WO2021139012A1 - 活化聚四氟乙烯的方法及应用 - Google Patents

活化聚四氟乙烯的方法及应用 Download PDF

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WO2021139012A1
WO2021139012A1 PCT/CN2020/082740 CN2020082740W WO2021139012A1 WO 2021139012 A1 WO2021139012 A1 WO 2021139012A1 CN 2020082740 W CN2020082740 W CN 2020082740W WO 2021139012 A1 WO2021139012 A1 WO 2021139012A1
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polytetrafluoroethylene
ptfe
ultrasonic
activating
wastewater
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PCT/CN2020/082740
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English (en)
French (fr)
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高冠道
王炎锋
蒲良桃
丁杰
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南京大学
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Priority to US16/903,336 priority Critical patent/US11453753B2/en
Publication of WO2021139012A1 publication Critical patent/WO2021139012A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/12—Chemical modification
    • C08J7/123—Treatment by wave energy or particle radiation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/34—Treatment of water, waste water, or sewage with mechanical oscillations
    • C02F1/36—Treatment of water, waste water, or sewage with mechanical oscillations ultrasonic vibrations
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation
    • C02F1/725—Treatment of water, waste water, or sewage by oxidation by catalytic oxidation
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
    • C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
    • C08J2327/12—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
    • C08J2327/18—Homopolymers or copolymers of tetrafluoroethylene

Definitions

  • the present invention relates to the technical field of polytetrafluoroethylene (hereinafter referred to as "PTFE”) materials, in particular to a method for activating PTFE and its application in sewage treatment, electricity production, and hydrogen production.
  • PTFE polytetrafluoroethylene
  • inorganic piezoelectric materials such as barium titanate, lead titanate, strontium titanate, lithium gallate, lithium germanate, and organic piezoelectric materials such as polyvinylidene fluoride ( PVDF) and composite piezoelectric materials are widely used in transducers, piezoelectric actuators, pressure sensors, ultrasonic sensors, etc.
  • PVDF polyvinylidene fluoride
  • nano- or micro-piezoelectric catalysts have gradually been used in the treatment of environmental pollutants.
  • the basic principle of purifying pollutants is that the piezoelectric catalyst deforms after being subjected to external forces, and the positive and negative charge centers of the internal dipoles are no longer The coincidence causes the macroscopic polarization of the crystal to form an internal electric field.
  • the free interior of the catalyst carriers, such as electron (e -), the holes acting (+ h), including the separation electric field is obtained, free charge carriers migrate to the surface of the material and the body of water OH -, O 2, H +, etc.
  • the Chinese invention patent application document with publication number CN110092440A discloses a method for efficiently degrading dye wastewater using piezoelectric catalysis.
  • the application document deposits silver element on the basis of potassium sodium niobate piezoelectric ceramics, thereby improving the separation of positive and negative charges. Efficiency, has a good degradation effect on dye wastewater.
  • the Chinese invention patent application document with publication number CN109970153A discloses a method for efficiently degrading organic pollutants with WSe 2 nanosheet piezoelectric catalyst. This application document designs a thin-layer WSe 2 nanosheet, which makes full use of the variability and piezoelectricity. The advantage of high coefficient is that it can remove tetracycline and rhodamine B better under the action of ultrasound.
  • the invention provides a method for activating polytetrafluoroethylene (PTFE), which uses ultrasonic waves to activate PTFE. After PTFE is activated by ultrasonic waves, it will produce macroscopic polarization to form electrets, which have piezoelectric activity.
  • PTFE polytetrafluoroethylene
  • the activated PTFE is used for electricity generation under the action of external force; in addition, PTFE can be used for electricity generation, hydrogen production or pollutant purification while being activated.
  • the method for activating PTFE provided by the present invention is obtained by the following scheme: the method for activating polytetrafluoroethylene includes ultrasonic treatment of the polytetrafluoroethylene material.
  • the ultrasonic frequency range is 20 kHz to 15 MHz.
  • the ultrasonic frequency is preferably 40 kHz to 1 MHz.
  • the power density of the ultrasonic is in the range of 0.1 to 400 W/cm 2 .
  • the power density is preferably 0.1-5 W/cm 2 .
  • the greater the intensity of the ultrasonic wave the greater the force acting on the PTFE material, the greater the deformation of PTFE, and the better the performance of the resulting piezoelectric catalysis.
  • the shape of the polytetrafluoroethylene material may be one or any combination of granular, film or block.
  • the PTFE material can be activated under the action of ultrasound, the smaller the size of the PTFE particles of the same quality, the more reactive sites and the better the catalytic performance.
  • the present invention also provides a method for generating electricity by using polytetrafluoroethylene, which includes performing activation treatment on a polytetrafluoroethylene material such as the above-mentioned method for activating polytetrafluoroethylene.
  • the upper and lower sides of the, respectively, are connected to the positive and negative electrodes, and pressure is applied to the electrodes.
  • the shape of the polytetrafluoroethylene material is a film shape.
  • the thickness of the polytetrafluoroethylene material ranges from 10 nm to 500 ⁇ m. The greater the thickness of the PTFE membrane, the stronger the structure. After the external force acts on the surface of the thick PTFE membrane, the deformation of the PTFE membrane is very small, and the voltage generated by it is also very weak.
  • the pressure range is 0-100 kPa.
  • the pressure acting on the surface of the PTFE membrane should not be too large. Excessive pressure will cause the PTFE membrane structure to collapse, which cannot permanently restore the original deformation and lose the original piezoelectric activity.
  • polytetrafluoroethylene material is subjected to ultrasonic treatment in an air or water environment.
  • the present invention also provides a method for producing hydrogen by using polytetrafluoroethylene, which includes placing the polytetrafluoroethylene material in a water environment and using the above-mentioned method of activating polytetrafluoroethylene for ultrasonic treatment, and collecting the hydrogen generated in the ultrasonic process.
