Degradation Of Thiophene Research Articles

Synthesis of Nitronyl Nitroxide Radical-Modified Multi-Walled Carbon Nanotubes and Oxidative Desulfurization in Fuel.

Novel and highly stable nitronyl nitroxide radical (NIT) derivatives were synthesized and coated on the surface of multi-walled carbon nanotubes (MWCNTs) to improve their desulfurization performance. They were characterized by FTIR, UV-vis, SEM, XRD, Raman spectroscopy and ESR. Thiophene in fuel was desulfurized by molecular O2, and the oxidation activity of these compounds was evaluated. At a normal temperature and pressure, the degradation rates of thiophene by four compounds in 4 h can reach 92.66%, 96.38%, 93.25% and 89.49%, respectively. The MWCNTs/NIT-F have a high special activity for the degradation of thiophene, and their desulfurization activity can be recycled for five times without a significant reduction. The mechanistic studies of MWCNTs/NIT composites show that the ammonium oxide ion is the key active intermediate in catalytic oxidative desulfurization, which provides a new choice for fuel oxidative desulfurization. The results show that NIT significantly improves the photocatalytic performance of MWCNTs.

Effects of Thiophene Degradation on the Corrosiveness of Oil and the Properties of Oil–Paper Insulation in the Oil-Immersed Transformers

As a non-corrosive inactive sulfur, thiophene is one of the most common sulfides in mineral oil, which are retained in oil and used for improving the oxidation stability of the oil. However, thiophene may be decomposed and form low-molecular sulfide with strong corrosiveness because of rapid energy accumulation under operating conditions of the oil-immersed power transformer. Thus, this study explored the effect of thiophene degradation on the corrosiveness and properties of insulating oil under thermal and electrical aging conditions, including a case investigation of sulfur corrosion of a 500-kV electric reactor and the accelerated aging experiments of oil–paper insulation. The results showed that the degradation and pyrolysis of thiophene depend on energy accumulation induced by thermal and electric fields in the oil-immersed transformers. Under the premise of thiophene without degradation and transformation, thiophene can still delay the deterioration of insulating oil due to its high oxidation resistance. The continuous energy accumulation induced by thermal and electric fields may cause the molecular chains of thiophene molecules to break and form some corrosive low-molecular sulfides, thereby resulting in the increase of the corrosiveness of oil, the decrease of the properties of oil–paper, and posing a huge corrosion threat to the oil-immersed transformer.

Coupling of the optimized electro-Fenton-like process with pulsed laser ablation method to produce bimetallic nanoparticles of Fe°/Cu° and Fe°/Zn° in treatment of thiophene aqueous samples

In this study, an electro-Fenton-like method in the presence of iron particles was used for degradation of toxic thiophene pollutant from aqueous samples with performance > 99%. In an electrolytic reactor, the effect of current density, H2O2 dosage and pH of the sample on the treatment efficiency was investigated and optimized using response surface method in experimental design methodology. The conditions were optimized in current density 20 mA/cm2, H2O2 dosage 500 ppm and pH = 3.0. In this process, a laser pulse ablation was used to produce iron nanoparticles in the electro-Fenton reactor to decrease the treatment time. Also, two bimetallic iron-copper and iron-zinc were used to investigate the synergistic effect of bimetallic catalyst on degradation efficiency of thiophene. The removal of thiophene nearly 100% can be provided in presence Fe0.5/Cu0.5, Fe0.5/Zn0.5 and Fe alone in 10, 15 and 20 minutes, respectively. Also, the effect of hydroxyl scavenger and the consumption of catalysts were studied in the proposed procedure. Techniques of gas chromatography-flame ionization detector (GC-FID), gas chromatography-sulfur chemiluminescence detector (GC-SCD) and total sulfur analyzer were used to follow thiophene degradation. A thiophene petrochemical wastewater was treated by the proposed method and the results showed significant reduction of amounts of Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD).

