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Method for degrading perfluorinated compounds

A compound and substance technology, applied in the field of degrading perfluorinated substituted compounds, can solve the problems of non-substitution, harsh reaction conditions, and high equipment, and achieve the effects of reduced toxicity and simple process structure

Inactive Publication Date: 2009-09-09
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Although the adsorption method can effectively degrade PFCs, it is more dangerous to use the incineration method as the main follow-up treatment method, and improper treatment will cause secondary pollution; the thermochemical method requires high temperatures above 1000C, and has higher requirements for equipment; the sonochemical method can also Effectively degrade PFOS and PFOA, but the reaction conditions are harsh, how to control the concentration of interfacial bubbles is the key factor; in the photochemical method, 185nm vacuum ultraviolet light can effectively degrade PFOA, while 254nm ultraviolet light has almost no degradation effect
[0006] Photochemical method is widely used to degrade organic matter because of its special superior performance, but the commonly used photocatalytic oxidation method based on titanium dioxide photocatalyst cannot effectively degrade PFOA and PFOS, the reason is that this method mainly relies on free hydroxyl radicals to degrade organic matter, but hydroxyl radicals cannot replace fluorine in perfluorinated compounds or add to perfluorinated compounds to trigger the decomposition of perfluorinated compounds

Method used

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  • Method for degrading perfluorinated compounds
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  • Method for degrading perfluorinated compounds

Examples

Experimental program
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Effect test

Embodiment 1

[0028] The photocatalytic degradation of embodiment 1, perfluorooctanoic acid (PFOA)

[0029] A reaction device for photocatalytic degradation of perfluorinated compounds such as figure 1 shown. The device includes the following components: a light source 1, which is used to emit ultraviolet light with a wavelength less than 400nm; a quartz sleeve 2, which can pass through ultraviolet rays, and is used to isolate ultraviolet rays from the reaction solution; a reaction vessel 3, which is a place for degradation of perfluorinated compounds; The aeration plate 4 is used to pass inert gases such as nitrogen and argon or reducing gases such as ammonia into the reaction vessel 3 to drive away the oxygen in the reaction vessel 3 and also to stir the reaction solution; the gas is added Port 5 is used to add inert gas or reducing gas to the reaction system; condensed water inlet and outlet 6; cooling water circulation device 7 is used for cooling water circulation to reduce the heat g...

Embodiment 2

[0033] The photocatalytic degradation of embodiment 2, perfluorooctane sulfonate (PFOS)

[0034] To 100mL 7.25×10 -5 Add β-Ga to mol / L PFOS aqueous solution 2 o 3 Powder and reducing substance Na 2 S 2 o 3 , stirred for 3h, a clear homogeneous solution was obtained, and the β-Ga in the homogeneous solution 2 o 3 The final concentration was 2.67×10 -3 mol / L, Na 2 S 2 o 3 The concentration is 5×10 -5 mol / L.

[0035] like figure 1 As shown, open the aeration plate 4 at the bottom of the reaction device, pass nitrogen gas into the reaction vessel 3 from the gas inlet 5, then add the clear homogeneous solution obtained above into the reactor 3, and aerate for about half an hour , and then turn on the cooling water circulation device 7 and the light source 1 to start the reaction. Take the reaction solution from the sampling port 8 at regular intervals, detect the concentration of PFOS and its short-chain perfluorocarboxylic acid compounds, and use the electrospray neg...

Embodiment 3

[0037] Embodiment 3, the photocatalytic degradation of PFOA under the condition that reducing substance exists

[0038] To 100mL 7.25×10 -5 Add β-Ga to mol / L PFOA aqueous solution 2 o 3 powder, and then add reducing substances KI, Na 2 S 2 o 3 and methanol, stirred for 3h to obtain a clear homogeneous solution, in which β-Ga 2 o 3 The final concentration was 2.67×10 -3 mol / L, KI, Na 2 S 2 o 3 and methanol at a final concentration of 5 × 10 -5 mol / L.

[0039] like figure 1 As shown, open the aeration plate 4 at the bottom of the reaction device, pass nitrogen gas into the reaction vessel 3 from the gas inlet 5, then add the clear homogeneous solution obtained above into the reactor 3, and aerate for about half an hour , and then turn on the cooling water circulation device 7 and the light source 1 to start the reaction. Take the reaction solution from the sampling port 8 at regular intervals, detect the concentration of PFOA and its short-chain perfluorocarboxylic...

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Abstract

The invention discloses a method for degrading perfluorinated compounds, comprising the following steps: under the oxygen-free condition, belta-Ga2O3 is adopted as a photocatalyst. Ultraviolet with the wavelength of 185-254nm is used for irradiating the perfluorinated compounds to be degraded. The method for degrading the perfluorinated compounds has the advantages that: the technique has a simple structure and can be implemented under normal temperature and normal pressure without complex equipment; the initial concentration of the perfluorinated compounds is not required, and the perfluorinated compounds with any concentration and any pH value can be processed by the method of the invention; the toxicity of degraded products is lowered, and the products can be further processed by other methods.

Description

technical field [0001] The invention relates to a method for degrading perfluorinated substituted compounds. Background technique [0002] Perfluorinated compounds (Perfluorinated Compounds, PFCs) refer to compounds in which the hydrogen (H) connected to the carbon atom (C) in the organic structure is replaced by fluorine (F). Due to the high electronegativity of fluorine, the structure of such compounds is extremely stable and difficult to be degraded. Especially perfluorooctanoic acid (Perfluorooctanoic acid, PFOA, C 7 f 15 COOH) and perfluorooctane sulfonate (Perfluorooctane sulfonate, PFOS, C 8 f 17 SO 3 - ) as a representative of perfluorinated substituted compounds, it is difficult to degrade them by traditional treatment techniques. [0003] Perfluorinated substituted compounds have been used since the 1950s and are widely used in industrial and consumer goods industries, including protective coatings for fabrics and carpets, paper coatings, insecticide compone...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): A62D3/176B01J23/08C02F1/32A61L9/20A62D101/22A62D101/28C02F101/36
Inventor 张彭义赵宝秀
Owner TSINGHUA UNIV
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