Method for selectively absorbing and separating thiocyanates and thiosulfates in water solution

A technology of thiosulfate and thiocyanate, applied in the field of water treatment, can solve the problems of unrecoverable structure and unrecoverable decomposition products, and achieve the effect of solving pollution problems

Active Publication Date: 2010-10-13
BEIJING UNIV OF CHEM TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the "memory effect" is related to thermal decomposition behavior, when the temperature is too high, the decomposition products cannot return to the structure of hydrotalcite
Generally speaking, the recovery of the structure is possible when the calcination temperature is within 500°C. Taking MgAl-LDHs as an example, after the calcined product is exposed to water at a temperature of 500°C, its structure can be partially restored to have an ordered layered structure. LDHs; when the calcination temperature is above 600 ° C, the calcination product with a spinel structure is generated, resulting in an irreversible structure

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] Mg 6 al 2 (OH) 16 CO 3 .yH 2 O was calcined at 430°C for 4h to obtain an oxide with a Mg / Al molar ratio of 3:1, abbreviated as Mg 3 Al-LDO;

[0016] Take 800mL of mixed salt solution with the same concentration of thiosulfate and thiocyanate as 0.015mol / L, and add it to a 1000mL reaction vessel. 3 Al-LDO was stirred for 6 hours, and the adsorbent was recovered by filtration. The thiosulfate was adsorbed between the hydrotalcite layers, and the thiocyanate remained in the aqueous solution.

[0017] The residual concentrations of thiosulfate and thiocyanate were determined to be 0.00228mol / L and 0.0135mol / L, respectively, and the adsorption rates were 84.8% and 10%, respectively.

Embodiment 2

[0019] Mg 4 al 2 (OH) 12 CO 3 .yH 2 O was calcined at 450°C for 4 hours to obtain an oxide with a Mg / Al molar ratio of 2:1, abbreviated as Mg 2 Al-LDO;

[0020] Take 800mL of mixed salt solution with the same concentration of thiosulfate and thiocyanate as 0.01mol / L, and add it to a 1000mL reaction vessel, keep the water bath at 25°C, add 4g Mg 2 Al-LDO was stirred for 4 hours, the adsorbent was recovered by filtration, the thiosulfate was adsorbed between the hydrotalcite layers, and the thiocyanate remained in the aqueous solution.

[0021] The residual concentrations of thiosulfate and thiocyanate were determined to be 0.001237mol / L and 0.008842mol / L, respectively, and the adsorption rates were 87.63% and 11.58%, respectively.

Embodiment 3

[0023] Mg 6 al 2 (OH) 16 CO 3 .yH 2 O was calcined at 450°C for 4 hours to obtain an oxide with a Mg / Al molar ratio of 3:1, abbreviated as Mg 3 Al-LDO;

[0024] Take 800mL of mixed salt solution with the same concentration of thiosulfate and thiocyanate as 0.01mol / L, and add it to a 1000mL reaction vessel. 3 Al-LDO was stirred for 4 hours, the adsorbent was recovered by filtration, the thiosulfate was adsorbed between the hydrotalcite layers, and the thiocyanate remained in the aqueous solution.

[0025] The residual concentrations of thiosulfate and thiocyanate were determined to be 0.003496mol / L and 0.01mol / L, respectively, and the adsorption rates were 65.04% and 0%, respectively.

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Abstract

The invention provides a method for selectively absorbing and separating thiocyanates and thiosulfates in water solution. The invention uses the difference absorption effect of the layered bihydroxide mixed metal oxide roasted products (LDO) on the ion absorption quantity of thiosulfate radicals and thiocyanate radicals, the LDO is used as absorbing agents to be placed into the water solution containing thiosulfates and thiosulfates, firstly, the thiosulfates in the solution are absorbed into the LDO, then, the replacement and the purification are carried out, and next, the thiosulfates in the rest solution are separated, so the goal of separating and purifying two salts is reached. The used LDO is obtained through roasting Mg-Al hydrotalcites with the constitutional formula of Mg<1-x>Alx(OH)2(An<->)x / 2.yH2O at 400 to 500 DEG C for 3 to 4 h. The method can be used for treating waste water in the solution containing the thiosulfates and the sulfates for solving the problem of water body and soil pollution by the thiosulfates and the sulfates, and at the same time, the two salts can be perfectly recovered.

Description

technical field [0001] The invention belongs to the technical field of water treatment and provides a purification and separation treatment method for separating thiocyanate and thiosulfate in an aqueous solution. Background technique [0002] Thiosulfate and thiocyanate coexist in many wastewaters, such as coking wastewater, photofinishing wastewater, electroplating wastewater, printing and dyeing wastewater, and mining wastewater. Sulfur-containing compounds are the main pollutants in these wastewaters, and thiosulfate is a nutrient for organisms, which can easily cause eutrophication of water bodies. However, thiocyanate is toxic to organisms. If it is directly discharged into water bodies without treatment, it will bring great harm to humans and aquatic organisms. [0003] Some scholars have tried many methods in order to deal with sulfur-containing wastewater, such as oxidative decomposition (Environ.Sci.Technol., 2003, 37:452), activated carbon adsorption (Trans.IChem...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F1/28C01B17/90C01C3/20
Inventor 雷晓东于晓张法智徐赛龙段雪
Owner BEIJING UNIV OF CHEM TECH
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