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Title:
PHOTOCATALYST CARBON FILTER MEDIUM AND PREPARATION METHOD AND USE THEREOF
Document Type and Number:
WIPO Patent Application WO/2018/019635
Kind Code:
A1
Abstract:
The present invention relates to the field of end point drinking water treatment, and to a water purification filter. Disclosed are a photocatalyst carbon filter medium and a preparation method and use thereof. It comprises a carbon filter medium body, with a photocatalyst layer being provided on the carbon filter medium body, and the carbon filter medium is used as a support. The carbon filter medium has a complex pore structure, so can adsorb, at a deep level, minute particles, colloids, bacteria and suspended matter in filtered water. The carbon filter medium is used as a support, effectively combining adsorption with degradation, and can greatly enhance the photocatalytic efficiency of TiO2, to effectively remove organic pollutants, which degrade with difficulty, from drinking water. Moreover, the invention also has characteristics such as an easily controlled reaction and easy operations, and has very broad prospects for market development and applications in the field of purification of household end point drinking water.

Inventors:
CHEN LEI (CN)
CHEN LIANJIE (CN)
HUANG MIAOQUAN (CN)
PENG KAIQIN (CN)
SU FENG (CN)
TAN TAO (CN)
TU JINJUN (CN)
ZHANG ZHONGQI (CN)
Application Number:
PCT/EP2017/068012
Publication Date:
February 01, 2018
Filing Date:
July 17, 2017
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
UNILEVER PLC (GB)
ZHEJIANG QINYUAN WATER TREAT S T CO LTD (CN)
International Classes:
C02F1/32; C02F1/28
Foreign References:
EP2181720A12010-05-05
EP1656985A12006-05-17
JPH11319580A1999-11-24
CN104150561A2014-11-19
CN102641731A2012-08-22
Other References:
None
Attorney, Agent or Firm:
REIJNS, Tiemen Geert Pieter (NL)
Download PDF:
Claims:
Claims

1. A solid photocatalyst carbon filter medium, comprising a carbon filter medium body (1 ), wherein a photocatalyst layer (2) is provided on the carbon filter medium body (1 ).

2. A photocatalyst carbon filter medium according to claim 1 , wherein the carbon filter medium body (1 ) is cylindrical, and the photocatalyst layer (2) is applied to an inside wall of the carbon filter medium body (1 ).

3. A filter comprising a photocatalyst carbon filter medium according to claims 1 or

2 as a filter, wherein a lamp (3) is provided in the carbon filter medium body (1 ).

4. A filter apparatus according to claim 3, wherein, the lamp (3) is an ultraviolet germicidal lamp.

5. The filter apparatus according to claims 3 or 4, wherein carbon filter medium body (1 ) is provided with a bottom end cover (4) at the bottom.

6. A method for preparing the photocatalyst carbon filter medium according to claims 1 or 2, the method comprising the steps of: a. washing a carbon filter medium body (1 ) in a solvent and water, and drying, ;

b. mixing a titanium precursor and anhydrous solvent to form a solution, and applying the solution uniformly to inner surface of the carbon filter medium body (1 ) obtained from step a, then drying;

c. calcining the carbon filter medium body (1 ) processed in step b to obtain a nano photocatalyst carbon filter medium.

7. A method for preparing a photocatalyst carbon filter medium according to claim 1 , wherein the solvent of step a is ethanol.

8. A method for preparing a photocatalyst carbon filter medium according to claims

3 or 4, wherein the solvent of step b is ethanol.

9. A method for preparing a photocatalyst carbon filter medium according to anyone of the preceding claims 3 to 5, wherein volume ratio of ethanol to water in the step a ranges from 1 : 3 to 1 :1 , and the washing time in each case ranges from 0.5 to 2 h.

10. A method for preparing a photocatalyst carbon filter medium according to anyone of the preceding claims 3 to 6, wherein in the solution of step b, volume ratio of tetrabutyl titanate to solvent ranges from 1 :6 to 1 :1.

1 1 . A method for preparing a photocatalyst carbon filter medium according to anyone of the preceding claims 3 to 7, wherein, the calcining process in step c comprises: increasing the temperature of the carbon filter medium processed in step b to 120 - 180°C at the rate of 3 - 5°C/min at first, maintaining it for 1 to 2 hours, then increasing it to 350 to 550°C at the rate of 3 - 5°C/min, and maintaining for 2.5 - 5.5 h, and allowing the carbon filter medium to cool.