Radiolytic degradation of thiophene: Performance, pathway and toxicity evaluation

Thiophene is one of typical refractory organic pollutants in coal chemical wastewater, which cannot be effectively removed by traditional biological treatment processes. In this study, ionizing radiation was used to degrade thiophene. The effect of absorbed dose, initial concentration and pH on the thiophene degradation was investigated. The results showed that thiophene could be completely degraded when the its initial concentration was 5 mg/L, the pH was 9, and the absorbed dose was 5 kGy. The results of quenching experiments indicated that all the hydroxyl radicals, hydrated electron and hydrogen radicals were responsible for the degradation of thiophene, which explained the wide range of pH application for the thiophene degradation by ionizing radiation. Four degradation intermediates were identified, including thiophene 1-oxide, thiophen-2-ol, 2,3-dihydrothiophen-2-ol and acetic acid, and two possible pathways of thiophene degradation were thus proposed. Ecological structure activity relationships program analysis suggested that thiophene 1-oxide and thiophen-2-ol were more toxic than thiophene. In general, ionizing radiation is an effective technology for thiophene degradation.

Photocatalytic Degradation of Synthetic Sulfur Pollutants in Petroleum Fractions under Different pH and Photocatalyst

Thiophene is one of the sulfur compounds in the petroleum fraction that can be harmful to living things and lead to a critical effect on the ecosystem. Photocatalytic degradation is one of the promising methods in treating wastewater as it can mineralization of pollutants into carbon dioxide and water. Other than that, this method is non-toxic and relatively low cost. The production of hydroxyl radicals playing a vital role in the degradation of organic pollutants. It has been claimed that the usage of zinc oxide (ZnO) nanoparticles could give an excellent degradation process as this photocatalyst have high photosensitivity, low cost and chemically stable. However, the preparation method of ZnO nanoparticles will affect the agglomeration, particle size, shape and morphology of particles and lead to influence the photocatalytic activity in degrading thiophene. Therefore, this study focused on the effectiveness of ZnO nanoparticles in the presence of fibrous nanosilica (KCC-1) and polyethylene glycol (PEG) as the capping agent to degrade synthetic thiophene. ZnO/KCC-1 had been synthesized via the precipitation method and characterized by using Fourier Transform Infrared (FTIR). The chemical bond and nature of the photocatalyst from the FTIR results proved that the synthesis process to produce the ZnO/KCC-1 was succeed. The large surface area of KCC-1 increases the effectiveness of ZnO which is supported by the experimental data. Accordingly, the optimum condition for photocatalytic degradation of thiophene is under pH 7 by using ZnO/KCC-1 as photocatalyst. Hence, it is believed that this research could be implemented to remove the thiophene in petroleum fraction from the actual industrial effluents and this can preserve nature in the future.

Application of SrRuO3 Nanoparticles Supported with Reduced Graphene Oxide for Degradation of Thiophene Under Visible Light Irradiation

Application of SrRuO3 Nanoparticles Supported with Reduced Graphene Oxide for Degradation of Thiophene Under Visible Light Irradiation

Catalytic Conversion of Synthetic Sulfur-Pollutants in Petroleum Fractions Under Different Photocatalyst Loadings and Initial Concentration

In the oil and gas industry which applied to petroleum sources, thiophene is one of the sulphur contaminants that may harm the environment. The contents of sulphur in petroleum product gives out concern regarding the negative and harmful effect of sulphur contaminants onto environment and living health. One of the promising methods to degrade thiophene is photocatalytic degradation process. The usage of ZnO nanoparticles in photocatalytic degradation process has been wider due to its broad band gap, greater excitation of energy binding, and high stability. Several studies have discovered the ability of ZnO with capping agent in photocatalytic activity. Photocatalytic activity of photo-catalyst was affected by particle size, shape and morphology that are depending on the preparation method. Hence, this study put on priori-ties on synthesizing ZnO nanoparticles using precipitation method with the addition of KCC-1 which act as capping agent and used in the degradation of synthetic thiophene solution. The characterization of ZnO-KCC-1 using FTIR has confirmed that the successfulness produc-tion of ZnO-KCC-1 via precipitation method. There are three different loading of ZnO-KCC-1 (0.05 g/L, 0.10 g/L and 0.15 g/L) and thio-phene concentration (100 ppm, 300 ppm and 600 ppm) had been carried out in photocatalytic degradation of thiophene. The pH value for all fixed condition remains constant at natural pH range which is pH 7. The optimum condition of degrading synthetic thiophene under natural pH range by using ZnO-KCC-1 is at its loading of 0.05 g/L with the initial concentration of synthetic thiophene of 300ppm.The kinetic study of this research has been confirmed to be at the first-order of kinetic reaction.

