Degradation Of Phenol In Wastewater Research Articles

Degradation of phenol in wastewater by cathodic microarc plasma electrolysis

ABSTRACTIn this paper, the cathodic microarc plasma electrolysis (CMPE) was tentatively performed to degrade the phenol in aqueous solution by vapor-gaseous envelope discharge around the Ti cathode. Degradation efficiency of phenol was measured and the intermediate products were evaluated. The suspended particles in solution were analyzed and the decomposition mechanism of phenol in the process of cathodic microarc plasma degradation was discussed. The instantaneous current efficiency reached a peak value firstly and then decreased with the discharge time. In the cathodic plasma region, the Cl substituted the hydrogen on benzene ring in the initial time, which was replaced by a hydroxyl immediately, then the polyhydroxy phenol was easily decomposed. In addition, optical emission spectroscopy was carried out to characterize the plasma features during the CMPE process. The temperature of electron around the microarc discharge envelope reached about 4000 K; thus the phenol was partly carbonized to become graphite particles. CMPE is a promising approach to degrade quickly the phenol in wastewater.

New insight into the enhanced visible light-driven photocatalytic activity of Pd/PdCl2-doped Bi2WO6 photocatalysts

A bismuth-based compound, Bi2WO6, was successfully synthesized using a facile hydrothermal method. Aiming to improve its photocatalytic activity under visible light irradiation, Pd/PdCl2 was first doped onto the surface of Bi2WO6 via a photo-reduction method. The prepared Pd/PdCl2-Bi2WO6 samples were characterized based on crystal structures, chemical states, atomic compositions, and morphologies as well as photoabsorption properties. In the screening tests for photocatalytic activity, the 4% Pd-Bi2WO6 sample performed with the highest removal efficiency with respect to the degradation of phenol in wastewater. This sample exhibited better in complete degradation of phenol under visible light irradiation, compared to TiO2 under ultraviolet irradiation. A possible mechanism for the enhanced visible light-driven photocatalytic activity by means of loading Bi2WO6 with Pd was also suggested. This work sheds light on the potential applications of noble metal nanoparticles in visible light-driven photocatalysis.

The Effect of Polyethylene Glycol (PEG) Modification on Fe Dispersal and the Catalytic Degradation of Phenol Wastewater

Modification of a catalyst with polyethylene glycol (PEG) created a dramatic increase in the catalytic activity for the degradation of phenol wastewater. The Fe/PEG-modified γ-Al2O3 catalyst was prepared by an impregnation method. The as-prepared catalyst was characterized by X-ray photoelectron spectroscopy, wide- and small-angle X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and N2 adsorption-desorption experiments, and the results showed that the Fe species were highly dispersed on the surface of the PEG-modified support. At the same time, the PEG modification resulted in an increase in the Brunauer-Emmett-Teller surface area and pore volume. The catalytic activity test showed that the Fe/PEG-modified γ-Al2O3 catalyst exhibited a superior performance for the degradation of phenol wastewater in this study, and the phenol and COD removal values reached 94.1 and 88.9%, respectively, within 60 min. The results clearly show that PEG modification is a promising methodology for the preparation of a catalyst with good dispersal of the active component on the support.

Toxicity of Phenol and Salt on the Phenol-Degrading Pseudomonas aeruginosa Bacterium

