Optimization and modeling of betamethasone removal from aqueous solutions using a SiO2/g-C3N5@NiFe2O4 nanophotocatalyst by RSM

Abstract This study presents the preparation of SiO2/g-C3N5@NiFe2O4 nanophotocatalyst for the removal of betamethasone from aqueous solutions. The SiO2/g-C3N5@NiFe2O4 nanophotocatalyst was synthesized using the solvothermal method, and its structure and optical properties were characterized and confirmed through XRD, FESEM, EDX, DRS, BET, VSM and PL analysis. Photocatalytic removal of betamethasone was optimized using a central composite design. The band gap of pure g-C3N5, NiFe2O4, and SiO2/g-C3N5@NiFe2O4 was obtained 2.4 eV, 2.7 eV, and 1.4 eV, respectively using the Tauc plot. The F-value of 909.88 and Lack of Fit F-value of 0.41 confirm the obtained model is significant. Also, the value of R 2 = 0.9988 along with R 2adja = 09977 demonstrates excellent model performance. Maximum removal efficiency of betamethasone was approximately 87.15% under the following optimal conditions: nanophotocatalyst dosage of 0.005 g/50 mL, a betamethasone concentration of 20 mg/L, and an irradiation time of 40 min under visible light. This performance closely aligns with the actual value of 80.65%. In conclusion, the SiO2/g-C3N5@NiFe2O4 nanophotocatalyst demonstrates excellent photocatalytic ability for the removal of betamethasone from aqueous solutions.