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

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.% H 2 SO 4 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.

Statistical modeling/optimization and process intensification of microwave-assisted acidified oil esterification

“…However, the acidified oil contains a lot of FFAs and cannot be directly processed with alkaline-catalysis technology [7]. To avoid saponification, FFAs in acidified oil is firstly esterified by acid-catalysts [8,9].…”

Kinetic and thermodynamic studies of the esterification of acidified oil catalyzed by sulfonated cation exchange resin

“…However, as a major source of cooking oil in China, the output of vegetable oils falls far short of industrial demands. As a result, non-edible oil and waste grease such as the tung oil [7], acidified oil [8], waste cooking oil [9][10][11], microalgae [12,13] and Jatropha oil [14] become a main source of raw material for biodiesel syntheses. However, the acidified oil contains large amounts of FFAs and cannot be processed with the commonly practiced alkaline-catalysis technology.…”

A flow-through tubular catalytic membrane reactor using zirconium sulfate tetrahydrate-impregnated carbon membranes for acidified oil esterification

“…The biodiesel becoming more popular due to the renewable nature, ability to replace dwindling petroleum based production technologies for being environmental friendly, and the overwhelming opportunities to overcome an imminent forthcoming energy crisis [3,4]. This fuel is biodegradable and nontoxic, has low undesirable tailpipe emission profiles, and is as effective as petroleum diesel in powering unmodified or slightly modified diesel engines [5,6]. From the ideal material point of view, refined vegetable oil becomes a desirable raw material for biodiesel production.…”