Inherent Safety Assessment of Solvent Alternatives for Palm Oil Recovery

Solvent extraction is a method implemented with the purpose to recover the remaining oil in spent bleaching earth. n-hexane is the most commonly used solvent in solvent extraction due to its advantages such as able to easily extract the oil and can be separated easily with low chances to form emulsions during the extraction process. Although n-hexane is a good solvent for extraction, n-hexane can easily vaporise to the surroundings due to its volatility making it a threat to human health and environment due to its high toxicity and high flammability characteristics. N-hexane should be replaced with greener solvents in term of safety and environmental impacts. This paper aims to evaluate the inherent safety of the solvents designed by the previous work involving three new solvents which are cyclohexane, 2-pentanone and isopropyl acetate and compare it with the existing solvent which is n-hexane. The inherent safety assessment of these solvent were done using the Numerical Descriptive Inherent Safety (NuDIST) technique. In this technique, scores are assigned to each solvent according to their inherent safety level in term of three parameters. The parameters involved are flammability, explosiveness and toxicity. In NuDIST, higher scores indicate higher hazard and is not preferable compared to lower scores. According to the assessment done, cyclohexane is the least hazardous solvent with CSTS of 191.53 while n-hexane is evaluated as the most hazardous solvent with CSTS of 198.32. Inherent safety assessment done between cyclohexane and n-hexane using the NuDIST method indicates cyclohexane as the inherently safer choice than n-hexane. This further supports the result produced by the previous work which indicates cyclohexane as having more promising properties as a solvent in order to extract palm oil in spent bleaching earth compared to n-hexane.