scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD), absorbance of ultraviolet and visible light (UV–vis), surface wettability measurements and photoluminescence (PL). Photocatalytic activity of the layers was evaluated by means of photocatalytic oxidation activity (PCO) of several organic pollutants, namely, methyl-tert-butyl ether (MTBE), humic acid (HA), N,N-dimethyl p-nitrosoaniline (RNO), and prednisolone (PNL); the results were compared to the performance of well-established commercial photocatalyst, P25 titanium dioxide (Evonik). MTBE was the most efficiently degradable compound by all objects, while RNO was effectively degraded by plain structures only. In HA photocatalysis, needle-like ZnO as the most efficient material; PNL was the least degradable by ZnO layers. In the degradation of MTBE, RNO and HA, ZnO objects have shown activity comparable to or highly exceeding that of P25 TiO2. The explanation of the differences in ZnO objects׳ photoactivity is proposed to be the different character of oxidising species produced by the ZnO objects, and different interactions of these with the degradation substrates, based on the relative amount of surface defects, surface morphology and hydroxylation of the ZnO structures׳ surface.

The efficient photocatalytic degradation of methyl tert-butyl ether under Pd/ZnO and visible light irradiation.

Methyl tert-butyl ether is a commonly used fuel oxygenate that is present in gasoline. It was introduced to eliminate the use of leaded gasoline and to improve the octane quality because it aids in the complete combustion of fuel by supplying oxygen during the combustion process. Over the past decade, the use of MTBE has increased tremendously worldwide. For obvious reasons relating to accidental spillage, MTBE started to appear as an environmental and human health threat because of its nonbiodegradable nature and carcinogenic potential, respectively. In this work, MTBE was degraded with the help of an advanced oxidation process through the use of zinc oxide as a photocatalyst in the presence of visible light. A mixture of 200 mg of zinc oxide in 350mL of 50 ppm MTBE aqueous solution was irradiated with visible light for a given time. The complete degradation of MTBE was recorded, and approximately 99% photocatalytic degradation of 100 ppm MTBE solution was observed. Additionally, the photoactivity of 1% Pd-doped ZnO was tested under similar conditions to understand the effect of Pd doping on ZnO. Our results obtained under visible light irradiation are very promising, and they could be further explored for the degradation of several nondegradable environmental pollutants.

Physiological and genetic screening methods for the isolation of methyl tert-butyl ether-degrading bacteria for bioremediation purposes

Bioremediation of groundwater contaminated with methyl tert-butyl ether (MTBE) has been widely described since their cost/efficient ratios are lower than other physic-chemical methodologies. The present study focused on the isolation and selection of MTBE degrading microorganisms from contaminated soil and groundwater samples based on results from growth on mineral media amended with MTBE and BTEX, presence or absence of the monooxygenase genes and specific ability to degrade MTBE. Three bacterial strains were selected and identified as Rhodococcus ruber, strains EE1 (CECT 8555), EE6 (CECT 8612) and A5 (CECT 8556), showing the ability to degrade 60.0, 36.0 and 10.0 mg l−1 MTBE, respectively. Moreover, all the R. ruber strains showed the presence of genes encoding MTBE-degrading enzymes. One isolated strain was identified as Paenibacillus sp. SH7 (CECT 8558) and demonstrated the greatest MTBE degradation value (100 mg l−1), but together with the last strain selected and identified as Agrobacterium sp. MS2 (CECT 8557) did not result in positive amplification of any of the monooxygenase primers tested. The lowest toxicity (as EC50) was observed after 4-days growth of R. ruber EE6 on MTBE-supplemented mineral medium. The potential application of these strains in bioremediation processes is discussed.

