Floatable photocatalyst LaFeO3/modified expanded perlite composite for photocatalytic ammonia degradation

Abstract

In this research, visible-light active perovskite photocatalyst, lanthanum orthoferrite (LFO), and floating photocatalyst composites, namely LFO/expanded perlite (EP) and LFO/modified EP (MEP) were successfully synthesized for ammonia degradation. Sodium hydroxide was used to modify EP as it could transform the structure of EP into a mesoporous structure, thereby increasing the surface attachment of LFO and improving contact with ammonia. The characterization of EP, MEP, LFO/EP, and LFO/MEP composites was performed using UV–Vis, XRD, BET surface area, FTIR, SEM, FESEM, and zeta potential. Photocatalytic degradation of ammonia was studied and LFO/MEP showed the best performance. The optimal operational parameters for degrading ammonia using LFO/MEP were the catalytic dosage of 8 g L−1, the initial ammonia concentration of 10 ppm, and the pH of the reaction medium of 8, with the maximum ammonia degradation efficiency of 45.7%. A reusability study of LFO/MEP composite on the photocatalytic degradation of ammonia was performed for 3 cycles, where the composite demonstrated high stability. The reaction rate constant, k, was 0.0079 min−1, the kinetic data was 10.08 μmol/g-catalyst/h, and the quantum yield was 6.686 × 10−6 molecules/photon. The floatable photocatalyst LFO/MEP composite can be an effective method for the photodegradation of ammonia. The photocatalyst could be easily recovered and is reusable for several cycles of treatment. The reaction occurs at ambient conditions under visible light and there is limited by-product production, with the nitrate and nitrite ions of 0.48 and 0.0024 ppm, respectively. These properties demonstrated that the proposed method is an environmentally friendly method for removing ammonia from water.