In situ hydrothermal preparation and photocatalytic desulfurization performance of graphene wrapped TiO2 composites

Organosulfur impurities in fuels cause severe environmental pollution and poison the catalysts used in vehicle exhausts’ gas converters. Here we developed a facile “In suithydrothermal” method to prepare reduced graphene oxide (RGO) supported TiO2 catalyst and applied it for oxidative desulfurization of thiophene(T) in model fuel. The RGO/TiO2 catalysts were characterized by FT-IR, XPS, SEM, XRD and UV–Vis spectroscopy. The photocatalytic properties were evaluated by the degradation of thiophene in model fuel. The catalytic activity of RGO/TiO2 composites for the oxidation of thiophene in n-octane is relatively higher than those of pure GO or TiO2 power. Moreover, the thiophene conversion rate reached 94.3% with RGO/TiO2 composite catalyst after treatment for 100 min at atmospheric pressure. The graphene oxide is partially reduced during the “in situ hydrothermal” process. The photocatalysis mechanism indicated that RGO/TiO2 photocatalysts are facilitating to electron transfer fromTiO2 to RGO and enhance the adsorption of the target pollutants to improve the oxidative desulfurization (ODS) performance.

Intensified desulfurization of simulated crude diesel containing thiophene using ultrasound and ultraviolet irradiation.

A novel desulfurization approach involving ultrasound, ultraviolet irradiation and additives (catalyst and/or oxidants) was investigated for degradation of thiophene (model sulphur compound) present in n-hexane considered as simulated crude diesel. The approaches based on ultrasonic horn also involved combination with various additives such as titanium oxide, zinc oxide, peracetic acid and hydrogen peroxide (H2O2) operated under ambient conditions. All the lab scale studies were performed under fixed condition of 100 W as power and 80% as duty cycle at 500 ml as the operating capacity. The combination of ultrasound and peracetic acid at optimum loading of 8% resulted in higher extent of desulfurization (actual value as 23.4%) compared to the desulfurization obtained using 0.3% loading of zinc oxide and 0.3% loading of titanium oxide combined with ultrasound with desulfurization extent as 13.5 and 22.5% respectively under optimized conditions. The approach of ultrasound and UV light combined with titanium oxide and hydrogen peroxide at optimized loading has also been studied. Maximum desulfurization was obtained as 99% for the combined approach of ultrasound, ultraviolet irradiation, titanium oxide at loading of 0.3 g/L and H2O2 at loading of 300 ppm. Higher degree of desulfurization with the minimum sulphur retention up to 1-2 PPM under intensified processing conditions in terms of lesser treatment time, lesser requirement of oxidants and better cost effectiveness were the main advantages of the combined approach established in the current work as compared to the conventional desulfurization approaches.

Electric Field Assisted Technology for Improving the Screening and Application of a Thiophene-Biodegrading Strain

For the screening of functional strain and biodegradation, two devices of electric field assisted screening (EFAS) and electric field assisted biodegradation (EFAB) were developed in the current work. Candida tropicalis CZ12 capable of thiophene degradation was enriched and isolated from oily soil by the EFAS device at a voltage range of 10–14 v. In EFAB, the thiophene degradation velocity of this strain was accelerated by an assisted electric field, and it could reach 74% at 2 h in aqueous thiophene solution. Furthermore, the removal efficiency of the continuous EFAB device for treating thiophene-containing model fuel was 79.76% under the following conditions: aqueous–hydrocarbon ratio of 5:1, electric field assisted voltage of 15 V, and residence time of 120 min. It was clear that the above advantages of EFAS and EFAB were conducive to facilitating applications in biorefractory organics.