12. A photocatalyst carbon filter medium obtainable by method according to claims 6 to 1 1.

13. Use of a photocatalyst carbon filter medium according to claims 1 , 2 or 12 in water purification.

14. Use of nano form of ΤΊΟ2 in a carbon filter medium for degradation of organic contaminants in water in the carbon filter medium.

15. Use of a Titanium precursor for use in a method to prepare photocatalyst carbon filter medium according to claims 1 or 2.

Description:
PHOTOCATALYST CARBON FILTER MEDIUM AND PREPARATION METHOD

AND USE THEREOF

Field of the invention

The present invention relates to the field of end point drinking water treatment, in particular to a water purification filter.

Background of the invention

At present, water supply systems in generally comprise water source ground, a municipal water supply plant, and a pipe network system for distributing water, which finally arrives at end users' homes. A municipal water supply plant generally employs a conventional process of coagulation, sedimentation, filtration, and disinfection by chlorination. This process principally removes suspended matter and colloidal impurities from water source water, and the main indices for process control are the outputted water's turbidity, colour and total number of bacteria. However, the capacity of the process for removing soluble organic matter from water is low, especially in the case of disinfection by-products which form after chlorination. Moreover, the process is largely unable to effectively remove contaminants such as permanganate index, ammonia nitrogen and pathogenic protozoa, largely unable to effective resolve the contradiction between water source contamination and the raising of water quality standards, and even less able to effectively respond to sudden water contamination events. Furthermore, when water sits in a pipe network system for distributing water for a period of time, various physical, chemical and microbial effects etc. will cause the water quality to deteriorate. All of these factors mean that the safety of the end user's drinking water cannot be guaranteed.

When a T1O2 semiconductor material is excited by visible light or ultraviolet (UV) light, electrons (e-) in the valence band thereof will be excited into the conduction band, and migrate to the particle surface under the action of an electric field, forming holes (h+) in the valence band, and thereby forming electron/hole pairs with very high activity. An electron/hole pair can oxidize OH- and H2O on the T1O2 particle surface to form strongly oxidizing ΌΗ. At the same time, holes themselves can also seize electrons from organic pollutants adsorbed on the T1O2, causing them to be mineralized and decomposed into harmless CO2 and H2O. In addition, ΤΊ02 has advantages such as being free of toxicity, having good stability, a low cost and high catalytic activity, and being able to be used more than once.

Summary of the invention

First aspect of the present invention provides a solid photocatalyst carbon filter medium, comprising a carbon filter medium body, wherein a photocatalyst layer is provided on the carbon filter medium body.

Second aspect of the present invention provides a method for preparing the photocatalyst carbon filter medium according to the first aspect, the method comprising the steps of: a. washing a carbon filter medium body in a solvent and water, and drying; b. mixing a titanium precursor and anhydrous solvent to form a solution, and applying the solution uniformly to inner surface of the carbon filter medium body obtained from step a, then drying;

c. calcining the carbon filter medium body processed in step b to obtain a nano photocatalyst carbon filter medium.

A third aspect of the present invention provides a photocatalyst carbon filter medium obtainable by method of the second aspect.

Another aspect of the present invention provides use of a photocatalyst carbon filter medium according to the first or third aspect in water purification.

Another aspect of the present invention provides use of nano form of ΤΊΟ2 in a carbon filter medium for degradation of organic contaminants in water in the carbon filter medium.

Another aspect of the present invention provides use of a Titanium precursor for use in a method to prepare photocatalyst carbon filter medium according to the first aspect.

Brief Description of the Accompanying Drawings Figures 1 and 2 are structural schematic diagram of different embodiments of the present invention.

Detailed description of the invention

In response to the problem in the prior art that the treatment of end point drinking water has room for further improvement, the present invention provides a photocatalyst carbon filter medium for use in a filtration apparatus and a preparation method thereof.

The term nano form means nano sized, which is nanomaterials with diameters of <100 nm.

