Concentration Dependent Photocatalytic Degradation of Methylene Blue Using Green Synthesized Fe<sub>3</sub>O<sub>4</sub>/ Cdots Nanocomposites Utilizing Moringa Oleifera Leaf Extracts

Fe 3 O 4 /CDots nanocomposites by combining Fe 3 O 4 synthesized using Moringa oleifera extract and CDots produced from watermelon rinds have been successfully carried out. The Fe 3 O 4 /CDots nanocomposites with various CDots concentration was carried out through a sonication process. Test results using an X-ray diffractometer show that the crystal structure of the nanocomposite is a cubic inverse spinel. The presence of CDots resulted in a decrease in the size of Fe 3 O 4 crystallites from 10.6 nm to 8.4 nm. Fourier transform infrared analysis confirmed the formation of Fe 3 O 4 /CDots nanocomposites with the appearance of Fe-O and C=C functional groups. The absorbance spectrum of the nanocomposite shows a dominant profile of Fe 3 O 4 /CDots, with an increase in band gap energy by the increase of CDots concentration in the range of 2.65 – 2.77 eV. The attachment of CDots to Fe 3 O 4 is indicated by the luminescence produced in the photoluminescence test. The magnetic properties of Fe 3 O 4 and Fe 3 O 4 /CDots nanocomposites show superparamagnetic characteristics with saturation magnetization values ​​of 54.2 emu/g and 34.3 emu/g, respectively. The magnetic properties of Fe 3 O 4 /CDots nanocomposites can support the separation feature of the liquid phase with the help of an external magnet. In testing photocatalytic activity, it was able to degrade methylene blue organic dye waste up to 96.7% in 10 minutes of UV radiation. Therefore, Fe 3 O 4 /CDots have potential as promising heavy metal removal agents and photocatalysts for effective and efficient environmental remediation.