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Item Photocatalytic Degradation of Caffeine Using Biogenic Silver Doped Zinc Oxide Nanoparticles(Springer Science and Business Media Deutschland GmbH, 2025) Gudadur, K.S.; Mohan Balakrishnan, R.; Kadam, V.V.This study explores the degradation of caffeine using biogenic silver-doped zinc oxide (Ag/ZnO) nanoparticles (NPs) as a heterogeneous photocatalyst. Zinc nitrate (Zn(NO3)2) and silver nitrate (AgNO3) were utilized as precursors in the biogenic synthesis of Ag/ZnO NPs. The synthesis involved incubating the mixtures for 72 h at pH 11 and a temperature of 28 °C ± 1 °C. The incorporation of silver resulted in a reduction of the bandgap energy of ZnO from 3.33 to 2.29 eV, confirming the successful synthesis of Ag/ZnO NPs. Key parameters were optimized to enhance caffeine degradation efficiency, including catalyst loading (5, 10, 15, and 20 mg), initial pollutant concentration (20, 40, 60, 80, 100, 120, and 140 ppm), hydrogen peroxide (H2O2) concentration (1, 3, 5, and 7 mM), and radiation exposure duration (20 to 200 min). The optimal conditions achieved a maximum degradation efficiency of 85.78% with a pollutant concentration of 60 ppm, catalyst loading of 15 mg/100 mL at pH 8, 5 mM H2O2 as an electron acceptor, and a radiation exposure duration of 160 min. The kinetics of caffeine degradation were found to follow a pseudo-first-order reaction. After 160 min of irradiation, the removal rates of chemical oxygen demand (COD) and total organic carbon (TOC) were 71.23% and 67.87%, respectively, indicating significant mineralization of caffeine. Additionally, the photocatalyst demonstrates impressive reusability and stability, maintaining 81.3% of its degradation capacity for caffeine even after five cycles. This highlights the excellent reusability of Ag/ZnO, making it a sustainable and environmentally friendly choice for treating industrial wastewater. Notably, the method is environmentally friendly and does not involve toxic chemicals.; To synthesize Ag@ZnO NPs using an endophytic fungal isolate from medicinal plant. Nothapodytes foetida. To study the morphological, structural, optical, and stability properties of biogenic Ag@ZnO NPs. To investigate the caffeine degradation and its underlying kinetic analysis. To characterize caffeine degradation using total organic carbon (TOC) and chemical oxygen demand (COD) analysis. © University of Tehran 2025.; © University of Tehran 2025.Item Stimulation of peroxymonosulfate using nickel ferrite nanoparticles for the degradation of Lomefloxacin hydrochloride and caffeine(Springer Science and Business Media Deutschland GmbH, 2025) Ilango, I.; Mohan Balakrishnan, R.; Visvanathan, C.; Bui, X.-T.Lomefloxacin Hydrochloride (LFH), an antibacterial agent, and caffeine (CAF), a cognitive enhancer, are excreted by humans and end up in municipal sewage effluents and surface waters. This pharmaceutical concentration in bodies of water/treatment plants poses a serious threat to both aquatic habitats and humans. A laboratory batch study on the degradation of LFH, CAF and LC (CAF and LFH mixed solution) was carried out using NFO nanoparticles to stimulate potassium peroxymonosulfate (PMS). The NFO nanoparticles were synthesized through a co-precipitation method and characterised using FTIR, XRD, FESEM/EDX, TGA/DTA/DTG, BET, AFM, VSM, and Zeta potential. The particle size distribution from FESEM (using ImageJ software) revealed that 83.3% of particles are ? 100 nm, its mean and standard deviation were estimated to be 43.87 nm and 20 to 25 nm. The NFO nanoparticles’ specific surface area was estimated to be 112.02 m2/g, and the magnetic properties of the NFO nanoparticles were investigated using VSM analysis. The parametric study included bare NFO, PMS without catalyst, pH, catalyst dosage, PMS variation with optimized catalyst, initial concentration of LFH and CAF, and reaction time, with nearly 94.34% LFH was degraded in 220 min, 100% CAF was degraded in 80 min, 78.07% LC was degraded in 40 min. The degraded compounds m/z of LFH, CAF and LC were identified using LC–MS. The recycling and regeneration of NFO nanoparticles were investigated to determine the stability of the NFO nanoparticles in the degradation of LFH and CAF in which the degradation efficiency decreased to 90.68% and 64.1% respectively upon the third wash with distilled water. As a result, the NiFe2O4/PMS system showed improved degradation even after three recycle runs, making it an efficient and economical system for degrading LFH, CAF and even to multi-pharmaceutical pollutants. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2025.