Structural framework effect of various CeO2-loaded zeolites on the adsorptive removal of fipronil

Adsorption behavior of phenylpyrazole insecticide-fipronil, an endocrine disrupting compound was explored. The zeolites with microporous and mesoporous structures were modified by ion-exchange method with a cerium precursor which outlines metal oxides on the surfaces and named as Ce-beta, Ce-mordenite and Ce-13X adsorbents. They were characterized by X-ray powder diffraction, HR-TEM, BET analysis for surface area, SEM and EDS. The XPS technique was employed to verify the cerium metal exchange onto the zeolites. The batch experiments were done to investigate the effect of adsorption parameters: FIP concentration (600-1000 ppm), adsorbent dose (0.50-3.0 g/L), pH (2-11), time of contact (20-140 min), stirring speed (50-250 rpm) and temperature (25-45 degrees C). The equilibrium data were fitted in various adsorption isotherms and Langmuir adsorption isotherm fits properly, indicating monolayer adsorption. The best fitted pseudo-second-order model signifies a higher adsorption rate. Thermodynamics revealed the spontaneous and exothermic adsorption process. The structural comparison was also made between the 13X, Mordenite and Beta zeolite frameworks.

Automated summary

The study investigated the adsorption behavior of phenylpyrazole insecticide-fipronil, an endocrine disrupting compound, on modified zeolites. The results showed that the Langmuir adsorption isotherm and pseudo-second-order kinetic model well described the adsorption process. Thermodynamics revealed that the adsorption process is spontaneous and exothermic.