Photocatalytic activity of Bi2S3 enlargement by decoration of silver for visible light thiophene degradation

Bi2S3 nanofibers were prepared via a hydrothermal technique and a photoassisted deposition way was applied to prepare silver-decorated Bi2S3 nanocomposites. Bi2S3 nanofibers and silver-decorated Bi2S3 nanocomposites were investigated using many characterization tools such as X-ray diffraction, field-emission scanning electron microscopy, photoluminescence emission spectra, X-ray photoelectron spectroscopy, ultraviolet and visible spectroscopy, and BET surface area. Photocatalytic destruction of thiophene was selected to determine the photocatalytic performance of Bi2S3 nanofibers and silver-decorated Bi2S3 nanocomposites. XRD results confirm the formation of Bi2S3 nanofibers. FSEM results reveal Bi2S3 nanofiber structure and silver was decorated on surface of Bi2S3 nanofibers. XPS results reveal that state of decorated silver is metallic. Decoration of Bi2S3 nanofibers by silver decreases electron–hole recombination rat, decreases bandgap, and increases photocatalytic activity. 0.3 wt% Ag/Bi2S3 photocatalyst has the top photocatalytic activity by which 100% thiophene was degraded within 60 min using 1.6 g/l photocatalyst dose. 0.3 wt% Ag/Bi2S3 photocatalyst has photocatalytic stability for five times use.

Photocatalytic desulfurization of thiophene base on molecular oxygen and zinc phthalocyanine/g-C3N4

Oxidative desulfurization is considered to be one of the promising new methods for super-deep desulfurization of fuel oil. Herein, zinc phthalocyanine/g-C3N4 (g-C3N4/ZnTcPc) composites were synthesized by a facile in situ hydrothermal technique, utilizing g-C3N4, Zn(CH3COO)2 and 1,2,4-benzenetricarboxylic anhydride as the precursors. The crystal structure, morphology and chemical environment of the catalysts were respectively confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Photocatalytic activity of the resulting g-C3N4/ZnTcPc composites was evaluated by desulfurization of thiophene in fuel under visible light with molecular O2 as the oxidant. Compared with pure g-C3N4 and ZnTcPc, g-C3N4/ZnTcPc presented a significantly enhanced photocatalytic activity for the degradation of thiophene in fuel under visible irradiation. Sulfur content of model gasoline (800 ppm) after desulfurization for 90 min was decreased to 125 ppm. The possible preparation pathway of g-C3N4/ZnTcPc has been proposed according to the results of XRD and TEM. The formation mechanism of g-C3N4/ZnTcPc–O2 complex is proposed to be desulfurization by molecular oxygen.

Enlargement of photocatalytic efficiency of BaSnO3 by indium doping for thiophene degradation

BaSnO3 nanorods were produced by a sol–gel mode. Indium, as dopant, was introduced to the surface of BaSnO3 via photo-assisted deposition technique. Phase composition, microstructure and surface area of the synthesized samples were identified via X-ray diffraction, field emission scanning electron microscopy (FESEM) and BET techniques, respectively. State of element, band gap energy and position of emission energy were measured via X-ray photoelectron spectroscopy (XPS), ultraviolet and visible spectroscopy (UV–Vis) and photoluminescence emission spectra (Pl), respectively. Furthermore, the catalytic performance of both BaSnO3 and In/BaSnO3 specimens was implemented for photocatalytic destruction of thiophene solution via visible light irradiation. XPS results displayed the patterns corresponding to the In–In at about 443.8 eV, illustrating the presence of indium metal in a nano-sized scale. A red shift was observed after indium loading within the BaSnO3 lattice which was proved via the UV–Vis analysis. 100% oxidation efficiency percent was attained using 0.3 wt% In/BaSnO3 photocatalyst after 1 h reaction time. The enhancement of the photocatalytic activity was mainly attributed to the indium doping into BaSnO3 as a result of its capability to hinder the e−–h+ re-combination. The catalyst was reused up to five cycles without any change in its efficiency.