To solve the abovementioned technical problem, the present invention employs the following technical solution:

A photocatalyst carbon filter medium, comprising a carbon filter medium body, with a photocatalyst layer provided on the carbon filter medium body. The photocatalyst layer is provided on an inside wall of the carbon filter medium body. Since the carbon filter medium has a complex pore structure, it can adsorb, at a deep level, minute particles, colloids, bacteria and suspended matter in filtered water. The carbon filter medium is used as a support, and a photocatalyst material is loaded on the carbon filter medium for use. The problem of poor dispersibility of photocatalyst material can be effectively ameliorated, greatly enhancing the photocatalytic efficiency of T1O2.

Preferably, the carbon body is cylindrical, and the photocatalyst layer is applied to an inside wall of the carbon body.

The present invention provides a solid photocatalyst carbon filter medium, comprising a carbon filter medium body, wherein a photocatalyst layer is provided on the carbon filter medium body.

It is preferred that the carbon filter medium body is cylindrical, and the photocatalyst layer is applied to an inside wall of the carbon filter medium body. It is preferred that a lamp is provided in the carbon filter medium body. It is further preferred that the lamp is an ultraviolet germicidal lamp

It is preferred that carbon filter medium body is provided with a bottom end cover at the bottom.

The present invention also provides a method for preparing the photocatalyst carbon filter medium according to the present invention, the method comprising the steps of: a. washing a carbon filter medium body in a solvent and water, and drying; b. mixing a titanium precursor and anhydrous solvent to form a solution, and applying the solution uniformly to inner surface of the carbon filter medium body obtained from step a, then drying; c. calcining the carbon filter medium body processed in step b to obtain a nano photocatalyst carbon filter medium.

It is preferred that the solvent of step a is ethanol. It is also preferred that the solvent of step b is ethanol.

It is preferred that volume ratio of ethanol to water in the step a ranges from 1 : 3 to 1 : 1 , and the washing time in each case ranges from 0.5 to 2 h.

It is preferred that the solution of step b, volume ratio of tetrabutyl titanate to solvent ranges from 1 :6 to 1 :1 .

It is preferred that the calcining process in step c comprises: increasing the temperature of the carbon filter medium processed in step b to 120 - 180°C at the rate of 3 - 5°C/min at first, maintaining it for 1 to 2 hours, then increasing it to 350 to 550°C at the rate of 3 - 5°C/min, and maintaining for 2.5 - 5.5 h, and allowing the carbon filter medium to cool.

Preferably, the method comprises the following steps: a. washing a carbon filter medium body alternately in ethanol and water, then sun- drying, air-drying or oven-drying to a humidity of 65% - 80%, in preparation for use;

b. mixing tetrabutyl titanate and anhydrous ethanol to form a mixed solution, and applying the mixed solution uniformly to an inner surface of the carbon filter medium body processed in step a, then air-drying naturally;

c. putting the carbon processed in step b into a calcining furnace and calcining to obtain a nano photocatalyst carbon filter medium .

The T1O2 loading amount in the nano photocatalyst carbon filter medium obtained by this method can reach 5 - 20 mg/cm 2 , effectively improving the result in terms of degradation of organic contaminants in drinking water.

Preferably, the volume ratio of ethanol to water in step a is 1 : 3 to 1 : 1 , and the washing time in each case is 0.5 to 2 h.

Preferably, the volume ratio of tetrabutyl titanate to anhydrous ethanol in the mixed solution in step b is 1 : 6 - 1 : 1 ; the natural air-drying time is 24 to 96 h.

Preferably, in the calcining process in step c, too fast a rate of temperature increase will result in poor T1O2 formation, and a higher temperature will cause the crystal form of T1O2 to change. Therefore, the choice is made to increase the temperature to 120 to 180°C at the rate of 3 to 5°C/min at first, to maintain this temperature for 1 to 2 h, then to increase the temperature to 350 to 550°C at the rate of 3 to 5°C/min, to maintain this temperature for 2.5 to 5.5 h, and finally to cool naturally.

A filter apparatus with a photocatalyst carbon filter medium as a filter, with a lamp also provided in a carbon body. The carbon can, through adsorptive action, remove harmful substances such as some heavy metals, residual chlorine, abnormal colours and abnormal tastes from the original water. The photocatalyst material can, under the action of the lamp, completely decompose organic matter in water, which organic matter is harmful to the human body, into harmless CO2 and H2O. The carbon filter medium has a complex pore structure, so can adsorb, at a deep level, minute particles, colloids, bacteria and suspended matter in filtered water. The carbon filter medium is used as a support, effectively combining adsorption with degradation, and can greatly enhance the photocatalytic efficiency of the photocatalytic material, to effectively remove organic pollutants, which degrade with difficulty, from drinking water.

