Degradation Of Quinoline Research Articles

Nitrite accumulation and nitrous oxide emission during denitrification processes with quinoline or indole as the sole carbon source

AbstractBACKGROUNDBatch experiments were conducted to investigate nitrite accumulation and N2O emission during the denitrification processes when quinoline or indole was used as the sole carbon source. The effects of COD/NO3−‐N ratio and pH were studied.RESULTSWhile both significant transient nitrite accumulation and N2O emission occurred when quinoline was used as the carbon source, little denitrification intermediates were observed when indole was used as the carbon source. The optimal COD/NO3−‐N ratio for both complete denitrification and degradation of quinoline and indole were 6.8 and 5.1. Denitrification was inhibited under acidic conditions no matter with quinoline or indole as the carbon source. The optimal pH was 7.5 for both quinoline (or indole) degradation and denitrification. The nitrite accumulation and different carbon source further influenced N2O emission. When quinoline was used as the carbon source, N2O emission was observed at COD/NO3−‐N ≤ 5 and pH ≤ 7.5; when indole was used as the carbon source, N2O emission was observed at COD/NO3−‐N ≤ 3 and pH ≤ 6.5. Higher concentration of N2O was emitted at lower COD/NO3−‐N ratio and pH.CONCLUSIONCOD/NO3−‐N ratio, pH and the types of carbon source significantly influenced the accumulation of denitrification intermediates. © 2014 Society of Chemical Industry

Visible light driven photodegradation of quinoline over TiO2/graphene oxide nanocomposites

Visible light responsive titanium dioxide/graphene oxide composites (TGO) were synthesized via electrostatic attraction at a low temperature of 80°C. A superior visible light driven photocatalytic degradation of quinoline for TGO was achieved (75.56%), which was 6.17 times as high as that of P25 under the same reaction condition. The recycling experiment showed that 93.32% photocatalytic activity was remained after four cycles of repetitive uses. The excellent visible light driven photocatalytic activity and recycle stability could be attributed to the extending optical absorption edge and easy photogenerated electron-hole separation by trapping the electrons generated from titanium dioxide in the presence of graphene oxide. A tentative mechanism was postulated for the photodegradation of quinoline over TGO.

Internal loop photo-biodegradation reactor used for accelerated quinoline degradation and mineralization

Biofilm biodegradation was coupled with ultra-violet photolysis using the internal loop photobiodegradation reactor for degradation of quinoline. Three protocols-photolysis alone (P), biodegradation alone (B), and intimately coupled photolysis and biodegradation (P&B)-were used for degradation of quinoline in batch and continuous-flow experiments. For a 1,000 mg/L initial quinoline concentration, the volumetric removal rate for quinoline was 38 % higher with P&B than with B in batch experiments, and the P&B kinetics were the sum of kinetics from the P and B experiments. Continuous-flow experiments with an influent quinoline concentration of 1,000 mg/L also gave significantly greater quinoline removal in P&B, and the quinoline-removal kinetics for P&B were approximately equal to the sum of the removal kinetics for P and B. P&B similarly increased the rate and extent of quinoline mineralization, for which the kinetics for P&B were nearly equal to the sum of kinetics for P and B. These findings support that the rate-limiting step for mineralization was transformation of quinoline, which was accelerated by the simultaneous action of photolysis and biodegradation.

Isolation and Degradation Kinetics of the Quinoline Degradation Bacterium Strains from Coking Wastewater

An aerobic bacterial strain Q1 capable of utilizing quinoline as sole source of carbon, nitrogen and energy was isolated from activated sludge of a coke plant wastewater treatment process. The morphological properties and the phylogenetic analysis based on 16S rDNA sequences showed strain Q1 belonged to thePseudomonassp.. Another strain Q2 was unable to utilize quinoline as sole source of energy alone can coexist with Q1 when quinoline was sole energy. The coexistence of Q1 and Q2 has synergistic effect to quinoline degradation. The biodegradation tests suggested that the kinetics of quinoline biodegradation by Q1 or the combaination of Q1and Q2 strain can be described by Haldane equation kinetically.

