Uptake of dehydroabietic acid using organically-tailored zeolites

Tetramethylammonium (TMA) and hexadecyltrimethylammonium (HDTMA) cations, applied to Na+-saturated zeolites (clinoptilolite, heulandite, chabazite) in doses varying from 0–150% of the mineral cation exchange capacity (CEC), were used to elucidate the mechanisms of adsorption of tailoring cations, as well as to determine the potential of organically-tailored zeolites for removal of approximately 40 mg/l of deprotonated dehydroabietic acid (DHA) dissolved in aqueous solution (pH 7.25). Langmuir-type adsorption isotherms indicated that both TMA and HDTMA cations, applied in doses less than the mineral external CEC (ECEC), were firmly bound by electrostatic forces on only the external surfaces of zeolite. HDTMA cations improved the DHA uptake capacity of heulandite and chabazite by twenty-fold, ensuring 100% removal of DHA with 20 g/l of tailored aggregates. Analysis of factorial experiments indicated that partitioning of DHA into the hydrophobic HDTMA layer was strongly dependent on the mineral concentration (41% of model variability), while the effects of cation loading, initial DHA concentration and aggregate size were marginal (9%). Over the range examined, temperature and time of treatment did not affect DHA removal. These initial promising results provide a rationale for further research aimed at investigating removal of extractives present in pulp and paper waste waters.