Synthesis of a new magnetic adsorbent using green tea leaf extract and its application in phenol removal by RSM method

Green synthesis of metal nanoparticles (NPs) has attracted a lot of attention in recent years because of lower costs and being environmentally friendly in comparison to the chemical methods. One of the most considered methods is production of metal NPs using organisms. Among these organisms, plants seem to be the best candidates and suitable for the biosynthesis of large-scale NPs. The produced NPs by plants are more stable and their synthesize are faster than microorganisms. In this research, the green synthesis of iron oxide magnetic NPs (Fe₃O₄-MNPs) has been performed using aqueous extract of green tea (Camelia sinensis) as a reducing and capping agent. Evaluation of properties and morphology of Fe₃O₄-MNPs is performed using scanning electron microscopy, X-ray diffraction, infrared spectroscopy, and vibrational magnetometer. The synthesized NPs were crystalline in nature and spin-shaped with a mean diameter of ≤ 20 nm and also has super-magnetic properties. The systematic study of the synthesis process was performed using Design Expert 10 software to determine the relationship between the four process variables, namely iron concentration, extract volume, time, and temperature. The square model was significant for the response variables. In the final, synthesized Fe₃O₄-MNPs were applied for magnetization of activated carbon that then used for efficient removal of phenol (up to 98%) from aqueous media. Various parameters affecting the removal process such as pH, extraction time, and adsorbent amount were optimized by using response surface methodology.