Photocatalytic degradation of malachite green using titanium dioxide immobilised on oil palm empty fruit bunch derived cellulose

Abstract

Titanium dioxide (TiO2), cellulose and TiO2 immobilised on cellulose at 10–70 wt% were synthesised through hydrothermal method. These samples were characterised by using X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX) and Fourier transmission infra-red spectroscopy (FTIR). The TiO2 produced was in an amorphous phase. TiO2 particles were spherical and composed of titanium (Ti) and oxygen (O) elements only. TiO2 showed O-Ti-O bonds due to the presence of TiO2 precursor. Cellulose possesses peak at 2894 cm−1 due to the vibration of the carbon (C) – hydrogen (H) bond. The effect of various parameters such as amount of TiO2 immobilised on cellulose (10–70 wt%), catalyst concentration (0.3 g/L to 1.1 g/L), dye concentration (20 ppm to 100 ppm), solution pH (pH 1 to 9) and solution temperature (27 °C to 65 °C) for photocatalytic degradation were studied in order to determine the optimum conditions. It was found that the highest photocatalytic degradation efficiency of malachite green (78.27%) after 1 h was achieved in the presence of 50 wt% TiO2 immobilised on cellulose (50 T/C) at the optimum conditions with the catalyst concentration of 0.9 g/L, initial dye concentration of 20 ppm, natural solution pH 5 and solution temperature of 27 °C. In addition, 100% chemical oxygen demand (COD) removal was achieved at the prescribed optimum condition. In the reusability study, it was found that the reused 50 T/C which regenerated through washing by distilled water and 0.1 M of sodium hydroxide maintained high photocatalytic activity (78%) after three catalytic cycles. This study proved that appropriate amount of TiO2 immobilised on cellulose potentially to be used as an effective and efficient photocatalyst to degrade the organic dye in water.