The Synthesis Of Sorbitan Monooleate Emulsifying Power

Sorbitan monooleate(Span-80) made from esterification of sorbitan and oleic acid, is a kind of typical nonion surfactant that has been widely used. The usage, research background and main routes of synthesizing Span-80 was introduced in this paper.The overall one -step reaction system of sorbitan with loeic acid involving ten kinds of catalyst, which concludes acidic catalyst, alkali catalyst and metal oxide catalyst, has been studied. The factors that affect the reaction have been discussed, such as reaction temperature, reaction time. ZnO was discovered to be a good catalyst. By using it the content of monooleate can be up to 84%. Compounding catalysts have been discussed in the continuous two-step reaction system of synthesizing Span-80 which is made by using first acid catalyst (CH3C6H4SO3H,H3PO4 ) and then alkali catalyst (MgO, NaOH). The relationship between dehydration and esterfication, as well as their effects on the quality of products were studied. The result shows that in the two-step method, the compound of CH3C6H4SO3H and NaOH, H3PO4 and NaOH is good. They distribute balance between the sorbitan monooleate and the sorbitan dioleate. The compound that was mixed by NaOH, MgO and CH3C6H4SO3H was also discovered to be a good catalyst.Span-80 is a good emulsifying agent. Emulsifying ability has been discussed in this paper. The effect of concentration, temperature and different preparation methods on the emulsifying properly has been studied. And the emulsifying ability of Span-80 compounded with other surfactant is also discussed. It is discovered that Span-80 compounded with Tween has good emulsifying ability.