Characterization of AC/TiO<sub>2</sub>/Fe<sub>3</sub>O<sub>4</sub> Nanocomposite on Cork Ball Coating Material as Floating Photocatalyst to Degrade Wastewater

Water pollution due to inadequate waste treatment causes damage to the ecosystem to various diseases in humans such as itching, and other skin diseases. One of the efforts to treat wastewater is photocatalyst. TiO 2 is one of the materials that can be used as wastewater treatment because it has good photocatalyst properties. However, TiO 2 has a wide band gap so that this material is only optimal at UV wavelengths. This can be overcome by adding Fe 3 O 4 to TiO 2 which can help narrow the band gap and good magnetic properties so as to increase its photocatalyst activity. AC has advantages such as having a large cross-sectional area and being able to absorb waste well. AC/TiO 2 /Fe 3 O 4 nanocomposite was synthesized by hydrothermal method, then deposited on cork ball by spray coating and heating technique. SEM analysis showed that AC/TiO 2 /Fe 3 O 4 nanocomposites had an average size ranging from 124-225 nm and were successfully deposited on the surface of cork balls. In addition, the increase in porosity is related to the smaller diameter size with a large surface area. AC/TiO 2 /Fe 3 O 4 nanocomposites are dominated by the elements C, O, Ti, and Fe confirmed from EDX analysis. The smallest area is in sample 3 worth 1.39 m 2 /g and adsorbs the highest worth 116.33 nm so as to increase the effectiveness of the photocatalyst. Based on UV-Vis results, the absorption area of TiO 2 and Fe 3 O 4 at a wavelength of 325 nm and in the AC/TiO 2 /Fe3O 4 nanocomposite shows absorption between 295-330 nm. Fe 3 O 4 has a relatively small band gap increase. The band gap energy of nanocomposite samples 1-5 decreased from 3.5 eV to 3.0 eV. O-H stretching vibrations in hydroxyl and carboxyl functional groups were confirmed with the addition of Fe 3 O 4 mass. The most optimal river water photodegradation test results were shown in sample 3 with DO levels increased by 98.38%, phosphate levels decreased by 97.9% and water color decreased by 100%. After photodegradation for 150 minutes, the pH test results are still in accordance with the river discharge water quality standards. Overall, this material is very useful for the treatment of organic pollutants and wastewater.