  • the present invention also provides a method for purifying waste water by using polytetrafluoroethylene, which includes placing polytetrafluoroethylene materials in a waste water environment and using the above-mentioned method of activating polytetrafluoroethylene for ultrasonic treatment to obtain substances with strong oxidizing ability or Substances with strong reducing ability, said substances with strong oxidizing ability can be used to oxidize pollutants in wastewater, and said substances with strong reducing ability can be used to reduce pollutants in wastewater.
  • the wastewater can be domestic wastewater or industrial wastewater.
  • Industrial wastewater includes printing and dyeing wastewater, pesticide wastewater, pharmaceutical wastewater, tanning wastewater, and metallurgical wastewater.
  • the substance with strong oxidizing ability includes one or more of hydroxyl radicals, superoxide radicals and singlet oxygen. These substances have good oxidation removal effects on domestic wastewater, printing and dyeing wastewater, pesticide wastewater, medical wastewater, tanning wastewater, and metallurgical wastewater in domestic wastewater and industrial wastewater.
  • the substance with strong reducing ability is active hydrogen radical.
  • the dosage of the polytetrafluoroethylene material is 10-2000 mg/L. Because PTFE is hydrophobic and the dosage is too high, the excess PTFE cannot be well dispersed in the aqueous solution, and the piezoelectric catalytic performance cannot be exerted under the action of ultrasonic waves.
  • PTFE is an organic perfluoropolymer, which has the advantages of high temperature resistance, corrosion resistance, and low friction coefficient. It is insoluble in any strong acid, strong alkali and other organic solvents below 300°C. Due to its superior chemical and physical properties, it is currently widely used in the fields of electronics, medicine, chemical industry, aerospace, etc.
  • the PTFE activation method provided by the present invention more specifically, uses ultrasonic waves to activate PTFE.
  • PTFE After PTFE is activated by ultrasonic waves, it will produce Macroscopically polarized to form electrets, which have piezoelectric catalytic activity. Compared with the previously reported inorganic piezoelectric catalysts, the structure of PTFE is more stable; compared with the piezoelectric catalytic reaction under the same conditions, the performance of PTFE piezoelectric catalytic degradation of pollutants is also better.
  • PTFE is considered to be resistant to acids, alkalis and various organic solvents, and is currently used as an extremely inert material in real life.
  • the present invention provides a method for activating PTFE by using ultrasonic technology, which can broaden the current understanding of PTFE.
  • the present invention provides a method for activating PTFE using ultrasonic waves.
  • PTFE has a wide range of applications during and after activation. After PTFE is activated by ultrasound, it transforms from its original inert state to a polarized state, and has excellent piezoelectric catalytic performance.
  • the ultrasonic wave is applied to the continuous PTFE, PTFE causes a hole (h +), hydroxyl radical ( ⁇ OH), superoxide radical ( ⁇ O 2 -) and strong singlet oxygen (1 O 2) oxidation, etc.
  • reactive species and e - strong active hydrogen radical ( ⁇ H) and other reactive species reducing ability can realize the oxidation and reduction removal of refractory pollutants in domestic and industrial wastewater in the water environment, and can also realize the decomposition of water to produce hydrogen.
  • the activated PTFE becomes a new catalyst, which is less affected by the pH, salinity and temperature of the actual wastewater, and its structure is still stable after repeated use.
  • PTFE is activated by ultrasound, it becomes a new piezoelectric material, which has potential applications in machinery, highway transportation, construction, medicine, aviation and navigation.
  • Figure 1 shows the performance diagram of PTFE membrane degrading methyl orange under the action of ultrasonic.
  • Figure 2 is a piezoelectric micrograph of PTFE before and after ultrasonic activation (A in the figure is the initial state of PTFE, and B is after ultrasonic activation).
  • Figure 3 shows the electricity generation diagram of the PTFE membrane under different external forces after ultrasonic activation.
  • Figure 4 is a diagram of free radicals generated by PTFE micropowder under the action of ultrasound (in the figure, A is with PTFE powder and B is without PTFE powder).
  • Figure 5 is a performance diagram of PTFE micropowder degrading methyl orange (A) and tetrachlorophenol (B) under the action of ultrasound.
  • Figure 6 is a performance diagram of PTFE micropowder degrading methyl orange under the action of high frequency ultrasound.
  • Figure 7 shows the hydrogen production diagram of PTFE micropowder under the action of ultrasound.
  • the invention provides a method for activating polytetrafluoroethylene (PTFE), which uses ultrasonic waves to activate PTFE. After PTFE is activated by ultrasonic waves, it will produce macroscopic polarization to form electrets, which have piezoelectric activity.
  • PTFE polytetrafluoroethylene
  • the activated PTFE is used for electricity generation under the action of external force; in addition, PTFE can be used for electricity generation, hydrogen production or pollutant purification while being activated.
  • the method of activating polytetrafluoroethylene includes: ultrasonic treatment of polytetrafluoroethylene material.
  • the environment of ultrasonic treatment can be in the water environment or in the air.
  • PTFE is an organic perfluoropolymer, which has the advantages of high temperature resistance, corrosion resistance, and low friction coefficient. It is insoluble in any strong acid, strong alkali and other organic solvents below 300°C. Due to its superior chemical and physical properties, it is currently widely used in the fields of electronics, medicine, chemical industry, aerospace, etc.
  • the PTFE activation method provided by the present invention more specifically, uses ultrasonic waves to activate PTFE.
  • PTFE After PTFE is activated by ultrasonic waves, it will produce Macroscopically polarized to form electrets, which have piezoelectric catalytic activity. Compared with the previously reported inorganic piezoelectric catalysts, the structure of PTFE is more stable; compared with the piezoelectric catalytic reaction under the same conditions, the performance of PTFE piezoelectric catalytic degradation of pollutants is also better.
  • the ultrasonic treatment equipment includes, but is not limited to, an ultrasonic cleaning machine, an ultrasonic treatment instrument, and a cell disruptor.
