Selective transport of chromium (Ⅲ), cobalt (Ⅱ), barium (Ⅱ) and strontium (Ⅱ) ions through polymer inclusion membranes

摘要

In the present work the separation of chromium(III), cobalt(II), barium(II) and strontium(II) from chloride solution using polymer inclusion membranes (PIMs) was investigated. PIMs doped with amide derivatives of 2-a m inobenzoic acid [2-dodecanamidobenzoic acid (DABA), 2-tetradeca nam idobenzoic acid (TABA), 2-palmitamidobenzoic acid (PABA) and 2-stearamidobenzoic acid (SABA)] as fixed carriers, cellulose triacetate (CTA) as base polymer and dioctyl phthalate (DOP) as a plasticizer have been prepared. The amide derivatives were prepared by reaction of 2-aminobenzoic acid with fatty acids (lauric, myristic, palmitic and stearic acid) in the presence of N,N'-dicyclohexylcarbodiimide (DCC) as dehydrating agent. The chemical structure of the prepared carriers was confirmed by Fourier transform infra-red (FTIR) and nuclear magnetic resonance ('HNMR), while the prepared membranes were characterized using different techniques such as FTIR, X-ray diffraction and scanning electron microscopy (SEM). The competitive transport of Cr(III), Co(II), Ba(II) and Sr(II) ions through PIM was investigated and optimized as a function in transport time, pH, membrane composition, type of receiving phase and its concentration. Results showed that the initial flux of chromium(III) transport increased with different carriers in the order DABA TABA PABA SABA through the cellulose triacetate membranes. The chromium(III) ions were transported with a highest rate, and the selectivity order was as follows: Cr(III) Co(II) Ba(II) Sr(II). The best results of normalized initial flux and recovery were obtained for membranes containing 40% of each carrier. The obtained results showed that around 96.3% of Cr(III) was transported from the source phase containing equimolar mixture of all metals at pH 4.1 through PIM after 10 h into 3.0 M HCl using carrier SABA.