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Optimasi Degradasi Methylene Blue Menggunakan Komposit Rgo/Tio2
LARA ISMANO FITRI, NIM. 2010242048 Optimization of Methylene Blue Degradation Using rGO-TiO2 Composite, supervised by Desi Heltina and Amun Amri.
The increasing water pollution, especially from organic dye waste, poses a serious threat to human health. According to World Bank data (2019), 20% of global wastewater originates from the textile industry. In Indonesia, many textile industries lack adequate wastewater treatment facilities, resulting in direct discharge into the environment. One of the dyes used is methylene blue (MB), which is carcinogenic and difficult to degrade. The permissible concentration of MB in water is 5-10 mg/L, but its use in the dyeing process results in waste that contaminates water. A promising method for textile wastewater treatment is semiconductor-based heterogeneous photocatalysis, such as titanium dioxide (TiO2). This study modifies TiO2 with carbon-based materials, such as Reduced Graphene Oxide (rGO), to enhance photocatalytic activity by reducing the band-gap and shifting light absorption to the visible region. This research investigates the effect of rGO-TiO2 composite on methylene blue degradation based on variations in time, calcination temperature, and mass ratio, identifies the optimal degradation conditions using response surface methodology (RSM), and studies the reaction kinetics of the rGO-TiO2 composite.
The results are characterized using crystal structure analysis (XRD) and morphology (SEM-EDX), functional group analysis (FT-IR), surface area (BET), and degradation concentration using UV-Vis Spectrophotometer. Design Expert v.12 software is used to determine the optimal conditions. The results indicate that an optimal temperature of 500°C increases the crystallinity of TiO2 without reducing the specific surface area, while an optimal time of 4 hours yields the ideal particle size for photocatalytic activity. An optimal rGO mass of 1 wt% enhances electron conductivity and electron-hole pair separation, achieving the highest photocatalytic efficiency. SEM-EDX analysis confirms the presence of C, O, and Ti components in the rGO-TiO2 composite. FTIR and XRS analyses show peaks reflecting the interaction between TiO2 and rGO. Photodegradation optimization results using RSM reveal that a calcination temperature of 600°C, a calcination time of approximately 3.375 hours, and an rGO mass of 1.047% provide a desirability of 1 with a degradation rate of 95.177%, indicating these conditions are optimal for photocatalytic application. Reaction kinetics results show that the reaction fits better with zero-order kinetics, as the R² value is higher at all temperatures compared to first and second-order kinetics, with a consistent increase from 0.3715 mol·min−1 at 30°C, 0.3817 mol·min−1 at 40°C, to 0.3910 mol·min−1 at 50°C.
Keywords: rGO-TiO2 Composite, Optimization, RSM, Reaction Kinetics
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