Assessment of degumming and bleaching processes for used cooking oils upgrading into oleochemical feedstocks

Abstract

Used Cooking Oils (UCOs) can be exploited as second-generation raw materials for the synthesis of green chemicals, in particular for biobased epoxides and polyols. However, impurities in UCOs generate major drawbacks to fulfill the required specifications of the oleochemical feedstocks used in epoxidation processes. Thus, this work assessed different UCOs pretreatment processes to produce a suitable feedstock for further valorization. UCOs were collected from chicken restaurants in Bogota, Colombia, and characterized prior processing. Similar to edible oils refining, physical and/or chemical pretreatment was carried out via water degumming, adsorption with filter earths, bleaching with hydrogen peroxide, and extraction with solvents (methanol, ethanol, isopropanol). Treatment effectiveness was assessed with respect to the original characteristics of UCOs. Characterization was done by tracking the change in photometric color index, and characterizing acid value and polar compounds content in bleached samples. The most effective pretreatment was achieved by using degumming with a water loading of 10.0 % wt. at 70 °C, and hydrogen peroxide bleaching with loading of 5% v/v at 90 °C, 200 rpm and 30 min. Under these conditions, 1.24 % wt. of the mass was removed as hydratable solids, and a color index reduction of 74.2 % was achieved.