Reduksi Logam Berat Kromium (VI) Menggunakan Sistem Katalis TiO2-N/KA dengan Variasi Waktu Proses Hidrotermal

Abstract

Chromium (VI) is a hazardous industrial waste because it is carcinogenic and difficult to decompose in nature. One way to treat Cr(VI) waste is to reduce it to Cr(III) which is not dangerous. The photocatalytic method with TiO2 is one of the techniques that can be applied. The less effective performance of TiO2 in visible light can be overcome by doping it with nitrogen. Meanwhile, the low adsorption power of TiO2 can be improved by combining it with sorbent materials such as activated carbon to form TiO2-N/KA composite materials. TiO2-N/KA composite material was synthesized using the hydrothermal method with variations of hydrothermal process time (7, 8, 9, 10, and 11 hours). This study aims to determine the physical characteristics of all composite materials and their ability to reduce Cr(VI). The results showed that the hydrothermal process time did not affect the functional groups and crystal phases produced. All TiO2-N/KA composite materials have the functional groups Ti-O-Ti, Ti-N, C=C, C=O, and hydroxyl groups -OH and have an anatase crystal phase. The crystal size, crystallinity, and band gap energy of the TiO2-N/KA composite material vary depending on the length of the hydrothermal process. The ability of the TiO2-N/KA composite material to reduce Cr(VI) is better than that of pure TiO2. The combination of photocatalytic and adsorption mechanisms on TiO2-N/KA material has been proven to increase its photocatalytic activity. The material with the highest photocatalytic activity is TiO2-N/KA-9, which can reduce Cr (VI) by 54,41% after 15 hours of UV irradiation.