Green Synthesis and Characterization of Magnetite Nanoparticles Using Ocimum gratissimum Leaf Extract for Enhanced Adsorption of Cefuroxime in Water

Abstract Pharmaceutical contaminants, such as cefuroxime, a widely used second-generation cephalosporin, are frequently detected in wastewater due to incomplete removal during conventional treatment, posing risks to aquatic ecosystems and contributing to antimicrobial resistance. This study was carried out to green-synthesize and characterize magnetite (Fe 3 O 4 ) nanoparticles using the aqueous leaf extract of Ocimum gratissimum (scent leaf) via co-precipitation, and to evaluate their efficiency in adsorbing cefuroxime from aqueous solution. The nanoparticles were synthesized using iron (III) chloride and iron (II) sulfate precursors in the presence of the leaf extract, which served as a reducing and capping agent, and were characterized using UV-vis spectrophotometry, FTIR spectroscopy, XRD, and SEM-EDX. UV-vis analysis confirmed nanoparticle formation with a surface plasmon resonance peak at 265 nm, while FTIR identified phytochemical functional groups and an Fe − O stretching band at 713 cm − 1, confirming the magnetite phase. XRD identified magnetite as the dominant crystalline phase (55.6% by weight) alongside minor hematite, quartz, and clinochlore, consistent with a poorly crystalline, uncalcined green-synthesis product, and SEM revealed irregular, densely packed agglomerates. Batch adsorption studies showed that cefuroxime removal was favoured under acidic conditions, with pH 2 selected as optimum, and equilibrium attained within 120 min. The adsorption kinetics followed the pseudo-second-order model (R 2 = 0.999), while equilibrium data fitted the Langmuir isotherm (R 2 = 0.996) better than the Freundlich isotherm (R 2 = 0.972), indicating monolayer adsorption with a maximum capacity of 62.5 mg/g. An adsorbent dosage of 25 mg gave the highest removal efficiency (29.4%), and thermodynamic analysis revealed the adsorption process to be spontaneous, endothermic (ΔH° = +7.8 kJ/mol), and accompanied by increased randomness at the solid−liquid interface (ΔS° = +28.2 J/mol·K). These findings indicate the feasibility of Ocimum gratissimum as a low-cost, locally available green reducing agent for synthesizing magnetite nanoparticles with potential for the remediation of pharmaceutical pollutants from water.