Heterogeneous Catalytic Ozonation of COD and Quinoline from Coal Gasification Wastewater Secondary Effluent with Carbon Supported Copper Oxides as Catalyst

Coal gasification wastewater (CGW) is a refractory and toxic wastewater. The secondary effluent quality usually cannot meet the discharge standards after conventional biological treatment processes. Heterogeneous catalytic ozonation is a promising technology for solving this problem. Two carbon materials were investigated as ozonation catalysts for the removal of the quinoline and COD in a real CGW secondary effluent. Results were indicated that CuOx /GAC presented a higher catalytic performance than granular activated carbon and single ozone, efficiency of removal of quinoline and COD were 69%, 92% respectively. Higher pH had positive effect on the degradation of quinoline due to the formation of hydroxyl radical (removal of quinoline rapidly reached above 90% in pH=10). The presence of the radical scavenger tert-butanol (TBA) evidenced the participation of hydroxyl radicals (•OH) in the oxidation mechanisms of quinoline. The stability of the catalysts was demonstrated by carrying repetitive experiments reusing catalysts sample.

Low-temperature synthesis of water-dispersible anatase titanium dioxide nanoparticles for photocatalysis

Water-dispersible anatase TiO2 nanoparticles were synthesized at a low temperature (80°C) without using surfactants via the mechanism of electrostatic stabilization. The water-dispersible TiO2 nanoparticles solution was stable and no precipitation occurred after 3months. Photocatalytic evaluation demonstrated that the as-synthesized TiO2 nanoparticles possess excellent quinoline degradation performance (a 2.33×10−2min−1 apparent reaction rate constant comparing to 1.22×10−2min−1 for P25) and recycle stability (the photocatalytic activity remained 96.6% of the initial activity after four cycles of repetitive uses). These could be attributed to the small size and good water-dispersibility of the as-synthesized TiO2 nanoparticles that led to large specific surface area and easy photogenerated electron–hole transportation.

Photocatalytic degradation of quinoline in aqueous TiO2 suspension

Anatase TiO2 nanoparticles with an average size of 16nm were synthesized via a modified sol–gel method and were employed to degrade quinoline under UV irradiation (λ=365nm). The influence of reaction parameters such as TiO2 dosage, initial quinoline concentration and pH was investigated. Under the optimized reaction condition, 91.5% photodegradation efficiency of quinoline was achieved. When the TiO2 nanoparticles were reused for four times, the photodegradation efficiency was still as high as 90.6%. The analysis of the organic intermediates suggested that superoxide radical (O2) predominantly attacked the pyridine ring of quinoline leading to the formation of 2-aminobenzaldehyde, 2-quinolinone, 4-quinolinone; while the hydroxyl radical (OH) contributed much less by attacking benzene rings resulting in the formation of 5-hydroxyquinoline. The photocatalytic performance of the as-synthesized TiO2 nanoparticles was comparable to the commercial P25. A tentative mechanism was postulated for the photodegradation of quinoline over TiO2 nanoparticles.

Application of Porous Nickel-Coated TiO2 for the Photocatalytic Degradation of Aqueous Quinoline in an Internal Airlift Loop Reactor

P25 film, prepared by a facile dip-coating method without any binder, was further developed in a recirculating reactor for quinoline removal from synthetic wastewater. Macroporous foam Ni, which has an open three-dimensional network structure, was utilized as a substrate to make good use of UV rays. Field emission scanning electron microscopy and X-ray diffraction analysis showed that the coated/calcinated P25 films consisted of two crystal phases, and had a number of uniform microcracks on the surface. The effects of initial quinoline concentration, light intensity, reaction temperature, aeration, and initial pH were studied. Increased reaction time, light intensity, environmental temperature, and gas aeration were found to significantly improve the quinoline removal efficiency. The aeration effect of oxygen dependency on the quinoline degradation had the trend pure oxygen > air > no gas > pure nitrogen with free O2. The solution pH crucially affected quinoline photodegradation; the high electrostatic adsorption of quinoline molecules on the TiO2 surface was strongly pH dependent. 2-Pyridine-carboxaldehyde, 3-pyridinecarboxaldehyde, and 2(1H)-quinolinone were identified as the major intermediates of quinoline degradation. Based on these intermediates, a primary degradation mechanism was proposed. This reusable P25 film benefits the photodegradation of water contaminants and has potential in other various applications.

