Study On Ellagic Acid Preparation

Ellagic acid is a natural polyphenol components have antioxidant, anti-cancer, anti-bacterial, anti-inflammatory, anti-virus, anti-HIV and prevention of diabetes and other effects, and has broad application prospects. In this paper, I studied how to use pomegranate rind, gall, pomegranate rind extracts as raw materials to prepare ellagic acid, and the purification of ellagic acid, lead-off process. It is of great significance for the production and application of ellagic acid, its main the findings are as follows:1 The ellagic acid content in the pomegranate rind which are from different area have some difference, range from 5.27% to 8.16%. Only one alkali-soluble and acid precipitation and a washing can make ellagic acid purity of about 40% to 50% and then increased alkali-soluble and acid precipitation or washing steps may improve the purity, but the product quality has declined; ellagic acid crude purified directly used without drying, it will not affect the purification effect; the material balance for the entire process of the purification, the result shows that the process of alkali-soluble lost the ellagic acid least, while the twice washing process lost most, followed by acid precipitation process; I studied sulfurous acid hydrolysis process for preparing granatum ellagic acid and obtained the optimum hydrolysis conditions:5% sulfuric acid concentration, solid-liquid ratio of 1:10, hydrolysis temperature is 120℃, the reaction time was 14h, the resulting crude ellagic acid purity is 27.71%, the yield is 6.66%.2 I studied gallnut tannins extraction process parameters, the result shows the times and solid-liquid ratio have greater impact on the effect of extraction, extraction time and temperature have less impact on the effect of extraction. And when extracting for 3 times, extraction temperature of 60℃, solid-liquid ratio of 1:10, extraction time 2h, can be about 98% of the total Chinese gall tannin extracted. I Also found the pH in the reaction system has a great impact on tannic acid oxidation reaction, when initial pH is 8.5 and remain the pH unchanged, ellagic acid yield could reach 44.13%, and identified 16h is the end of tannic acid oxidation, and when the end of the pH of the acid precipitation is 4 or 2, the purity, yield, structure of ellagic acid product have no significant difference, but when the terminal pH is 4, ellagic acid look more favorable.3 I Researched and optimized process parameters of producing ellagic acid with pomegranate peel extract as raw by hot sulfuric acid hydrolysis, when sulfuric acid concentration is 3%, the hydrolysis time was 12h, solid-liquid ratio of 1:8, hydrolysis temperature 90℃, ellagic acid yield was 4.76%. This experimental program has put into pilot scale after making some related improvements e, finally deal with pomegranate peel extract about 6000 L, get ellagic acid crude 1.1t; the original purification process was optimized and improved, the original acid precipitation step by step divided into two steps, the first pH adjusted to 8 so ellagic acid precipitation, followed by centrifugation for second ellagic acid and acid precipitation, the pH to 4, and so ellagic acid structure intact. Such purification steps can make ellagic acid purity of purified up to 80%; for the production of solid-liquid separation process each step of the way to do a comparison and selection; point out the precautions of hydrochloric acid drops acceleration in acid precipitation process,4 Using EDTA · 2Na as a chelating agent to remove the lead in ellagic acid, when using 1mmol EDTA · 2Na, the content of the lead in ellagic acid down to 0.12ppm, in line with national requirements, to meet the requirements of the promotion of the use. When the amount of EDTA · 2Na is 2mmol or more, the lead in ellagic acid can be removed about 100%.