The effect of the types of oil such as used oil, waste cooking oil, palm oil and soybean oil and different types of alcohol such as methanol, ethanol and mixture of methanol and ethanol on the settling behaviour of glycerol has been investigated. The experiments were undertaken via transesterification using sodium hydroxide (NaOH) as a catalyst under optimum reaction conditions. The yield of biodiesel produced in each variation was determined and the equal ratio of the product (biodiesel) and the by product (glycerol) obtained from each batch experiment were vigorously re-mixed and subsequently, the settling behaviour of glycerol was investigated. The results revealed that optimum conditions can not be selected from by considering only the settling behaviour of the glycerol. The yield of the biodiesel and prices of the alcohol and oil should be taken in account. This work has been very successful in establishing the link between the yield of biodiesel (the desired product) and the settling behaviour of the glycerol (the byproduct).

Keywords: Settling behaviour, Glycerol, Biodiesel, Transesterification