Biodegradation characteristics and bioaugmentation potential of a novel quinoline-degrading strain of Bacillus sp. isolated from petroleum-contaminated soil

Quinoline and its derivatives are widely considered to be environmental pollutants. In this study, the biodegradation characteristics and bioaugmentation potential for a novel strain were described. The strain, named Q2, which could utilize quinoline as the sole carbon, nitrogen and energy source, was isolated and identified as a Bacillus sp. The optimum temperature, initial pH and shaker rotary speed for quinoline degradation were 30°C, pH 8–10 and 100–200rpm, respectively. During the biodegradation process, the quinoline-N was released as ammonium and the culture broth became yellow, pink and brown in turn, which indicated that several intermediates were generated. GC/MS analysis showed that 2(1H)-quinolinone and 8-hydroxycoumarin were produced. Furthermore, the bioaugmentation of Q2 into the sludge consortium, which was taken from refinery wastewater treatment plant, to degrade quinoline was investigated. The results showed that it could coexist with the other microbes and the remarkably enhanced quinoline biodegradation ability was achieved.

Facile Preparation of P-25 Films Dip-Coated Nickel Foam and High Photocatalytic Activity for the Degradation of Quinoline and Industrial Wastewater

Facile Preparation of P-25 Films Dip-Coated Nickel Foam and High Photocatalytic Activity for the Degradation of Quinoline and Industrial Wastewater

Facile Preparation of P-25 Films Dip-Coated Nickel Foam and High Photocatalytic Activity for the Degradation of Quinoline and Industrial Wastewater

A kind of P-25 TiO2 films coated nickel foam was synthesized by a facile dip-coating/calcination route, and used to fabricate a continuous-flow three-phase photocatalytic reactor. The morphology, crystal phase structure, surface composition and specific surface area of P-25 films coated nickel foam were investigated by field emission scanning electron microscope (FE-SEM), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS) and nitrogen adsorption-desorption measurements, respectively. The results indicated that the coated/ calcined P-25 films had the porous surface structure fabricated by nano-sized titanium dioxide consisted of two crystal phases and incorporated with a NiO interlayer. The increase of P-25 contents enhanced the specific surface area; however, 20 percent of initial P-25 sol would result in visible large cracks because of too high P-25 content and consequently cause the peeling of films. The photocatalytic activities of nickel foam with different coating amounts of P-25 for the degradation of quinoline aqueous solutions were investigated with a continuous-flow three-phase photocatalytic reactor based on the P-25 films coated nickel foam. The results suggested that nickel foam coated with 10 percent of P-25 sol had an optimal photocatalytic activity for the degradation of quinoline aqueous solutions. The continuous-flow three-phase photocatalytic reactor fabricated with P-25 films coated nickel foam with an optimal P-25 coating amount shows high photocatalytic activity and stability for the degradation of quinoline aqueous solutions and industrial wastewater. The treated industrial wastewater meets the international discharge standard.

Preparation of biological activated bamboo charcoal and its use to remove quinoline from waste water

A strain of bacterium(BC027) for quinoline degradation was inoculated on an activated bamboo charcoal(ABC) substrate to obtain biological activated bamboo charcoal(BABC).SEM micrographs showed that microbe can grow well on ABC.The quinoline removal by the BABC was divided into 3 stages,adsorption,interim and degradation.The degradation played a key role in these stages,which was related to the optical density of bacteria in the solution.In contrast,the adsorption of quinoline on BABC only happened at the first stage.The BABC exhibited higher treatment capacity and longer use life than did ABC.

