Hydrophobic zeolites as adsorbent media for pre-concentration of emerging contaminants in aqueous dilute solutions

Research is documenting with increasing frequency that many chemical compounds (pharmaceuticals, personal care products, flame retardants, etc.), that have not historically been considered as contaminants, are detected in natural waters in concentrations ranging from a few ng/L to a few μg/L: these are generally referred to as “contaminants of emerging concern” because the risk to human health and the environment may not be known. Conventional wastewaters and recycled water treatments are only partially effective in their removal or degradation, so they are continuously discharged into the environment [1]. Therefore, it is important to develop analytical methods able to detect these molecules in accurate way; sorption based technologies were demonstrated to be efficient and economical methods both for the removal of trace pollutants from water and for their enrichment. Among the large number of inorganic adsorbents, zeolites were proven to be efficient in the adsorption [2, 3] and the pre-concentration [4] of organic micropollutants from environmental matrixes. The aim of the present work is to evaluate the application of hydrophobic zeolites (Beta and Y) as medium for solid phase extraction systems of pre-concentration, towards drugs in aqueous dilute solutions. After adsorption experiments, the drug release has been evaluated by varying some parameters of the extracting phase like pH, ionic strength and organic modifier content. Since the drugs adsorption onto zeolites is driven by both hydrophobic and electrostatic interactions, satisfactory percentages of release have been obtained by employing aqueous extracting phases in a pH range in which electrostatic interactions are repulsive, thus limiting the use of organic solvents. Moreover, the zeolites can be completely regenerated after desorption of the analyte, without loss of adsorption efficiency: this allows their reuse, with a considerable saving of materials. [1] Gros M., Petrović M., Ginebreda A., Barceló D.; Environment International 36 (2010) 15–26 [2] Martucci A., Pasti L., Marchetti N., Cavazzini A., Dondi F., Alberti A.; Microporous and Mesoporous Materials 148 (2012) 174–183 [3] Pasti L., Sarti E., Cavazzini A., Marchetti N., Dondi F., Martucci A., Journal of Separation Science (2013) 36, 1604–1611 [4] Costa A. A., Wilson W. B., Wang H., Campiglia A. D., Dias J. A., Dias S. C.L.; Microporous and Mesoporous Materials 149 (2012) 186–192