Enhanced Photocatalytic Performance of Fe3O4/Phthalhydrazide/Chitosan Composites for Tetracycline Degradation

Abstract

This study evaluates the photocatalytic performance of two innovative nanocomposites, Fe₃O₄/chitosan and Fe₃O₄/phthalhydrazide/chitosan, for the degradation of tetracycline (TC) under visible light irradiation. The synthesized photocatalysts were characterized using Fourier-transform infrared (FTIR) spectroscopy, X-Ray diffraction (XRD), field emission scanning electron microscopy (FESEM), UV-Vis spectroscopy, and energy-dispersive X-Ray spectroscopy (EDS) to confirm their structural, morphological, optical, and elemental properties. These analyses provide insights into the role of phthalhydrazide in enhancing photocatalytic activity. The isoelectric point (pH_iep) of the Fe₃O₄/phthalhydrazide/chitosan composite was found to be 9.2, indicating favorable electrostatic stability. Photocatalytic tests demonstrated that the Fe₃O₄/phthalhydrazide/chitosan composite exhibited significantly superior degradation efficiency, achieving 93% TC removal after 120 min, compared to 53% for the Fe₃O₄/chitosan composite. The effect of catalyst dosage on photocatalytic activity was also investigated, revealing optimal performance at concentrations between 0.01 g and 0.02 g. Furthermore, the influence of TC concentration on degradation efficiency was examined, showing a decline in photocatalytic activity at higher TC concentrations due to competitive adsorption on active sites. The optimal concentration for achieving the highest photocatalytic activity appears to be around 10 to 20 ppm. pH studies showed in alkaline media about 12 the photodegradation efficiency is reached to about 100% due to enhancing the hydroxyl radicals and surface charges of photocatalyst. Mechanistic studies employing scavengers confirmed the involvement of reactive species, providing further insight into the degradation pathways of TC. The incorporation of phthalhydrazide into the Fe₃O₄/chitosan composite significantly enhanced its photocatalytic efficiency, presenting a promising strategy for the environmental remediation of pharmaceutical pollutants. These findings emphasize the critical role of optimizing catalyst design and operational conditions to enhance the effectiveness of photocatalytic processes in wastewater treatment applications.