Multi-stage countercurrent extraction method for azadirachtin

Abstract

The invention provides a multi-stage countercurrent extraction method for azadirachtin, which is characterized in that: coarsely crushed neem seeds are put into a multi-stage countercurrent extraction device, and a solvent is pumped into the multi-stage countercurrent extraction device for dynamic countercurrent extraction at normal temperature or by heating properly; and the extracting solution is concentrated to prepare a solid extract containing 10 to 20 percent of azadirachtin, and the solid extract is used for preparing azadirachtin pesticides. The method has the advantages of short process flow, high extraction speed, high yield of azadirachtin, energy and solvent conservation, low production cost, easy industrial production and the like.

Description

technical field [0001] The invention relates to a method for extracting insecticides from plants, in particular to a method for extracting azadirachtin from neem seeds in a tank group countercurrent manner. Background technique [0002] Azadirachtin insecticides have the characteristics of broad spectrum, high efficiency, low toxicity, no residue, no toxic and side effects on humans and animals, safe to natural enemies of pests, and not easy to produce drug resistance. They are currently one of the most widely researched and used biological pesticides at home and abroad. 1. It has been listed as a pollution-free pesticide recommended by the Green Food Office of the State Council. [0003] Extracting azadirachtin from neem seeds is the first step and an important operation unit in the production of azadirachtin insecticides. The content of azadirachtin in neem seeds is very low (generally 0.3% to 0.4%, high up to 0.6%), and the extraction of azadirachtin is relatively diffic...

AI Technical Summary

Problems solved by technology

Contain 20%~30% oil in the neem seed, direct mechanical pulverization is difficult to finely crushed, influences the leaching of azadirachtin, its raw material pretreatment mode mostly adopts shelling, pressing degreasing at present (as Chinese patent CN1158928C, CN1184222C, CN1362020A, CN1423938A, CN1423939A, CN1524858A, CN101440099A), but the thermostability of azadirachtin is poor, and the degradation rate of azadirachtin significantly increases when greater than 35 DEG C, and the degradation rate of azadirachtin is the largest during 65 DEG C, so in the degreasing process of pressing because of high temperature promptly has About 40% of azadirachtin is degraded, causing the yield of azadirachtin to decline; there are also solvents or supercritical CO degreasing (such as Chinese patents CN1049091C, CN1199980C, CN101029276A, CN1116394C), although it can reduce the loss of azadirachtin, but increase Reduced processing time and cost

Chinese patent CN100448871C neem seeds only need to be shelled, without degreasing, they can be cut, stirred, pulverized and extracted with high-speed blades, so that the materials and solvents have better fluidity, and the yield of azadirachtin is higher, but neem seeds need 3 ~5 times of polar organic solvent presoaked for 6~12 hours, the extraction time is 3~5 hours / time, repeat 2~5 times, it takes at least 15 hours to complete an extraction cycle, at least 9 times of solvent extraction is required, and high-speed stirring Crushing is easy to overheat, and the extraction temperature is difficult to control. It is necessary to use jacket or coil cooling to reduce the degradation of azadirachtin and increase energy consumption.