Synthesis of Porphyrin-based MOF/Cloisite-30B nanocomposite for selective dye adsorption: Optimization by Design-Expert, Adsorption, and Kinetic Study

In this paper, the novel PCN-224/cloisite-30B composite is prepared through the solvothermal method. Cloisite-30B, a natural, nonpoisonous, and inexpensive substance, has been composited with porphyrinic-based-MOF for the first time. The mentioned composite has been characterized by X-ray diffraction analysis, Fourier-transform infrared spectroscopy, thermogravimetric analysis, Brunauer–Emmett–Teller analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Also, the quadratic model for predicting methylene blue (MB) removal efficiency is presented (R² = 0.9984, R²_adj = 0.9954). Moreover, the optimum condition for MB adsorption has been assessed through Design-Expert software (80 initial dye concentration, 20 mg adsorbent, 30 min adsorption time, pH = 7). At the optimum condition, the adsorption capacity of adsorbent toward four other dyes has been studied, including methyl orange (MO), rhodamine B (RhB), congo red (CR), and eriochrome black T (EBT). The adsorption (Langmuir, Freundlich, and Temkin model) and kinetic (first and second order) study were calculated based on non-linear equations. PCN-224/cloisite-30B is an efficient adsorbent in dye removal and acts selectively when it is in contact with anionic and cationic species with close molecular size. Furthermore, the composite is highly recyclable, after ten washing cycles, it has the same efficiency as the first cycle in MB removal.