Synthesis and evaluation of the Cr(VI) extraction ability of amino/nitrile calix[4]arenes immobilized onto a polymeric backbone

Three new calix[4]arene based polymeric resins (6, 7 and 8) have been synthesized via nucleophilic substitution reactions involving 5,11,17,23-tetrakis-[(N,N-dimethylamino)methyl]-25,26,27,28-tetrahydroxycalix[4]arene 3, and 5,11,17,23-tetracyanomethyl-25,26,27,28-tetrahydroxycalix[4]arene 4 as precursors with a Merrifield resin. The extraction studies were made by using liquid-liquid extraction, solid-liquid batchwise and packed-column sorption procedures, and effect of different anion to extraction of dichromate anion was examined by using NO3-, Cl−, SO42- and their mixtures. The experimental results showed that these calix[4]arene based polymeric resins have high extraction abilities towards Na2Cr2O7 as compared to their monomeric precursors, and also dichromate anion was extracted in high ratios even in presence of different anions.