Catalytic Degradation Of Phenol Research Articles

Catalytic Degradation of Phenol by Co3O4 Nanocubes

Catalytic Degradation of Phenol by Co3O4 Nanocubes

Supported cobalt catalysts by one-pot aqueous combustion synthesis for catalytic phenol degradation

Cobalt oxides (Co) and Al2O3-, SiO2-, and TiO2-supported cobalt oxide catalysts were prepared by an aqueous combustion method using urea and glycine as fuels. Their catalytic performance in activation of OXONE® for phenol degradation in aqueous solution was investigated. It was found that unsupported Co oxide and supported Co oxide presented different mechanisms in activation of OXONE® for phenol degradation. The supported Co catalysts presented higher activity in activation of OXONE® for phenol degradation due to higher dispersion of Co3O4 on the supports and Co(II) coordination sites. The major oxidizing radicals were identified to be SO4- by competitive radical reactions. The Co oxides synthesized from urea or glycine showed a similar activity; however, the supported Co catalysts prepared by glycine fuel exhibited better activity than those prepared by urea. For Al2O3-, SiO2-, and TiO2-supported Co catalysts, Co/TiO2 presented a higher activity in phenol degradation compared with Co/SiO2 and Co/Al2O3. But, Co/SiO2 showed the best stability among the catalysts. Total organic carbon could be reduced by 80%, 72%, and 45% on Co/TiO2, Co/SiO2, and Co/Al2O3, respectively, at 30ppm phenol. Phenol degradation was found to follow the zero-order kinetics. The causes of deactivation were investigated, and the regeneration methods were proposed.

α-MnO2 activation of peroxymonosulfate for catalytic phenol degradation in aqueous solutions

Abstract Several α-MnO2 catalysts in the forms of nanosphere, nanorod and nanowire were synthesized, characterized and tested in heterogeneous activation of peroxymonosulfate for phenol degradation in aqueous solutions. The α-MnO2 materials exhibited varying activities in activation of peroxymonosulfate to produce sulfate radicals for phenol degradation depending on structure and morphology. Crystalline structure of MnO2 is more important than porous structure in influencing the activity because crystalline α-MnO2 exhibited higher phenol degradation. Nanowired α-MnO2 presented the highest activity with stable performance while the mesoporous α-MnO2 nanosphere with amorphous structure presented the lowest activity and stability. Kinetic study showed that phenol degradation on α-MnO2 followed the first order kinetics.

Catalytic degradation of phenol in sonolysis by coal ash and H 2O 2/O 3

This study demonstrated that coal ash, as widely distributed solid waste disposal, would function as a media for organic pollutants removal in the presence or absence of H 2O 2/O 3 under ultrasonic radiation. Coal ash could act as a catalyst to generate OH radicals with the presence of H 2O 2/O 3 and consequently enhance the phenol degradation. Experimental results showed that when using coal ash as a catalyst under ultrasonic irradiation, 83.4% and 88.8% of phenol was degraded in the presence of H 2O 2 or O 3, respectively. The degradation rate of phenol would increase with increasing amount of O 3, while there was an optimal concentration of H 2O 2 (1.5 mM) for phenol degradation. Higher dosage of coal ash could result in higher phenol degradation rates. H 2O 2/coal ash/ultrasonic system could achieve better performance for phenol degradation under more acidic conditions, while more alkaline condition in O 3/coal ash/ultrasonic system favored phenol degradation. This study provides a new approach for wastewater treatment especially when contaminated with phenolic pollutants.

Electrochemical catalytic treatment of phenol wastewater

The slurry bed catalytic treatment of contaminated water appears to be a promising alternative for the oxidation of aqueous organic pollutants. In this paper, the electrochemical oxidation of phenol in synthetic wastewater catalyzed by ferric sulfate and potassium permanganate adsorbed onto active bentonite in slurry bed electrolytic reactor with graphite electrode has been investigated. In order to determine the optimum operating condition, the orthogonal experiments were devised and the results revealed that the system of ferric sulfate, potassium permanganate and active bentonite showed a high catalytic efficiency on the process of electrochemical oxidation phenol in initial pH 5. When the initial concentration of phenol was 0.52 g/L (the initial COD 1214 mg/L), up to 99% chemical oxygen demand (COD) removal was obtained in 40 min. According to the experimental results, a possible mechanism of catalytic degradation of phenol was proposed. Environmental estimation was also done and the results showed that the treated wastewater have little impact on plant growth and could totally be applied to irrigation.

Comparison of catalytic decomposition of hydrogen peroxide and catalytic degradation of phenol by immobilized iron oxides

Abstract Immobilized iron oxides on silica matrixes in fluidized bed reactors, including SiG1, SiG2, C1, and the commercial catalyst FeOOH, were used in the catalytic decomposition of H2O2 and the catalytic degradation of phenol. They were characterized using XRD, SEM, N2-sorption, and elucidation of the kinetics of dissolved iron by oxalic acid in dark surroundings. XRD patterns reveal that SiG1, SiG2, and C1 exhibit amorphous structures, and FeOOH exhibits the poor crystallinity of goethite. The SEM images reveal that the surfaces of all the iron oxides are smooth and that the iron oxides are aggregated by the iron oxide floc. The N2-sorption isotherm indicates that SiG1 and SiG2 are non-porous materials, and that C1 and FeOOH are typical type II and typical type IV materials, respectively. A kinetic model for iron dissolved by oxalic acid is established. The order of apparent first-order dissolution rate constants (kc) is SiG1 > SiG2 > FeOOH ∼ C1. The immobilized iron oxides, SiG1 and SiG2, are weakly bonded to the support (silica sand) in the presence of oxalic acid. The decomposition of H2O2 follows pseudo-first-order kinetics. The number of active sites for the decomposition of H2O2 is similar among all iron oxides at a particular kapp (1.8 × 10−3 min−1). There are no interactions between phenol and iron oxides in the absence of hydrogen peroxide at pH 4. SiG1 and SiG2 exhibit much higher catalytic activities in phenol degradation than either C1 or FeOOH. The reactivity of iron oxides in catalyzing the phenol degradation by H2O2 relates to the tendency of iron to be dissolved by oxalic acid. The intermediates of phenol degradation, such as catechol and oxalic acid, promote the dissolution of iron from SiG1 and SiG2 by reductive and non-reductive pathways and lower the pH values. The catalyses of SiG1 and SiG2 involve heterogeneous and homogeneous reactions.

Evaluación del Peróxido de Hidrógeno en la Oxidación de Fenol con Hierro Soportado Sobre Tela de Carbón Activado

This study presents the generation and evaluation of three different materials containing activated carbon and iron for the heterogeneous Fenton degradation of phenol. Three different materials: (i) commercial cloth containing activated carbon, and (ii) pellet activated carbon and (iii) a chemically activated carbon with KOH, were explored to support iron by means of impregnation. These three materials were used for the catalytic degradation of phenol with H2O2. The oxidation was performed at 42°C, pH between 2,0-2,5, atmospheric pressure, an initial phenol concentration of 0,01064M and H2O2 0.89M. A relation of impregnation of 1,39gFe/gAC is obtained on the activated carbon cloth. During the oxidation of phenol, the disappearance of the H2O2 was followed as an indirect indication of the kinetics, reaching a minimal concentration of 0.002M of H2O2 by the cloth and the pellet activated carbon. The study shows that the use of cloth activated carbon as catalytic support for the decomposition of phenol is competitive with other conventional porous materials.