Factors controlling alkylbenzene sorption to municipal solid waste

The sorption of toluene and o-xylene to individual municipal solid waste (M SW) constituents [office paper, newsprint, model food and yard waste, high density polyethylene, and poly(vinyl chloride) (PVC)] was evaluated. Effect s of sorbent decomposition and solvent composition on alkylbenzene sorption were studied by evaluating biodegradable sorbents in both fresh and anaero bically decomposed form and by complementing single-solute isotherm tests w ith experiments conducted in acidogenic and methanogenic leachate. Alkylben zene sorption to plastics was greater than to biopolymer composites, and di fferences in sorbate/sorbent solubility parameter compatibility explained t his observation. Alkylbenzene sorption to biopolymer composites yielded lin ear isotherms, and sorption capacities [log(K-oc/K-ow)] decreased linearly with increasing sorbent polarity as expressed by the O-alkyl/alkyl ratio. L eachate composition had little effect on alkylbenzene sorption with one exc eption; volatile fatty acids in acidogenic leachate appeared to convert PVC from a glassy to a rubbery polymer. The results of this study showed that sorbent organic matter affinity for hydrophobic organic contaminants (HOCs) increases with increasing extent of MSW decomposition because of the recal citrance of plastics and the preferential degradation of polar biopolymers. Furthermore, the plasticizing effect of volatile fatty acids in acidogenic leachate may enhance the bioavailability of HOCs sorbed to glassy organic matter in MSW or in soils contaminated with acidogenic leachate.