The Isolation, Characterization, and Diesel Oil Denitrification of a Quinoline-Degrading Bacteria

Quinoline is a poisonous organic compound and not easily biodegraded. From soil, wastewater, and activated sludge 19 bacterial strains were isolated by enrichment culture, which are able to use quinoline as the sole nitrogen source. Of the 19 strains, the HY9 strain is the best quinoline-degradation bacterium. Curves of the growth of HY9 and degradation of quinoline show that the growth of the HY9 strain and degradation of quinoline are concurrent, the optimum time is 50–70 hr, which is the stationary phase. Effects of carbon resource and the quantity of initial quinoline on degradation of quinoline are studied. The optimal carbon resource and quantity of initial quinoline amount are glucose 0.14 mL/100 mL. The orthogonal test determined optimal temperature, pH, time, and agitation speed, which are respectively 35°C, 7.0, 4 days, 125 rev/min. Temperature is the key factor, followed by pH and agitation speed, and time of culture is the least important factor. The denitrification rate of diesel oil is very low, only 13%. This is probably because the oil and water could not mix well; the key to strengthening the compatibility of oil and water is to try to improve the denitrification rate of diesel oil.

Carbon and hydrogen isotope fractionation during anaerobic quinoline degradation

Quinoline is a N-heterocyclic compound often found at tar oil contaminated field sites. To provide information whether stable isotope analysis can help to characterize the fate of quinoline within contaminated aquifers, carbon and hydrogen isotope fractionation of quinoline were investigated during biodegradation under sulfate-reducing conditions. No significant carbon isotope effect was observed, however, substantial hydrogen isotope fractionation was detected. Thus, hydrogen isotope fractionation may be used as an indicator for in situ biodegradation of quinoline. The bulk hydrogen isotope enrichment factor was εH bulk = −33 ± 12 ‰. During the biodegradation of quinoline the primary intermediate 2-hydroxyquinoline was detected indicating hydroxylation at the C2-position. According to this reaction mechanism, the reactive position specific hydrogen enrichment factor ( εH reactive position) and apparent kinetic hydrogen isotope effect (AKIE H) were calculated and gave values of εH reactive position = −205 ± 75 ‰ and AKIE H = 1.26 ± 0.12, respectively. The missing carbon isotope effect may be explained by strong masking or an enzymatic direct side-on insertion of oxygen from the Mo OH(H) group of the molybdenum center across the C H bond at the C2-position of quinoline with concomitant hydride transfer. The later assumption is supported by recent studies showing that initial step of hydroxylation of N-heteroaromatic compounds proceeds via a similar reaction mechanism.

Biodegradation characteristics of quinoline by Pseudomonas putida

A quinoline-degrading strain was isolated from activated sludge of the municipal wastewater treatment plant and identified as Pseudomonas putida on the basis of its partial 16S rRNA gene sequence analysis. The characteristics of quinoline degradation were investigated. The experimental results showed that quinoline at the concentration of 500 mg/L could be completely removed within 3 h, but could not be mineralized because special pigments were observed in the process of quinoline biodegradation. The N-atom in the quinoline ring was released as NH 3; some metabolic intermediates were identified, including 2-hydroxyquinoline, 2,8-dihydroxyquinoline and 8-hydroxycoumarin. The metabolic pathway of quinoline by P. putida was tentatively proposed, that is, via 8-hydroxycoumarin pathway, namely, the biodegradation was initiated by hydroxylation at position 2 to form 2-oxo-1,2-dihydroquinoline (2-hydroxyquinoline), which was then oxidized to 8-hydroxy-2-oxo-1,2-dihydro-quinoline (2,8-dihydroxyquinoline) and 8-hydroxycoumarin.

Preparation and performance of biologically activated bamboo charcoal for removing quinoline

A strain of bacterium (BC027) for quinoline degradation was inoculated on the activated bamboo charcoal (ABC) substrate. SEM observation showed that the bacterium grew well on the charcoal substrate and thus obtained biologically activated bamboo charcoal (BABC). The investigation on quinoline removal showed that BABC has greater capacity for removing quinoline than ABC or dissociate BC027. The removal ability of BABC is influenced by initial concentration and domestication process. Adsorption of carbon substrate only occurred at the beginning stage, while it had no effect on the bacterium inoculation and activity. The bacteria enhanced the treatment capacity of ABC and prolonged its usage life.

