Degradation Of Aniline Research Articles

Degradation of aniline with zero-valent iron as an activator of persulfate in aqueous solution

Zero valent iron (ZVI) can activate persulfate to generate sulfate free radicals which are a strong oxidant to degrade organic pollutants. The oxidative degradation of aniline in aqueous solution by persulfate activated with zero valent iron was studied under laboratory conditions. Batch experiments were conducted to investigate the effects of different parameters such as pH, ZVI concentration, aniline concentration, persulfate concentration and reaction temperature on aniline degradation. The results showed that aniline degradation increased with increasing temperature. The optimum dosage of ZVI was 0.4 g L−1 and 85% aniline degradation was observed. Maximum aniline degradation was observed at pH 4.0, whereas at pH above or below 4.0, aniline degradation efficiency was decreased. In the persulfate-ZVI system, the apparent energy of activation for aniline degradation was 14.85 kJ mol−1. The existence of persulfate radicals and hydroxyl radicals produced during the degradation of aniline were identified with scavenger ethanol and tert-butyl alcohol. The reaction intermediates nitrobenzene, nitroso-benzene and p-benzoquinone were detected by gas chromatography-mass spectrometry and based on these intermediates obtained a probable pathway for aniline degradation has been proposed.

Photocatalytic Degradation of Aniline Using Supported TiO2/Charcoal Composite

Photocatalytic Degradation of Aniline Using Supported TiO2/Charcoal Composite

Orthogonal Study on the Degradation of Aniline Process Parameters by Ultrasonic

Objective: To optimize the ultrasonic degradation of aniline wastewater process parameters. Methods: ultrasonic power, ultrasonic time, ultrasonic temperature, pH value, etc. 4 orthogonal factors and determine the optimum process conditions. Results: In the ultrasonic power 320W, ultrasonic time was 60min, ultrasonic temperature is 30 °C, pH value of 4 under the action of ultrasound sonication best, under optimum conditions, aniline degradation rate of 90.08%, and the various factors the impact of the size order of ultrasonic temperature> ultrasonic time> ultrasonic power> solution pH. Conclusion: Ultrasonic degradation of organic matter, is easy to operate, efficient, non-polluting or less polluting characteristics, is a better degradation of aniline wastewater new technology.

English

  Corynebacterium sp was isolated from the soil by using 3-5 dinitro benzoic acid (DNB) as a sole carbon source. The highest rate of degradation of aniline (AN) or DNB was found in the exponential phase of the growth of the bacterium. After 24 h, about 50% of DNB and 30% of AN were degraded by Corynebacterium sp. At a concentration of 0.5 to 1 g/L of AN or DNB, good growth was obtained and the protocatechuic acid was detected. The optimum concentration of yeast extract was 2 g/l. Catechol 1-2 dioxygenase was induced in the cells grown on a medium containing AN or DNB. A significant activity of this enzyme was detected, which means that ortho cleavage pathway may be present inCorynebacterium sp.   Key words: Corynebacterium sp., degradation, dinitrobenzoic acid (DNB), aniline (AN),protocatechuic acid, catechol, catechol 1-2 dioxygenase, Ortho cleavage, high performance liquid chromatography (HPLC).

Analysis Degradation Effect of Aniline Wastewater by Ultrasound

aniline solution for the study, the effects of ultrasonic time, reaction factors such as temperature, ultrasonic power, and the pH of its ultrasonic degradation rate. Experimental results show that: as time increases, the ultrasonic degradation rate of aniline also rise, When the ultrasound the irradiation time 80min, aniline degradation rate reached 89.3%, 90min when the degradation rate of 92.1%, the degradation rate of aniline with decreases with the rise of the temperature of the solution, more than 40°C the degradation rate decreased significantly. Aniline degradation rate increased with the initial solution pH value increases, indicating that the alkaline conditions are favorable for degradation of aniline solution. Relative to the traditional method, the method is fast, simple, degradation rate, etc..

