Destruction Of Phenol Research Articles

Development of a model for the wet air oxidation of phenol based on a free radical mechanism

A model for the wet air oxidation of phenol is proposed, based on elementary radical reactions that are known to occur in the oxidation process. By applying this model to associated experimental data, unknown rate constants have been calculated using numerical techniques to solve the system of differential equations that describes the proposed mechanism. The activation energy and pre-exponential factor for the elementary reaction between phenol and the phenoxyperoxyl radical (PhOO•) were estimated to be 47±3 kJ mol -1 and 1.7± 0.1×10 10 l mol -1 s -1 respectively, while values of 126±4 kJ mol -1 and 4.7±0.2×10 10 s -1 were found for the decomposition of phenoxy hydroperoxide (PhOOH). The operating parameters of temperature, oxygen concentration, pH and addition of free radical promoters (H 2O 2) have been studied, and in general, a good agreement has been obtained between experimental data and calculated concentration profiles. According to the proposed mechanism, it is shown that hydroxyl radicals (OH•) and phenoxyperoxyl radicals (PhOO•) are primarily responsible for the destruction of phenol, with perhydroxyl radicals (HO 2•) having a less significant role to play in the process. The principles described in this paper may be applied to understand the wet air oxidation mechanism of other organic compounds.

New reactor system for supercritical water oxidation and its application on phenol destruction

A new reactor system for supercritical water oxidation which can treat reaction variables independently was developed. With this system, phenol oxidation experiments were carried out at temperatures 380–440°C and pressures 190–270 atm. Reaction time was varied from 12 to 120 s, and corresponding conversion was 11–99%. The initial phenol concentration was below 8.8 mM based on reaction volume. The initial oxygen concentration ranged from 100 to 1750% of the stoichiometrically required amount for complete oxidation of phenol. According to the results of kinetic experiments, oxidation rate was dependent on temperature and concentration of water, oxygen and phenol. However, the oxidation rate was not dependent on the pressure itself. As the ratio of oxygen concentration to phenol concentration increases, the reaction rate increases asymptotically. In the case where oxygen concentration was greater than 300%, the oxygen content did not affect the reaction rate any more. Water has a significant effect on the reaction rate, and oxidation rate increased as water concentration increased. Various reaction mechanisms in which water can affect the reaction rate were considered, and this consideration suggested that the water participates in the reaction as a reactant to generate active radicals. The global reaction order was 1.38 ± 0.24 for water and 1 for phenol. The effect of oxygen on reaction rate was expressed as a Langmuir-type equation with the ratio of oxygen to phenol concentration as a variable, whose constant was 2.89 ± 1.43. The corresponding activation energy was 23.8 ± 2.2 kcal/mol, and this was larger than that of a gas-phase reaction, but smaller than that of a liquid-phase reaction. A previously suggested reaction model and equation were used to predict phenol conversion. The multi-step reaction model suggested by Tufano cannot predict the conversion well, but it seems to explain the effects of each parameter qualitatively. The equation proposed by Gopalan and Savage predicts conversion fairly well when the concentration of oxygen is adjusted to 300% of the stoichiometrically required amount.

PHOTOCATALYTIC DESTRUCTION OF PHENOL AND SALICYLIC ACID WITH AEROSOL-MADE AND COMMERCIAL TITANIA POWDERS

The photocatalytic destruction of phenol and salicylic acid in aerated aqueous suspensions of titania powders made in flame reactors was studied. These powders were made in five hydrocarbon diffusion flames by hydrolysis and oxidation of TiCI4that resulted in powders of high specific surface area and high anatase content. The photoactivity of the flame-made titania powders was comparable and slightly better to that of commercial Degussa P25. Doping the titania with SiO2 was detrimental to the photoactivity of the powders in contrast with what was seen in non-aerated suspensions. The photodegradation of phenol followed a first-order law while the Langmuir-Hinshelwood model was found to most accurately represent the photodegradation of salicylic acid.