Nitrate-dependent biodegradation of quinoline, isoquinoline, and 2-methylquinoline by acclimated activated sludge

The anaerobic degradation of quinoline, isoquinoline and 2-methylquinoline was investigated under nitrate-reducing conditions with acclimated activated sludge. Quinoline was completely transformed during degradation with an optimum COD/NO(3)-N ratio of 7. Isoquinoline and 2-methylquinoline were also completely transformed; however, nitrate consumption was much lower with the optimum COD/NO(3)-N ratios being in the ranges of 83-92 and 21-26, respectively. GC-MS analyses showed that during degradation, quinoline and isoquinoline were transformed by hydroxylation into 2(1H)-quinolinone and 1(2H)-isoquinolinone, respectively. While quinoline was completely mineralized, only 92% of isoquinoline was mineralized, and 1(2H)-isoquinolinone remained in the effluent. 2-Methylquinoline was transformed by hydrogenation to 1,2,3,4-tetrahydro-2-methyl-quinoline, and further degradation resulted in cleavage of the heterocyclic ring leaving 4-ethyl-benzenamine. Both the metabolites remained in the effluent, resulting in the low mineralization of 2-methylquinoline (58%). This is the first time that 2-methylquinoline is observed degradable under denitrifying conditions, and its metabolites are identified.

Solid-State 13C NMR Characterization of Carbon-Modified TiO2

13C-modified TiO2 was prepared to facilitate study of the dopant atoms and trace their chemical fate throughout the process. In the preannealed material, NMR showed strong evidence of many Ti−O−C bonds. After annealing, surface-bound coke is a major component. NMR also showed that a washing step before annealing led to the generation of orthocarbonate (C(OR)4) centers, observed at 126 ppm, which are located deep inside the TiO2 particles. Both NMR and XPS confirmed the presence of small amounts of regular sp2-hybridized carbonate species in all briefly annealed samples, while annealing for longer times led to a reduction removal of the COn centers. Quantitative NMR also shows the degree of carbon loss that accompanies annealing. Some variation in the chemical degradation of quinoline is noted among the catalysts, but coke-containing TiO2 catalysts are not qualitatively better catalysts for use with visible light with this substrate.

Isolation and Characteristics of Quinoline Degrading Bacteria from Wastewater Denitrifying Bioreactor

Quinoline, a nitrogenous heterocyclic compound (NHC), is a common pollutant in many fossil industries wastewaters, such as coking plant wastewater. Due to the limitation of knowledge for the diversity of quinoline degrading bacteria, the isolation of diverse degrading bacteria from quinoline contaminated environment is important work not only for understanding the process of quinoline degradation, but also for optimizing the wastewater treatment. In this study, 56 strains of quinoline degrading bacteria were isolated from quinoline acclimated bioreactor and coking wastewater treatment bioreactor under different culture conditions. These strains were grouped into 12 OTUs by ADRDA and the representative sequences of these OTUs were affi liated to Ochrobactrum, Bacillus, Pseudomonas and Rhodococcus. Some of these strains were used for measuring their quinoline degrading capabilities. Most of the assayed strains showed high degrading effi ciency, except that a few strains could not degrade quinoline independently. As we know, it is the fi rst report that the bacteria of Ochrobactrum could degrade quinoline so far. Fig 2, Tab 3, Ref 31

Degradation of quinoline by Rhodococcus sp. QL2 isolated from activated sludge

A novel aerobic gram-positive bacterial strain capable of utilizing quinoline as sole source of carbon, nitrogen and energy was isolated from activated sludge of a coke plant wastewater treatment process. The isolate was identified as Rhodococcus sp. QL2 based on its morphology, physiochemical properties in addition to the results from 16S rDNA sequence analysis. The optimum temperature and the pH for its growth were 35–40 °C and 8.0, respectively. Extra nitrogen sources stimulated the bacterial growth on quinoline. Strain QL2 had strong quinoline degradability, and its degradation kinetics could be described with Haldane's model. Strain QL2 also had a broad range of substrate utilization. Identification of intermediates by GC/MS showed Rhodococcus sp. QL2 degraded quinoline via two pathways simultaneously.