Function of a Glutamine Synthetase-Like Protein in Bacterial Aniline Oxidation via γ-Glutamylanilide

Acinetobacter sp. strain YAA has five genes (atdA1 to atdA5) involved in aniline oxidation as a part of the aniline degradation gene cluster. From sequence analysis, the five genes were expected to encode a glutamine synthetase (GS)-like protein (AtdA1), a glutamine amidotransferase-like protein (AtdA2), and an aromatic compound dioxygenase (AtdA3, AtdA4, and AtdA5) (M. Takeo, T. Fujii, and Y. Maeda, J. Ferment. Bioeng. 85:17-24, 1998). A recombinant Pseudomonas strain harboring these five genes quantitatively converted aniline into catechol, demonstrating that catechol is the major oxidation product from aniline. To elucidate the function of the GS-like protein AtdA1 in aniline oxidation, we purified it from recombinant Escherichia coli harboring atdA1. The purified AtdA1 protein produced gamma-glutamylanilide (γ-GA) quantitatively from aniline and l-glutamate in the presence of ATP and MgCl2. This reaction was identical to glutamine synthesis by GS, except for the use of aniline instead of ammonia as the substrate. Recombinant Pseudomonas strains harboring the dioxygenase genes (atdA3 to atdA5) were unable to degrade aniline but converted γ-GA into catechol, indicating that γ-GA is an intermediate to catechol and a direct substrate for the dioxygenase. Unexpectedly, a recombinant Pseudomonas strain harboring only atdA2 hydrolyzed γ-GA into aniline, reversing the γ-GA formation by AtdA1. Deletion of atdA2 from atdA1 to atdA5 caused γ-GA accumulation from aniline in recombinant Pseudomonas cells and inhibited the growth of a recombinant Acinetobacter strain on aniline, suggesting that AtdA2 prevents γ-GA accumulation that is harmful to the host cell.

Degradation of aniline by plate and rod electrode fered‐fenton reactors: Effects of current density, Fe2+, H2O2, and aniline concentrations

This study investigates the degradation of aniline by the Fered‐Fenton process with a plate and rod electrode. The effects of electric current, H2O2, Fe2+, and aniline concentrations on the kinetic models, H2O2 efficiency, and energy consumption in aniline and chemical oxygen demand (COD) removal were examined. The kinetics of aniline degradation using the Fered‐Fenton process was second‐order. The H2O2, Fe2+, and aniline concentrations affected the COD removal efficiency more than electric current. The kinetics of aniline degradation using the Fered‐Fenton process was second‐order. In both Fered‐Fenton reactor systems, increasing the electric current, H2O2, Fe2+ and aniline concentrations significantly decreased the efficiency of H2O2 in reducing aniline and COD. The reactor design substantially affected the rate constant of aniline degradation. In general, the rate constants of aniline degradation in the plate electrode Fered‐Fenton reactor were around 1.1–6.3 times higher than that in the rod electrode Fered‐Fenton reactor. At various H2O2 concentrations, the rod electrode Fered‐Fenton reactor consumed twice as much energy in removing aniline and COD compared with the plate electrode Fered‐Fenton reactor. Additionally, COD removal required twice the energy needed to remove aniline. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 410–418, 2014

Aniline degradation in aqueous solution by UV-aeration and UV-microO3 processes: Efficiency, contribution of radicals and byproducts

The use of combination of air and UV irradiation for organic matters removal has drawn attention since degradation efficiency would be significantly enhanced in the presence of oxygen. Considering the fact that a low-pressure mercury UV lamp (emitting at 254nm and 185nm) could dissociate oxygen in gas phase and generate ozone, UV irradiation with addition of ozone enriched air, generated by the same UV lamp, was introduced. This technology was called UV-microO3 because the concentration of ozone generated by UV irradiation was relatively low (lower than 1mgL−1). The degradation of aniline by UV-aeration and UV-microO3 processes was comparatively analyzed. It was shown that aniline underwent much faster and more complete degradation in UV-microO3 process than in UV-aeration system. Hydroxyl radical (OH) exposure in UV-microO3 process was 2.46times of that in UV-aeration system. Furthermore, increasing inlet air flow rate would be of benefit to maintaining high dissolved oxygen (DO) level in UV-aeration system, thus the aniline removal was improved. While concentration of ozone generated by UV irradiation increased at first and then declined as the air flow rate increased from 1.8Lmin−1 to 4.8Lmin−1 in UV-microO3 process, and similar trend for aniline removal rate was observed. The contributions of radicals on aniline removal in UV-aeration and UV-microO3 processes were calculated to be 23.1% and 67.7%. The formation of 4-aminophenol, 4-Hydroxydiphenylamine, azobenzene and 4-Phenylazophenol was observed as the major intermediates in UV-aeration and UV-microO3 processes, mechanism of aniline degradation was proposed based on experimental evidence.

