Synthesis of activated carbon from Lemna minor plant and magnetized with iron (III) oxide magnetic nanoparticles and its application in removal of Ciprofloxacin

The current study was done by preparing activated carbon from the common duckweed, Lemna minor, after magnetization using Fe₃O₄ nanoparticles. The resultant product (Fe₃O₄-ACLM) was employed to adsorb ciprofloxacin (CIP) from the contaminated water, in the batch adsorption mode. The characteristic distinctive features or parameters of the materials utilized were ascertained with the aid of scanning electron microscopy (SEM), energy–dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM); the Brunauer–Emmett–Teller (BET) and Barrett–Joyner–Halenda (BJH) analysis, point of zero charge (pH_pzc), and vibrating sample magnetometry (VSM) were also used. From the results, it was clear that when the initial CIP concentration was 25 mg/L, and pH was 3, in the presence of Fe₃O₄-ACLM in a 0.75 g/L dosage, and contact time of 75 min, 100% removal percentage was achieved. However, the adsorbent recycling and reuse tests demonstrated that in just six periods of adsorbent use a marginal 8.5% decrease was noted in the adsorbent efficiency. The Fe₃O₄-ACLM was observed to show super-paramagnetic behavior with 37.6 emu/g saturation magnetization. Four models namely the Langmuir, Freundlich, Dubinin–Radushkevich (D-R), and Temkin isotherms were used for the adsorption isotherm studies. From the results of the goodness-of-fit parameters, the Langmuir isotherm revealed greater consistency with the equilibrium data, demonstrating maximum adsorption capacities of 134.2, 149.5, 161.4, and 178.7 mg/g at temperatures of 20, 30, 40, and 50 °C, respectively. Further, the CIP adsorption onto the Fe₃O₄-ACLM surface was, by nature, endothermic and spontaneous, according to the thermodynamic study. In conclusion, the Fe₃O₄-ACLM was proven to be efficient, recyclable, and excellent as an alternative adsorbent capable of CIP antibiotic removal from contaminated water.