Photocatalytic Degradation of Cephalexin, Amoxicillin, and Phenol Red Using a Green‐Synthesized Folic Acid–ZnO–Bi 2 O 3 Nanoporous System

The persistent presence of pharmaceutical pollutants like amoxicillin (AMX) and cephalexin (CPX), and industrial dyes such as phenol red (PR) in wastewater poses serious ecological and public health risks, including antibiotic resistance. It necessitates efficient and low‐cost remediation technologies. Photocatalysts employing innovative and engineered nanomaterials such as bismuth oxide (Bi 2 O 3 ) and zinc oxide (ZnO) nanostructures exhibit considerable potential for eliminating pollutants. This study focused on the photodegradation of AMX, CPX, and PR utilizing green‐synthesized folic acid–ZnO–Bi 2 O 3 nanoparticles (F‐Zn‐Bi NPs) under visible light irradiation. Characterization of the synthesized photocatalyst was conducted using various techniques of powder x‐ray diffraction (PXRD), field emission scanning electron microscopy, energy dispersive x‐ray analysis, Fourier‐transform infrared (FT‐IR) spectroscopy, Brunner–Emmett–Teller (BET) analysis, thermal gravimetric analysis, and photoluminescence (Pl) and UV‐visible (UV‐vis) measurements. The characteristic properties of F‐Zn‐Bi NPs obtained by PXRD confirmed the coexistence of monoclinic phases of α ‐Bi 2 O 3 and ZnO, with an average crystallite size of 36.4 nm. Electron microscopy and BET analysis revealed a porous morphology with a specific surface area of 159.6 m 2 g −1 , which is favorable for surface adsorption of the pollutants. FT‐IR spectra of F‐Zn‐Bi NPs corroborated successful folic acid integration. A reduced band gap of 2.32 eV was also obtained by Tauc plot constructed from UV‐vis absorption and Pl data. F‐Zn‐Bi NPs exhibited degradation efficiencies of 93.7%, 90.0%, and 95.0% for PR, AMX, and CPX, respectively, within 300 min through a first‐order reaction kinetics. The novel F‐Zn‐Bi NPs demonstrated considerable potential for the remediation of pharmaceutical/dye–contaminated wastewater.