Catalytic Oxidation Of Phenol Research Articles

Studies on the Phenol Oxidation with H2O2 Catalyzed by Metallomicelle Made from Crowned Schiff Base Mn(III) Complexes

Metallomicelles made from two Schiff base manganese(III) complexes (MnL1 and MnL2) and surfactants (CTAB and Brij35) were used as mimetic peroxidase in the catalytic oxidation of phenol by H2O2. The catalytic activity of the complexes (MnL1 and MnL2) were investigated. The mechanism and a kinetic mathematic model of the phenol catalytic oxidation were also studied. The results show the optimum acidity of the enzyme-like system in the paper is ca. pH 7.0, the optimum temperature which is ca. 35°C and the optimum molar ratio of H2O2 to the complex is ca. 30 in the complexes-H2O2-buffered solution; the Schiff base manganese(III) complexes and their metallomicelles as peroxidase mimics exhibit good catalytic activity and similar catalytic character to natural enzyme.

Peroxidase-like activity of water-soluble cupric oxide nanoparticles and its analytical application for detection of hydrogen peroxide and glucose

Water-soluble cupric oxide nanoparticles are fabricated via a quick-precipitation method and used as peroxidase mimetics for ultrasensitive detection of hydrogen peroxide and glucose. The water-soluble CuO nanoparticles show much higher catalytic activity than that of commercial CuO nanoparticles due to their higher affinity to hydrogen peroxide. In addition, the as-prepared CuO nanoparticles are stable over a wide range of pH and temperature. This excellent stability in the form of aqueous colloidal suspensions makes the application of the water-soluble CuO nanoparticles easier in aqueous systems. A colorimetric assay for hydrogen peroxide and glucose has been established based on the catalytic oxidation of phenol coupled with 4-amino-atipyrine by the action of hydrogen peroxide. This analytical platform not only confirms the intrinsic peroxidase-like activity of the water-soluble cupric oxide nanoparticles, but also shows its great potential applications in environmental chemistry, biotechnology and medicine.

The Catalytic Oxidation of Aqueous Phenol by H2O2Using a Macrocyclic (N-Donor) Cobalt(Ii) Complex

A new macrocyclic (N-donor) cobalt(II) complex, denoted CoR, was synthesized and characterized, and used as a mimetic peroxidase in the catalytic oxidation of phenol by H2O2. The catalytic system displayed high catalytic activity and the catalytic character of a metalloenzyme, although it did not attain the catalytic efficiency of enzymes. The final products were maleic and oxalic acids. Intermediate products, such as catechol and hydroquinone and p-benzoquinone, were detected by high-pressure liquid chromatography (HPLC) and UV-Vis spectrophotometry. The effects of temperature and the pH of the system on the rate of the catalytic oxidation were investigated. A reaction mechanism and kinetic model for the catalytic oxidation are proposed, which are supported by the results of the experimental and calculation data.

Performance of CuO/Oxone system: Heterogeneous catalytic oxidation of phenol at ambient conditions

CuO particles were synthesized by a hydrothermal method and used to activate Oxone for advanced oxidation of phenol in aqueous solution. The effects of several parameters on the degradation efficiency of the process were investigated. The as-prepared catalyst exhibited high activity in degradation of phenol and 100% decomposition and 86% TOC removal could be achieved in 60 min at the optimum conditions. Moreover, the catalyst was demonstrated to have good stability and reusability. Radical quenching studies were conducted to classify the type of active radicals present in the reaction and X-ray photoelectron spectroscopy (XPS) was applied to investigate the transformation of the chemical state of copper. According to the experimental results, a reasonable mechanism was proposed to interpret the catalytic process.