Heterogeneous and homogeneous wastewater treatment — Comparison between photodegradation with TiO 2 and the photo-fenton reaction

The oxidative destruction of phenol, cyclohexanol (CyOH), and 4-nitroaniline (4-NA) in aqueous solution by the photo-Fenton reaction and TiO 2/UV-A is described and compared. The decomposition mechanisms were investigated by studying the intermediate products by HPLC and a photodiode array. The degradation of 4-NA was monitored by GC/MS to trace the decomposition products (nitrobenzene, p-benzoquinone, hydroquinone and resorcine). During the photochemical degradation of 4-NA nitrate ions were detected by an ion selective electrode. The degradation rates with the photo-Fenton reaction had the following order: Phenol > 4-NA >> CyOH, in contrast to the order CyOH > Phenol > 4-NA obtained with TiO 2/UV-A. The same intermediate decomposition products were obtained for each substrate by both methods.

Destruction of phenol in water with sun, sand, and photocatalysis

The photocatalytic degradation and oxidation to carbon dioxide of aqueous phenol solutions have been studied using natural sunlight in geometries simulating shallow ponds. The photocatalyst was titanium dioxide freely suspended in the solution or immobilized on sand or silica gel. Photodegradation rates were approximately three times faster with the free suspension than with the immobilized catalyst under the same conditions, and were dependent on the time of the year and the time of the day. The seasonal variation correlated roughly with seasonal solar irradiance tabulations for the UV component of the spectrum. For 10 ppm of phenol the maximum rate of solar degradation resulted in a decrease in concentration to 10 ppb in less than 80 min with total mineralization in 110 min. Maintaining the same geometry, 30 L of solution covering 1 m 2 would degrade to the same extent.

Destruction of phenol from wastewater by oxidation with sulfite-oxygen

Destruction of phenol from wastewater by oxidation with sulfite-oxygen

Reduction of vitrinites with lithium in ethylamine and the chemistry of the products

The reduction of a set of hand-picked vitrinite concentrates from various American seams with lithium in ethylamine has been studied. When the extent of reduction is plotted against carbon content and previously reported data are included, there is much scatter. Neither the use of ethylenediamine at 100 °C nor the use of extended reaction times has any consistent effect in increasing reduction. The same is true of the increase in extractability by pyridine. Carbonyl absorption in the infrared spectra of the products is thought to be due to reduction of phenols to cyclohexanones. Aliphatic C-H absorption is greatly increased, as expected. There is tendency for the hydroxyl content of higher-rank coals to increase on reduction and of lower-rank bituminous coals to decrease; this may be due to a change with rank of the relative importance of creation of new phenols by ether cleavage and destruction of phenols by reduction to cyclohexanones. Reduction is accompanied by substantial increases in extractability in chloroform (10–35%). Methyl absorption at 1375 cm −1 in the infrared spectra of the reduced products is greater than that of the raw coal and is quite intense in chloroform-soluble reduction products, as is 1H n.m.r. resonance in CDCl 3 solution. Evidently analogues of dibenzyl ether and diphenylethane are cleaved during reduction. N.m.r. spectra detect no aromatic-bound hydrogen in the chloroform-soluble products.

Efferent vagal innervation of canine ventricle

The route efferent vagal fibers travel to reach the left ventricle is not clear and was the subject of this investigation. We measured left ventricular and septal effective refractory period (ERP) changes during vagal stimulation and a constant infusion of norepinephrine, before and after phenol was applied at selected sites of the heart to interrupt efferent vagal fibers that may be traveling in that area. Phenol applied to the atrioventricular (AV) groove between the origin of the right coronary artery anteriorly to the posterior descending branch of the circumflex coronary artery completely eliminated vagal-induced prolongation of ERP in the anterior and posterior left ventricular free wall and reduced, but did not eliminate, ERP prolongation in the septum. A large (3-cm radius) epicardial circle of phenol prevented vagal-induced ERP prolongation within the circle in all dogs, while a small (1-cm radius) epicardial circle of phenol failed to prevent vagal-induced ERP changes within the circle in any dog. An intermediate (2-cm radius) circle eliminated vagal effects on ERP in 13 of 18 dogs. Arcs of phenol, to duplicate the upper portion of the circle, applied sequentially from apex to base eliminated efferent vagal effects only when painted near or at the AV groove. We conclude that the majority of efferent vagal fibers enroute to innervate the anterior and posterior left ventricular epicardium cross the AV groove within 0.25-0.5 mm (depth of phenol destruction) of the epicardial surface.(ABSTRACT TRUNCATED AT 250 WORDS)

