Temperature- and solvent-dependent migrations of di(2-ethylhexyl)phthalate, the hazardous plasticizer from commercial PVC blood storage bag

Abstract

Towards a process development for the bioremediation of phthalic acid esters (PAE) blended in various plastics, we explored the type of PAE in commercially available PVC blood storage bags (BB), its solvent- and temperature-dependent migrations and coefficient of diffusion (D) behaviors at static condition by solvent extraction method. The PAE [about 34 % (w/w)] in BB was confirmed as DEHP by UV, TLC and GC-MS analyses. When effects of five solvents on the rate of migration of intact DEHP from BB tested (40 °C), order of migration during the initial hrs was: n-hexane>methanol>t-butyl alcohol>isopropyl alcohol>ethanol. At 40 °C, about 60 % (of total) DEHP in BB migrated into n-hexane, which rose to 80 % at 60 °C and almost 95 % at boiling (69 °C) in the first h. DEHP diffusion from BB was dependent on its concentration and nature of surrounding medium and temperature. Fickian approximation was used to calculate D values for DEHP migration, and in n-hexane average values were: 1.26 × 10−7, 1.92 × 10−7 and 2.18 × 10−7cm2 sec−1 at 40, 50 and 60 °C, respectively. This study shows that n-hexane is the preferred solvent to extract DEHP from used or waste medical and allied PVC products for small scale, especially screening studies. Briefly, DEHP and solvent were separated individually upon distillation of the extract; thus DEHP, microporous PVC BB sheet and solvent were recovered for reuse inexpensively without environmental contamination.