| During the production of biological diesel oil from jatropha curcas, every ton of biodi-esel is accompanied by 0.1 ton of byproduct glycerol. The key to the commercialization of biodiesel from jatropha curcas is that the byproduct glycerol is utilized with a high value. The measurement of glycerol content plays an important role in the refine process of glyce-rol. At present there are many literature reporting the methods of the measurement of glyce-rol content:oxidation by sodium periodate and acid-base tritration, oxidation and reduction by sodium periodate, densitometric method, refractometry, spectrophotometry, GC, HPLC. These methods have deficiencies in different ways. ELSD is a common detector emerging in the nineties of the twentieth century. Any sample less volatile than mobile phase could be detected by ELSD except the compounds including chromophoric group. Glycerol has a simple chemical structure and has no UV absorption; its boiling point is 290℃, which is much higher than acetonitrile. On the basis of the advantages of ELSD and the property of glycerine, the application of ELSD in the measurement of the glycerol content was investi-gated.During the experiment ELSD with respect to mobile phase, flow velocity, column temperature, atomization temperature, gasification temperature and carrier gas flow were investigated. Experimental results showed that there was a favorable linear relation between the injection volume (0.16-4.096μg) and the area of main peak, the average recovery per-cent was above 93.00%, and the relative standard deviation (RSD) of precision was less than 1.50%(n=5), when the chromatographic column was Interstil NH2 (250mm×4.6 mm, 5μm), and the mobile phase was acetonitrile-water (80:20).Potassium hydroxide (KOH) was the catalytic agent during the transformation process of jatropha curcas to biodiesel. Dilute sulphuric acid (H2SO4) adjusted the PH during the extraction process of glycerol from byproducts. Thus, inorganic salt potassium sulphate (K2SO4) was formed in process of jatropha curcas to glycerine. Potassium sulphate is the principal component of chloride-free potash fertilizer. And cash crops are dominant in China, such as tea, tobacco, fruit trees and so on, which should avoid chloride potash fertilizer. So our country has a large consumption of potassium sulphate. At present potassium sulphate is in great demand in China, meanwhile the region badly short of potassium includes China. Therefore, it was necessary to recycle the solid residue in process of extracting glycerol.In the experiment, recycling the solid residue in rough glycerol extraction has the following advantages:(1) reduce pollution to the environment. Solid residue contains inorganic salt mostly, also a few grease, if directing emissions to nature, it will lead to the heavy pollution to the environment.The recycling will reduce pollution to the environment; (2) Get high purity of potassium sulphate; (3) biodiesel-potassium sulphate cogeneration will reduce the cost of biodiesel. At present the price of the potassium sulphate are expens-ive in our country. Through the recycling of potassium sulphate, on one hand, the cost of biodiesel could be reduced, on the other hand, the biodiesel increases the addtional revenue. Based on GB20406-2006 national standards specified, if the mass fraction of K2O is greater than 50%, the Potassium Sulphate can be decided to the premium grades.In the experiment, Through the solid residual dissolving, K2O is 53.45% the mass fraction of potassium sulfate after recrystallization. It indicates the recycling of solid residue, the classy article potassium sulfate can be acquired. |
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