Emission of Volatile Organic Compounds to the Atmosphere in the Solvent Sublation Process. I. Toluene

Abstract

The mass of volatile organic compounds emitted to the atmosphere during solvent sublation was determined experimentally, using toluene as a test compound. It is shown that the emission of toluene to the atmosphere can be significantly reduced by using solvent sublation instead of air stripping under the same experimental conditions. The parameters which affect emission are the air flow rate, the nature and thickness of the organic layer, and the nature and concentrations of the co-solutes. Emissions are reduced as the thickness of the organic layer on the top of the column is increased. The use of decyl alcohol as the layer compound decreases emission to a greater extent than does paraffin oil. The emission of toluene during solvent sublation is further reduced as the air flow rate is lowered. The rate of toluene removal from water in solvent sublation is somewhat higher than in air stripping under the same experimental conditions. The effect of added anionic or cationic surfactants or alcohol was to improve the efficiency of water separation, but it also allowed more of the toluene to be emitted from the system.

Application of Solvent Sublation for the Determination of Organophosphorous Pesticides in Vegetables by Gas Chromatography with a Flame Photometric Detector

“…It is a kind of adsorptive bubble separation technique, in which the hydrophobic compounds in water are adsorbed on the bubble surfaces of an ascending gas stream and then collected in an immiscible liquid layer (usually an organic solvent lighter than water) placed on top of the water column. This method, with its advantages of simultaneous separation and enrichment, attracts much attention in the fields of environmental analysis and wastewater treatment [8][9][10][11][12][13][14][15][16] recently. Solvent sublation has practical and theoretical advantages over other extraction methods (such as solvent extraction and solid-phase extraction).…”

A mathematical model and mechanism of sublation of dye-surfactant ion complexes

“…Karger [10] then qualitatively described the possible transport pathways in solvent sublation, for which two predominated transport processes existed: (1) transport within and on the surface of the bubbles, (2) a diffusive transport between the phases driven by a concentration gradient. Wilson et al then worked on building the mathematical models of the solvent sublation process [11,12,13]. However, their results have some discrepancy between the calculated and experimental results.…”

“…Most of these studies have focused on the removal of organic pollutants from aqueous systems, such as alkyl phthalate, volatile chlorinated organics, dichlorobenzenes, nitrophenols, polynuclear aromatics and chlorinated pesticides [5,6,7,8,9,10,11], and the emission of volatile organic compounds (volatile chlorinated organics and toluene) to the atmosphere in the solvent sublation [12,13]. Other studies concern the solvent sublation of dyes in aqueous solution, such as the separation of methyl orange from rhodamine B [14,15], the solvent sublation of bromophenol blue-hexadecyl pyridium chloride ion pair [16], magaenta (a cationic dye) with sodium lauryl sulfate [17] and direct red and acid red (two anionic dyes) with hexadecyltrimethylammonium ions [18,19].…”

The removal of humic acids from water by solvent sublation

“…Most of these studies have been focused on the removal of organic pollutants from aqueous systems, such as alkyl phthalate, volatile chlorinate organics, dichlorobenzenes, nitrophenols, polynuclear aromatics, and chlorinated pesticides [6][7][8][9][10][11], and the emission of volatile organic compounds (volatile chlorinated organics and toluene) to atmosphere in the solvent sublation [12,13]. Other studies are the solvent sublation of dyes in the aqueous solution, such as removal of bromophenol blue from water by solvent sublation with hexadecyl pyridium chloride into isopentanol [14,15], the separation of methyl orange from Rhodamine B [16], the solvent sublation of the methyl orange-hexadecyltrimethylammonium ion pair [17], Magenta (a cationic dye) with sodium lauryl sulfate [18], and Direct Red and Acid Red (two anionic dyes) with hexadecyltrimethylammonium ion [19,20].…”