Spent FCC catalyst as sorbent for pesticides microextraction: a sustainable approach towards waste recycling and reuse

This work presents the use of spent fluid catalytic cracking (FCC) catalyst as sorbent for the extraction of pesticides from wastewater. The spent FCC catalyst was pretreated and modified to form set of sorbent materials for the extraction of pesticides. The sorbent materials were characterized using powder X-ray diffraction (PXRD), surface area characterization (BET), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). Among the sorbent materials, the spent FCC catalyst pretreated by washing with water-methanol solution gives the best extraction performance due to its increased surface area, improved porosity, and enhanced active sites for adsorption. All parameters related to the microextraction process were optimized using a univariate approach. Consequently, 10 mg of sorbent dosage, 5 min extraction time and 20 min desorption time, using 300 mu L ethyl acetate as desorption solvent were achieved. The study demonstrates the successful use of spent FCC catalysts for pesticide extraction, achieving a wide linear range (5-1000 ppb), low limit of detection (0.36-152 ppb), and multiple reusability, as evidenced by consistent performance across multiple cycles of use. The established procedure demonstrated the detection of four pesticides in the actual treated wastewater sample, including Pirimicarb, Penconazole, Chlorfenapyr, and Mefenacet. The wastewater was spiked with three concentrations chosen from the linear range (5, 200, and 1000 ng/mL). The results showed high relative recovery rates (84.9-99.5%) with acceptable %RSDs (3.21-17.9%).