Production of biodiesel from fat of secondary crab materials

Production of biodiesel from the fat-containing entrails of king crab is investigated. These secondary raw materials are massively disposed (released into the sea) after separation of limbs. Routine technologies of the biodiesel production from vegetable and fish oils are used. The fatty acid composition of the fat is analyzed and the acid and peroxide numbers are determined. A high content of PUFAs (42.5 %) is detected, including the omega-3 (30.6 %) and omega-6 (12.3 %) fatty acids. High acid number (5.5 mg KOH per g fat) and peroxide number (85.6 mmol of active oxygen per g fat) of the crab fat do not meet the requirements for edible fish oils. The biodiesel in the form of fatty acid ethyl esters was produced from the crab fat with three indicators (NaOH, KOH, and H2SO4). Reactions with alkali did not give positive results due to formation of large amounts of soap. The best yield of esters was obtained in the experiment with sulfuric acid: 52.2 g of biodiesel was produced from 50.0 g of fat. Mechanisms of the reaction are explained and mass balances of the process are presented. Kinematic viscosity, total contamination, and acid number of biodiesel (4.96 mm2/s, 8 mg/kg, 0.35 mg KOH/g, respectively) meet the requirements of the national standard GOST R 53605-2009 (EN 14214:2003).