Determination of catalytic oxidation products of phenol by RP-HPLC

A reversed-phase high-performance liquid chromatography (RP-HPLC) with ultraviolet detection was established for the determination of phenol, catechol, hydroquinone, and p-benzoquinone in the reaction solution of catalytic oxidation of phenol using hydrogen peroxide as the oxidant and copper-doped FeSBA-15 zeolite as the catalyst. Separation was accomplished on a reversed-phase C18 column, and the elution condition was optimized by changing the composition of the mobile phase. A good resolution of all of the relative components in the reaction solution was achieved when the mobile phase was methanol–water–1% acetic acid aqueous solution = 10:50:40 (v/v/v). The concentrations of phenol, catechol, hydroquinone, and p-benzoquinone were determined in 11 different reaction solutions by the external standard method. The proposed HPLC method was simple, accurate, reliable, and suitable for tracing the amount of target products during the catalytic oxidation reaction of phenol. The results can provide data support for evaluating the properties of catalysts, and, thus, guide the selection of catalysts for the industrial production of dihydric phenol.

Synthesis of recyclable catalyst–sorbent Fe/CMK-3 for dry oxidation of phenol

The magnetic mesoporous material Fe/CMK-3 acting as a catalyst–sorbent was synthesized by using ordered mesoporous carbon CMK-3 as the supporter, Fe(NO 3) 3 as the iron source, and glycol as the reducing agent. The samples synthesized were characterized by powder X-ray diffraction (XRD), N 2 adsorption–desorption, scanning electron microscope (SEM) and transmission electron microscopy (TEM). The results show that the prepared Fe/CMK-3 preserved the ordered mesoporous structure of CMK-3, and magnetic species was mainly Fe 3O 4, which was dispersed inside channels of CMK-3 as nanoparticles with the diameter of around 10 nm. The adsorption and catalytic dry oxidation efficiency of the prepared Fe/CMK-3 were determined. The results also show that Fe/CMK-3 had good adsorption performance of phenol in aqueous solution and could be easily separated from water and recycled due to its ferromagnetic nature. Iron oxides supported on CMK-3 were excellent catalysts for dry oxidation of phenol. After 15 adsorption–catalytic oxidation cycles, the phenol adsorption capacity of Fe/CMK-3 only decreased a little, suggesting the good practicality. Combined thermogravimetry and mass spectrum (TG–MS) instrument was used to investigate the catalytic oxidation of phenol on Fe/CMK-3 and the ignition characteristics of the catalyst–sorbent. The supported Fe 3O 4 was found to be not only the magnetic component but also the active catalyst for the oxidation of phenol. The adsorbed phenol could be oxidized into CO 2 and H 2O at 220 °C at which no obvious phenol desorption or CMK-3 ignition occurred.

First observation of tetranitro iron (II) phthalocyanine catalyzed oxidation of phenolic pollutant assisted with 4-aminoantipyrine using dioxygen as oxidant

A novel system for catalytic oxidation of phenol and chlorophenol pollutant in water by tetranitro iron (II) phthalocyanine (TNFe(II)Pc) is reported for the first time. In this system, several phenolic substrates (phenol, 2-chlorophenol, 4-chlorophenol and 2,4-dichlorophenol) could be easily oxidized by naturally dissolved oxygen in the presence of TNFe(II)Pc, and then rapidly combined with 4-aminoantipyrine to generate the pink dye. The catalytic oxidation process and resulting products were monitored by UV–Vis spectroscopy and high performance liquid chromatography–mass spectrometer (HPLC–MS) technique. Control experiments demonstrated that the generation of superoxide anion radical was crucial for the dye formation, and a possible mechanism involved a successive single electron transfer from phenolic substrates to O 2 via the axis of TNFe(II)Pc was proposed. Potentially, this system is promising for application in chromogenic identification of phenolic pollutant.

Catalytic wet peroxide oxidation of phenol over Cu–Ni–Al hydrotalcite

Liquid phase catalytic oxidation of phenol was carried out over Cu–Ni–Al hydrotalcite at ambient temperature and pressure using hydrogen peroxide as oxidant. The results showed that the hydrotalcite catalyst had high catalytic activity, where phenol could be completely oxidized by H 2O 2 into oxalic acid, formic acid and CO 2 within 2 h at 30 °C. The catalytic oxidation process was zero-order kinetics with an activation energy of 61.5 kJ mol − 1 . A feasible reaction system could be proposed as follows: 0.8 g L − 1 of catalyst, n (H 2O 2)/n (phenol) = 15, temperature of 40 °C, 2.66 mM of phenol and time of 2 h. Furthermore, it was found that the presence of inorganic chlorides promoted markedly the oxidation rate of phenol, probably due to the formation of intermediate products containing chlorine such as quinones and/or radicals.