In situ hydrothermal preparation and photocatalytic desulfurization performance of metallophthalocyanine sensitized SnO2

Photocatalytic oxidation technology has been demonstrated to be an effectively method to remove thiophene from fuel. Herein, metallophthalocyanine/SnO2 (MTcPc/SnO2) composites were synthesized by a facile “in situ hydrothermal” technique, utilizing Sn(OH)4 and MTcPc as the precursors. The crystal structure, morphology and chemical environment of the catalysts were respectively confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Photocatalytic activities of MTcPc/SnO2 composites were evaluated by the oxidation of thiophene in fuel under visible light with O2 as the oxidant. Compared with pure SnO2, MTcPc/SnO2 presented a significantly enhanced photocatalytic activity for the degradation of thiophene in fuel under visible irradiation. The desulfurization reaction mechanism by molecular oxygen was proposed to be the formation of the SnO2/ZnTcPc–O2 complex.

Sulfur isotope exchange between thiophenes and inorganic sulfur compounds under hydrous pyrolysis conditions

Sulfur isotope fractionation during thermal degradation of aromatic organic sulfur compounds was studied utilizing quartz tube-hydrous pyrolysis at 360°C. BT (benzothiophene), DBT (dibenzothiophene), 3-PT (3-phenylthiophene) and 2-OT (2-octylthiophene) were used to represent organic sulfur compounds with a range of thermal stabilities. These compounds were heated for 40h with and without the addition of reduced inorganic sulfur species: elemental S, sodium sulfide (Na2S∗9H2O) and sodium sulfite (Na2SO3). The extent of degradation of each compound showed good correlations with its aromatic stabilization and strongly depended on the added inorganic sulfur species, with DBT being the most stable and 2-OT the least stable. Sulfur isotope enrichments up to 2.2‰ resulted from the thermal degradation of thiophenes. A significant decrease in stability of thiophenes was observed in the presence of reduced sulfur species. In contrast, BT and DBT did not show any exchange of S isotopes with external reduced S pool, while 3-PT did experience S isotope exchange. The results of the present study suggest that the main controls on the δ34S values of BT and DBT during TSR are the relative rates of their degradation and their formation from the reaction between TSR-H2S and petroleum hydrocarbons. This finding improves our confidence in using the δ34S of individual thiophenes as reliable proxies for the occurrence and extent of thermal maturation and thermochemical sulfate reduction.

New Visible‐Light Pt/PbS Nanoparticle Photocatalysts for the Photocatalytic Oxidation of Thiophene

AbstractPbS nanoparticles were prepared using a hydrothermal route, and Pt was deposited onto the PbS nanoparticles via a photo‐assisted deposition route. The photocatalytic performances of the PbS and Pt/PbS samples were examined for the photocatalytic oxidation of thiophene under visible light. Deposition of Pt onto the surface of PbS led to a shift in the absorption of PbS to a higher wavelength (red shift). The 0.15 wt% Pt/PbS nanoparticles had the highest photocatalytic efficiency % (100%) for the degradation of thiophene under visible light after 40 min of reaction time. The 0.15 wt% Pt/PbS nanoparticles can be used six times for the degradation of thiophene without a loss of photocatalytic activity.

Preparation and characterization of core–shell polyaniline/mesoporous Cu2O nanocomposites for the photocatalytic oxidation of thiophene

