Synthesis and Characterization of TiO_2/Zeolite Nanocomposite by Utilizing Coal Fly Ash for Zeolite Synthesis Using an Alkaline Fusion-Hydrothermal Method Linda J Kusumawardani (a*), Ennita Lusiana Sinaga (a), Ani Iryani (a)
a) Departement of Chemistry, Faculty of Mathematics and Natural Science, Universitas Pakuan, PO BOX 452, Bogor, 16143, Indonesia.
*linda.wardani[at]unpak.ac.id
Abstract
Fly ash is one of the wastes from coal production. More than half of the fly ash produced is disposed of as waste in landfills. The high levels of metal oxides, such as SiO_2 and Al_2O_3 make fly ash potentially develop into an adsorbent material, namely zeolite. Zeolite was prepared from fly ash by using the alkaline fusion and hydrothermal method. This combined method was chosen to increase the surface area, mechanical properties, and reactivity of zeolite. These properties could be utilized for emerging pollutants in aqueous media by coupling it with a photocatalyst due to the adsorption capacity of photocatalyst materials being generally lower than that of adsorbent materials. This study combined zeolite from fly ash as an adsorbent and TiO_2 as a photocatalyst to manufacture TiO_2/zeolite nanocomposite. This nanocomposite was investigated in its structural and optical properties. TiO_2/zeolite nanocomposite was prepared by sol-gel method with various aging times of 14, 16, and 20 hours and characterized by XRD, FTIR, SEM, UV DRS, and BET. The results show The results show that the products contain zeolite X as the major phase which the crystallinity reach 96% and specific surface area of zeolite A is 164.78 m^2/g. Meanwhile, the type of zeolite combination of TiO_2 with zeolite was increasing the light absorption in the visible region. DRS showed 14 hours aging time of TiO_2/zeolite nanocomposite has the lowest decreasing band gap energy, from 3,2 to 2,50 eV. The surface area of TiO_2/zeolite nanocomposites from 14 hours of aging time also showed the largest surface area of 189.483 m^2/g calculated from the BET adsorption plot. XRD characterization found the TiO_2/Zeolite nanocomposite has an anatase crystal with a crystal size of 9-69 nm with crystallinity 99%. Meanwhile, photocatalytic activity is evaluated through methylene blue (MB).
