Laboratory studies on leaching of HBCDD from building insulation foams

Abstract

A series of laboratory experiments were conducted to study emissions of hexabromocyclododecane (HBCDD) into aqueous leaching fluid under simulated landfill conditions. Expanded (EPS) and extruded (XPS) polystyrene building insulation foam samples containing HBCDD were contacted with deionised Milli-Q water containing 0, 100 and 1000 mg L−1 dissolved humic matter (DHM) as leaching fluid. Concentrations of HBCDD were determined in the resulting fluid and single and serial batch experiments conducted. The impacts on HBCDD concentrations in the leaching fluid temperature and pH were examined. Data from these experiments show that HBCDD concentrations in leaching fluid following contact with EPS and XPS almost all exceeded the aqueous solubilities for each diastereomer and the technical HBCDD formula. This indicates that agitation and abrasion of EPS and XPS were significant mechanisms of HBCDD emission to leaching fluid. Specifically, under such conditions, HBCDD is likely associated with fine abraded particles of the foam and concentrations in the leaching fluid are therefore not limited by the aqueous solubility of HBCDD. Consistent with this, the length of contact time had a significant positive effect on concentrations of all diastereomers in the leaching fluid for XPS and for the least soluble diastereomer, γ-HBCDD for EPS. Generally, the presence of DHM in the leaching fluid and elevated leaching fluid temperatures had significant positive effects on HBCDD concentrations in leaching fluid for both EPS and XPS. Overall, while leaching fluids of pH 8.5 significantly enhanced concentrations of α-HBCDD released from EPS, pH exerts a minor effect on concentrations of HBCDD in leaching fluid. Keywords: Expanded polystyrene, Extruded polystyrene, Hexabromocyclododecane, Landfill, Brominated flame retardants