  • the operating parameters of ultrasonic equipment when PTFE is activated include ultrasonic frequency, ultrasonic power density and ultrasonic time.
  • the conditions of the ultrasonic treatment are 20kHz-15MHz; the ultrasonic power density is 0.1-400W/cm 2 .
  • the greater the intensity of the ultrasonic wave the greater the force acting on the PTFE material, the greater the deformation of PTFE, and the better the performance of the resulting piezoelectric catalysis.
  • the ultrasonic frequency is more preferably 40 kHz to 1 MHz.
  • the power density of ultrasound transmitting power (W) of ultrasound/transmitting area (cm 2 ), more preferably 0.1 to 200 W/cm 2 ; still more preferably 0.1 to 50 W/cm 2 ; still more preferably It is 0.1 to 10 W/cm 2 ; most preferably, it is 0.1 to 5 W/cm 2 .
  • the ultrasonic frequency is preferably 40 kHz to 1 MHz; the ultrasonic power density is 0.1 to 5 W/cm 2 .
  • an ultrasonic cleaning machine or an ultrasonic therapeutic apparatus can be used.
  • the ultrasound time is unlimited. Once PTFE is subjected to ultrasound, it can be activated and has excellent piezoelectric catalytic reaction activity. At the same time, as long as the ultrasonic waves are always acting on the PTFE, the PTFE can always generate free carriers, and the piezoelectric catalytic reaction can continue to occur.
  • the shape of the polytetrafluoroethylene material can be one or any combination of granular, film or block.
  • the PTFE material can be activated under the action of ultrasound, the smaller the size of the PTFE particles of the same quality, the more reactive sites and the better the catalytic performance.
  • the granular polytetrafluoroethylene material includes polytetrafluoroethylene nano-particles and polytetrafluoroethylene micro-particles, with a particle size of 0.1 nm to 500 ⁇ m; the thickness of the film-shaped polytetrafluoroethylene material is 10 nm to 500 ⁇ m; The size of the PTFE material is 0.01cm 3 ⁇ 1cm 3 .
  • the invention also provides a method for purifying sewage and generating clean energy by using polytetrafluoroethylene.
  • the purification of sewage includes the purification of domestic wastewater, the oxidation and reduction removal of industrial wastewater, printing and dyeing wastewater, pesticide wastewater, medical wastewater, tanning wastewater, and metallurgical wastewater; the production of clean energy includes electricity and hydrogen production.
  • activating polytetrafluoroethylene and simultaneously purifying the wastewater includes: placing the polytetrafluoroethylene material in the wastewater to be treated for ultrasonic treatment.
  • the wastewater to be treated is domestic wastewater or industrial wastewater, and industrial wastewater includes printing and dyeing wastewater, pesticide wastewater, medical wastewater, tanning wastewater, and metallurgical wastewater.
  • the ultrasonic treatment conditions are the same as the ultrasonic treatment conditions activated by PTFE.
  • PTFE catalytically degrades pollutants under the action of ultrasound: PTFE is activated under the action of ultrasound, and the continuous action of ultrasound will produce reactive species with strong oxidizing ability such as h + , ⁇ OH, ⁇ O 2 - and 1 O 2. These active species have good oxidation removal effects on domestic wastewater, printing and dyeing wastewater, pesticide wastewater, medical wastewater, tanning wastewater, and metallurgical wastewater in domestic wastewater and industrial wastewater.
  • the PTFE material is PTFE nano particles or powder, PTFE micro particles or powder and PTFE membrane, and the dosage of PTFE material in the wastewater to be treated is 10-2000 mg/L. Because PTFE is hydrophobic and the dosage is too high, the excess PTFE cannot be well dispersed in the aqueous solution, and the piezoelectric catalytic performance cannot be exerted under the action of ultrasonic waves.
  • PTFE will produce reactive species with strong oxidation ability such as h + , ⁇ OH, ⁇ O 2 - and 1 O 2 during the catalytic reaction process .
  • reactive species with strong oxidation ability such as h + , ⁇ OH, ⁇ O 2 - and 1 O 2 during the catalytic reaction process .
  • h + is produced by PTFE itself during the reaction process; OH is converted from OH- or other intermediate free radicals; ⁇ O 2 - and 1 O 2 are obtained by the reaction of O 2 ; in the piezoelectric catalytic reaction process dominated by PTFE, the dissolved oxygen in the wastewater catalyzes The reaction has no obvious effect.
  • PTFE is catalytically reduced to produce hydrogen under the action of ultrasound: PTFE is activated under the action of ultrasound.
  • active species with strong oxidizing ability it can also produce active species with strong reducing ability such as e - and ⁇ H. Two H can produce hydrogen after recombination.
  • activating PTFE to produce hydrogen at the same time includes: placing the PTFE material in a water environment for ultrasonic treatment, and collecting the hydrogen generated during the ultrasonic process.
  • the ultrasonic treatment conditions are the same as the ultrasonic treatment conditions when PTFE is activated.
  • the water environment may be pure water, or domestic wastewater or industrial wastewater.
  • the dissolved oxygen concentration in the domestic wastewater or industrial wastewater It is 0 ⁇ 0.1mg/L.
  • the activation is performed at the same time to generate electricity.
  • the upper and lower sides of the PTFE material are connected with positive and negative electrodes, and the material is placed in an air or water environment for ultrasonic treatment, and the voltage generated during the ultrasonic process is collected.
  • the upper and lower sides are connected to the positive and negative electrodes respectively, and pressure is applied to the electrodes, and electricity can also be realized.
  • Ultrasonic activated PTFE is used for electricity generation: In addition to the continuous generation of free radicals during the ultrasonic process, PTFE also changes the positive and negative charge centers of its internal dipoles. Before ultrasonic activation, the positive and negative charge centers in PTFE are symmetrical, but after ultrasonic activation, the positive and negative charge centers inside are no longer symmetrical, resulting in PTFE always in a polarization state, and the polarization state will not be in a short time. disappear. From the piezoelectric force microscope image (Figure 2), it can be seen that obvious ferroelectric domains appear on the surface of PTFE after ultrasound, indicating that it is in a polarized state. Before ultrasound, no ferroelectric domains were observed on the surface of PTFE.