Analysis of biodegradation by-products of nitrobenzene and aniline mixture by a cold-tolerant microbial consortium

A cold-tolerant microbial consortium, which can use nitrobenzene (NB) and aniline (AN) as sole carbon, nitrogen and energy sources, was isolated from an NB and AN contaminated site. Pilot 454 pyrosequencing analysis of the consortium showed that it was mainly made up of Pseudomonas spp. (98%). At 10°C, the consortium degraded the mixture of 50mg/L NB and 50mg/L AN at a similar rate as those achieved at 20°C and 30°C. The biodegradation by-products with different initial NB and AN concentrations at 10°C were analyzed. Azobenzene, azoxybenzene and acetanilide were observed in NB and AN mixtures degradation. These by-products are generated by the reaction between different intermediates resulting from the NB and AN degradation as well as the parent compounds. To the best of our knowledge, this is the first report confirming the by-products of NB and AN mixture biodegradation by a cold-tolerant microbial consortium.

Morphology-controlled synthesis of SnO2 nanostructures using hydrothermal method and their photocatalytic applications

SnO 2 hierarchical architectures were synthesized by a surfactant-free hydrothermal synthesis route. The influence of hydrothermal temperature and treatment time on the final morphology of the nanomaterials was studied. The as-synthesized nanoparticles were characterized by X-ray powder diffraction (XRD), UV–vis spectroscopy, scanning electron microscopy (SEM) and adsorption isotherm measurement. Degradation of aniline, 4-nitroaniline and 2,4-dinitroaniline as model organic pollutants was studied in the presence and absence of ultraviolet radiation. The effects of experimental parameters including irradiation time, solution pH and organics structure on the degradability were studied. The photodegradation of the pollutants followed first-order kinetics. The influence of SnO 2 morphology on its photocatalytic activity was comparatively investigated. The SnO 2 flower-shaped catalysts showed higher activity compared with others suggesting that the morphology of the catalysts exerts a noticeable influence on their performances.

Degradation of aniline by Fe2+-activated persulfate oxidation at ambient temperature

The aniline degradation by persulfate activated with ferrous ion (Fe2+) was investigated in batch reactor at ambient temperature. The experimental factors in aqueous solutions including persulfate concentration, Fe2+ concentration, pH and ionic strength level were discussed. It is demonstrated that, aniline degradation rate increases with increasing persulfate concentration, but much more ferrous ion inhibits the aniline degradation. When the aniline concentration is 0.10 mmol/L, the maximum aniline degradation occurs at the S2O8 2− to Fe2+ molar ratio of 250/5 at pH 7.0. In the pH range of 5.0–8.5, increasing pH causes higher aniline degradation. What’s more, the increase of ionic strength in solution causes inhibiting in the reaction. Produced intermediates during the oxidation process were identified using gas chromatography-mass spectrometry (GC-MS) technology. And degradation pathways of aniline were also tentatively proposed.

Real-time PCR for rapidly detecting aniline-degrading bacteria in activated sludge

We developed a detection method that uses quantitative real-time PCR (qPCR) and the TaqMan system to easily and rapidly assess the population of aniline-degrading bacteria in activated sludge prior to conducting a biodegradability test on a chemical compound. A primer and probe set for qPCR was designed by a multiple alignment of conserved amino acid sequences encoding the large (α) subunit of aniline dioxygenase. PCR amplification tests showed that the designed primer and probe set targeted aniline-degrading strains such as Acidovorax sp., Gordonia sp., Rhodococcus sp., and Pseudomonas putida, thereby suggesting that the developed method can detect a wide variety of aniline-degrading bacteria. There was a strong correlation between the relative copy number of the α-aniline dioxygenase gene in activated sludge obtained with the developed qPCR method and the number of aniline-degrading bacteria measured by the Most Probable Number method, which is the conventional method, and a good correlation with the lag time of the BOD curve for aniline degradation produced by the biodegradability test in activated sludge samples collected from eight different wastewater treatment plants in Japan. The developed method will be valuable for the rapid and accurate evaluation of the activity of inocula prior to conducting a ready biodegradability test.

