Organic compounds Ozone

In some cases (particularly reactive dyes) dyes can pass the aerobic, anaerobic degradation step and colored water is observed at the end of the treatment. In such cases a special treatment of the colored wastewater (reduction, adsorption, precipitation) has to be introduced [105,134-137]. In the presence of low concentrations of organic compounds, ozonation can be used as a final polishing step. 

Finlayson-Pitts, B. J., and J. N. Pitts, Jr., Volatile Organic Compounds Ozone Formation, Alternative Fuels, and Toxics, Chem. Ind., 796-800, October (1993). 

There are four vapor phase treatment processes (a) thermal destruction, (b) catalytic incinerahon, (c) ozone destruction with ultraviolet radiation, and (d) granular carbon adsorption (GAC). Processes a-c are not widely utilized due to cost and/or effectiveness of treatment. Thermal destruction is an effective process, but the operating cost is very high due to energy requirements. Catalytic incineration, shown in Fig. 7, has lower energy requirements compared to the thermal destruction process, but it is not effective in eliminating low levels of chlorinated organic compounds. Ozone destruction with an ultraviolet radiation process has limited performance data available as a result, the performance of this process must be examined in a pilot study for the particular VOC in question in order to determine operational parameters. The most commonly used vapor phase treatment process for VOC is carbon adsorption. 

Finlayson-Pitts, B. and Pitts, J. N Jr., Volatile organic compounds Ozone formation, alternative fuels and toxics. Chemistry Industry, Oct. 18 796-800 (1993). 

Stover, E. K., A. Eazel, and D. E. Kincannon. 1985. Powdered activated carbon and ozone-assisted activated sludge treatment for removal of toxic organic compounds. Ozone Sci. Eng. 7(3) 191-203 cited in Chem. Abstr. CA 104(14) 115399V. 

Modem solvents Removal of adhesives and solder paste Wide process window Cleaning at room temperature Do not oxidize/corrode stencil Flammable Emits solvent vapors into work area Slow drying VOC (volatile organic compound) Ozone depletion potential Require explosion proof equipment... 

Reactivities compared for selected organic compounds with respect to ozone formation. 

See Airpollution Atmospheric models Fluorine compounds, organic-fluorinated aliphatic compounds Ozone. 

The rate of aqueous ozonation reactions is affected by various factors such as the pH, temperature, and concentration of ozone, substrate, and radical scavengers. Kinetic measurements have been carried out in dilute aqueous solution on a large number of organic compounds from different classes (56,57). Some of the chemistry discussed in the foUowing sections occurs more readily at high ozone and high substrate concentrations. 

Ozonation can be enhanced by the addition of ultraviolet (uv) radiation. This combination can be effective in degrading chlorinated organic compounds and pesticides. In addition, metal ions such as iron, nickel, chromium, and titanium [7440-32-6] can act as catalysts, as can ultrasonic mixing. 

In 1966, the Los Angeles Air Pollution Control Board designated trichloroethylene as a photochemically reactive solvent that decomposes in the lower atmosphere, contributing to air pollution. In 1970 all states were requited to submit pollution control plans to EPA to meet national air quaUty standards. These plans, known as State Implementation Plans (SIPS), controlled trichloroethylene as a volatile organic compound (VOC). They were designed to have each state achieve the National Ambient Air QuaUty Standard (NAAQS) for ozone. The regulations were estabUshed to control the emission of precursors for ozone, of which trichloroethylene is one. 

Volatile organic compounds and other ozone precursors (CO... 

Prepai ative isolation of nonvolatile and semivolatile organic compounds fractions (hydrophobic weak acids, hydrophobic weak bases, hydrophobic neutrals, humic and fulvic acids) from natural and drinking waters in optimal conditions was systematically investigated by solid-phase extraction method with porous polymer sorbents followed by isolation from general concentrate of antropogenic and/or toxic semivolatile compounds produced in chlorination and ozonation processes. 

H. Ozonizalion of organic compounds. The ozonization of each unsaturated organic compound is more or less an individual problem, but some general comments may be made. Organic ozonides are highly explosive, and hence it is safest to carry out the ozonization in a solvent which dissolves both the original compound and the ozonide. In all cases, a shatterproof screen of laminated safety glass should be placed between the operator and the tubes H, I, and J. A second screen should be placed back of the tubes to protect other pieces of the apparatus. 

The ozonizer may be operated at higher rates of flow of oxygen than shown in Tables I and II, provided that the organic compound reacts with ozone at a reasonably rapid rate. Some data on high rates of flow are given in Table IV. 

Carter, W. P. L., "Development of Ozone Reactivity Scales for Volatile Organic Compounds," EPA 600/3-91-050. U.S, Environmental Protection Agency, August 1991. 

Hundreds of chemical species are present in urban atmospheres. The gaseous air pollutants most commonly monitored are CO, O3, NO2, SO2, and nonmethane volatile organic compounds (NMVOCs), Measurement of specific hydrocarbon compounds is becoming routine in the United States for two reasons (1) their potential role as air toxics and (2) the need for detailed hydrocarbon data for control of urban ozone concentrations. Hydrochloric acid (HCl), ammonia (NH3), and hydrogen fluoride (HF) are occasionally measured. Calibration standards and procedures are available for all of these analytic techniques, ensuring the quality of the analytical results... 

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