Removal of emerging contaminants from water by zeolite-rich composites: A first approach aiming at diclofenac and ketoprofen

In this study, composites of the natural zeolites and cationic surfactants cetylpyridinium chloride and Arquad® 2HT-75 were used for removal of two emerging contaminants – diclofenac sodium and ketoprofen. Modifying a clinoptilolite- and a phillipsite-rich tuff, with surfactants with one or two hydrophobic tails, resulted in composites in monolayer and bilayer forms. The intention was to better evaluate interactions of composites with selected molecules. Starting materials and composites were characterized by ATR–FTIR and STA coupled with EGA. The adsorption capacities of the prepared sorbents were estimated by determination of adsorption isotherms and kinetic runs. Maximum adsorption capacity, obtained from the Langmuir model, showed that the best results were for the bilayer form of the composites up to 35 mg/g. Between the two surfactants, composites with cetylpyridinium chloride gave better results. Zeta potential measurements showed that the surfactants turned out to be unstable on the zeolite surface, the only exception being bilayers prepared using the two-tailed surfactant Arquad® 2HT-75. These results suggested possible applications of these composites for water treatment purposes.