The previous esterification of used frying oil was able to reduce the acid number
from 1.77 to 1.00 mg(KOH) g-1.
Alkene and reactive free radicals derived from thermal pyrolysis could be oxidized to form acid oxygen-containing compounds (peaks 11, 12, 31, 36, and 43), which lead to increasing acid number
. Table 4 listed the acid number
of experimental oils under different temperatures.
This quality parameter is closely related to the viscosity and acid number
of biodiesel .
ASTM D664-11a, standard test method for acid number
of petroleum products by potentiometric titration.
The liquid phase in the sealed tubes was analyzed for Total Acid Number
(TAN), by Ion Chromatography (IC), and High Performance Liquid Chromatography (HPLC) to identify and/or measure the concentration of remaining process chemicals and/or decomposition products.
Property Method Unit Specific gravity ASTM D4052 kg [m.sup.-3] at 20[degrees]C (ASTM, 2002) Flash Point ASTM D93 [degrees]C (ASTM, 2001) Acid Number
ASTM D664 mg KOH [g.sup.-1] (ASTM, 2001) Free Glycerin ASTM D6584 % m [m.sup.-1] (ASTM, 2003) Total Glycerin ASTM D6584 % m [m.sup.-1] (ASTM, 2003) Monoglyceride ASTM D6584 % m [m.sup.-1] (ASTM, 2003) Diglyceride ASTM D6584 % m [m.sup.-1] (ASTM, 2003) Triglyceride ASTM D6584 % m [m.sup.-1] (ASTM, 2003) Methanol EN 14110 % m [m.sup.-1] (CEN, 2003) Ester content EN 14110 % m [m.sup.-1] (CEN, 2003) Water content EN 12937 mg [kg.sup.-1] (CEN, 2000) Property Limit Result Specific gravity 850-900 880.6 at 20[degrees]C Flash Point Min.
The acid number
measurements were performed in a potentiometric titrator, model 877 Titrino plus (Metrohm AG).
Lactic acid, proprionic acid and a few others also can contribute to the total volatile acid number
. To the extent that all of these acids are present, techniques.
These new test methods are: ASTM D664 (for acid number
of petroleum products by potentiometric titration), ASTM D5291 (for instrumentation determination of carbon, hydrogen, and nitrogen in petroleum products and lubricants), and ASTM D5622 (for determination of total oxygen in gasoline and methanol fuels by reductive pyrolysis).
The progress of reaction was monitored by determination of weight loss and acid number
(AN) of reaction mixture.