Evaluation of Intrinsic Bioremediation of Methyl Tert-butyl Ether (MTBE) Contaminated Groundwater

This paper reported the use of real-time polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE), and the culture-based method in the intrinsic bioremediation study at a petroleum contaminated site. The study showed that phenol hydroxylase gene was detected in groundwater contaminated with benzene, toluene, ethylbenzene, xylene isomers (BTEX) and methyl tert-butyl ether (MTBE). This indicated that intrinsic bioremediation occurred at the site. DGGE analyses revealed that the petroleum-hydrocarbon plume caused the variation in microbial communities. MTBE degraders including Pseudomonas sp. NKNU01, Bacillus sp. NKNU01, Klebsiella sp. NKNU01, Enterobacter sp. NKNU01, and Enterobacter sp. NKNU02 were isolated from the contaminated groundwater using the cultured-based method. Among these five strains, Enterobacter sp. NKNU02 is the most effective stain at degrading MTBE without the addition of pentane. The MTBE biodegradation experiment indicated that the isolated bacteria were affected by propane. Biodegradation of MTBE was decreased but not totally inhibited in the mixtures of BTEX. Enterobacter sp. NKNU02 degraded about 60% of MTBE in the bioreactor study. Tert-butyl alcohol (TBA), acetic acid, 2-propanol, and propenoic acid were detected using gas chromatography/mass spectrometry during MTBE degraded by the rest cells of Enterobacter sp. NKNU02. The effectiveness of bioremediation of MTBE was assessed for potential field-scale application.

Tailoring the nitrogen sources of bacterial culture to enhance methyl tert-butyl ether degradation

Four methyl tert-butyl ether (MTBE)-degrading bacteria were isolated from a processing plant in Malaysia. Based on 16S rDNA sequences, the four isolates were identified as Exiguobacterium profundum P1M-2, Bacillus megaterium P1M-11, Alishewanella sp. P2A-12 and Pseudomonas mendocina P2M-8. Each of the isolates obtained optimum growth using a different source of nitrogen (0.1- 0.03 % yeast or peptone) and all four isolates were able to biodegrade 92.05-99.98 % of MTBE within seven days. Amongst the four isolates, the highest percentage of MTBE degradation was achieved using B. megaterium P1M-11. The highest growth on tert-butyl alcohol (TBA), tert-amyl alcohol (TAA) and 2-hydroxyisobutyric acid (2-HIBA) was also observed in B. megaterium P1M-11. This study suggests MTBE degradation by each of the bacteria can be enhanced by choosing the right nitrogen source. Furthermore, the ability of B. megaterium P1M-11 to grow on primary metabolites of MTBE and other structurally related ethers suggests the secretion of diverse degradative enzymes, making this isolate a good candidate to be applied in MTBE bioremediation strategies.

The Effect of Loading Palladium on Zinc Oxide on the Photocatalytic Degradation of Methyl tert‐Butyl Ether (MTBE) in Water

A series of heterogeneous catalysts was prepared by doping zinc oxide with different palladium loadings in the range of 0.5%-1.5%. The prepared catalysts were characterized by SEM, TEM and XRD. These catalysts were applied to study the degradation of Methyl tert-Butyl Ether (MTBE). An amount of 100mg of each of these catalysts was added to an aqueous solution of 100ppm of MTBE. The resulting mixtures were irradiated with UV light for a period of 5h. A 99.7% removal of MTBE was achieved in the case of the zinc oxide photocatalyst particles doped with 1% Pd. The photoreaction was found to be a first-order one.

Response surface analysis of photocatalytic degradation of methyl tert-butyl ether by core/shell Fe3O4/ZnO nanoparticles

The degradation of methyl tert-butyl ether (MTBE) was investigated in the aqueous solution of coated ZnO onto magnetite nanoparticale based on an advanced photocatalytic oxidation process. The photocatalysts were synthesized by coating of ZnO onto magnetite using precipitation method. The sample was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibration sample magnetometer (VSM). Besides, specific surface area was also determined by BET method. The four effective factors including pH of the reaction mixture, Fe3O4/ZnO magnetic nanoparticles concentration, initial MTBE concentration and molar ratio of [H2O2]/ [MTBE] were optimized using response surface modeling (RSM). Using the four-factor-three-level Box–Behnken design, 29 runs were designed considering the effective ranges of the influential factors. The optimized values for the operational parameters under the respective constraints were obtained at PH of 7.2, Fe3O4/ZnO concentration of 1.78 g/L, initial MTBE concentration of 89.14 mg/L and [H2O2]/ [MTBE] molar ratio of 2.33. Moreover, kinetics of MTBE degradation was determined under optimum condition. The study about core/shell magnetic nanoparticles (MNPs) recycling were also carried out and after about four times, the percentage of the photocatalytic degradation was about 70%.