Exploration of Detecting Method of Waste Oil

In this paper, the relative change rates of content of conjugated fatty acid glycerides, content of tans-fatty acid glycerides, unsaturation and linear long-chain fatty acid glycerides were explored after being at high temperature for several hours by using FTIR-ATR. The results hints:1.Starting from 160°C, the contents of conjugated fatty acids glycerides and trans-fatty acid glycerids in the vegetable oils increase but unsaturation and content of linear long-chain fatty acid glycerides decreases with heating temperature and heating time increasing; 2. When heating temperature reaches 200°C or more, the heating time up to four hours or longer, the four indicators (conjugated fatty glycerids, trans-fatty acid glycerids, unsaturation and linear long-chain fatty acid glycerides) of five kinds of vegetable oils have substantial changes; 3. The content of linoleic acid in the vegetable oil has some contributions to the change amplitude of contents of conjugated fatty acid glycerides, and the content of oleic acid in the vegetable oil has some contributions to the change amplitude of content of trans-fatty acid glycerides. Because refined “waste oil” experiences a longer history at temperature higher than 200 °C compared to the vegetable oil, four index value and its variation can be used as specific indicators for it.