Purification du Glycérol obtenu à partir de la réaction de transestérification des huiles végétales (Coton, Palme, Palmiste) par adsorption sur le Basalte à Olivine.

Abstract

The aim of our work is to purify crude glycerol obtained from the transesterification of three vegetable oils (cotton seed oil, palm kernel oil and palm oil) by adsorption one olivine basalt. Crude glycerol sample obtained from the alkaline transesterification of these oils in the following conditions: alcohol / oil molar ratio 8:1, time of reaction 2 hours, 1% w /w NaOH and heating temperature of 70 °C was purifies using three-stages physico-chemical purification process consisting of acidification using orthophosphoric acid and neutralisation using sodium hydroxide, polar solvent extraction using ethanol and adsorption with olivine basalt in the presence of hexane: After acidification and neutralization of crude glycerol, the percentage removal is 97.388 % for crude glycerol cotton seed oil, 83.34% for crude glycerol palm kernel oil, 97.651 % for crude glycerol palm oil. After polar solvent extraction with ethanol, the percentage removal is 94.45 % for glycerol cotton seed oil, 82.64 % for glycerol palm kernel oil, 96.05 % for glycerol palm oil. The complet discoloration was obtain using olivine basalt as adsorbent The percentage removal show that after the three stages of purification process apply, higher amount of pigments and others impurities was remove, 94.45 % in crude glycerol cotton seed oil, 82.64 % in crude glycerol palm kernel oil and 96.05 % in crude glycerol palm oil. The glycerin samples obtained were nearly colorless and odorless and had the following physical properties: density 1.235 for glycerol cotton seed oil, 1.314 for glycerol palm kernel oil, 1.227 for glycerol palm oil at room temperature This result show that the crucial stage of physico-chemical purification use in these study is acidification-neutralisation, in fact the soap present in crude glycerol is converted by ortho phosphorique acid in to free fraty acid insoluble in glycerol, in addition olivine basalt is unuseful adsorbent to remove the remain impurities in glycerol, nevertheless the glycerol obtain has the physical properties closer to the physical properties of commercial glycerol..