Green synthesis of magnetic type Zeolites 4A as catalyst for the elimination of quinoline yellow by the Fenton process: Optimization and kinetic investigation

Abstract

This work describes the hydrothermal synthesis and characterization of zeolite 4A (Zeo-4A) and magnetite zeolite (Zeo-4A@Fe₃O₄) from Cameroonian raw kaolin. The study also explores the efficiency of Zeo-4A@Fe₃O₄ for the removal of quinoline yellow (E104) via Fenton process. XRD, FTIR, SEM, EDX, NMR-MAS and TGA-DSC characterizations show that Zeo-4A is crystalline with cubic morphology, while Zeo-4A@Fe₃O₄ exhibits a bonding interaction between zeolite and Fe₃O₄ nanoparticle leading to morphological structural changes. The degradation of quinoline yellow by heterogeneous Fenton process was carried out by varying several parameters, namely solution pH (3–7), H₂O₂ concentration (0.5–1.5 mol/L), quinoline yellow concentration (50–100 mg/L), and catalyst mass (50–100 mg). The results of catalytic performance tests reveal that the degradation efficiency of synthetic Zeo-4A, Zeo-4A@Fe₃O₄ and Fe₃O₄ were 1.71 %, 93.60 % and 92.65 %, respectively, after 60 min. Confirmatory tests were carried out by response surface methodology based on the Box-Behnken design, and a degradation rate of 98.81 % was obtained under optimum conditions of pH 3.84, 50.14 mg/L, 100 mg, and 1.5 g/L; which is well in line with the model predictions. A significant quadratic regression model R² = 91.35 % and the adjusted coefficient of determination value (adjusted R² = 82.04 %) were observed using the analysis of the variance. The study of catalyst recovery and reusability shows that the catalysts remain stable with a degradation rate greater than 66 % after five cycles. The kinetics results show that the degradation of E104 follows first and second order kinetic models, influenced by pH and catalyst mass, with optimum efficiency at pH 3. The characterization results of the material after degradation show that it maintains its structural integrity after use.