  • the PTFE material is selected as a membrane material; the thickness of the membrane material is 10 nm to 500 ⁇ m. The greater the thickness of the PTFE membrane, the stronger the structure. After the external force acts on the surface of the thick PTFE membrane, the deformation of the PTFE membrane is very small, and the voltage generated by it is also very weak. Therefore, the thinner, flexible and flexible PTFE membrane has better power generation performance under the action of external force.
  • the external pressure acting on the surface of the PTFE is 0-100 kPa.
  • the pressure acting on the surface of the PTFE membrane should not be too large. Excessive pressure will cause the PTFE membrane structure to collapse, which cannot permanently restore the original deformation and lose the original piezoelectric activity.
  • PTFE is considered to be resistant to acids, alkalis and various organic solvents, and is currently used as an extremely inert material in real life.
  • the present invention provides a method for activating PTFE by using ultrasonic technology, which can broaden the current understanding of PTFE.
  • the present invention provides a method for activating PTFE using ultrasonic waves.
  • PTFE has a wide range of applications during the activation process and after activation. After PTFE is activated by ultrasound, it transforms from its original inert state to a polarized state, and has excellent piezoelectric catalytic performance.
  • PTFE will produce reactive species with strong oxidizing power such as h + , ⁇ OH, ⁇ O 2 - and 1 O 2 and reactive species with strong reducing power such as e-and ⁇ H.
  • reactive species can realize the oxidation and reduction removal of refractory pollutants in domestic and industrial wastewater in the water environment, and can also realize the decomposition of water to produce hydrogen.
  • the activated PTFE becomes a new catalyst, which is less affected by the pH, salinity and temperature of the actual wastewater, and its structure is still stable after repeated use.
  • PTFE is activated by ultrasound, it becomes a new piezoelectric material, which has potential applications in machinery, highway transportation, construction, medicine, aviation and navigation.
  • the raw materials used in the examples are all commercially available products.
  • a round PTFE membrane with a diameter of 2.5cm and a thickness of 100 ⁇ m and a volume of 50mL of deionized water are put into a 100mL beaker, and the beaker is placed in an ultrasonic cleaning machine.
  • the power density of the ultrasonic cleaning machine is 0.3W/cm 2.
  • the ultrasonic frequency is 40kHz.
  • the PTFE membrane is taken out and dried at 60°C.
  • the polarization state of the PTFE membrane is measured under a piezoelectric force microscope. The specific results are shown in Figure 2B.
  • the PTFE membrane was not subjected to ultrasonic treatment, and the polarization state was directly measured under a piezoelectric force microscope. The specific results are shown in Figure 2 A.
  • a piece of square PTFE membrane with a length of 3cm and a volume of 50mL of deionized water are put into a 100mL beaker, and the beaker is placed in an ultrasonic cleaning machine.
  • the power density of the ultrasonic cleaning machine is 0.3W/cm 2 and the ultrasonic frequency is 40kHz.
  • After ultrasonic for 1 hour remove the PTFE membrane and dry it at 60°C.
  • the upper and lower sides of the ultrasonically treated PTFE membrane are connected to the copper mesh with conductive glue, and the copper mesh is connected to the voltage acquisition device. By applying different pressures on the PTFE membrane, the voltage changes at both ends of the copper mesh are detected.
  • the specific results are shown in Figure 3.
  • Example 3 Same as Example 3, the only difference is that the PTFE membrane has not been subjected to ultrasonic treatment. After the copper mesh is connected, the surface voltage is measured after applying pressure on the surface. The specific results are shown in Figure 3.
  • Example 7 Same as Example 7, except that PTFE micropowder was not added to the beaker; after sonicating for 1 hour, the absorbance of methyl orange was measured, and the experimental result was the same as that of Comparative Example 1.
  • Example 11 Same as Example 11, except that PTFE micropowder was not added to the sealed silk-top bottle; after 2 hours of ultrasonication, almost no hydrogen was detected.
  • Example 1 the removal rate of methyl orange by the PTFE membrane reached 71.3 ⁇ 0.3%.
  • Example 2-3 compared with the PTFE membrane that has not undergone ultrasonic treatment, the PTFE membrane after ultrasonic treatment can clearly see the existence of ferroelectric domains, and the voltage can be clearly detected by applying a certain pressure on the surface of the membrane. exist.
  • the PTFE powder may be generated during activation of the ultrasonic ⁇ OH, ⁇ O 2 -, 1 O 2 and ⁇ H; and in the control (without PTFE) Example 4-6 embodiment, the reaction system not detected ⁇ OH, ⁇ O 2 -, and ⁇ H, detected only a weak 1 O 2.
  • the removal rate of methyl orange and tetrachlorophenol can reach 89.7 ⁇ 0.01 and 96.3 ⁇ 1.3% by PTFE micropowder under the action of ultrasound, while the PTFE powder, methyl orange and tetrachlorophenol are not added.
  • the removal rate of phenol is only 1.1 ⁇ 0.3% and 6.1 ⁇ 0.9%.
  • the PTFE micropowder can also be excited to produce piezoelectric catalytic performance at a frequency of MHz. According to Example 11 and its control group, PTFE can produce hydrogen under the action of ultrasound.
  • PTFE can be activated under the action of ultrasound, and can produce oxidation and reduction active species during continuous action, which can realize the degradation and removal of environmental pollutants and the generation of clean energy hydrogen.

