Sintesis Zeolit dan Nanokomposit Zeolit/TiO2 dari Abu Layang dan Waterglass serta Uji Adsorpsi dan Fotodegradasinya

Abstract

Coal fly ash contains 20.74% Si and 4.09% Al, rendering its possibility to be synthesized to zeolite. Zeolite was synthesized by smelting at 550 °C, and continued with hydrothermal method at 90 °C for 6 hours. The weighed fly ash was melted with solid NaOH and various amounts of waterglass at 550 °C for 1 hour, which were coded ZK1 for 1.0 g of waterglass added, ZK2 (1.5 g), ZK3 (2.5 g), ZK4 (5.0 g), and ZK5 (7.5 g). The results indicated that the zeolite has the character as type P1. ZK1 zeolite had the highest crystallinity (65%), therefore it was used further to synthesize zeolit/TiO2 nanocomposite. The nanocomposite was formed to improve the zeolite characters, especially adsorption-photodegradation capacity. The synthesized zeolite and the nanocomposite were tested for their adsorption capacities. The results showed that the ZK1 has the highest adsorption capacity, i.e. 147 mg/g. Optimization was performed on ZK1 and zeolit/TiO2 nanocomposite to compare their adsorption capacity and to determine their optimum conditions for adsorption. The optimum concentration of adsorbate that can be adsorbed by ZK1 was obtained at 400 ppm using 0.02 g adsorbent, with the adsorption time of 3 hours. Zeolite/TiO2 nanocomposite has optimum concentration of 250 ppm with the weight of adsorbent of 0.01 g, and the adsorption time of 1 hour. The nanocomposite zeolite was able degrade methylene blue under ultraviolet radiation for 6 hours at λ=365 nm.