Comparison of Aniline Degradation by Fenton and Electro‐Fenton Reactors Using Plate and Rod Electrodes

Aniline degradation was investigated using the conventional Fenton process and an electro‐Fenton (EF) process with plate and rod electrode EF reactors. The performance of the two EF reactors was evaluated by determining the effect of important parameters (Fe2+, H2O2, and aniline concentrations) on the aniline removal efficiency and the initial aniline degradation rate. The change in the biochemical oxygen demand (BOD5) and ratio BOD5/COD of a high concentration of aniline were also studied.Experimental results reveal that compared with conventional Fenton process, aniline degradation and chemical oxygen demand (COD) removal in the EF process increased 43% and 10%, respectively. In the two EF reactors, the aniline was completely degraded (100%) when the ratio of [H2O2]:[Fe2+]:[aniline] was 5.8:0.1:1. Within the range of Fenton's reagent used in the two reactors, controlling the H2O2 concentration was the key point of promoting the aniline oxidation. The plate electrode system had a higher efficiency than rod electrode system in terms of H2O2 efficiency, due to the reactor design of decreasing the electrical resistance. Treatment with a high concentration aniline increased biodegradability (BOD5 and ratio BOD5/COD) of pollutant when plate and rod electrode EF reactors were used. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 1111–1117, 2013

Reaction kinetics of the degradation of chloroanilines and aniline by aerobic granule

The reaction kinetics of the degradation of ClAs and AN by aerobic granules were studied in a stable sequencing airlift bioreactor (SABR). Results showed that the degradation of ClAs and AN by aerobic granules followed the Haldane equation. The maximum substrate degradation rates (Vmax) for different pollutants were as follows: AN>4-ClA>2-ClA>3-ClA>3,4-DClA, and the order of inhibition constant (Ki) was AN>3-ClA>4-ClA>2-ClA>3,4-DClA. The biodegradabilities of ClAs and AN was well relevance to their spatial parameters and thermodynamic coefficients. At the same time, the values of Vmax and Ki increased along with the granular diameter (peaked at 1.25–2.0mm), and then Ki increased but Vmax decreased. The results demonstrated that the formation of aerobic granule favours enhancing the degradability of toxic organic compounds, and controlling the granular diameter is important for optimising the performance of bioreactors.

A new approach for the degradation of high concentration of aromatic amine by heterocatalytic Fenton oxidation: Kinetic and spectroscopic studies

In the present investigation an attempt was made to degrade aniline in the synthetic effluent by homogeneous and heterogeneous Fenton oxidation process. Experiments were carried out under the batch and continuous operating conditions. The effect of time, pH and the mass of mesoporous activated carbon on the degradation of aniline in the synthetic wastewater was critically examined through eexperimental design and optimization by central composite design (CCD) under the response surface methodology (RSM). The kinetic constants and the thermodynamic parameters for the oxidation of aniline in synthetic wastewater were determined. The degradation of aniline in synthetic wastewater was confirmed using FT-IR, NMR and UV–visible spectroscopy.

Characterization of the nitrobenzene-degrading strain Pseudomonas sp. a3 and use of its immobilized cells in the treatment of mixed aromatics wastewater

A bacterial strain Pseudomonas sp. a3 capable of degrading nitrobenzene, phenol, aniline, and other aromatics was isolated and characterized. When nitrobenzene was degraded, the release of NH(4) (+) was detected, but not of NO(2) (-). This result implied that nitrobenzene might have a partial reductive metabolic pathway in strain a3. However, aniline appeared as one of the metabolites during the aerobic degradation of nitrobenzene. Moreover, the appearance of 2-aminophenol during aniline degradation by strain a3 indicated that novel initial reactions existed during the degradation of nitrobenzene and aniline by strain a3. Strain a3 was immobilized in the mixed carrier of polyvinyl alcohol and sodium alginate to improve its degrading efficiency. The optimal concentrations of polyvinyl alcohol and sodium alginate in the mixed carrier were 9 and 3 %, respectively. The immobilized cells had stable degradation activity and good mechanical properties in the recycling tests. The immobilized cells also exhibited higher tolerances in acidic (pH 4-5) and highly saline (10 % NaCl) environments than those of free cells. The biodegradation of nitrobenzene mixed with aniline and phenol using immobilized cells of Pseudomonas sp. a3 was also greatly improved compared with those of free cells. The immobilized cells could completely degrade 300 mg L(-1) nitrobenzene within 10 h with 150 mg L(-1) aniline and 150 mg L(-1) phenol. This result revealed that the immobilized cells of Pseudomonas sp. a3 could be a potential candidate for treating nitrobenzene wastewater mixed with other aromatics.

