Monday August 31st, 4pm, Mann Hall 323
Abstract: Sorption and desorption are important processes governing the distribution and fate of hydrophobic organic contaminants (HOCs) in landfills. The principal objective of this research was to evaluate factors that control the sorption and desorption of HOCs from municipal solid waste (MSW).
Desorption rates of toluene, o-xylene and tetrachloroethene from individual MSW components [high-density polyethylene (HDPE); poly(vinyl chloride) (PVC); office paper (OP); newsprint (NP); and rabbit food (RF), a model food and yard waste] were determined. The effects of sorbent and sorbate properties, solvent composition (ultrapure water, acidogenic and methanogenic leachates), and contact time (aging) on desorption rates were evaluated. HOC desorption rates from plastics were rapid for HDPE but slower for PVC. For biopolymer composites, 45 to 94% of sorbed HOCs are rapidly released while the remaining fraction desorbed slowly.
Sorption affinity and (de)sorption rates of toluene were compared for individual MSW post-consumer plastics (drinking water container, prescription drug bottle, soda bottle, disposable cold cup, computer casing, furniture foam, carpet, formica sheet and vinyl flooring) and model polymers (HDPE, PVC) at dilute aqueous concentrations. Generally, partition coefficients of toluene in plastic materials were 1 to 2 orders of magnitude higher than in OP and NP. Toluene sorption to plastics was affected by the amorphous fraction but not the organic carbon fraction. The diffusivity of toluene in rubbery plastics (model HDPE, drinking water container, and prescription drug bottle) was similar. Among glassy plastics (model PVC, soda bottle, computer casing, disposable cold cup), the diffusivity of toluene was also similar but two orders of magnitude smaller than for the rubbery plastics.