Study On The Purification Technology Of Biodiesel

For the past few years, the study on biodiesel is especially hot. There are many enterprises initiate to produce biodiesel .But the purification technology of biodiesel is not consummate in China. Relatively speaking, the biodiesel government standard had formal enforced in May 2007 was a higher standard. Now a bulk of manufacturers of produce biodiesel can not achieve in our country. So the study on the purification technology of biodiesel is an important exploratory development work.Using virgin rapeseed oil and methanol as raw material prepared biodiesel by base catalysis, then rotary evaporation in vacuum to recover methanol, then named it untreated biodiesel. The paper studied on water purification technology and ceramic membrane micro-filter purification technology using untreated biodiesel.The main results show as follows:(1) Considered the effective of eluting free glycerine and eluting methanol, it obtained the optimization condition of water purification technology . It was that the agitating rate 400r/min, agitating time 30minutes, the temperature 50℃, the ratio of biodiesel to water 2:1, washing at least 3 times. During the optimum conditions, the free glycerine and methanol residual conformed the American ASTM D6751-02 standard.(2)The content of Phospholipids and the tungsten of K,Na,Mg,Ca degraded in the biodiesel filtered by 0.2μm ceramic membrane, and their residual conformed the European standards EN14214; The effect of removal methanol was highly significant using ceramic membrane to filtered biodiesel. The methanol residual were under the standard of all. Even though the free glycerine residual exceeded the national standards, the effect of removal free glycerine was highly significant and the removal rate were above 72%.(3)The permeate flux will decrease and the time of service will decurtate and the need size will increase when the ceramic membrane was polluted. So controlling the pollution of membrane and choosing the suitable method to clean and reactivate membrane are fairly important for whether or not succeed in the use of membrane filter and achieving industrialization scale. The steps of cleaning and reactivating in the paper show as follows :first using ligroin to clean, then using water, then using the solution of 1% sodium hydroxide, then water, last using ligroin .Through cleaning and reactivating , the permeate flux of the ceramic could retrieve 99.5%.The method is economic ,valid and feasible.