Charles Springer

Solvent sublation for the removal of hydrophobic chlorinated compounds from aqueous solutions

Abstract Solvent sublation, a surface chemical technique, was used to remove mono-, di-, trichlorobenzenes and a chlorinated pesticide (DDT) from aqueous solutions, Considerable improvement in efficiency of removal as compared to conventional fine bubble aeration was observed when bubbles of very small size (

Equilibrium vapor phase adsorption of volatile organic chemicals on dry soils

Abstract Equilibrium vapor phase adsorption of volatile organic chemicals (VOC) can be described adequately by the BET equation. The adsorption of five VOCs (benzene, dichloropropane, methylcyclohexane, ethyl ether and methanol) on four types of soils of moisture contents less than 2% at 30°C are reported. The adsorption of VOCs by dry soils is quite considerable and dominated by mineral adsorption. It also appears that most of the adsorption occurs on the external surface of the soils. Polar compounds show a larger degree of adsorption than non polar and slightly polar adsorbates. The high degree of adsorption observed will retard the movement of volatile organics from hazardous waste landfills and on surface soil for land application of hazardous waste when dry soil conditions exist.

Models of mechanisms for the vapor phase emission of hazardous chemicals from landfills

Abstract Quantities of hazardous chemicals have been placed in sanitary landfills in conjunction with solid waste. This paper presents three vapor phase transport mechanisms: molecular diffusion, bio-gas convection, and barometric pressure pumping. These mechanisms are incorporated into a dynamic model that simulates the emission flux rate of chemicals, as a function of landfill and environmental variables. The simulation model is driven by time-varying atmospheric pressure fluctuations. Darcys law is used to simulate gas movement through the landfill cap material to and from the landfill cells. With all mechanisms operative, a rate of 290 g benzene/m 2 d was obtained from the model using benzene as a test chemical. Atmospheric pressure fluctuations pump toxic vapors and gases from the storage cells of hazardous waste landfills to the air above. This pumping enhances the vapor phase molecular diffusion process. The calculated benzene flux rate with diffusion and atmosphere pumping was 13 g/m 2 d. Uncertainties and limitations of the model are considered which include: vapor and gas circulation in and between cells, adsorption onto solids and multi-cell landfills. The model presented is a practical tool for initial evaluation studies of volatile chemical emissions from landfills and provides a basis upon which to construct more realistic simulation models.

Removal of Traces of Pentachlorophenol from Aqueous Acidic Solutions by Solvent Extraction and Solvent Sublation

Abstract The removal of pentachlorophenol (a hydrophobic compound of low vapor pressure) from aqueous acidic solutions was studied using solvent sublation (a surface chemical technique) and solvent extraction. Both methods gave appreciable removals in highly acidic solutions (pH = 2.5), but solvent sublation had the added advantage of minimal phase contact of the organic solvent with water and increased removals under certain circumstances. Solvent sublation was also found to be more effective than conventional fine bubble aeration. The removal of pentachlorophenol (PCP) was considerably smaller at pHs near the pKa of PCP. PCP removal by solvent sublation was enhanced by increasing ionic strength and also by the presence of small amounts of an ionic surfactant in the aqueous phase. The technique of solvent sublation was tried on an actual wastewater sample from a wood preserving industry. pH adjustment, removal of suspended solids, addition of sodium chloride, and subsequent solvent sublation into minera...

Mathematical models for predicting chemical vapor emissions from landfills

Abstract Mathematical models are described for estimating steady-state chemical vapor emissions from landfills. The various vapor-transport mechanisms that give rise to the chemical flux rates through soil cover layers are reviewed. Four different vapor-transport models are described and comparisons made between them by simulating results on benzene and Aroclor 1248 volatilization from a landfill cover. Specific recommendations are made as to the use of algorithms and procedures for computing vapor emissions from sources beneath the ground. The limitations of the models are also discussed.

Transport of chemical vapors through soil: A landfill cover simulation experiment

Abstract Experimental simulation studies of the transport of volatile organic chemical vapors by both diffusion and convection through soil covers, as in landfi