| In this thesis,the process purifying glycerol from biodiesel production was founded.The purification process consisted of demulsification by acidification,degumming by flocculation,stream deodorization and decolor and vacuum distillation.For demulsification by acidification,the effects of acid,methanol usage,pH on purification of glycerol were investigated.In the conditions of methanol and glycerol volume ratio of 1:1,pH 4.5 adjusted by phosphoric acid,123.4%glycerol with purity of 85.30%was recovered.For degumming by flocculation,the effect of alum and FeCl3 on glycerol separation was studied and compared,the effects of pH and the flocculant concentration on glycerol purification were invesitgated.99.0%glycerol with pu.rity of 90.50%was recovered when pH was between 4.5,2%alum aqueous solution was used as flocculant.The glycerol after pretreatment was smelly.The odour could be removed by steam distillation.The effects of vapor flowrate,crude glycerol flowrate on deodorization were studied.The odour of glycerol could be removed completely when crude glycerol flow acrossΦ40mm×800mm column at 0.58L/h,steam flowrate was 4L/min,deodorization temperature was 120℃.The color of glycerol could be removed by active carbon adsorption.The effect of active carbon usage on decolor was investigated.Colorless and transparent glycerol with purity of 97.17%could be achieved when the glycerol after deodorization was mixed with 2%wt active carbon for 20min at 80 ℃,the yield of glycerol was 97.9%.Clear,colorless,odourless and viscous glycerol with purity of 99.9%could be obtained by vaccum distillation with distillation pressure less than 450Pa,reflux ratio 3:1,top temperture between 157℃and 159℃.The yield of glycerol was 86.5%.The indexs of refined glycerol,including color,chloride,sulfate,fatty acids,esters,carbide,easy ignition residue,heavy metal and iron salts and glycerol purity,were tested according to the USP standards of pharmaceutical glycerin.On the whole,the tested results showed the refined glycerol by the process in the thesis satisfied the requirement of the USP standards of pharmaceutical glycerin. |
