Technology for reclaiming low-concentration formaldehyde from pesticide wastewater through ionic liquid supported liquid membrane pervaporation-distillation coupling technology

An ionic liquid, supporting liquid membrane technology, applied in the separation/purification of carbonyl compounds, organic chemistry, chemical instruments and methods, etc., can solve the problems of the general application of advanced oxidation method, high operating cost, large consumption of oxidant, etc. To achieve the effect of solving treatment and discharge, simple production equipment, and reducing energy consumption

Inactive Publication Date: 2011-04-06
NANJING UNIV
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  • Abstract
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Problems solved by technology

[0007](3) Current formaldehyde wastewater treatment technology
Various oxidation technologies have the advantages of simple methods, good oxidation treatment effects, a...

Method used

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  • Technology for reclaiming low-concentration formaldehyde from pesticide wastewater through ionic liquid supported liquid membrane pervaporation-distillation coupling technology

Examples

Experimental program
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Effect test

Embodiment 1

[0042] Embodiment 1. Concentrate and recover low-concentration formaldehyde solution by using pervaporation membrane module and rectification column coupling technology.

[0043] In this example, the pervaporation membrane module is used, and the self-made ionic liquid is used to support the liquid membrane, and the membrane liquid is the ionic liquid [C4mim] [PF 6 ], with the first step by the n-bromobutane of the amount of N-methylimidazole and other substances in the round bottom flask stirring reaction, bromoalkane will be slowly added dropwise, the reaction temperature is 70 ℃, after 24 hours of reaction, Cool to room temperature, wash 2-3 times with ethyl acetate, and finally wash off the ethyl acetate in the ionic liquid with ether to synthesize [C4mim]Br; the second step weighs a certain amount of synthesized imidazolium bromide salt and dissolves it in water, and adds an appropriate amount of KPF 6 , stirred and reacted for 12 hours, poured off the upper aqueous phas...

Embodiment 2

[0047] Embodiment 2. The film-making method is a decompression method. A certain amount of ionic liquid is placed above the bottom film and placed together in a vacuum drying oven. A pump is used to extract the air in the aperture below the film, and the vacuum is maintained for 24 hours. The membrane was suspended for 24 hours, and the excess ionic liquid on the surface was removed. In the process of pervaporation concentration of formaldehyde, the feed liquid temperature is 30°C, the permeate side pressure is 2100Pa, and other experimental conditions are the same as in Example 1. The experimental results are basically the same as in Example 1.

Embodiment 3

[0048] Embodiment 3. The film making method is the atmospheric pressure immersion method. The inert base film is soaked in an appropriate amount of ionic liquid, and the capillary force is used to make it penetrate into the pores. The film is suspended for 24 hours, and the excess ionic liquid on the surface is removed. In the process of pervaporation and concentration of formaldehyde, the temperature of the feed liquid is 40°C, and the pressure on the permeation side is 2500Pa. All the other experimental conditions were the same as in Example 1. The experimental results are basically the same as in Example 1.

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Abstract

The invention relates to technology for reclaiming low-concentration formaldehyde from pesticide wastewater through ionic liquid supported liquid membrane pervaporation-distillation coupling technology. The technology comprises the following steps that: (1) a pervaporation device provided with an ionic liquid supported liquid membrane is adopted to perform pre-enrichment of low-concentration formaldehyde-containing pesticide wastewater on a transmission side; and (2) the formaldehyde wastewater subjected to pre-enrichment enters the middle part of a rectification column, a catalytic reaction is performed in a reaction section of the rectification column filled with a solid acid catalyst, the stay time is reasonably controlled in a way of outside pump circulation to allow free formaldehyde obtained by depolymerizing polymeric formaldehyde to enter a rectification section to be concentrated, high-concentration formaldehyde solution is obtained, and wastewater solution from which the formaldehyde is removed is obtained in a stripping section. Because the formaldehyde solution is subjected to pre-enrichment by the pervaporation device provided with the ionic liquid supported liquid membrane and is then separated through rectification, compared with the single rectification, the technology can greatly save energy consumption and reduce the cost. Therefore, the technology is more economic and reasonable.

Description

technical field [0001] The invention relates to a technology for recovering low-concentration formaldehyde in pesticide waste water through the pervaporation-rectification coupling technology supported by an ionic liquid. Background technique [0002] (1) Sources and hazards of formaldehyde wastewater [0003] Formaldehyde-containing wastewater mainly comes from the production processes of organic synthesis, synthetic rubber, paints and coatings, plastics, tanning, textiles, and wood adhesives. In addition, exhaust gases from internal combustion engines, flue gases from power plants, etc. are also possible. Formaldehyde is highly toxic to humans and warm-blooded animals. It can irritate the skin, easily cause dermatitis, and easily cause respiratory tract infections, allergies, abnormal lung function, abnormal liver function, abnormal immune function, etc. The lethal dose to humans is 142mg kg -1 . If humans drink water polluted by formaldehyde for a long time, it will ca...

Claims

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Application Information

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IPC IPC(8): C07C47/058C07C45/81C02F9/10
Inventor 李磊张志炳李雪茹金凯洪
Owner NANJING UNIV
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