Supercritical water oxidation process

Supercritical fluid extraction — During the past two decades, important progress was registered in the extraction of bioactive phytochemicals from plant or food matrices. Most of the work in this area focused on non-polar compounds (terpenoid flavors, hydrocarbons, carotenes) where a supercritical (SFE) method with CO2 offered high extraction efficiencies. Co-solvent systems combining CO2 with one or more modifiers extended the utility of the SFE-CO2 system to polar and even ionic compounds, e.g., supercritical water to extract polar compounds. This last technique claims the additional advantage of combining extraction and destruction of contaminants via the supercritical water oxidation process."... 

P.C. Dell Orco, L. Li, E.F. Gloyna., The Separation of Particles from Supercritical Water Oxidation Processes, Separation Science and Technology, 28, (1993), 625. 

Supercritical Water Oxidation Process for the Treatment of VX Hydrolysate... 

SUPERCRITICAL WATER OXIDATION PROCESS FOR THE TREATMENT OF VX HYDROLYSATE... 

Modell M. Supercritical water oxidation process of organics with inorganics. U.S. Patent 5,252,224, 1993. 

The solubility of inorganic compounds, such as e.g. salts, decreases in the same way as the solubility of organic compounds in the supercritical state increases. This decrease is combined with the decrease of the dielectric constant of water. The supercritical water oxidation process is described in the following figure. 

The destruction of hazardous chemical wastes by oxidation in supercritical water is a promising new technology which has several advantages over conventional methods of toxic chemical waste disposal. Although the feasibility of the supercritical water oxidation process has been demonstrated, there is little kinetic information available on the underlying reaction mechanisms. We have recently determined the oxidation kinetics of several model compounds in supercritical water, and now report on our results of the oxidation of methanol, a conunon industrial solvent, in supercritical water. Globd kinetic expressions are presented and our attempts to model the reaction using a free-radical mechanism with 56 elementary reactions are discussed. The inability of the elementary reaction model to represent oxidation in supercritical water is demonstrated and future model modifications are discussed. 

More polymerization reactions carried out at supercritical conditions, select biomass conversion supercritical fluid technologies for hydrogen production, wider use of supercritical water oxidation processes, portfolio of self-assembly applications, a spate of opportunities in process intensification, many supercritical fluid aided materials synthesis applications, and numerous reactions for synthesis of specialty chemicals are expected for years to come. 

Supercritical fluids can be applied to remove polluting materials from the environment. Theory and practice of this technology is of increasing interest at the present time. In Supercritical fluids and reductions in environmental pollution by Koji Yamanaka and Hitoshi Ohtaki focus their attention to start with the thermodynamics and structure of supercritical fluids and then describe the supercritical water oxidation process, the extraction of pollutant from soils with supercritical carbon dioxide and other supercritical fluids, and recycle of used plastic bottles with supercritical methanol. Andrew I. Cooper et al. report on Supercritical carbon dioxide as a green solvent for... 

Critical curves in water-salt system are extended usually toward temperatures higher than the critical temperature of water hence a high-temperature shift of immiscibility region upon addition of salt is a common phenomenon. It was mentioned in (Krader and Franck, 1987 Smits et al., 1997b,c) that this phenomenon is similar to the salting-out effect of ions observed in water-nonpolar gases mixtures at ambient conditions, and the electrolytes could be regarded as an anti-solvent for the volatile reactants and reaction products in supercritical water oxidation processes. 

The supercritical water oxidation process is based on the ability of water to perform as... 

The supercritical water oxidation process can be adapted to a wide range of feed mixtures and scales of operation, making it a... 

Fig. 3.7. Process flow diagram of supercritical water oxidation process. (Modar, Inc., Houston, TX courtesy EPA.)...

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