Carbon nanostrutured materials as direct catalysts for phenol oxidation in aqueous phase

The catalytic oxidation of phenol in aqueous phase (CWAO) over different carbon nanostrutured materials, nanofibres (CNFs), carbon nanotubes (CNTs) and high surface area graphite (HSAG), and the derivative materials prepared by surface oxidation, has been comparatively studied. Furthermore, in order to determine the effect of the oxidation treatment the samples were characterized by thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and BET measurements. Important differences among these carbon materials were found in terms of catalytic activity. The oxidized CNFs (ox/CNFs), which probably exhibits the most homogeneous surface after introduction of carboxylic groups by oxidation were the most catalytically active. Particular emphasis has been paid to understand the role of different surface chemistry on the produced oxidation intermediates during the phenol CWAO reaction. Samples with higher concentration of carboxylic surface groups, ox/CNFs and ox/CNTs, show less accumulation of refractory short chain acids, like formic, malonic and oxalic acid during the reaction.

Surfactant-Induced Electrodeposition of Layered Manganese Oxide with Large Interlayer Space for Catalytic Oxidation of Phenol

Electrolysis of aqueous Mn2+ ions at an anodic potential of +1.0 V (vs Ag/AgCl) in the presence of cationic surfactants led to the formation of multilayered manganese oxides intercalated with the surfactant molecules. Their interlayer spacings are much larger than that (∼0.7 nm) of conventional birnessite; i.e., 3.1 nm with cetyltrimethyl ammonium (C16) and 2.4 nm with dodecyltrimethyl ammonium (C12). According to XPS analysis, the molar ratio of C16 to MnO2 was estimated to be 0.74, in which the C16 fraction of 0.42 is associated with Cl− anions and the other (0.32) interacts with negative charges on the Mn oxide layer. C16 surfactants accommodated between the Mn oxide layers were not ion-exchanged with Na+ ions in solution but extracted with ethanol. Anodic oxidation of the C16-intercalated Mn oxide (C16/MnO2) film took place in an aqueous Na2SO4 solution, accompanied with insertion of SO42- anions for charge compensation, and not deintercalation of the surfactants. As a result, the layered structure wi...

Cobalt exchanged zeolites for heterogeneous catalytic oxidation of phenol in the presence of peroxymonosulphate

Several cobalt ion-exchanged zeolite catalysts based on ZSM-5, zeolite-A, and zeolite-X were prepared and tested for heterogeneous oxidation of phenol in the presence of various oxidants such as H2O2, persulphate, and peroxymonosulphate. It is found that Co-ZSM-5 is highly effective in heterogeneous activation of peroxymonosulphate to produce sulphate radicals but exhibits low activity for the activation of H2O2 and persulphate for organic oxidation in water. Co-zeolite-A and Co-zeolite-X show much faster reaction rate in homogeneous activation of peroxymonosulphate due to decomposition of the catalysts and leaching of Co ions into aqueous solution. Co-ZSM-5 also presents stable performance in heterogeneous activation of peroxymonosulphate for phenol degradation. The phenol degradation depends on catalyst loading, phenol concentration, oxidant concentration and temperature. Kinetic studies indicate that phenol degradation follows zero-order kinetics with an activated energy of 69.7kJ/mol.

Synthesis of polymer-supported copper complexes and their evaluation in catalytic phenol oxidation

Polymer-supported metal complexes have been used as catalysts for the catalytic wet hydrogen peroxide oxidation (CWPO) of phenol. The synthesis of six catalysts derived from three polymer-supports (a polybenzimidazole resin and two poly(styrene-divinylbenzene) resins) and two Cu(II) salts. The catalytic oxidation of phenol with initial phenol concentration of 1 g L −1 was performed in a 200 mL batch stirred tank reactor at 30 °C and atmospheric pressure. Under these conditions, phenol conversion and total organic carbon conversion were evaluated. The highest phenol conversion was 93% obtained for poly(DVB-co-VBC) functionalised with iminodiacetic acid (IMDA) and loaded with copper acetylacetonate, however metal leaching was very unsatisfactory. If metal leaching was taken into consideration, it was found that polybenzimidazole loaded with copper sulphate appeared to be the most stable yielding 54% of mineralisation and 0.75 TOC/phenol conversion efficiency with simultaneously low release of metal during the oxidation.