Preferably, the lamp is an ultraviolet germicidal lamp. The shell of the ultraviolet germicidal lamp not only enables the lamp to realize a catalysing effect on the photocatalytic material, but also endows the lamp with a germicidal action, further improving water purification capability.

Preferably, the bottom of the carbon filter medium body is provided with a bottom end cover.

Due to the adoption of the technical solution described above, the present invention has the following significant technical effects:

The use of a carbon filter medium as a support in the present invention greatly improves the photocatalytic efficiency of the photocatalyst T1O2, so organic pollutants which degrade with difficulty can be effectively removed from drinking water. Moreover, the invention also has characteristics such as an easily controlled reaction and easy operations, and has very broad prospects for market development and applications in the field of purification of household end point drinking water.

The present invention provides a photocatalyst carbon filter medium obtainable by method of the present invention.

The present invention provides use of a photocatalyst carbon filter medium according to the present invention.

The present invention provides use of nano form of T1O2 in a carbon filter medium for degradation of organic contaminants in water in the carbon filter medium.

The present invention provides use of a Titanium precursor for use in a method to prepare photocatalyst carbon filter medium according to the present invention. The names of the parts represented by numerals in the drawings are as follows: 1 - carbon filter medium body; 2 - photocatalyst layer; 3 -lamp; 4 - bottom end cover.

The present invention is described in further detail below in conjunction with the accompanying drawings and embodiments.

The present invention provides a photocatalyst carbon filter medium, as shown in Fig. 1 , comprises a carbon filter medium body 1 which is cylindrical. A photocatalyst layer 2 is provided on the carbon filter medium body 1 ; specifically, the photocatalyst layer 2 is uniformly applied to an inside wall of the carbon filter medium body 1 . Since the photocatalyst material T1O2 has very strong hydrophilicity, and ultra-fine T1O2 aggregates very easily, and has poor dispersibility, it does not puce good results when used directly in the end point drinking water field. The carbon filter medium has a complex pore structure, so can adsorb, at a deep level, minute particles, colloids, bacteria and suspended matter in filtered water. The carbon filter medium is used as a support, and a photocatalyst material is loaded on the carbon filter medium for use. Adsorption and degradation can be effectively combined, and the photocatalytic efficiency of T1O2 can be greatly enhanced.

The present invention also provides a preferred method for preparing a photocatalyst carbon filter medium, comprising the following steps: a. step a: washing a carbon filter medium body 1 alternately in ethanol and water, wherein the volume ratio of ethanol to water is 1 : 3 to 1 : 1 , and the washing time in each case is 1 h, then sun-drying to a relative humidity of 65% - 80%, in preparation for use;

b. step b: mixing tetrabutyl titanate and anhydrous ethanol to form a mixed solution, wherein the volume ratio of tetrabutyl titanate to anhydrous ethanol in the mixed solution is 1 : 6 to 1 : 1 ; in this embodiment, stirring 4.34 mL of tetrabutyl titanate with 25 mL of anhydrous ethanol to mix evenly, then uniformly applying the mixed solution to an inner surface of the carbon filter medium body 1 processed in step a, then air-drying naturally for 24 h.

c. Step c: putting the carbon filter medium processed in step b into a calcining furnace and calcining to obtain a nano photocatalyst carbon filter medium , wherein a calcining process is specifically as follows: the temperature is increased to 120°C at the rate of 3°C/min at first, this temperature is maintained for 1 h, then the temperature is increased to 350°C at the rate of 3°C/min, this temperature is maintained for 2.5 h, and finally natural cooling takes place, to give the required nano photocatalyst carbon filter medium . The T1O2 loading amount in the nano photocatalyst carbon filter medium obtained by this method is 5 mg/cm 2 .

The present invention also provides a method, wherein, except that in step a of the method for preparing a nano photocatalyst carbon filter medium , oven-drying is used to bring the relative humidity to 65% - 80%, and in step b, a volume of 8.68 mL of tetrabutyl titanate is used, to obtain a T1O2 loading amount of 10 mg/cm 2 .