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Abstract

本发明公开一种活化聚四氟乙烯的方法及应用，其中活化聚四氟乙烯的方法包括：对聚四氟乙烯材料进行超声处理。PTFE经过超声波活化后会产生宏观极化，形成驻极体，其具有压电活性。经过活化的聚四氟乙烯作为压电材料，在外力作用下可用于产电。聚四氟乙烯在超声活化过程中能产生氧化能力较强的还原和氧化自由基，可用于产氢或污染物净化等。

Description

活化聚四氟乙烯的方法及应用 技术领域
本发明涉及聚四氟乙烯(以下记作“PTFE”)材料技术领域，具体涉及一种活化PTFE的方法及其在污水治理、产电、产氢中的应用。
背景技术
自1880年居里兄弟发现电气石具有压电效应以来，无机压电材料如钛酸钡、钛酸铅、钛酸锶、镓酸锂、锗酸锂，有机压电材料如聚偏氟乙烯(PVDF)以及复合压电材料被广泛应用于换能器、压电驱动器、压力传感器、超声波传感器等。
近十年，纳米或者微米压电催化剂逐渐被应用于环境污染物治理中，其净化污染物的基本原理是：压电催化剂受到外力作用后发生形变，内部偶极子的正负电荷中心不再重合，导致晶体发生宏观极化，形成内电场。催化剂内部的自由载流子如电子(e -)、空穴(h +)在内电场的作用得到分离，自由载流子迁移到材料表面后与水体中的OH -、O 2、H +等反应产生氧化能力极强的羟基自由基(·OH)、超氧自由基(·O 2 -)和单线态氧( 1O 2)以及还原能力极强的活性氢自由基(·H)，这些自由基可以对水中的污染物达到良好的氧化以及还原去除效果。
公开号为CN110092440A的中国发明专利申请文献公开了一种利用压电催化高效降解染料废水的方法，该申请文献在铌酸钾钠压电陶瓷的基础上沉积银单质，从而提高正负电荷的分离效率，对染料废水有良好的降解效果。公开号为CN109970153A的中国发明专利申请文献公开了一种WSe 2纳米片压电催化剂 高效降解有机污染物的方法，该申请文献设计了一种薄层WSe 2纳米片，充分利用易变性和压电系数高的优势，在超声波的作用下对四环素和罗丹明B有较好的去除效果。
发明内容
本发明提供一种活化聚四氟乙烯(PTFE)的方法，利用超声波来活化PTFE，PTFE经过超声波活化后会产生宏观极化，形成驻极体，其具有压电活性。经过活化后的PTFE在外力作用下用于产电；此外，PTFE在活化的同时可用于产电、产氢或污染物净化等。
本发明提供的活化PTFE的方法通过以下方案获得：活化聚四氟乙烯的方法，包括对聚四氟乙烯材料进行超声处理。
进一步地，对所述聚四氟乙烯材料进行超声处理时，超声频率范围为20kHz～15MHz。
进一步地，所述超声频率优选为40kHz～1MHz。
进一步地，对所述聚四氟乙烯材料进行超声处理时，超声的功率密度范围为0.1～400W/cm 2。
进一步地，所述功率密度优选为0.1～5W/cm 2。在一定范围内，超声波的强度越大，作用于PTFE材料上的作用力也越大，PTFE能够发生更大的形变量，产生的压电催化的性能也越好。
进一步地，所述聚四氟乙烯材料的形状可以为颗粒状、薄膜状或者块状中的一种或任意组合。只要是PTFE材料都能够在超声波的作用下被活化，同等质量的PTFE的颗粒，其尺寸越小，反应活性位点越多，催化性能也越好。
本发明还提供一种采用聚四氟乙烯产电的方法，包括对聚四氟乙烯材料如 上述的活化聚四氟乙烯的方法进行活化处理时或者活化处理后，在所述聚四氟乙烯材料的上下两面分别连接正负电极，并对所述电极施加压力。
进一步地，所述聚四氟乙烯材料的形状为薄膜状。
进一步地，所述聚四氟乙烯材料的厚度范围为10nm～500μm。PTFE膜的厚度如果越大，其结构越结实，外力作用于结构厚实的PTFE膜表面后，PTFE膜的形变量非常小，其产生的电压也很弱。
进一步地，所述压力范围为0～100kPa。作用于PTFE膜表面的压力不能太大，过大的压力会造成PTFE膜结构塌陷，不能永久恢复原来的形变，失去原来的压电活性。
进一步地，所述聚四氟乙烯材料在空气或者水环境中进行超声处理。
本发明还提供一种采用聚四氟乙烯产氢的方法，包括将聚四氟乙烯材料置于水环境中采用上述的活化聚四氟乙烯的方法进行超声处理，收集超声过程中产生的氢气。
本发明还提供一种采用聚四氟乙烯净化废水的方法，包括将聚四氟乙烯材料置于废水环境中采用上述的活化聚四氟乙烯的方法进行超声处理，获得具有强氧化能力的物质或者具有强还原能力的物质，所述具有强氧化能力的物质可用于氧化废水中的污染物，所述具有强还原能力的物质可用于还原废水中的污染物。废水可为生活废水或工业废水，工业废水包括印染废水、农药废水、医药废水、制革废水、冶金废水。
进一步地，所述具有强氧化能力的物质包括羟基自由基、超氧自由基和单线态氧中的一种或多种。这些物质对生活废水、工业废水中的印染废水、农药废水、医药废水、制革废水、冶金废水都有较好的氧化去除效果。
进一步地，所述具有强还原能力的物质为活性氢自由基。
进一步地，所述聚四氟乙烯材料的投加量为10～2000mg/L。由于PTFE呈疏水性，投加量过高，多余的PTFE不能较好分散在水溶液中，在超声波的作用下不能发挥压电催化的性能。