Polyaniline/mesoporous Cu2O core–shell nanocomposites with different mass ratios of polyaniline/mesoporous Cu2O were prepared using a hydrothermal method. For comparison, Cu2O nanoparticles and polyaniline/Cu2O nanoparticles were also prepared using a hydrothermal method. The catalytic performance of the samples during the photocatalytic oxidation of thiophene under visible-light irradiation was determined. The surface areas of the mesoporous and nanoparticulate Cu2O materials were 140 and 40m2/g, respectively. Adding polyaniline to mesoporous and nanoparticulate Cu2O decreases the surface areas of the nanoparticles to 120 and 32m2/g, respectively. TEM images reveal that the mesoporous and nanoparticulate Cu2O materials occur as uniform microspheres and spherical nanoparticles, respectively. The polyaniline/mesoporous Cu2O and polyaniline/Cu2O nanoparticles are core–shell and spherical nanoparticles, respectively. The photocatalytic degradation of thiophene under visible-light irradiation while using 4% polyaniline/mesoporous Cu2O was 2.87, 2.20, and 1.34 times more effective than that observed when using Cu2O nanoparticles, polyaniline/Cu2O nanoparticles, and mesoporous Cu2O, respectively.

Visible light photocatalytic degradation of thiophene using Ag–TiO2/multi-walled carbon nanotubes nanocomposite

Ag–TiO2 nanocatalyst, supported on multi-walled carbon nanotubes, was synthesized successfully via a modified sol–gel method, and the prepared photocatalyst was used to remediate aqueous thiophene environmentally by photocatalytic oxidation under visible light. The prepared Ag–TiO2/multi-walled carbon nanotubes nanocomposite photocatalyst was characterized through X-ray diffraction, Brunauer–Emmett–Teller (BET), transmission electron microscopy, and UV–vis spectra (UV–vis). The results showed that both Ag and TiO2 nanoparticles were well-dispersed over the MWCNTs and formed a uniform nanocomposite. Ag doping can eliminate the recombination of electron–hole pairs in the catalyst, and the presence of MWCNTs in the TiO2 composite can change surface properties to achieve sensitivity to visible light. The optimum mass ratio of MWCNT:TiO2:Ag was 0.02:1.0:0.05, which resulted in the photocatalyst's experimental performance in oxidizing about 100% of the thiophene in a 600mg/L solution within 30min and with 1.4gL−1 amount of catalyst used.

Use of TiO 2/Cr-MCM-41 molecular sieve irradiated with visible light for the degradation of thiophene in the gas phase

Photocatalytic processes using TiO 2 and UV radiation to eliminate pollutants are not yet suitable for industrial facilities due to their high consumption of energy. Transition metals incorporated onto mesoporous MCM-41 molecular sieves impregnated with TiO 2 constitute an alternative that allows the use of solar light. In this study, Cr-substituted MCM-41 were synthesized (Si/Cr = 100, 50 and ∞) and impregnated with TiO 2 (10 and 20 wt.%). Raman results showed the formation of anatase. Electronic spectroscopy and EPR exposed the formation of trivalent chromium after impregnation with TiO 2, which is related to a Cr–TiO 2 interaction. The synthesized photocatalysts, as well as TiO 2 P25, were tested in the degradation of thiophene in gaseous phase. A test with UV lamp showed 100% of conversion for 20%TiO 2/Cr-MCM-41(100) and exceeded the activity of TiO 2 P25, probably due to the higher dispersion of TiO 2 on the surface of the molecular sieve. During tests using visible light and 20%TiO 2/Cr-MCM-41(50) higher conversions than those of 20%TiO 2/Cr-MCM-41(100) and TiO 2 P25 were observed. These results indicate that chromium concentration is a key factor influencing the photocatalytic activity under visible light.

Naphtho[1,2- b]thiophene degradation by Pseudomonas sp. HKT554: involvement of naphthalene dioxygenase.

Pseudomonas sp. strain HKT554 degrades naphtho[1,2- b]thiophene and two other isomers, naphtho[2,1- b]thiophene and naphtho[2,3- b]thiophene, by cometabolism, in the absence of any specific inducer, at similar degradation rates. A mutant of strain HKT554, deficient in dibenzothiophene degradation, was generated by using a recently developed transposition system. Sequence analysis of the mutant revealed that the knocked out gene was almost identical to naphthalene dioxygenase (EC 1.14.12.12). The mutant, HKT554M, degraded neither the naphthothiophene isomers nor dibenzothiophene, suggesting that the naphthalene dioxygenase is responsible for the initial catabolic reactions onto naphthothiophenes and dibenzothiophene.