SUMMARY
In this study, a novel heterogeneous catalyst was synthesized from drinking water treatment sludge obtained during defluoridation in biodiesel production by transesterification. More specifically, the sludge was converted into an effective catalyst by calcination at 950 ºC for 3 h. The catalyst was characterized using X-ray diffraction, Fourier transform infrared spectroscopy, Thermogravimetric analysis, Scanning electron microscopy, Hammett titration method, and ion exchange method. The catalyst had a basicity of 12.57 mmol/g and a basic strength of 9.8 < H <17.2. It showed good catalytic activity in biodiesel synthesis. The maximum biodiesel yield obtained was 89% for the following reaction conditions: catalyst loading of 4 wt%, a reaction temperature of 65 ºC, the methanol-to-oil molar ratio of 12:1, and reaction time of 3 h. Thus, it was found that harmful waste can be used as an effective solid base heterogeneous catalyst.