Method for removing organic pollutants in water by using hydroxyl free radicals generated by organic membrane

A technology based on organic pollutants and free radicals, applied in the field of photochemical technology and sewage treatment, can solve problems such as difficulty in popularization and application, high cost of ray method, poor continuous operability, etc. Effect of Water Treatment Costs

Active Publication Date: 2016-11-09
HENAN POLYTECHNIC UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The chemical catalytic method generally adopts the Fenton reaction, and uses iron ions to catalyze the decomposition of hydrogen peroxide to generate hydroxyl radicals. This method is simple, easy and relatively cheap, but it will produce a large amount of iron-containing sludge when it is applied on a large scale, which will bring about no change to the subsequent treatment; Ozone and hydrogen peroxide undergo photolysis under the action of ultraviolet light to produce hydroxyl radicals, but the precursors of hydroxyl radicals, ozone and hydrogen peroxide, need to be added, and there are many side reactions; semiconductor titanium dioxide particles are used as catalysts to photocatalyze hydroxyl radicals. It is necessary to ensure that the catalyst is in a suspended state, and photocatalysis also needs to separate the photocatalyst, which has poor continuous operability, and dissolved oxygen has a great influence on the generation of hydroxyl radicals by photocatalysis of titanium dioxide; And its catalytic components have high requirements, and the current efficiency is low; the ray method has the problems of high cost and great harm to human body
[0004] Therefore, several methods for producing hydroxyl radicals that are commonly used at present either have more side reactions, or have poor operability and low efficiency, or have greater harm to the environment or the human body. Therefore, the existing methods for producing hydroxyl radicals are all There are their own problems, it is difficult to popularize and apply

Method used

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  • Method for removing organic pollutants in water by using hydroxyl free radicals generated by organic membrane
  • Method for removing organic pollutants in water by using hydroxyl free radicals generated by organic membrane
  • Method for removing organic pollutants in water by using hydroxyl free radicals generated by organic membrane

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Effect test

Embodiment 1

[0044] In this example, the ESR qualitative analysis of the photocatalytic generation of hydroxyl radicals on the surface of the nitrocellulose membrane was carried out.

[0045] Cut the nitrocellulose membrane into strips with a length of 2 cm and a width of 0.1 cm, insert them into a quartz sample tube, and inhale 100 mM picoline N-oxide (dimethyl pyridine N-oxide, DMPO for short), and carry out in-situ electron autosynthesis. Detection by spin resonance spectroscopy. In the case of 180W solar light, the generation of hydroxyl radicals is monitored in real time. The result is as figure 1 As shown, when there is no light, the background signal is basically a flat line. When the light is 4min, 8min and 16min, the characteristic signal of hydroxyl radical and DMPO adduct can be observed, and 4 peaks appear, and the peak height ratio is 1:2. :2:1, hyperfine splitting constant a H =a N =14.9 Gauss, the peak height increases linearly as the illumination time increases, confir...

Embodiment 2

[0047] Embodiment 2 (generation situation of hydroxyl radicals under different membrane areas)

[0048] In a 100mL beaker, add 50mL of 10mM benzene solution, put the whole, one-half, one-fourth and one-eighth nitrocellulose membranes with a diameter of 47mm (φ47mm), and make the membrane The film is still at the bottom of the beaker and placed under a 180W sun lamp to irradiate. The hydroxyl radical formed by the nitrocellulose membrane reacts with benzene to generate phenol. Samples were taken every 20 minutes, and the change of phenol concentration in the solution was analyzed by high performance liquid chromatography, reflecting the generation of hydroxyl radicals. The result is as figure 2 As shown, it can be seen that the amount of hydroxyl radicals produced is basically linear with the increase in the area of ​​the nitrocellulose membrane, indicating that the nitrocellulose membrane can generate hydroxyl radicals quantitatively and stably. In order to clarify the caus...

Embodiment 3

[0049] Embodiment 3 (solution phase nitrate radical and nitrite radical illumination produce the elimination of hydroxyl radical)

[0050] In terms of chemical structure, nitrocellulose membrane is a nitrate ester of cellulose, which may undergo hydrolysis to produce nitrate or nitrite. At present, it cannot be ruled out that the latter two can also produce hydroxyl radicals under light. In order to rule out the above possibility, the hydrolysis experiment of nitrocellulose membrane was carried out. Put a φ47mm nitrocellulose membrane in pure water, hydrolyze it at 35°C, use ion chromatography to measure the nitrate and nitrite produced by hydrolysis, and compare it with the blank and standard, the results are as follows image 3 shown. It can be seen that the nitrocellulose membrane can only be slightly hydrolyzed in water; compared with the standard, after 2 hours of hydrolysis, only 0.8 μM nitrite and 2.3 μM nitrate were produced in the solution. Under the same conditions...

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Abstract

The invention provides a method for removing organic pollutants in water by using hydroxyl free radicals generated by an organic membrane. The method adopting a nitrocellulose membrane as a photocatalysis material comprises the following steps: placing the nitrocellulose membrane in water, and illuminating the nitrocellulose membrane with sunshine or a sun lamp with the wavelength being greater than 280 nm as a light source to make the nitrocellulose membrane undergo a membrane surface photochemical reaction in order to generate hydroxyl free radicals, wherein the generation rate of the hydroxyl free radicals is adjusted through adjusting the surface area of the membrane and the light intensity. The generated hydroxyl free radicals can well remove phenol, bisphenol A, thiamphenicol and other typical organic pollutants in water. The hydroxyl free radical generation method has the advantages of simplicity, high economy, high efficiency, no introduction of any hydroxyl free radical precursors to an aqueous solution, and no secondary pollution due to generation of the hydroxyl free radicals on the surface of a solid membrane, and can be applied to the field of wastewater treatment.

Description

technical field [0001] The invention belongs to the field of photochemical technology and sewage treatment, and in particular relates to a method for using an organic film to generate hydroxyl radicals and remove organic pollutants in water. Background technique [0002] Hydroxyl radical (·OH) is a kind of active oxygen radical, which has strong oxidizing property, and its oxidation-reduction potential is 2.80V, second only to fluorine atom, and can interact with most inorganic or organic substances at a diffusion-controlled rate For the reaction, the reaction rate constant is generally greater than 10 8 mol L -1 the s -1 . In the field of environmental science, hydroxyl radicals are used for the degradation of organic pollutants, and are the most important active intermediates in the advanced oxidation process wastewater treatment process. [0003] There are many ways to generate hydroxyl radicals, which can be roughly divided into chemical catalysis, ozone / hydrogen per...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F1/30B01J31/06C02F101/34
CPCB01J31/06B01J35/004C02F1/30C02F2101/34C02F2305/10B01J31/061B01J35/065C02F1/32C02F1/725C02F2101/345C02F2209/44C02F2305/023Y02W10/37B01D69/02B01D71/20B01D2255/802B01J35/00C02F1/72
Inventor 邰超张少栋赵同谦宋党育冯磊毛宇翔齐永安张国成张立军王娟
Owner HENAN POLYTECHNIC UNIV
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