Application of SnO2@CTAB-modified zeolitic clay nanocatalyst for the efficient sonocatalytic degradation of methylene blue in wastewater: Structural characterization, catalytic activity, and mechanistic insights

This study investigates the sonocatalytic degradation of dyes in wastewater using SnO2 nanoparticles and a hybrid SnO2@CTAB-modified zeolitic clay (SnO2@M-ZLT) nanocatalyst. The catalysts were synthesized in solution medium and characterized by XRF, XRD, FT-IR, SEM, TEM, and nitrogen adsorption-desorption analyses, confirming their successful formation and suitable surface properties. The effects of critical parameters including initial dye concentration, catalyst dosage, pH, water matrix, and radical scavengers on the removal of methylene blue (MB) were systematically evaluated. Under optimal conditions (10 g L−1 catalyst, 10 mg L−1 MB, Ultrasonic power: 300 W/L, pH for MB: Natural pH), the SnO2@M-ZLT nanocatalyst achieved 97.40 % ± 1.12 % degradation within 120 min, while 95.05 % ± 1.25 % efficiency was observed at 5 g L−1 catalyst and 5 mg L−1 MB. The sonocatalytic degradation of MB over SnO₂@M-ZLT followed pseudo-first-order kinetics, with kapp values ranging from 0.004 to 0.082 mg L−1 min−1 depending on catalyst dosage, 0.012–0.083 mg L−1 min−1 with varying MB concentration, and 0.030–0.055 mg L−1 min−1 across different water matrices. The optimal degradation efficiency was obtained at a catalyst dosage of 2–2.5 g L−1, an initial MB concentration of 5–10 mg L−1, and in distilled water, confirming the strong dependence of the reaction rate on both operational and environmental factors. Reusability tests showed that SnO2@M-ZLT retained high catalytic activity after five cycles. These results highlight the strong potential of SnO2@M-ZLT as an efficient and stable nanocatalyst for sustainable wastewater treatment.