Application of adductive crystallization method for terephthalic acid recovery

Adductive crystallization is a special separation method.Terephthalic acid(TA)could be dissolved and re-crystallized in certain acylamide solvents such as N,N-dimethylacetamide(DMAC) spontaneously even at constant temperature,solvent adduct crystals could be formed with 1:2 molar ratio of TA and DMAC through hydrogen bonding.This adductive crystallization method showed a high selectivity in TA recovery from the TA residue of the single-step crystallization,through which the 90%—95% colored impurities initially contained in the residue could be removed.