目前在环境污染治理中常用的压电催化剂为无机压电材料，对于压电系数较小的有机压电材料未见应用。PTFE是一种有机全氟聚合物，具有耐高温、耐腐蚀、摩擦系数小等优点，在300℃以下不溶于任何强酸、强碱以及其他有机溶剂。由于其优越的化学和物理性能，目前被广泛应用于电子、医药、化工、航天等领域，本发明提供的PTFE活化方法，更具体的说是利用超声波来活化PTFE，PTFE经过超声波活化后会产生宏观极化，形成驻极体，其具有压电催化活性。相比现有报道的无机压电催化剂，PTFE的结构更稳定；相比同等条件下的压电催化反应，PTFE的压电催化降解污染物的性能也更优。
本发明至少具有如下有益效果为：
(1)PTFE被视为具有抗酸、抗碱和抗各种有机溶剂等特点，目前在实际生活中当做一种极其惰性的材料使用。本发明提供的一种利用超声波技术来活化PTFE的方法，其可以拓宽目前对PTFE的认知。
(2)本发明提供利用超声波来活化PTFE方法，PTFE在活化的过程中以及在活化后具有广泛的应用。PTFE被超声波活化后，从原来的惰性状态转化为极化状态，具有优越的压电催化性能。当超声波持续作用于PTFE上时，PTFE会产生空穴(h +)、羟基自由基(·OH)、超氧自由基(·O 2 -)和单线态氧( 1O 2)等氧化能力强的反应活性物种以及e -、活性氢自由基(·H)等还原能力强的反应活性物种。这些反应活性物种在水环境中可以实现生活和工业废水中难降解污染物的氧化和还原去除，也能够实现水的分解产氢。
(3)相比绝大多数的催化剂，活化之后的PTFE成为一种新的催化剂，受 实际废水的pH、盐度和温度等影响较小，多次使用后其结构仍然稳定。在空气介质中，PTFE经过超声波的活化后，其成为一种新的压电材料，在机械、公路交通、建筑、医学、航空航海等方面具有潜在应用。
附图说明
图1为PTFE膜在超声波的作用下降解甲基橙的性能图。
图2为PTFE超声波活化前后的压电力显微镜图(图中A为PTFE初始状态，B为经过超声活化)。
图3为PTFE膜经过超声活化后在不同外力作用下的产电图。
图4为PTFE微粉在超声波的作用下产自由基图(图中A为加PTFE粉，B为未加PTFE粉)。
图5为PTFE微粉在超声波的作用下降解甲基橙(A)和四氯酚(B)的性能图。
图6为PTFE微粉在高频超声波的作用下降解甲基橙的性能图。
图7为PTFE微粉在超声波的作用下产氢图。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
除非另有定义，本文所使用的所有的技术和科学术语与属于本发明的技术领域的技术人员通常理解的含义相同。本文中在本发明的说明书中所使用的术 语只是为了描述具体的实施例的目的，不是旨在于限制本发明。
本发明提供一种活化聚四氟乙烯(PTFE)的方法，利用超声波来活化PTFE，PTFE经过超声波活化后会产生宏观极化，形成驻极体，其具有压电活性。经过活化后的PTFE在外力作用下用于产电；此外，PTFE在活化的同时可用于产电、产氢或污染物净化等。
活化聚四氟乙烯的方法，包括：对聚四氟乙烯材料进行超声处理。超声处理的环境可以是水环境中也可以是空气中。
目前在环境污染治理中常用的压电催化剂为无机压电材料，对于压电系数较大的有机压电材料未见应用。PTFE是一种有机全氟聚合物，具有耐高温、耐腐蚀、摩擦系数小等优点，在300℃以下不溶于任何强酸、强碱以及其他有机溶剂。由于其优越的化学和物理性能，目前被广泛应用于电子、医药、化工、航天等领域，本发明提供的PTFE活化方法，更具体的说是利用超声波来活化PTFE，PTFE经过超声波活化后会产生宏观极化，形成驻极体，其具有压电催化活性。相比现有报道的无机压电催化剂，PTFE的结构更稳定；相比同等条件下的压电催化反应，PTFE的压电催化降解污染物的性能也更优。
以下还提供了若干可选方式，但并不作为对上述总体方案的额外限定，仅仅是进一步的增补或优选，在没有技术或逻辑矛盾的前提下，各可选方式可单独针对上述总体方案进行组合，还可以是多个可选方式之间进行组合。
可选的，超声处理的设备包括但不限于超声清洗机，超声波治疗仪以及细胞破碎仪。活化PTFE时的超声设备运行参数包括超声频率、超声功率密度和超声时间。
可选的，所述超声处理的条件：超声频率为20kHz～15MHz；超声的功率密度为0.1～400W/cm 2。在一定范围内，超声波的强度越大，作用于PTFE材料上 的作用力也越大，PTFE能够发生更大的形变量，产生的压电催化的性能也越好。
对于超声频率，进一步优选为40kHz～1MHz。
对于超声的功率密度，超声波的功率密度＝超声波的发射功率(W)/发射面积(cm 2)，进一步优选为0.1～200W/cm 2；更进一步优选为0.1～50W/cm 2；更进一步优选为0.1～10W/cm 2；最优选为0.1～5W/cm 2。
对于超声频率和超声功率密度的进一步组合优选为，超声频率为40kHz～1MHz；超声功率密度为0.1～5W/cm 2。例如，可采用超声清洗机或超声波治疗仪。超声时间为不受限制。PTFE一旦受到超声波的作用后就能够被活化，具有优越的压电催化反应活性。同时只要超声波一直作用于PTFE上，PTFE就能一直产生自由载流子，压电催化反应就能持续发生。
优选的，聚四氟乙烯材料的形状可以为颗粒状、薄膜状或者块状中的一种或任意组合。只要是PTFE材料都能够在超声波的作用下被活化，同等质量的PTFE的颗粒，其尺寸越小，反应活性位点越多，催化性能也越好。
