Novel ?Green? Solvents for the Removal of Toxic Dyestuffs from Wastewater
Mentor 1
Mark Dietz
Location
Union Wisconsin Room
Start Date
27-4-2018 1:00 PM
Description
Dyestuffs constitute one of the most significant sources of water pollution. Of the more than one million tons produced worldwide each year, more than 10% is ultimately either discharged directly to the environment or lost during the coloration process. Most dyes are both toxic to aquatic life and not readily biodegradable, and as a result, there has long been interest in processes by which they can be removed easily and inexpensively from aqueous waste streams. Most commonly, dyes are adsorbed onto a solid support such as activated carbon (e.g., charred coconut husks). While effective, this approach can result in the generation of a new waste stream, namely, dye-laden sorbent. To avoid this, regeneration of the sorbent is required, but this can be time-consuming, difficult, and expensive.
Solvent extraction, in which an aqueous solution of the dye is contacted with an immiscible organic solvent into which the dye can partition, has also been proposed as an approach to wastewater treatment. Most conventional organic solvents, however, are unacceptably toxic and/or volatile. In this work, we have investigated the use of a comparatively non-toxic (“green”) alternative, butyl acetate (BuOAc), as an extraction solvent for dyestuff removal from water. Our results indicate that for certain dyes, solvent extraction with BuOAc may represent a viable alternative to adsorption-based methods for dye removal. In particular, efficient dye extraction and facile back-extraction (i.e., stripping / recovery) can be achieved by proper choice of aqueous phase conditions.
Novel ?Green? Solvents for the Removal of Toxic Dyestuffs from Wastewater
Union Wisconsin Room
Dyestuffs constitute one of the most significant sources of water pollution. Of the more than one million tons produced worldwide each year, more than 10% is ultimately either discharged directly to the environment or lost during the coloration process. Most dyes are both toxic to aquatic life and not readily biodegradable, and as a result, there has long been interest in processes by which they can be removed easily and inexpensively from aqueous waste streams. Most commonly, dyes are adsorbed onto a solid support such as activated carbon (e.g., charred coconut husks). While effective, this approach can result in the generation of a new waste stream, namely, dye-laden sorbent. To avoid this, regeneration of the sorbent is required, but this can be time-consuming, difficult, and expensive.
Solvent extraction, in which an aqueous solution of the dye is contacted with an immiscible organic solvent into which the dye can partition, has also been proposed as an approach to wastewater treatment. Most conventional organic solvents, however, are unacceptably toxic and/or volatile. In this work, we have investigated the use of a comparatively non-toxic (“green”) alternative, butyl acetate (BuOAc), as an extraction solvent for dyestuff removal from water. Our results indicate that for certain dyes, solvent extraction with BuOAc may represent a viable alternative to adsorption-based methods for dye removal. In particular, efficient dye extraction and facile back-extraction (i.e., stripping / recovery) can be achieved by proper choice of aqueous phase conditions.
