Design of solvents for palm oil recovery using computer-aided approach

Abstract

In palm oil refinery process, bleaching earth is used in bleaching process. Used bleaching earth, also known as spent bleaching earth (SBE) is removed from the process as waste which contains some remaining oil. Many studies have been done to fully utilise the SBE before it is turned into waste. One of the known studies includes the extraction of remained palm oil from SBE. The extractions process is either using solvent or supercritical fluids processes. The commonly used solvents for extraction are hexane, ethanol and methanol. These solvents have some disadvantages, for example hexane is flammable and has low extraction yield as well as high in toxicity. New suitable solvents are needed to improve the performance in the extraction process. Through this study, new solvent for extraction of oil in SBE was obtained with the implementation of Computer Molecular Design (CAMD). Both linear and non-linear target properties were included during designing the solvent. Property models are used in order to meet the needs of the specified properties. The properties that are needed for solvent design were obtained from literature study. CAMD was used to generate possible solvent candidates. The steps involved are, first, data of solvent, SBE and palm oil was collected from the literature, then the problem definition is formulated to solve the design problem. Next, designing the solvent was performed by using CAMD based on the input data obtained and the defined problem in the previous steps. CAMD generated all the possible structures of solvents. The solvent candidates were screened based on specified target properties. Lastly, solvent performance evaluation was done by using Aspen-HYSYS simulation software in order to evaluate the performance of the five best solvent candidates that were selected after the screening process. Through this study, it is found that, cyclohexane is the best solvent to replace n-hexane as it satisfied all the target properties. Based on the simulation result, cyclohexane is capable to extract up to 90.19 % of palm oil remained in the spent bleaching earth. Meanwhile, the toxicity parameter of cyclohexane is only 2.07 mol/L which is lower than n-hexane, 3.02 mol/L. On the other hand, the boiling point of cyclohexane, 353.15 K is slightly higher than n-hexane, 340.15 K.