Wet hydrogen peroxide catalytic oxidation of phenol with FeAC (iron-embedded activated carbon) catalysts

This investigation aims at exploring the catalytic oxidation activity of iron-embedded activated carbon (FeAC) and the application for the degradation of phenol in the wet hydrogen peroxide catalytic oxidation (WHPCO). FeAC catalysts were prepared by pre-impregnating iron in coconut shell with various iron loadings in the range of 27.5 to 46.5% before they were activated. The FeAC catalysts were characterised by measuring their surface area, pore distribution, functional groups on the surface, and X-ray diffraction patterns. The effects of iron loading strongly inhibited the pore development of the catalyst but benefited the oxidation activity in WHPCO. It was found that the complete conversion of phenol was observed with all FeAC catalysts in oxidation. High level of chemical oxygen demand (COD) abatement can be achieved within the first 30 minutes of oxidation. The iron embedded in the activated carbon showed good performance in the degradation and mineralisation of phenol during the oxidation due to the active sites as iron oxides formed on the surface of the activated carbon. It was found that the embedding irons were presented in gamma-Fe(2)O(3), alpha-Fe(2)O(3), and alpha-FeCOOH forms on the activated carbon. The aging tests on FeAC catalysts showed less activity loss, and less iron leaching was found after four oxidation runs.

Design of a carbon nanotube/magnetic nanoparticle-based peroxidase-like nanocomplex and its application for highly efficient catalytic oxidation of phenols

We report a novel nanotechnology-based approach for the highly efficient catalytic oxidation of phenols and their removal from wastewater. We use a nanocomplex made of multi-walled carbon nanotubes (MWNTs) and magnetic nanoparticles (MNPs). This nanocomplex retains the magnetic properties of individual MNPs and can be effectively separated under an external magnetic field. More importantly, the formation of the nanocomplex enhances the intrinsic peroxidase-like activity of the MNPs that can catalyze the reduction of hydrogen peroxide (H2O2). Significantly, in the presence of H2O2, this nanocomplex catalyzes the oxidation of phenols with high efficiency, generating insoluble polyaromatic products that can be readily separated from water.

CuO impregnated activated carbon for catalytic wet peroxide oxidation of phenol

This paper presents an original approach to the removal of phenol in synthetic wastewater by catalytic wet peroxide oxidation with copper binding activated carbon (CuAC) catalysts. The characteristics and oxidation performance of CuAC in the wet hydrogen peroxide catalytic oxidation of phenol were studied in a batch reactor at 80 °C. Complete conversion of the oxidant, hydrogen peroxide, was observed with CuAC catalyst in 20 min oxidation, and a highly efficient phenol removal and chemical oxygen demand (COD) abatement were achieved in the first 30 min. The good oxidation performance of CuAC catalyst was contributed to the activity enhancement of copper oxide, which was binding in the carbon matrix. It can be concluded that the efficiency of oxidation dominated by the residual H 2O 2 in this study. An over 90% COD removal was achieved by using the multiple-step addition in this catalytic oxidation.

Modeling of a pilot-scale trickle bed reactor for the catalytic oxidation of phenol

A mathematical model was developed to simulate the catalytic wet air oxidation (CWAO) of aqueous phenol in a trickle bed reactor (TBR). Both ‘axial dispersion’ and ‘plug flow’ models were proposed. ‘Steady-state’ mass transfers across different phases inside the reactor have all been considered in parallel with oxidation reactions catalyzed by heterogeneous copper catalyst supported on activated carbon. The changes in the concentrations of oxygen and phenol in various phases were thus depicted as a function of bed length. In order to validate the accuracy of the established TBR model, a series of experiments on phenol oxidation were performed on a pilot-scale TBR containing 5.6 l of catalysts. The model was found able to give satisfactory predictions for nearly half of all the runs. The discrepancies between the experimental and modeling results were investigated for the less promising runs. It was also noticed that similar simulation results could be attained from ‘axial dispersion’ model against ‘plug flow’ model. Following the discussion on the changes of phenol and oxygen concentrations in the various phases, it is finally concluded that the performance of the TBR of this study depends largely on gas-to-liquid mass transfer process. Further suggestions with regards to reactor optimization are also proposed on the basis of experimental outcome.