Background: Phenolic compounds, phenol and phenol derivatives are environmental contaminants in some industrial effluents. Entrance of such substances into the environment causes severe environmental pollution, especially pollution of water resources. Biological treatment is a method that uses the potential of microorganisms to clean up contaminated environments. Among microorganisms, bacteria play an important role in treating wastewater contaminated with phenol. Objectives: This study aimed to examine the effects of Pseudomonas aeruginosa on degradation of phenol in wastewater contaminated with this pollutant. Methods: In this method, the growth rate of P. aeruginosa bacteria was investigated using different concentrations of salt and phenol. This is an experimental study conducted as a pilot in a batch reactor with different concentrations of phenol (25, 50, 100, 150, 300 and 600 mg L-1) and salt (0%, 0.5%, 1%, 2.5% and 5%) during 9, 12 and 15 hours. During three days, from 5 experimental and 3 control samples, 18 samples were taken a day forming a sample size of 54 samples for each phenol concentration. Given the number of phenol concentrations (n = 6), a total of 324 samples were analyzed using a spectrophotometer at a wavelength of 600 nm. Results: The phenol concentration of 600 mg L-1 was toxic for P. aeruginosa. However, at a certain concentration, it acts as a carbon source for P. aeruginosa. During investigations, it was found that increasing the concentration of phenol increases the rate of bacteria growth. The highest bacteria growth rate occurred was at the salt concentration of zero and phenol concentration of 600 mg L-1. Conclusions: The findings of the current study indicate that at high concentrations of salt, the growth of bacteria reduces so that it stops at a concentration of 50 mg L-1 (5%). Thus, the bacterium is halotolerant or halophilic. With an increase in phenol concentration, the growth rate increased. Phenol toxicity appears at a concentration of 600 mg L-1.

Degradation of phenol wastewater by a new electromagnetic induction photo-catalytic reactor

A new inductive photo-catalytic reactor was obtained by the alternative magnetic field and optical coupling, which was driven by AC supply. In the cylinder reactor, UV-LED lights with the wavelength of 375-380nm were evenly distributed, and the phenol solution was used as simulated wastewater. The effects of initial phenol concentration, pH, TiO2, H2O2, alternative magnetic frequency, current, and reaction time on the phenol degradation were investigated under an imposed alternative magnetic field. The optimized conditions and results were as follows: phenol concentrations of 15mg/L, pH of 7, H2O2 of 15μL, TiO2 of 0.18g and alternative magnetic frequency of 12 KHz and current of 2A. With these conditions, the phenol degradation ratio reached 47.1% in 1 h reaction time. The new reactor is very promising for the effective treatment of refractory organic pollutants.

HRP Immobilization on Activated Carbon/Polyvinyl Formal Composite Materials for Degradation of Phenolic Wastewater

A novel method was developed for degradation of phenolic waste water using horseradish peroxidase (HRP) immobilization on activated carbon/polyvinyl formal (AC/PVFM) composite materials in this study. The materials were black-sponge-like, soft and elastic, and had three-dimensional porous network structure. Optimum conditions of immobilized HRP carrier preparation technology was selected by orthogonal experiment. The enzymatic properties were explored and compared between immobilized and free enzyme. The optimum pH of immobilized HRP and free HRP were both 4, nevertheless, the immobilization of HRP increased the enzyme activity. The optimum temperature of immobilized HRP was 20°C which was lower than that of free HRP (25°C), therefore the immobilized HRP could resist to lower temperature. The Km of immobilized HRP and free HRP were 0.23 mmol/L and 0.40 mmol/L, respectively. The lower Km value of immobilized HRP indicated higher affinity to the substrate. These results show that HRP immobilized on AC/PVFM composite materials is promising in phenolic wastewater degradation.

Synthesis of iron-based nanoparticles and comparison of their catalytic activity for degradation of phenolic waste water in a small-scale batch reactor

In the present work, iron-based nanoparticles were synthesized by sol–gel method (iron oxide I), modified co-precipitation method (iron oxide II), reduction of FeSO4 by NaBH4 (nano zero-valent iron I, nZVI I), and reduction of FeSO4 by NaBH4 in presence of chelating ligand EDTA (nZVI II) for use as a catalyst for degradation of phenol. Particle characterization was performed for each set of samples by UV–vis spectra, X-ray diffraction, Fourier transformed infrared spectroscopy (FTIR), dynamic light scattering (DLS), and field emission scanning electron microscopy (FESEM). FESEM was performed with iron oxide II and particle size was found to be 36.5 nm. The average particle diameter obtained for nZVI was in the range of 141–150 nm. nZVI(II) has been found to be most efficient with respect to high percentage degradation of phenol in an hour under optimum operating condition at room temperature which were as follows: catalyst concentration = 0.05 g/l, pH 3, phenol:hydrogen peroxide (50%) concentration = 1:14 (stoichiometric ratio), temperature = ambient. Brunauer–Emmett–Teller (BET) surface area measurement also showed higher surface area for nano zero-valent iron (nZVI) particles than compared to other iron oxides. The initial phenol concentration was varied in the range of 50–400 mg/l. Degradation efficiency was found decreasing with increasing initial concentration of phenol. Iron oxide I and II can be successfully recovered and reused.

