Applicability of liquid membranes in chromium(VI) transport with amines as ion carriers

Chromium(VI) transport across supported liquid membranes (SLMs) and polymer inclusion membranes (PIMs) with tertiary amines and quaternary ammonium salt (Aliquat 336) from chloride acidic aqueous solution to 0.1 M NaOH has been studied. The initial flux of Cr(VI) decreases linearly with logarithm of n-octanol/water partition coefficient increase for R3N amines (R = n-C6H13-n-C12H25). The chromate ions are transported across polymer inclusion membranes with lower rate using polyvinyl chloride (PVC) instead of cellulose triacetate (CTA) support. The decreasing of Cr(VI) initial fluxes in following order of plasticizers: o-nitrophenyl pentyl ether > bis(2-ethylhexyl) adipate > dibutyl phtalate was observed. The comparative Cr(VI) transport studies of bulk, supported and polymer inclusion membranes were done. The highest permeability coefficient values for Cr(VI) was found for SLM, while the lowers values were observed for BLM. The repeated transport experiments of SLM and PIM were shown and the stability of PIM was described using the Danesi's thermodynamic model. The long-term integrity of PIM was found. Non-contact atomic force microscope was applied to obtain images of pores in polymer inclusion membranes.