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Method for removing trace cadmium from aqueous solution

An aqueous solution and removal technology, applied in chemical instruments and methods, water/sewage treatment, water/sewage multi-stage treatment, etc., can solve the problems of introducing unwanted ions into water, unsatisfactory removal effect, and large amount of reagents, etc. , to achieve the effect of less reagent consumption, short processing time and less waste residue generation

Inactive Publication Date: 2011-11-23
TIANJIN UNIVERSITY OF TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The traditional method of removing cadmium is suitable for treating waste liquid with high cadmium content, but the removal effect is not ideal for waste liquid with low cadmium content. May introduce unwanted ions into the water column

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0014] Example 1: Measure 1 L of an aqueous solution with a cadmium content of 36 mg / L, add 50 mg of ferric nitrate nonahydrate, and 0.4 g of sodium dihydrogen phosphate, and control the temperature of the aqueous solution to 20°C. Under the conditions of vigorous stirring and controlling the pH of the system to 7-7.2 (adjust with sodium hydroxide or hydrochloric acid if necessary), add 50 mL of an aqueous solution containing 50 mg of sodium bicarbonate dropwise. After the dropwise addition was complete, stirring was continued for 1 hour. Afterwards, it was cooled to room temperature, allowed to stand, settled and filtered to remove cadmium-containing precipitates. The cadmium content of the filtrate is less than 0.01mg / L and the iron content is less than 0.01mg / L according to ICP (Inductively Coupled Plasma Emission Spectroscopy, the same below).

Embodiment 2

[0015] Embodiment 2: measure cadmium content and be the aqueous solution 1L of 36mg / L, add 8mg ferric chloride hexahydrate and 0.4g ammonium molybdate, then adjust the pH~7 of solution with sodium hydroxide solution, and control the aqueous solution temperature to be 10 ℃. Under the conditions of vigorous stirring and controlling the pH of the system to 7.2-7.5, add 6 mL of an aqueous solution containing 20 mg of sodium carbonate dropwise. After the dropwise addition was complete, stirring was continued for 1 hour. Afterwards, cool to room temperature, let stand, settle and centrifuge to remove cadmium-containing precipitate. The cadmium content of the filtrate analyzed by ICP is less than 0.01mg / L, and the iron content is less than 0.01mg / L.

Embodiment 3

[0016] Example 3: Measure 1 L of an aqueous solution with a cadmium content of 36 mg / L, and adjust the pH of the solution to 7. Under vigorous stirring at 30°C, 5 mg of sodium molybdate dihydrate and 0.4 g of ferrous carbonate were added. Control the pH of the solution to 7 (can be adjusted by adding sodium hydroxide or hydrochloric acid), and keep stirring for 1 hour. Afterwards, let stand, settle and centrifuge to remove the cadmium-containing precipitate. The cadmium content of the filtrate analyzed by ICP is less than 0.01mg / L, and the iron content is less than 0.01mg / L.

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Abstract

The invention discloses a method for removing trace cadmium from an aqueous solution. The method comprises the following steps: culturing and analyzing plants growing in a chrome environment, adjusting the pH value of a cadmium-containing aqueous solution with acid or alkali; simultaneously or separately adding ferriferous reagents, carbonates and phosphates or molybdates into the aqueous solution; standing still for depositing, separating out cadmium-slag containing water, wherein the cadmium content of the cadmium-slag containing water is detected to be less than 0.01 mg / L. The method disclosed by the invention is characterized in that through controlling the adding amounts of the ferriferous reagents, the carbonates and the phosphates or the molybdates and the pH value of the cadmium-containing aqueous solution, trace cadmium elements in the cadmium-containing aqueous solution can be removed, and the water treatment time is short, adopted materials are economic and easy to obtain, and no harmful element is added into a system, therefore, the method is an environment-friendly and economic treatment process, and the process can be widely applied to the treatment of cadmium-containing wastewater discharged in the fields of the metal processing industry, the electroplating industry, the leather making industry and the textile industry, and the like.

Description

【Technical field】 [0001] The invention relates to the field of wastewater treatment in environmental technology, in particular to a method for removing trace amounts of cadmium in aqueous solution. 【Background technique】 [0002] With the rapid increase of industrial waste, the heavy metal cadmium pollution in water is becoming more and more serious. Cadmium is often found in industrial wastewater, with the largest sources of cadmium pollution coming from the metal processing, electroplating, tanning and textile industries. These industrial effluents often contain a considerable amount of toxic cadmium compounds. [0003] The traditional method of removing cadmium is suitable for treating waste liquid with high cadmium content, but the removal effect is not ideal for waste liquid with low cadmium content. May introduce unwanted ions into the water column. 【Content of invention】 [0004] The purpose of the present invention is to provide a method for removing trace amou...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F9/04C02F1/62
Inventor 孙波牛力华吴新世安钢
Owner TIANJIN UNIVERSITY OF TECHNOLOGY
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