Degradation of Phenol in Wastewater with Ozone Produced by Self-design Ozone Generator

The optimized tube’s structure of the self-design ozone generator was made with the double dielectric inner electrode and small metal cones were embedded in the outside electrode. This ozone generator was used for the degradation of phenol in wastewater. The research was studied from ozone gas flow rate, reaction time, the initial pH and concentration of the phenol in wastewater. In addition, the article also discusses the reaction mechanism of ozone degraded the phenol in wastewater. The results illustrate that the ozone concentration of self-design ozone generator under the pure oxygen flux (1.0 L/min) were 7.06 mg/L, compared with the unoptimized ozone, the optimized ozone generator’s efficiency was improved 56.89%; the phenol removal rate was increased as the initial pH increased in wastewater, when pH was 12, the phenol removal rate was 80.17%; GC-MS analysis was adopted to analyze and determine the phenol intermediates. The results illustrate that the major oxidation degradation products of phenol may be p-benzoquinone benzenequinone, 4-cyclopentene-1, 3-dione and diacetone alcohol.

Pt nanoparticles/TiO2 for photocatalytic degradation of phenols in wastewater

Pt nanoparticles/TiO 2 catalysts were prepared and evaluated for UV-photocatalytic degradation of phenol and 2-chlorophenol (2-CP) in synthetic wastewater solutions. The catalysts were synthesized by immobilizing colloidal Pt nanoparticles onto titanium dioxide (rutile TiO 2). Analytical techniques, such as standard Brunauer–Emmett–Teller isotherms, X-ray diffraction, transmission electron microscope, were utillized for investigating the specific surface area, structure, and particle size distribution of the catalysts and its components. The photocatalytic activities of both phenol and 2-CP solutions were studied in a 1 L batch photoreactor independently, under 450 W UV irradiation. Samples were drawn at regular intervals and residual concentration of phenol and 2-CP in the samples was analysed using an UV-visible spectrophotometer. Parameters controlling the photocatalytic process, including catalyst concentration, solution pH, and initial phenol (2-CP) concentration, were investigated. The obtained results revealed that Pt/TiO2 showed higher photocatalytic degradation for both phenol and 2-CP pollutants in solution (as compared to the rutile TiO2). The degradation efficiencies of 87.7% and 100% were obtained for phenol and 2-CP, respectively, under optimized conditions (0.5 g/L catalyst with a pollutant concentration of 50 mg/L after irradiation time of 180 min).

Degradation of phenol in wastewater using anolyte produced from electrochemical generation of brine solution

This paper presents the degradation of phenol in wastewater using anolyte, which is generated from electrochemical activation process. Anolyte consists of reactive ions and free radicals, which contribute to its oxidizing behavior. The optimum conditions, which facilitate a complete degradation of phenol, were found using variation of dosage of anolyte and reaction time. It was found that about 20% of anolyte was the optimal dosage which corresponded to 98% degradation of phenol after a reaction time of 60 minutes. The main products during degradation of phenol by anolyte were found to be benzoquinone, hydroquinone, catechol, maleic acid, fumaric acid and oxalic acid.

Isolation and Characterization of the Phenol Degradation Bacterium <i>Diaphorobacter</i> P2 Strain from Coking Wastewater

A aerobic bacterium strain P2 isolated from coking wastewater, was able to utilize phenol, o-cresol and pyridine as its sole carbon and energy source. The morphological properties and the phylogenetic analysis based on 16S rDNA sequences showed strain P2 belonged to the genus Diaphorobacter sp.. The optimum biodegradation of phenol was 37°C, pH 7.0-9.0 and 0.25% NaCl , respectively. The growth arrearage period was prolonged with the phenol concentration. The growth of Diaphorobacter P2 and phenol-degradation were inhibited completely by 50 μmol/L metal ions, such as Cu2 +, Ni2+, Cd2+ or Cr6+. Orthogonal experiment indicated the order of metal toxicity to biodegradation of P2 was Zn2+>Mn2+>Pb2+ under various heavy-metal compounds. The phenol biodegradation in coking wastewater supplemented with 2/3 beef extract peptone medium was degraded fully in 3 days, indicating that nutrient solution was beneficial for P2 growth and phenol degradation in wastewater. Those results suggest that the Diaphorobacter P2 has potential for treatment of coking wastewater.

