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Method for purifying thiourea

A technology of thiourea and polyacrylamide, which is applied in the direction of organic chemistry, can solve the problems of low thiourea content, low bulk density, and fragile crystals, and achieve the effect of reducing storage, uniform product particle size, and meeting demand

Active Publication Date: 2020-01-24
SHANDONG EFIRM BIOCHEMISTRY & ENVIRONMENTAL PROTECTION CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide a method for purifying thiourea to solve the industrial problems of low thiourea content, high impurity content, brittle crystals and low bulk density

Method used

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  • Method for purifying thiourea
  • Method for purifying thiourea

Examples

Experimental program
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Effect test

Embodiment 1

[0020] In 1000g of 20% thiourea aqueous solution, add 0.5g of 0.1% polyacrylamide solution (cationic polyacrylamide, molecular weight: 2 million) prepared in advance, stir at 60°C for 1.5 hours, filter while hot, filter precision 0.5μm; get The solution was cooled and crystallized, and the temperature was slowly lowered to 10° C. over 13 hours, filtered to obtain thiourea crystals, and the product was obtained after drying. Measure its thiourea content 99.7%, impurity ion < 100ppm, bulk density 0.78g / ml.

Embodiment 2

[0022] In 1000g of 25% thiourea aqueous solution, add 0.8g of 0.05% polyacrylamide solution (cationic polyacrylamide, molecular weight: 3 million) prepared in advance, stir at 60°C for 2 hours, filter while hot, and the filter precision is 0.2μm; The solution was cooled and crystallized, and the temperature was slowly lowered to 12° C. over 15 hours, filtered to obtain thiourea crystals, and the product was obtained after drying. Measure its thiourea content 99.8%, impurity ion<100ppm, bulk density is 0.80g / ml.

Embodiment 3

[0024] Add 1.0 g of 0.01% polyacrylamide solution (non-ionic polyacrylamide, molecular weight 1 million) prepared in advance to 1000 g of 30% thiourea aqueous solution, stir at 70°C for 1 hour, and filter while hot, with a filter fineness of 0.8 μm; The obtained solution was cooled to crystallize, slowly cooled to 12° C. over 12 hours, filtered to obtain thiourea crystals, and dried to obtain the product. Measure its thiourea content 99.6%, impurity ion < 100ppm, bulk density 0.83g / ml.

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Abstract

The invention belongs to the technical field of fine chemical engineering, and particularly relates to a method for purifying thiourea. The method comprises the following steps: adding a diluted polyacrylamide solution into a high-concentration aqueous thiourea solution, carrying out stirring for a certain period of time, performing filtering, subjecting obtained clear liquid to cooling and crystallizing, and performing filtering and separating to obtain crystals after a cooling end point is reached. The thiourea obtained by using the method is high in purity, low in impurity content, uniformin granularity, high in stacking density and not easy to break; product quality can be improved; and the storage and transportation cost of the produced thiourea is reduced.

Description

technical field [0001] The invention belongs to the technical field of fine chemicals, and in particular relates to a method for purifying thiourea. Background technique [0002] Thiourea is a fine chemical product widely used in pesticide, medicine, printing and dyeing, synthetic resin, electroplating, flotation of metal minerals and other industries. As one of the physical parameters of thiourea crystals, bulk density will affect the storage and transportation costs of thiourea products. Therefore, it is very meaningful to study the influencing factors of the packing density of thiourea crystals. [0003] The content of industrial thiourea is 99.0% or even lower, which cannot meet the needs of high-end customers, and the synthesis process of industrial thiourea mainly uses calcium cyanamide as raw material, so there will be more calcium ions and other impurity ions in thiourea products. impact on downstream applications. [0004] The thiourea in the industry is flake cr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C335/02
CPCC07C335/02
Inventor 曹斌张超梁万根张宁崔卫华刘冠宏
Owner SHANDONG EFIRM BIOCHEMISTRY & ENVIRONMENTAL PROTECTION CO LTD