Proceso de sorción de metronidazol y clindamicina con dos diferentes zeolitas modificadas con tensoactivos

Abstract

In this work, the validation of the analytical method was carried out for the quantification of clindamycin and metronidazole in aqueous medium by High Resolution Liquid Chromatography (HPLC). The parameters, namely suitability, accuracy, linearity, limit of detection and quantification were determined. These parameters accomplished the national and international specifications. Two zeolitic materials were used, one from the State of Oaxaca (ZeO) and the other from the State of San Luis Potosí (ZeS); which were previously conditioned with a 0.1 M solution of sodium chloride (ZeONa and ZeSNa); both materials were modified with the cationic surfactants: hexadecyltrimethylammonium bromide (HDTMA), ZeOH and ZeSH materials were obtained and with the surfactant benzyl-dimethyl-hexadecyl ammonium chloride (BDHA) the ZeOB and ZeSB materials were generated. The effective cation exchange capacities were determined; it was found 0.94 and 0.49 meq/g for ZeO and ZeS respectively. In addition, the modified zeolitic materials (ZeOH, ZeSH, ZeOB and ZeSB) were characterized by infrared (IR) spectroscopy and the modification of the zeolites with the surfactants was evidenced with the bands at 2935-2919 cm-1 and 2869-2867 cm-1, which can be attributed to the CH2 groups present in the surfactant. Clinoptilolite, mordenite and muscovite were found in ZeO; while in ZeS the presence of clinoptilolite, quartz and mordenite were identified by X-ray diffraction, changes after being treated with HDTMA and BDHA were not observed. The sorption kinetics were carried out with metronidazole, the sorption systems with the four zeolitic materials modified with surfactants reached equilibrium at 15 h, the experimental data were adjusted to the Ho model. On the other hand, the sorption kinetics of clindamycin by the ZeOH and ZeSH materials presented equilibrium times of approximately 15 h; while the sorption systems using ZeOB and ZeSB reached equilibrium at 12 h. The experimental data were adjusted to the pseudo-second order model. The sorption isotherms of metronidazole and clindamycin were determined at three different temperatures (293, 303 and 313 K) with the four zeolitic materials (ZeOH, ZeSH, ZeOB and ZeSB), a linear behavior was observed. The thermodynamic behavior in the sorption of both drugs was exothermic and not spontaneous. The effect of pH showed that the sorption is most efficient between pH 5 and 7 for metronidazole and clindamycin between 7 and 11.