Synthesis of macrocyclic polyphenol resin by methylene crosslinked calixarene (MC-H) for the adsorption of palladium and platinum ions
A novel macrocyclic polyphenol resin, a calixarene derivative, namely, a methylene crosslinked calixarene (MC-H), was successfully synthesised by demethylation of MC-CH3. MC-CH3 was prepared by crosslinking CH3 with s-trioxane under acidic conditions. Methylation of calixarene (H) is strongly required to protect the oxygen atoms on the phenolic groups. It was found that the adsorption of palladium and platinum optimally occurred at low pH. The maximum loading capacity of palladium on the resin was found to be 0.41 mol kg−1 while that of platinum was 0.23 mol kg−1. The stoichiometries of metal ions were found to be 5 : 1 of the calixarene unit in MC-H to Pd(II) and 3 : 1 of that in MC-H to Pt(IV), respectively.