Enhancement of Photocatalytic Activity of ZnO/SiO2by Nanosized Pt for Photocatalytic Degradation of Phenol in Wastewater

ZnO- nanoparticles were synthesized by a sol-gel technique from and tetraethyl orthosilicate (TEOS). The synthesized samples were further modified by nanosized Pt from H2PtCl6solution through photoassisted deposition (PAD) and impregnation (Img) routes. The obtained samples were characterized by a series of techniques including X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy, N2adsorption, extended X-ray absorption fine structure (EXAFS), and transmission electron microscopy (TEM). The photocatalytic activity of the Pt-ZnO/ was evaluated by photocatalytic degradation of phenol in synthetic wastewater under UV-irradiation. Results obtained revealed that the surface area and the photocatalytic activity of the prepared samples were increased in the order ZnO/ < PAD: Pt-ZnO/ < img: Pt-ZnO/. The surface area decreased from 480 to 460 and 450 m2/g, while the efficiency of the phenol degradation increased from 80 to 85 and 100%, with the ZnO/, Img: Pt-ZnO-, and PAD: Pt-ZnO- samples, respectively.

Study on the Oxidation and Degradation of Phenol Wastewater by Synthetic Cryptomelane

A well-crystallized cryptomelane-like material (α-MnO2) has been synthesized by redox reaction between Mn2+ and MnO4- under acid condition at certain temperature. This composite material was characterized by X-ray diffraction, volumetric (N2 adsorption-desorption) and scanning electron microscopic analysis, as well as the Laser Raman spectroscopy. Synthetic cryptomelane was used in the oxidation of hydroxylation of phenol in order to study the oxidation activity. The result showed that the degradation rate of 50 mL of 100 mg/L phenol could recch to nearly 100%, under the conditions of pH 2.0, 3 g/L of synthetic cryptomelane with the grain size of 120~160 mesh, and the reaction time of 5 h at room temperature. The treated wastewater has achieved the industrial wastewater discharge standard. Moreover, the economic cost of synthetic cryptomelane was cheaper and the treatment effect of phenol becomed better. Therefore, the synthetic cryptomelane is believed to have a bright prospect in the development of industrial sewage treatment.

An Efficient Catalysis-Oxidation Method for the Degradation of Phenol in Wastewater

In this study, we developed an efficient catalysis-oxidation method for the degradation of phenol in wastewater, in which the Fe3O4 nanocrystals and H2O2 were employed as catalyst and oxidation agents respectively. Firstly, Fe3O4 nanocrystal coated with PEG was prepared via an oxygenation-deposition hydrothermal method, TEM, FT-IR, BET and XRD characterization indicated that the prepared Fe3O4 nanocrystals had an average size of 26 nm and the specific surface of 35.25 m2/g. Using the prepared Fe3O4 nanocrystals as catalyst, the phenol in wastewater was efficiently degraded by H2O2. The degradability of the phenol was investigated by FT-IR, HPLC and UV–visible spectrophotometer, and the experimental results showed that the phenol was efficiently degraded by H2O2 and the Fe3O4 nanocrystals could be efficiently recycled. Finally, the possible catalytic reaction mechanisms and pathways of phenol degradation were discussed.

Design of Photocatalytic Reactor for Degradation of Phenol in Wastewater

Abstract ― The photocatalytic reactors can operate using catalyst suspended in the solution or immobilized on various supports. Photocatalytic reactors with suspended catalyst give much better contact between the photocatalyst and dissolved impurities comparing to reactors with immobilized catalyst. Titanium dioxide (TiO 2 ) is a promising photocatalyst, when exposed to sunlight or UV rays, it decomposes the phenol present in wastewater. The available reactors are not so efficient in terms of light contact pattern. The aim of the present study was to design the new reactor and analyze its performance for removal of phenol from water with Titanium dioxide as the photocatalyst. The various parameters were studied to observe the behavior of designed reactor like variations in the initial feed concentration of phenol, mass of catalyst, and change in the intensity of UV light & its source, and aeration of the system. The reactor performance was evaluated on the basis on change in concentration with respect to time. The performance of the reactor was studied by running the reactor in fluidized state for a known feed concentration of phenol. The designed reactor has given a better degradation of phenol up to 95.27 % within one hours of time, which when compared to existing conversion of 94 % in two hours.

