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On-line Free Fatty Acid Measurement

Supplier: B-R Controls
08 November, 2007

The measurement of free fatty acid concentration is important in the refining of edible oils (vegetable oils) and in the manufacture of biodiesel. An on-line measurement provides manufacturers with real benefits in the optimisation of the process and in savings on expensive raw material costs.

Edible Oils

Free fatty acids are present in vegetable oils and are removed in the refining process. Removing the free fatty acids is performed by conditioning the oil with phosphoric acid to optimize precipitation of gums and trace elements. Caustic soda solution is mixed with the conditioned oil which neutralizes the acid as well as reacting with the free fatty acids in the oil and forming soap. The soap and precipitated materials agglomerate and are separated out from the neutralised oil.

As such the level of Free Fatty Acids are an important parameter in the processing of vegetable oils. By on-line measurement, we can optimise the refining process by reducing the chemical costs which in turn also provides for improved product quality

Biodiesel Production

The biodiesel reaction requires caustic (NaOH or KOH), which acts as a catalyst in the reaction of methanol and vegetable oil in the production of biodiesel. The oil feed stock for biodiesel plants varies in quality and as such contain different levels of free fatty acids (FFA). Similarly to the edible oil refining process the free fatty acids will react with caustic to make soap before the caustic has a chance to participate in the reaction to form the biodiesel end product.

Again, it is important to know the level of free fatty acid present in the feed stock so the appropriate amount of caustic can be added to react with the FFA and to still provide enough concentration to catalyse the reaction between the oil and methanol to produce the maximum amount of the desired biodiesel final product.

How do we measure FFA ?

The measurement of FFA can be performed by the Applikon on-line Titrator. The Applikon titrator uses a classical lab methodology to determine the concentration of FFA in a range of oils.

The titration involves reacting the sample with 50mL of an ethanol/ether mixture that also contains a phenolphthalein indicator. The sample is then titrated with a 0.05N solution of Potassium Hydroxide to the inflection point which is indicated by a change of colour of the phenolphthalein from yellow to red and is detected by a photometer at a wavelength of 560nm.

Sample Specification:

Temperature: up to 90 °C

Pressure: Max 10 bar

Measurement Range: 0.03 – 3% (Standard), other ranges available.

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