Cloning and functional analysis of the genes coding for 4-aminobenzenesulfonate 3,4-dioxygenase from Hydrogenophaga sp. PBC

The gene coding for the oxygenase component, sadA, of 4-aminobenzenesulfonate (4-ABS) 3,4-dioxygenase in Hydrogenophaga sp. PBC was previously identified via transposon mutagenesis. Expression of wild-type sadA in trans restored the ability of the sadA mutant to grow on 4-ABS. The inclusion of sadB and sadD, coding for a putative glutamine-synthetase-like protein and a plant-type ferredoxin, respectively, further improved the efficiency of 4-ABS degradation. Transcription analysis using the gfp promoter probe plasmid showed that sadABD was expressed during growth on 4-ABS and 4-sulfocatechol. Heterologous expression of sadABD in Escherichia coli led to the biotransformation of 4-ABS to a metabolite which shared a similar retention time and UV/vis profile with 4-sulfocatechol. The putative reductase gene sadC was isolated via degenerate PCR and expression of sadC and sadABD in E. coli led to maximal 4-ABS biotransformation. In E. coli, the deletion of sadB completely eliminated dioxygenase activity while the deletion of sadC or sadD led to a decrease in dioxygenase activity. Phylogenetic analysis of SadB showed that it is closely related to the glutamine-synthetase-like proteins involved in the aniline degradation pathway. This is the first discovery, to our knowledge, of the functional genetic components for 4-ABS aromatic ring hydroxylation in the bacterial domain.

Degradation kinetics and mechanism of aniline by heat-assisted persulfate oxidation

Oxidation of aniline by persulfate in aqueous solutions was investigated and the reaction kinetic rates under different temperature, persulfate concentration and pH conditions were examined in batch experiments. The results showed that, the aniline degradation followed pseudo first-order reaction model. Aniline degradation rate increased with increasing temperature or persulfate concentration. In the pH range of 3 to 11, a low aniline degradation rate was obtained at strong acid system (pH 3), while a high degradation rate was achieved at strong alkalinity (pH 11). Maximum aniline degradation occurred at pH 7 when the solution was in a weak level of acid and alkalinity (pH 5, 7 and 9). Produced intermediates during the oxidation process were identified using liquid chromatography-mass spectrometry technology. And nitrobenzene, 4-4′-diaminodiphenyl and 1-hydroxy-1,2-diphenylhydrazine have been identified as the major intermediates of aniline oxidation by persulfate and the degradation mechanism of aniline was also tentatively proposed.

Degradation of aniline catalyzed by heterogeneous Fenton‐like reaction using iron oxide/SiO2

The immobilized iron oxides on quartz granules (SG) were withdrawn from the fluidized bed reactors and then used to catalyze hydrogen peroxide (H2O2) from heterogeneous generating hydroxyl radical (•OH). The effects of the reaction conditions including the initial pH, SG loading, and concentrations of aniline on aniline degradation were examined. The experimental result showed that the decomposition of H2O2 decreased with increased concentrations of H2O2 once the concentration of H2O2 increased to more than 0.05 M. The rate constant of aniline degradation (kobs) increased when increasing amounts of SG were added. The evidence proved the initial pH = 4–6 in the solution is an optimum condition for the degradation of aniline using SG as a heterogeneous catalyst. The aniline degradation suggested that •OH initially attacked the aromatic ring‐NH2 bonding of aniline, and the ring opening of aniline was then formed. Results demonstrate that the iron oxides are recyclable, cheaper, and more active. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 187‐192, 2013

Photocatalytic Degradation of Aniline Using TiO2Nanoparticles in a Vertical Circulating Photocatalytic Reactor

Photocatalytic degradation of aniline in the presence of titanium dioxide (TiO2) and ultraviolet (UV) illumination was performed in a vertical circulating photocatalytic reactor. The effects of catalyst concentration (0–80 mg/L), initial pH (2–12), temperature (293–323 K), and irradiation time (0–120 min) on aniline photodegradation were investigated in order to obtain the optimum operational conditions. The results reveal that the aniline degradation efficiency can be effectively improved by increasing pH from 2 to 12 and temperature from 313 to 323 K. Besides, the effect of temperature on aniline photo degradation was found to be unremarkable in the range of 293–313 K. The optimum catalyst concentration was about 60 mg/L. The Langmuir Hinshelwood kinetic model could successfully elucidate the effects of the catalyst concentration, pH, and temperature on the rate of heterogeneous photooxidation of aniline. The data obtained by applying the Langmuir Hinshelwood treatment are consistent with the available kinetic parameters. The activated energy for the photocatalytic degradation of aniline is 20.337 kj/mol. The possibility of the reactor use in the treatment of a real petroleum refinery wastewater was also investigated. The results of the experiments indicated that it can therefore be potentially applied for the treatment of wastewater contaminated by different organic pollutants.