o-Cresol

Abstract: The ring-retaining products of the OH-initiated degradation of phenol and o -, m -, and p -cresol in the presence of NO x have been investigated and their formation yields determined. The experiments were carried out in a large volume reactor at (298±2) K and 1000 mbar total pressure of synthetic air using FT–IR spectroscopy for the analysis of reactants and products. The products observed and their respective molar yields were: from phenol: 1,2-dihydroxybenzene (80.4±12.1)%, 1,4-benzoquinone (3.7±1.2)% and 2-nitrophenol (5.8±1.0)%; from o -cresol: 3-methyl-1,2-dihydroxybenzene (73.4±14.6)%, methyl-1,4-benzoquinone (6.8±1.0)% and 6-methyl-2-nitrophenol (6.8±1.5)%; from m -cresol: 3-methyl-1,2-dihydroxybenzene (68.6±13.4)%, 4-methyl-1,2-dihydroxybenzene (9.7±2.7)%, methyl-1,4-benzoquinone (11.3±2.5)%, 5-methyl-2-nitrophenol (4.4±1.5)% and 3-methyl-2-nitrophenol (4.3±1.6)% and from p -cresol: 4-methyl-1,2-dihydroxybenzene (64.1±11.3)% and 4-methyl-2-nitrophenol (7.6±2.2)%. Reaction pathways leading to the observed products are proposed and potential ramifications for the atmospheric reaction mechanisms of aromatic hydrocarbons are considered.

Abstract: Studies were undertaken to determine the role of surface oxygen complexes and metals on activated carbon on adsorption of selected aromatics. Three kinds of activated carbons (F400, MP and Darco G60) were used in the study. The F400 carbon was treated by oxygenation, deoxygenation and HCl-washing processes. Batch adsorption tests were used to evaluate the effects of surface oxygen complexes and metals on adsorption of phenol under oxic and anoxic conditions. The isotherm results showed that the removal of hydrophilic structures (carboxylic acid groups) of activated carbon increased physisorption and surface polymerization of phenol. It was also found that the metal (Fe) itself can not catalyze the surface polymerization of phenol on the carbon surface at room temperature. The findings of this study suggest that the life of a regenerated carbon adsorption bed could be extended by removing the metal content in activated carbon, and mildly oxidizing the surface.

Abstract: The alkylation of phenol with methanol is conducted over Ni 1− x Co x Fe 2 O 4 ( x =0, 0.2, 0.5, 0.8 and 1.0) type systems prepared via low temperature route. Alkylation leads to predominantly ortho methylation of phenol, yielding o -cresol and 2,6-xylenol as the products. Under optimized conditions, the total ortho selectivity was ≥94%, regardless of the catalyst composition. Only traces of anisole is formed and hardly any other xylenol or cresol isomers are detected. Phenol conversion and the individual selectivities for o -cresol and 2,6-xylenol depend strongly on the catalyst composition. Selectivity for o -cresol was maximum for NiFe 2 O 4 (i.e., when x =0), whereas upon progressive substitution of Co 2+ ions for Ni 2+ ions, the 2,6-xylenol selectivity increases with a concomitant decrease in the o -cresol selectivity. Maximum phenol conversion and 2,6-xylenol selectivity (also total ortho selectivity) were observed over CoFe 2 O 4 ( x =1). The activity and selectivity were shown to be strongly dependent on the surface acid–base properties of the system. The influences of surface acidity, cation distribution in the spinel lattice and various reaction parameters are discussed.

Abstract: This work deals with a new abiotic oxidation process designed as a suitable pre-treatment step within a biological depuration of wastewater containing phenol or its derivatives (o-cresol, 2-chlorophenol and p-nitrophenol) or aniline. The reaction was carried out in a stirred tank reactor at 20 degrees C and atmospheric pressure in presence of the organic compound, 150mgl(-1), zero valent iron particles (10g), ethylenediamine tetraacetic acid (EDTA, 101mgl(-1)) and air. The experimental results show that 85% of phenol conversion can be achieved after 360min. 2-Chlorophenol was found to be more easily degradable and it is completely eliminated after 300min. The oxidation of o-cresol and aniline behaved more closely to phenol obtaining after 360min 70% and 68% of conversion respectively. p-Nitrophenol was a very refractory compound, giving only 28% of conversion after 360min. Moreover, the influence of some operating variables was studied over the following ranges: temperature from 20 to 50 degrees C, initial phenol concentration from 150 to 1000mgl(-1), EDTA concentration from 50 to 200mgl(-1) and iron particles from 5 to 20g. As expected, temperature strongly enhances phenol conversion. Also, an increase of the catalyst to phenol ratio or the iron or EDTA to phenol ratio improves the reaction rate. A preliminary kinetic analysis of the data shown that the rate of phenol disappearance is not first order with respect to the phenol.

Abstract: Due to the toxicity effects and endocrine disrupting properties of phenolic compounds, their removal from water and wastewater has gained widespread global attention. In this study, the photocatalytic degradation of phenolic compounds in the presence of titanium dioxide (TiO 2 ) nano-particles and UV light was investigated. A full factorial design consisting of three factors at three levels was used to examine the effect of particle size, temperature and reactant type on the apparent degradation rate constant. The individual effect of TiO 2 particle size (5, 10 and 32 nm), temperature (23, 30 and 37 °C) and reactant type (phenol, o-cresol and m-cresol) on the apparent degradation rate constant was determined. A regression model was developed to relate the apparent degradation constant to the various factors. The largest photocatalytic activity was observed at an optimum TiO 2 particle size of 10 nm for all reactants. The apparent degradation rate constant trend was as follows: o-cresol > m-cresol > phenol. The ANOVA data indicated no significant interaction between the experimental factors. The lowest activation energy was observed for o-cresol degradation using 5-nm TiO