优选的，颗粒状的聚四氟乙烯材料包括聚四氟乙烯纳米颗粒和聚四氟乙烯微米颗粒，粒径为0.1nm～500μm；薄膜状的聚四氟乙烯材料厚度为10nm～500μm；块状的聚四氟乙烯材料的尺寸为0.01cm 3～1cm 3。
本发明还提供采用聚四氟乙烯净化污水和产生清洁能源的方法。污水的净化包括生活废水的净化、工业废水中的印染废水、农药废水、医药废水、制革废水、冶金废水的氧化和还原去除；所述的清洁能源的产生包括产电和产氢气。
作为该废水净化应用的一种实施方式，活化聚四氟乙烯同时净化废水，包括：将聚四氟乙烯材料置于待处理废水中进行超声处理。所述的待处理废水为生活废水或工业废水，工业废水包括印染废水、农药废水、医药废水、制革废水、冶金废水。超声处理条件同聚四氟乙烯活化的超声处理条件。
PTFE在超声波作用下催化降解污染物：PTFE在超声波的作用下被活化，且在超声波持续的作用会产生h +、·OH、·O 2 -和 1O 2等氧化能力强的反应活性物种，这些活性物种对生活废水、工业废水中的印染废水、农药废水、医药废水、制革废水、冶金废水都有较好的氧化去除效果。
优选地，PTFE在活化的同时净化废水时，所述PTFE材料为PTFE纳米颗粒或粉末、PTFE微米颗粒或粉末以及PTFE膜，PTFE材料在待处理废水中的投加量为10～2000mg/L。由于PTFE呈疏水性，投加量过高，多余的PTFE不能较好分散在水溶液中，在超声波的作用下不能发挥压电催化的性能。
生活废水和工业废水中的pH为1～14。由于PTFE极其稳定，强酸和强碱对PTFE的稳定性没什么影响，对催化反应效果也无明显影响。
生活废水和工业废水中的溶解氧浓度为0～15mg/L。PTFE在催化反应过程中会产生h +、·OH、·O 2 -和 1O 2等具有强氧化能力的反应活性物种，这些活性物种中，h +是由PTFE本身在反应过程中产生；·OH是由OH -或其他中间态的自由基转化而来；·O 2 -和 1O 2是由O 2反应获得；在由PTFE主导的压电催化反应过程中，废水中的溶解氧对催化反应无明显影响。
优选地，PTFE在超声波作用下催化还原产氢：PTFE在超声波的作用下被活化，除了能够产生强氧化能力的活性物种外，也能够产生强还原能力的活性物种如e -和·H，两个·H通过复合后就能产生氢气。
当PTFE催化还原产氢时，生活废水和工业废水中的溶解氧浓度为0～0.1mg/L。氢气是通过·H复合产生的，如果反应环境中存在较多的氧气，·H会与氧气反应产生水，大大降低氢气的生成。
因此，作为产氢应用的一种实施方式，活化PTFE同时产氢，包括：将PTFE材料置于水环境中进行超声处理，收集超声过程中产生的氢气。超声处理的条 件同活化PTFE时的超声处理条件。
作为产氢的应用，可选的，所述水环境可为单纯的水，也可为生活废水或工业废水，当为生活废水或工业废水时，所述生活废水或工业废水中，溶解氧浓度为0～0.1mg/L。
作为活化方法的一种具体应用，活化同时进行产电，在PTFE材料上下两面连接正负电极，将材料置于空气或水环境中进行超声处理，收集超声过程中产生的电压。经过活化后的聚四氟乙烯，其上下两面分别连接正负电极，对电极施加压力，也能实现产电。
经过超声活化的PTFE应用于产电：PTFE除了在超声过程中能持续产生自由基外，其本身内部偶极子的正负电荷中心也发生了改变。在超声活化之前，PTFE中的正负电荷中心是对称的，而超声活化之后，其内部的正负电荷中心不再对称，导致PTFE一直处于极化状态，且在短时间内极化状态不会消失。从压电力显微镜图(图2)可知，PTFE经过超声之后其表面出现明显的铁电畴，说明处于极化状态。而超声之前，PTFE表面未观测到铁电畴。
活化PTFE用作压电材料时，在活化之后的PTFE表面黏上正负电极，同时将电极连接电压采集装置，通过在电极表面施加一定的压力，PTFE也会受到相应的形变，根据压电效应，在PTFE表面能检测到相应的电压。具体实施例结果见图3。
可选的，经过活化的PTFE在作为压电材料产电时，为了便于在PTFE材料表面施加压力以及黏上正负电极，所述PTFE材料选用膜材料；膜材料的厚度为10nm～500μm。PTFE膜的厚度如果越大，其结构越结实，外力作用于结构厚实的PTFE膜表面后，PTFE膜的形变量非常小，其产生的电压也很弱。因此，较薄且韧性柔软的PTFE膜在外力作用下其产电的性能较优。
优选地，作用于PTFE表面的外部压力为0～100kPa。作用于PTFE膜表面的压力不能太大，过大的压力会造成PTFE膜结构塌陷，不能永久恢复原来的形变，失去原来的压电活性。
本发明至少具有如下有益效果为：
(1)PTFE被视为具有抗酸、抗碱和抗各种有机溶剂等特点，目前在实际生活中当做一种极其惰性的材料使用。本发明提供的一种利用超声波技术来活化PTFE的方法，其可以拓宽目前对PTFE的认知。
(2)本发明提供的利用超声波来活化PTFE方法，PTFE在活化的过程中以及在活化后具有广泛的应用。PTFE被超声波活化后，从原来的惰性状态转化为极化状态，具有优越的压电催化性能。当超声波持续作用于PTFE上时，PTFE会产生h +、·OH、·O 2 -和 1O 2等氧化能力强的反应活性物种以及e -、·H等还原能力强的反应活性物种。这些反应活性物种在水环境中可以实现生活和工业废水中难降解污染物的氧化和还原去除，也能够实现水的分解产氢。
