Phenol destruction

Phenol is commonly present in industrial streams and is classified as a priority pollutant. At temperatures of 380 to 440°C and pressures of 190 to 270 atm, oxidation rates were calculated from kinetic Equation 10.16 by Minok et al. (1997). Their results showed that, under the designed system conditions, the rate of phenol destruction was dependent only on temperature, concentration of water, oxygen, and phenol but not on pressure. Water acts in the system as a reactant and was considered to be a reactive radical producer. The destruction rate of phenol can be expressed as follows ... 

When the oxygen concentration is equal to 300% in excess of stoichiometric oxygen demand, the global rate of phenol destruction can be expressed as ... 

The anodic oxidation of phenol (dissolved in sodium sulfate) was studied by De Sucre and Watkinson using two types of lead dioxide anodes [26]. The first was made of 2 mm lead shot that was oxidized for 12 h at 526mA/cm in 20% sulfuric acid while the second anode, electrodeposited lead dioxide flakes, was supplied by a commercial manufacturer. The phenol oxidized faster on the electrodeposited Pb02, which also turned out to be more corrosion-resistant than the oxidized lead shot. While all of the phenol oxidized rapidly (1.5 h) on the electrodeposited anode, not all of it formed CO2. It was found that 80% of the total organic carbon remained in solution after the phenol was completely oxidized. Phenol destruction increased with an increase in current density, and decreased as electrolyte flowrate, pH, and anode particle size were increased. 

The key issue in effective catalytic oxidation of organics is finding a suitable catalyst. Oxidation of aqueous phenol solutions by using different transition metal oxides as heterogeneous catalysts is already known [4-6]. On the other hand, the potential of molecular sieves to catalyze oxidative phenol destruction has not been examined yet. The objective of this contribution is to provide kinetic and mechanistic data on the catalytic liquid-phase oxidation of aqueous phenol solutions obtained in the presence of various transition metal oxides and molecular sieves. The reaction was studied in a semibatch slurry as well as two-and three-phase continuous-flow reactors. Another matter of concern was the chemical stability of catalysts under the reaction conditions. 

There are several observed effects of ultrasound on many reactions that are still not understood. Besides, there are many engineering issues (e.g. scale up, variation of sound field in reactors, etc.) still to be resolved before ultrasound can be put to use on a commercial scale. However, reports suggest (Gogate et al., 2004) that compared to the conventional sonic horn (which may be seen in some plants as a method for keeping equipment, such as heat exchangers, free from solid fou-lants), novel multiple frequency reactors would be better for large-scale use in, for example, phenol destruction. The critical factor in scale-up is achieving adequate... 

A CUO/AI2O3 catalyst used for phenol destruction showed leaching of Cu... 

Model pollutants (2-propanol, tert-butanol, acetic acid) were tested with a cement-supported CuO-ZnO catalyst. All these compounds were stable in the absence of a catalyst, but the catalyst managed to convert them almost completely at 380-390 C and 230-235 bar (X = 87-98%). In particular, the alcohols react with CO2 selectivities close to 100%. The same group investigated the performance of a CuO-ZnO-Co203 catalyst (Siid-Chemie AG, also tested in phenol destruction) in... 

I The phenol cannot always be isolated in good yield, particularly if it contains substituent groups, owing to the destructive action of the alkali fusion upon the radical R. 

Until the mid-1950s the main raw material source for the European plastics industry was coal. On destructive distillation coal yields four products coal tar, coke, coal gas and ammonia. Coal tar was an important source of aromatic chemicals such as benzene, toluene, phenol, naphthalene and related products. From these materials other chemicals such as adipic acid, hexamethylenedia-mine, caprolactam and phthalic anhydride could be produced, leading to such important plastics as the phenolic resins, polystyrene and the nylons. 

One would think that thermal destruction of polyethylene should be inhibited by hydroxides of alkali metals according to the following scheme, as with phenols ... 

Atmospheres polluted by oxidising agents, e.g. ozone, chlorine, peroxide, etc. whose great destructive power is in direct proportion to the temperature, are also encountered. Sulphuric acid, formed by sulphur dioxide pollution, will accelerate the breakdown of paint, particularly oil-based films. Paint media resistant both to acids, depending on concentration and temperature, and oxidation include those containing bitumen, acrylic resins, chlorinated or cyclised rubber, epoxy and polyurethane/coal tar combinations, phenolic resins and p.v.c. 

The production of coke involves the heating of coal in the absence of air, called the carbonization or destructive distillation of coal. Carbonization, besides its main purpose of production of coke, also results in a coproduct called coke oven gas from which various liquid products such as tar, benzol, naphthalene, phenol, and anthracene are separated. There are two main types of carbonization based on the temperature to which the coal is heated in the absence of air. One type is low-temperature carbonization (LTC) the other is high-temperature carbonisation (HTC). Some features of LTC and HTC are listed in Table 1.28. The LTC Process is mainly carried out to manufacture domestic smokeless fuel. This presentation, however, concentrates on the HTC process by which metallurgical coke is produced. 

Kidak R, Ince NH (2006) Ultrasonic destruction of phenol and substituted phenols a review of current research. Ultrason Sonochem 13 195-199... 

Matthews RW, McEvoy SR (1992) Destruction of phenol in water with sun, sand and photocatalysis. Sol Energy 49(6) 507-513... 

Gogate PR, Mujumdar S, Thampi J, Wilhelm AM, Pandit AB (2004) Destruction of phenol using sonochemical reactors scale up aspects and comparison of novel configuration with conventional reactors. Sep Purif Technol 34 25-34... 

Oxidation of benzene to phenol. This was attempted in the former U.S.S.R. and Japan on a pilot-plant scale. High yields were reported, but full-scale operation apparently was discontinued because of destruction of product by irradiation and the possibility of explosion in the reaction vessel. The latter danger can be controlled in the oxidation of halo-genated hydrocarbons such as trichloro- or tetrachloroethylenes, where a chain reaction leads to the formation of dichloro- or trichloro-acetic acid chlorides through the respective oxides. 

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