Evaluation of the efficiency of a multilayer photocatalyst in the removal of methylene blue

Abstract

This study developed a two-layer structured photocatalyst, featuring a magnetic nickel core and a shell composed of a tin-based semiconductor and carbon nitride. The composite core was synthesized using a green approach, leveraging rosemary plant extract. A notable advantage of this photocatalyst is forming a floating layer through a gelation process, facilitated by freeze-drying, which creates internal pores. These pores not only enhanced the floatability of the structure but also improved light penetration into the nanoparticles, thereby increasing the photocatalytic efficiency of the synthesized composite. Structural characterization of the nanoparticles, including FESEM, XRD, EDX, and FTIR analyses, confirmed the successful synthesis of the proposed photocatalyst. FESEM analysis revealed that the average particle diameter was less than 1.5 micrometers. The photocatalyst's performance was assessed in a continuous reactor under UV irradiation for methylene blue degradation across varying conditions: pH levels (3, 5, 7, 9, and 11), catalyst dosages (0.2, 0.4, 0.6, 0.8, and 1 g/L), and initial dye concentrations (10, 20, 30, 40, and 50 mg/L). Optimization studies identified the optimal conditions for photocatalysis as a pH of 11, a photocatalyst dosage of 0.6 g/L, and an initial dye concentration of 50 mg/L. Under these conditions, the methylene blue removal efficiency reached 82%. Furthermore, reusability studies demonstrated that the core structure of the photocatalyst retained its essential properties and effectiveness in removing organic pollutants even after five reuse cycles.