Industry News » HeNan Polytechnic University; Patent Issued for Method For Generating Hydroxyl Radical And Removing ...


HeNan Polytechnic University; Patent Issued for Method For Generating Hydroxyl Radical And Removing Organic Pollutants In Water By Utilizing An Organic Membrane (USPTO 10,364,165)

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HeNan Polytechnic University (Jiao Zuo, Henan, People's Republic of China) has been issued patent number 10,364,165, according to news reporting originating out of Alexandria, Virginia, by NewsRx editors.

The patent's inventors are Tai, Chao (Jiao Zuo, CN); She, Jiaping (Jiao Zuo, CN); Zhang, Shao Dong (Jiao Zuo, CN); Zhao, Tong Qian (Jiao Zuo, CN); Song, Dang Yu (Jiao Zuo, CN); Feng, Lei (Jiao Zuo, CN); Mao, Yu Xiang (Jiao Zuo, CN); Qi, Yong An (Jiao Zuo, CN); Zhang, Guo Cheng (Jiao Zuo, CN); Zhang, Li Jun (Jiao Zuo, CN); Wang, Juan (Jiao Zuo, CN).

This patent was filed on June 25, 2016 and was published online on August 12, 2019.

From the background information supplied by the inventors, news correspondents obtained the following quote: "Hydroxyl radical (.cndot.OH) is one of reactive oxygen radicals. Hydroxyl radical (.cndot.OH) has extremely strong oxidizing property with an oxidation reduction potential of 2.80 V, which is second only to that of fluorine atom and is capable of reacting with most inorganics or organics at a diffusion controlled rate with a reaction rate constant of generally greater than 10.sup.8 mol L.sup.-1 s.sup.-1. In the field of environmental science, hydroxyl radicals are used for degradation treatment of organic pollutants and are the most important reactive intermediates in the advanced oxidation processes (AOPs) for sewage treatment.

"There are many methods for generating hydroxyl radicals, which can be broadly classified into chemical catalysis method, ozone/hydrogen peroxide photolysis method, photocatalysis method, electrocatalysis method, ray method, and so on. The chemical catalysis method generally uses Fenton reaction, and hydroxyl radicals are generated by catalyzing decomposition of hydrogen peroxide with iron ions. Although the method is simple, easy and cheaper, a large amount of iron-containing sludge is generated when it is applied on a larger scale, causing inconvenient subsequent processing. Ozone and hydrogen peroxide are photolyzed under the irradiation of ultraviolet light and hydroxyl radicals can be generated; however, it is needed to add hydroxyl radical precursors, such as ozone and hydrogen peroxide, and there are more side reactions. Generating hydroxyl radicals by photocatalysis with semiconductor titanium dioxide particles and the like as a catalyst needs to ensure that the catalyst is in a suspended state, and it is also needed to separate the photocatalyst simultaneously for the photocatalysis, providing poor continuous operation, and the dissolved oxygen has a greater influence on the generation of hydroxyl radicals by photocatalysis using titanium dioxide. The method for generating hydroxyl radicals by electrocatalysis has higher requirements for the dissolved oxygen in water and its catalytic components, and has lower current efficiency. There are problems of higher cost and greater harm to the human body in the ray method.

"Therefore, the current commonly used methods for generating hydroxyl radicals have more side reactions, have poor operability and low efficiency, or have a great harm to the environment or the human body. Accordingly, the existing methods for generating hydroxyl radicals each have their own problems, and thus it is difficult for their popularization and application."

Supplementing the background information on this patent, NewsRx reporters also obtained the inventors' summary information for this patent: "In view of the drawbacks in the prior arts mentioned above, it is the object of the present invention to provide a novel method for generating hydroxyl radicals and a method for treating organic pollutants utilizing the generated hydroxyl radicals. It is desired that the inventive method has the advantages of adjustability, low cost, simple process, easy operation but no secondary pollution, and can remove phenol, bisphenol A, thiamphenicol and other typical organic pollutants in water very well.

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"Specifically, the present invention provides a method for generating hydroxyl radicals by utilizing an organic membrane, characterized in that, the method comprises:

"1) preparing a nitrocellulose sheet material;

"2) placing the nitrocellulose sheet material in an aqueous solution;

"3) irradiating the surface of the nitrocellulose sheet material by light with the wavelength above 280 nm, using the nitrocellulose sheet material as a photocatalytic material, so that the nitrocellulose sheet material undergoes a photochemical reaction at the membrane surface and generates hydroxyl radicals.

"Preferably, a light source used in irradiating the nitrocellulose sheet material is the sunlight or a sunlamp having a wavelength above 280 nm.

"Preferably, the nitrocellulose sheet material is a nitrocellulose membrane.

"Preferably, the time for irradiating the surface of the nitrocellulose sheet material is longer than or equal to 60 min.

"Preferably, the method further comprises adjusting the generation rate of hydroxyl radicals by adjusting the surface area of the membrane or adjusting intensity of the light.

"In another aspect, the present invention provides a method for generating hydroxyl radicals to remove organic pollutants in water by utilizing an organic membrane, characterized in that, the method comprises:

"1) preparing a nitrocellulose sheet material;

"2) placing the nitrocellulose sheet material in a liquid containing water and organic pollutants;

"3) irradiating the surface of the nitrocellulose sheet material by light having a wavelength of more than 280 nm, using the nitrocellulose sheet material as a photocatalytic material, so that the nitrocellulose sheet material undergoes a photochemical reaction at the membrane surface and generates hydroxyl radicals;

"4) carrying out oxidation decomposition of the organic pollutants in the liquid by utilizing the generated hydroxyl radicals.

"Preferably, the method is applied in removing phenol, bisphenol A and thiamphenicol in water.