Application of Process Control Techniques to Radiation Treatment of Waste Water

Download Hi-Res ImageDownload to MS-PowerPointCite This:Ind. Eng. Chem. Proc. Des. Dev. 1979, 18, 2, 269-274

THE INFLUENCE OF LIGHT OF DIFFERENT SPECTRAL REGIONS ON THE SYNTHESIS OF PHENOLIC COMPOUNDS IN GHERKIN SEEDLINGS IN RELATION TO PHOTOMORPHOGENESIS II. INDOLEACETIC ACID OXIDASE ACTIVITY AND GROWTH

1) Exposure to light of dark-grown gherkin seedlings causes an expansion of the cotyledons and inhibits the elongation of the hypocotyls. As was found earlier for the light-induced synthesis of phenolic compounds, at least two photoreactions seem to be involved: photoresponse I, the “high energy reaction”, and photoresponse II, the phytochrome reaction. 2) The gherkin seedlings contain an enzyme which, purified, oxidizes indoleacetic acid (IAA) 1) slowly. The IAA oxidase activity of a crude homogenate depends on phenolic cofactors; derivatives of p-coumaric acid. Ferulic acid derivatives, flavonols and ascorbic acid, the latter two only from the cotyledons, antagonize this stimulation. The IAA oxidase activity of a homogenate from cotyledons changes on standing due to enzymatic reactions involving the modifiers. 3) The photo-inhibition of hypocotyl elongation can be counteracted by supplying IAA externally, indicating that light lowers the level of IAA. Application of the naturally occurring p-coumaric acid cofactor of IAA oxidase to hypocotyl sections from dark-grown gherkin seedlings results in growth inhibition. 4) Qualitatively there is agreement between light-stimulated synthesis of the p-coumaric acid ester and inhibition of hypocotyl elongation, and between synthesis of IAA oxidase inhibitors and expansion of the cotyledons. The postulated causal relationship between light-dependent phenol synthesis and photoinhibition of hypocotyl elongation can only exist, however, if but a fraction of the phenolic compounds participates in the IAA regulating system, and the enzymatic oxidation of IAA is coupled to the destruction of phenols. 5) In at least one case the IAA oxidase hypothesis seems inadequate to explain the phenomena: the lag for inhibition of hypocotyl elongation in blue light is much shorter than for phenol synthesis.

Destruction of Phenols by Oxidation of Ozone

Destruction of Phenols by Oxidation of Ozone

The bacterial purification of gas-works liquors

ONE of the most widespread liquid trade wastes is what is commonly known as liquor, being waste liquor produced in gas works. It usually consists of a dilute solution of ammonium salts, phenols and other tar acids, salts of thiocyanic and thiosulphuric acids and small quantities of other substances. The most obvious way of treating any liquid trade waste is to admit it to the sewers and allow it to be purified or otherwise disposed of with the sewage. An investigation has therefore been carried out into the response of gas liquor to processes of sewage purification, and in the course of this work the behaviour of the individual substances contained in the liquor has been studied. Amongst these substances is ammonium (occasionally calcium) thiocyanate, the biological oxidation of which is the subject of this paper. In a previous communication [Happold & Key, 1932] the removal of phenol and of catechol derivatives from gas liquor was described and it was shown that a gram negative vibrio (0-1) which possessed an indophenol oxidase system was capable of utilizing phenol as a source of carbon and was responsible for its breakdown. In the study of phenol destruction on the bacteria beds it had been observed that the continuous action of the phenol on sewage effluents facilitated the isolation of vibrio 0-1 by exerting a selective bactericidal action on the rest of the flora. A similar result was expected in these further studies. The investigation has as before been approached from two separate angles, (i) the study of the conditions of breakdown on the bacteria beds where a large concentration of adapted bacterial life is readily available, and (ii) the study of the bacterial life present in the effluents from these beds and of the capacity of individual micro-organisms to oxidize ammonium thiocyanate. The two sections are divided for the purpose of this report.