Esterification and Deacidification of a Waste Cooking Oil (TAN 68.81 mg KOH/g) for Biodiesel Production

Jincheng Ding,Zheng Xia,Jie Lu

doi:10.3390/en5082683

Jincheng Ding, Zheng Xia + Show 1 more

Open Access

https://doi.org/10.3390/en5082683

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Abstract

Oils with high content of free fatty acid (FFA) can be treated by acid esterification where an alcohol reacts with the given oil in the presence of acid catalyst. The investigated parameters include methanol to oil ratio, temperature and amount of catalyst. The optimum conditions for acid esterification which could reduce FFA content in the feedstock to less than 1.88% (acid value 3.76 mg KOH/g waste cooking oil) were 50 °C, 20% methanol to oil ratio (by volume) and 0.4 vol.% H2SO4 after 5 h. However, oil with an acid value of more than 1 mg KOH/g oil cannot meet the alkaline catalyzed transesterification conditions. Under the conditions of NaOH concentration 0.5 N, excess alkali 15%, 60 °C, 40 min, the FFA removal rate for deacidification reached 77.11% (acid value 0.86 mg KOH/g esterified oil). The acid value of deacidification product was reduced below 0.86 mg KOH/g esterified oil, thus meeting the base-catalyzed trans-esterification conditions.

Highlights

Among various alternative fuels produced from renewable resources, biodiesel, which is well known as a replacement for the traditional petroleum diesel fuel [1], is currently becoming a fast-growing market product [2,3,4]
It is composed of mono-alkyl esters of long chain fatty acids derived from plant and animal oils and fats by transesterification with short carbon alcohols such as methanol
In practice, the methanol should be in excess to drive the reaction towards completion as the esterification of free fatty acid (FFA) with methanol [cf

Summary

Introduction

Among various alternative fuels produced from renewable resources, biodiesel, which is well known as a replacement for the traditional petroleum diesel fuel [1], is currently becoming a fast-growing market product [2,3,4]. It is composed of mono-alkyl esters of long chain fatty acids derived from plant and animal oils and fats by transesterification with short carbon alcohols such as methanol. No sulfur dioxide emissions occur because there is sulfur in biodiesel due to its vegetable origin [6]

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