"Preferably, a light source used in irradiating the nitrocellulose sheet material is the sunlight or a sunlamp having a wavelength of more than 280 nm.

"Preferably, the time for irradiating the surface of the nitrocellulose sheet material is greater than or equal to 60 min.

"Preferably, the method further comprises adjusting the generation rate of hydroxyl radicals by adjusting the surface area of the membrane or adjusting intensity of the light.

"The nitrocellulose mentioned in the present invention has a molecular structural formula as follows:

"##STR00001##

"In conclusion, the method for generating hydroxyl radicals according to the present invention generates hydroxyl radicals by adopting a nitrocellulose membrane as a photocatalytic material, placing the nitrocellulose membrane in water or an aqueous solution, illuminating with the sun or a sunlamp having a wavelength of greater than 280 nm as a light source, and causing the nitrocellulose membrane to undergo a photochemical reaction at the membrane surface, the generation rate of hydroxyl radicals can be achieved by adjusting a surface area of the membrane and a light intensity, and the generated hydroxyl radicals can remove phenol, bisphenol A, thiamphenicol and other typical organic pollutants in water very well.

"Nitrocellulose has high quality at a low price, and is widely used in the fields of ink, leather, plastic articles, etc. Nitrocellulose is the main material of microporous filtering membrane, and has a very mature membrane forming process. The invention finds that nitrocellulose can generate hydroxyl radicals under illuminating, and that nitrocellulose serving as a photocatalytic material for generating hydroxyl radicals under light radiation having a wavelength above 280 nm, has good effect of removing organic pollutants and thus is expected to be applied to the field of water treatment.

"The applicant finds that, compared with other wavelengths, UVB (280.about.320 nm) has extremely obvious advantageous when being used to photocatalyze the nitrocellulose membrane to generate hydroxyl radicals, the effect of which is 8 times of UVA (320.about.400 nm). Therefore, preferably, light in UVB spectrum range is used for illuminating the nitrocellulose membrane. Preferably, wavelength of illumination light source is 280.about.320 nm.

"In another preferred embodiment, the nitrocellulose membrane is made into a wavy shape with its surface in the form of a sine wave. The applicant finds that the light utilization rate of the nitrocellulose membrane having such structure is significantly higher than that of ordinary flat nitrocellulose membrane and also higher than those of other forms of cellulose membranes.

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"The invention has the advantageous effects as follows:

"1. In the inventive method, hydroxyl radicals are generated on the surface of the nitrocellulose membrane, facilitating recycling and reusing, and solving the problems of difficult recycling of particle catalysts, and the inventive method can stably and continuously generate hydroxyl radicals at a uniform speed, achieving controlled generation of hydroxyl radicals;

"2. The inventive method does not need to bring in any hydroxyl radical precursor, avoiding secondary pollution;

"3. Ultraviolet light radiation having a wavelength of greater than 280 nm can cause the nitrocellulose membrane to generate hydroxyl radicals, so the sunlight can be directly utilized, reducing the cost for water treatment;

"4. Since the mutual light-shading problem of particle catalysts has been overcome by adopting the nitrocellulose membrane, the generation rate of hydroxyl radicals can be adjusted by adjusting the area of the membrane or adjusting intensity of the light;

"5. As compared with currently adopted titanium dioxide catalyst, the nitrocellulose is low in price and is easily to be promoted and applied on a large scale."

The claims supplied by the inventors are:

"The invention claimed is:

"1. A method for generating hydroxyl radicals by utilizing an organic membrane, the method comprising: 1) preparing a nitrocellulose sheet material, which is used as the organic membrane; 2) placing the nitrocellulose sheet material in an aqueous solution; 3) irradiating a surface of the nitrocellulose sheet material by light having a wavelength of above 280 nm with the nitrocellulose sheet material as a photocatalytic material, so that the nitrocellulose sheet material undergoes a photochemical reaction at the surface of the nitrocellulose sheet material, generating hydroxyl radicals.

"2. The method according to claim 1, wherein the light used to irradiate the nitrocellulose sheet material is sunlight or light having a wavelength above 280 nm emitted by a sunlamp.

"3. The method according to claim 1, wherein the nitrocellulose sheet material is a nitrocellulose membrane.

"4. The method according to claim 1, wherein a time for irradiating the surface of the nitrocellulose sheet material is longer than or equal to 60 min.

"5. The method according to claim 1, further comprising: adjusting a generation rate of hydroxyl radicals by adjusting a surface area of the membrane and adjusting an intensity of the light.

"6. A method for generating hydroxyl radicals to remove organic pollutants in water by utilizing an organic membrane, the method comprising: 1) preparing a nitrocellulose sheet material, which is used as the organic membrane; 2) placing the nitrocellulose sheet material in a liquid containing water and organic pollutants; 3) irradiating a surface of the nitrocellulose sheet material by light having a wavelength of above 280 nm, using the nitrocellulose sheet material as a photocatalytic material, so that the nitrocellulose sheet material undergoes a photochemical reaction at the surface of the nitrocellulose sheet material and generates hydroxyl radicals; 4) carrying out oxidation decomposition of the organic pollutants in the liquid by utilizing the generated hydroxyl radicals.

"7. The method according to claim 6, wherein the organic pollutants removed from water are phenol, bisphenol A and thiamphenicol.

"8. The method according to claim 6, wherein the light used in irradiating the nitrocellulose sheet material is sunlight or light having a wavelength above 280 nm emitted by a sunlamp.

"9. The method according to claim 6, wherein a time for irradiating the surface of the nitrocellulose sheet material is greater than or equal to 60 min.

"10. The method according to claim 6, further comprising: adjusting a generation rate of hydroxyl radicals by adjusting a surface area of the membrane and adjusting an intensity of the light."


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