The present invention also provides a method, wherein, except that in step a of the method for preparing a nano photocatalyst carbon filter medium , air-drying is used to bring the relative humidity to 65% - 80%, and in step b, the volume of tetrabutyl titanate is 17.36 mL, to obtain a T1O2 loading amount of 20 mg/cm 2 .

The present invention provides a filterin which the photocatalyst carbon filter medium of the present invention is used as a filter is shown in Fig. 2; a lamp 3 is also provided in the carbon filter medium body 1 , the lamp 3 being an ultraviolet germicidal lamp. The bottom of the carbon filter medium body 1 is provided with a bottom end cover 4.

Under a certain water pressure, original water flows into the interior of the carbon filter medium body 1 from outside the carbon filter medium body 1 . During this process, the carbon filter medium filter adsorbs harmful substances such as some heavy metals, residual chlorine, abnormal colours and abnormal tastes from the original water. The photocatalyst material attached to the water purification chamber of the carbon filter medium, when irradiated by the ultraviolet germicidal lamp, subjects the water in the water purification chamber to a photocatalytic reaction, to remove from the water harmful organic matter that degrades with difficulty, and has a germicidal action. Moreover, in this embodiment, the lamp 3 is an ultraviolet germicidal lamp, which not only can have a catalysing effect on the photocatalyst, but at the same time can itself have a germicidal effect.

The nano photocatalyst carbon filter medium performs treatment to remove organic pollutants: a filter apparatus is used to perform a test; water containing different concentrations of organic pollutants has its flow speed adjusted by means of an electromagnetic flow meter, then is pressed in from outside the filter, and after undergoing the photocatalytic action of the photocatalyst on the inner surface, comes out; the original water and outputted water are respectively sampled to measure the change in the COD (chemical oxygen demand) thereof. Specifically, this is divided into the following cases:

First case: under the condition that the same initial COD concentration, incoming water flow speed and ultraviolet germicidal lamp power are used, a blank carbon filter medium is used or nano photocatalyst carbon filter medium filters with different ΤΊΟ2 loading amounts are used to perform a water passage test, to obtain different changes in COD. See table 1 for specific changes.

Second case: under the condition that the same initial COD concentration and incoming water flow speed are used, no ultraviolet germicidal lamp is used for irradiation or different ultraviolet germicidal lamp powers are used, and a nano photocatalyst carbon filter medium filter with a ΤΊΟ2 loading amount of 10 mg/cm 2 is subjected to a water passage test, to obtain different changes in COD. See table 2 for specific changes.

Third case: using different initial COD concentrations but the same incoming water flow speed and ultraviolet germicidal lamp power, a nano photocatalyst carbon filter medium filter with a T1O2 loading amount of 10 mg/cm 2 is subjected to a water passage test, to obtain different changes in COD. See table 3 for specific changes.

Fourth case: using the same initial COD concentration and ultraviolet germicidal lamp power, different incoming water flow speeds are used to subject a nano photocatalyst carbon filter medium filter with a T1O2 loading amount of 10 mg/cm 2 to a water passage test, to obtain different changes in COD. See table 3 for specific changes. EXAMPLES

Table 1 : treatment results for different loading amounts

Table 2: treatment results for carbon filter medium with T1O2 loading amount of 10 mg/cm 2 when irradiated by different UV germicidal lamps

Table 3: treatment results for carbon filter medium with T1O2 loading amount of 10 mg/cm 2 for different initial COD values

Index COD before COD after treatment Removal rate (%) Material treatment (mg/L) (mg/L)

Nano photocatalyst 10 0.1 99

carbon filter medium 20 0.8 96

50 6.5 87 (T1O2 loading

amount 10 mg/cm 2 )

Table 4: treatment results for carbon filter medium with T1O2 loading amount of 10 mg/cm 2 for different flow speeds

Therefore, the photocatalytic efficiency of the nano photocatalyst carbon filter medium is closely linked to the loading amount, UV light intensity, initial pollutant concentration and flow speed. Moreover, the tables above can also effectively prove that if a photocatalyst material is loaded on a carbon filter medium for use in water purification treatment, adsorption and degradation are effectively combined, and the removal rate of organic pollutants which degrade with difficulty from drinking water can be significantly increased.

The embodiments above are merely preferred embodiments of the present invention. All equivalent changes and modifications made within the patent application scope of the present invention shall be included in the scope of the present invention patent.