Extraction and Destruction of Organics in Wastewater Using Ozone-Loaded Solvent

ABSTRACT

Originally developed as a heat exchange fluid, Volasil 245 (decamethylcyclopentasiloxane) has been found to dissolve 10 times more ozone than water does. This article proposes and investigates the extraction of wastewater contaminants to ozone-loaded Volasil 245 as a means of providing rapid treatment. In a series of bench-scale tests, the effectiveness of ozone-loaded Volasil 245 contact was compared with that of conventional gas contact. Tests were conducted with respect to a range of organic compounds: namely, phenol, 2-chlorophenol, 2,3-dichlorophenol, 1,3-dichlorobenzene, o-nitrotoluene, and nitrobenzene. Contact with the ozone-loaded solvent was suggested to be the more rapid technique, reducing aqueous concentrations by at least 85% within 30 s. In the case of 2-chlorophenol, Volasil 245 contact was shown to require just ~0.5 min to achieve a residual aqueous fraction of 5%, as opposed to ~4.5 min of gas contact. However, water/solvent interfacial mass transfer resistance was suggested to limit the degree of aqueous decontamination ultimately achieved.

Keywords:

• Ozone
• Wastewater Treatment
• Solvent Extraction
• Volasil 245
• Polydimethylsiloxane
• Ozone-Loaded Solvent
• Chlorinated Organics
• Nitroaromatics

ACKNOWLEDGMENTS

The authors thank EPSRC (UK government) for funding this project, Merck Ltd. (Poole, UK) for supplying the Volasil 245 solvent, and Sulzer Chemtech (UK) Ltd. (Farnborough, UK) for providing SMV static mixing elements.