Continuous phenol degradation in wastewater by Rhodococcus jostii rha1; model batch test and continuous verification in a biofilter

Continuous phenol degradation in wastewater by Rhodococcus jostii rha1; model batch test and continuous verification in a biofilter

Degradation of phenol accumulated in a micellar molybdovanadophosphate nanoreactor by air at ambient temperature and atmospheric pressure

A novel route to facilitate the degradation of phenol is reported. This new approach is based on a micellar polyoxometalate (POM) catalytic system. The micellar POM catalyst could promote phenol molecules' degradation into a simple inorganic compound such as CO2 using only air as an oxidant under room conditions. The results of the recycling experiment suggests that the micellar POMs may be used as a potential catalyst for the degradation of phenol in wastewater.

COMPARISON OF PHENOL PHOTODEGRADATION BY UV/H2O2 AND PHOTO-FENTON PROCESSES

In this study, advanced photochemical oxidation processes, UV/H2O2 and photo-Fenton systems were investigated for phenol degradation in wastewater with low-pressure mercury vapor lamp. The results indicated that in the UV/H2O2 system, a sufficient amount of H2O2 was necessary, but a very high H2O2 concentration inhibited the photolysis rate. The optimum H2O2 concentration was achieved in the range of 0.05-0.1 mol/L at phenol concentration of 100 mg/L. No pH effects were observed in the range of 4-10. The results of study showed that the UV/H2O2/Fe(II) system was the most effective treatment process under acidic condition and generated a higher rate of phenol degradation at a very short time. It enhanced the oxidation rate by 3 times the rate for the UV/H2O2 process. For all these reactions, the degradation rates are evaluated by determining their first-order rate constants and half-life times. At the optimum condition, phenol completely disappeared with UV/H2O2 and UV/H2O2/Fe(II) systems in less than 50 min and 20 min, respectively.

Phenol degradation and microbial characteristics in upflow anaerobic sludge blanket reactors at ambient and mesophilic temperatures

A synthetic wastewater containing phenol as sole substrate was respectively treated at temperatures of 26±1°C and 37±1°C in 2.8 litre upflow anaerobic sludge blanket (UASB) reactors. At the two temperatures, pH 7.0?7.5, with a 1:1 effluent recycle ratio, phenol in wastewater was efficiently degraded in a UASB reactor. Microbial community analysis using denaturing gradient gel electrophoresis (DGGE) showed that less shift in the microbial community occurred with the temperature changing. Phenol degradation in wastewater was recommended to select ambient temperature in UASB reactors. The optimal HRT was 12 to 16 hours corresponding to 6.0?4.5 g COD/(l.d) loading rate at ambient temperature in UASB reactors. The distribution of archaeal and bacterial populations in the UASB granular consortium was revealed using fluorescence in situ hybridisation (FISH) technique.

Anaerobic degradation of phenol in wastewater at ambient temperature

Treating a synthetic wastewater containing phenol as the sole substrate at 26 degrees C, an upflow anaerobic sludge blanket reactor was able to remove over 98% of phenol up to 1,260 mg/l in wastewater with 12 h of hydraulic retention time, corresponding to 6.0 g-COD/(l x day). Results showed that benzoate was the key intermediate of phenol degradation. Conversion of benzoate to methane was suppressed by the presence of phenol. Based on DNA cloning analysis, the sludge was composed of five groups of microorganisms. Desulfotomaculum and Clostridium were likely responsible for the conversion of phenol to benzoate, which was further degraded by Syntrophus to acetate and H2/CO2. Methanogens lastly converted acetate and H2/CO2 to methane. The role of epsilon-Proteobacteria was, however, unclear.