Effect of operation conditions on Catalytic Oxidation of Phenol in Aqueous Solution

This work was conducted to study the oxidation of phenol in aqueous solution using copper based catalyst with zinc as promoter and different carrier, i.e. γ-Alumina and silica. These catalysts were prepared by impregnation method.The effect of catalyst composition, pH (5.6-9), phenol to catalyst concentration ratio (2-0.5), air feed rate (30-50) ml/s, stirring speed (400-800) rpm, and temperature (80-100) °C were examined in order to find the best conditions for phenol conversion.The best operating conditions which lead to maximum phenol conversion (73.1%) are : 7.5 pH, 4/6 phenol to catalyst concentration, 40 ml/s air feed rate, 600 rpm stirring speed, and 100 °C reaction temperature. The reaction involved an induction period and a steady state activity regime. Both of the regimes exhibiting first order behavior with respect to the phenol concentration. The rate constants k1 and k2 for the initial rate and steady state activity regime are represented by k1=1.9×10-3 ((cm3liq/gcat) 0.5s-1 and k2= 2.4×10-10 ((cm3liq/gcat) 2 s-1) respectively.

Studies on Phenol Oxidation with H2O2 Catalyzed by Schiff Base Cobalt(II) Complexes in Micellar Solution

The two Schiff base cobalt(II) complexes, CoL1 and CoL2, were synthesized and characterized. The metallomicelle made up of the cobalt(II) complexes and surfactants (CTAB, LSS and Brij35), as mimic peroxidase metalloenzyme, were used in the catalytic oxidation of phenol by H2O2. The mechanism and a kinetic mathematic model of the phenol catalytic oxidation were studied. The acid effect of reaction system, structural effect of the complexes, and effect of temperature on the rate of the phenol oxidation catalyzed by the mimetic peroxidases have been discussed. The results showed that the schiff base cobalt(II) complexes and their metallomicelles as peroxidase mimics exhibit good catalytic activity and similar catalytic character to natural enzyme.

Studies on the Phenol Oxidation by H2O2 Catalyzed by Metallomicelle Made from Crowned Schiff Base Co(II) Complexes Containing Benzoaza-15-crown-5

Three novel cobalt(II) complexes of the benzoaza-15-crown-5 Schiff base, CoL1, CoL2, and CoL3 were synthesized and characterized. Metallomicelles made from CoL and surfactants (CTAB, LSS, and Brij35) were used as mimetic peroxidase in the catalytic oxidation of phenol by H2O2. For comparison, the catalytic activity of the complexes (CoL1, CoL2, and CoL3) were also investigated. The mechanism and a kinetic mathematic model of the phenol catalytic oxidation were studied. The acid effect of reaction system, structural effect of the complexes, and effect of temperature on the rate of the phenol catalytic oxidation by the mimetic peroxidase were discussed. The results show that the Schiff base cobalt(II) complexes and their metallomicelles as peroxidase mimics exhibit good catalytic activity and similar catalytic character to natural enzyme.

Mechanism of Oxidation of Aqueous Phenol by H2O2 Catalysed by a Macrocyclic Iron(II) Complex

The iron(II) complex of the macrocyclic ligand 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraaza-cyclotetradecane was synthesized and characterized and used as a mimetic peroxidase in the catalytic oxidation of phenol with H2O2. The mechanism and a kinetic model of the catalytic oxidation are described. The results show: the catalyst as a peroxidase mimic exhibited strong catalytic activity; the main reaction products detected by high-pressure liquid chromatography (HPLC) were catechol, hydroquinone, p-benzoquinone, maleic acid and oxalic acid; the catalytic oxidation of phenol accords with the enzyme mechanism.