Uptake of dehydroabietic acid using organically-tailored zeolites

Tetramethylammonium (TMA) and hexadecyltrimethylammonium (HDTMA) cations, a pplied to Na+-saturated zeolites (clinoptilolite, heulandite, chabazite) in doses varying from 0-150% of the mineral cation exchange capacity (CEC), w ere used to elucidate the mechanisms of adsorption of tailoring cations, as well as to determine the potential of organically-tailored zeolites for re moval of approximately 40 mg/l of deprotonated dehydroabietic acid (DHA) di ssolved in aqueous solution (pH 7.25). Langmuir-type adsorption isotherms i ndicated that both TMA and HDTMA cations, applied in doses less than the mi neral external CEC (ECEC), were firmly bound by electrostatic forces on onl y the external surfaces of zeolite. HDTMA cations improved the DHA uptake c apacity of heulandite and, chabazite by twenty-fold, ensuring 100% removal of DHA with 20 g/l of tailored aggregates. Analysis of factorial experiment s indicated that partitioning of DHA into the hydrophobic HDTMA layer was s trongly dependent on the mineral concentration (41% of model variability), while the effects of cation loading, initial DI-IA concentration and aggreg ate size were marginal (9%). Over the range examined, temperature and time of treatment did not affect DHA removal. These initial premising results pr ovide a rationale for further research aimed at investigating removal of ex tractives present in pulp and paper waste waters. (C) 2000 Elsevier Science Ltd. All rights reserved.