(3)相比绝大多数的催化剂，活化之后的PTFE成为一种新的催化剂，受实际废水的pH、盐度和温度等影响较小，多次使用后其结构仍然稳定。在空气介质中，PTFE经过超声波的活化后，其成为一种新的压电材料，在机械、公路交通、建筑、医学、航空航海等方面具有潜在应用。
实施例中所用原料均为市购产品。
实施例1
两片直径为2.5cm，厚度为100μm的圆形PTFE膜和体积为50mL、浓度为5mg/L的甲基橙溶液放入100mL的烧杯中，将烧杯放置于超声清洗机中，超声清洗机的功率密度为0.3W/cm 2，超声频率为40kHz，超声1小时后，测定 甲基橙的吸光度，具体结果见图1。
对比例1
与实施例1相同，只是在烧杯中不加PTFE膜；超声1小时后，测定MO的吸光度，具体结果见图1。
结果显示，加入PTFE膜后进行超声，随着超声时间的增加，甲基橙的去除率随之增加，而未加PTFE膜的对比例中，去除率基本无变化。
实施例2
一片直径为2.5cm，厚度为100μm的圆形PTFE膜和体积为50mL的去离子水放入到100mL的烧杯中，将烧杯放置于超声清洗机中，超声清洗机的功率密度为0.3W/cm 2，超声频率为40kHz，超声1小时后，将PTFE膜捞出，60℃烘干后，在压电力显微镜测定PTFE膜的极化状态，具体结果见图2中B。
对比例2
PTFE膜未经过超声处理，直接在压电力显微镜下测定极化状态，具体结果见图2中A。
结果表明，PTFE膜经过超声处理后(B)，其表面存在铁电畴，说明经过超声处理后的PTFE膜具有压电活性，而未经过处理的PTFE膜未存在铁电畴(A)。
实施例3
一片长度为3cm的方形PTFE膜和体积为50mL的去离子水放入到100mL的烧杯中，将烧杯放置于超声清洗机中，超声清洗机的功率密度为0.3W/cm 2，超声频率为40kHz,超声1小时后，将PTFE膜捞出，60℃烘干。随后，用导电胶将超声处理过的PTFE膜的上下两面和铜网相连接，铜网则连接电压采集装 置。通过在PTFE膜上施加不同压力，检测铜网两端的电压变化，具体结果见图3。
对比例3
与实施例3相同，唯一不同的是PTFE膜未经过超声处理，连接铜网后在表面施加压力后测定表面电压，具体结果见图3。
结果显示，经过超声处理的PTFE膜在不同压力下的产电性能要远高于未经过超声处理的PTFE膜。
实施例4
0.5mg的PTFE微粉(平均粒径为5μm)和450μL去离子水、50μL浓度为1mol/L的5,5-二甲基-1-吡咯啉-N-氧化物(DMPO)放入1.5毫升离心管中，将离心管放在超声清洗机中，超声清洗机的功率密度为0.3W/cm 2，超声频率为40kHz，超声时间为10min，利用电子顺磁共振仪检测PTFE在活化过程中产生的·OH。具体结果见图4中A1。
对比例4
与实施例4相同，只是在离心管中不加PTFE微粉；超声10min后检测·OH。具体结果见图4中B1。
结果显示，在超声作用下，有PTFE微粉的体系中能产生·OH，而在不加PTFE微粉的体系中未明显检测到·OH。
实施例5
0.5mg的PTFE微粉和412.5μL去离子水、50μL浓度为1mol/L的5,5-二甲基-1-吡咯啉-N-氧化物(DMPO)和37.5μL二甲亚砜(DMSO)放入1.5毫升 离心管中，将离心管放在超声清洗机中，超声清洗机的功率密度为0.3W/cm 2，超声频率为40kHz，超声时间为10min，利用电子顺磁共振仪检测PTFE在活化过程中产生的·O 2 -。具体结果见图4中A2。
对比例5
与实施例5相同，只是在离心管中不加PTFE微粉；超声10min后检测·O 2 -。具体结果见图4中B2。
结果显示，在超声作用下，有PTFE微粉的体系中能产生·O 2 -，而在不加PTFE微粉的体系中未明显检测到·O 2 -。
实施例6
0.5mg的PTFE微粉和450μL去离子水、50μL浓度为0.5mol/L的2,2,6,6-四甲基-4-哌啶醇(TEMP)放入1.5毫升离心管中，将离心管放在超声清洗机中，超声清洗机的功率密度为0.3W/cm 2，超声频率为40kHz，超声时间为10min，利用电子顺磁共振仪检测PTFE在活化过程中产生的 1O 2。具体结果见图4中A3。
对比例6
与实施例6相同，只是在离心管中不加PTFE微粉；超声10min后检测 1O 2。具体结果见图4中B3。
结果显示，在超声作用下，有PTFE微粉的体系中能产生 1O 2，而在不加PTFE微粉的体系中未明显检测到 1O 2。
实施例7
12.5mg的PTFE微粉和体积为50mL、浓度为5mg/L的甲基橙溶液放入 100mL的烧杯中，将烧杯放置于超声清洗机中，超声清洗机的功率密度为0.3W/cm 2，超声频率为40kHz，超声1小时后，测定甲基橙的吸光度，具体结果见图5中(A)。
对比例7
与实施例7相同，只是在烧杯中不加PTFE微粉；超声1小时后，测定甲基橙的吸光度，实验结果同对比例1。
结果显示，加入PTFE微粉，随着超声时间的增加，甲基橙的去除率随之增加。
实施例8
50mg的PTFE微粉和体积为50mL、浓度为25mg/L的四氯酚溶液放入100mL的烧杯中，将烧杯放置于超声清洗机中，超声清洗机的功率密度为0.3W/cm 2，超声频率为40kHz，超声2小时后，测定四氯酚的剩余浓度和氯离子浓度，具体结果见图5中(B)。
对比例8
与实施例8相同，只是在烧杯中不加PTFE微粉；超声2小时后，测定四氯酚的剩余浓度和氯离子释放浓度。具体结果见图5中(B)。
结果显示，加入PTFE微粉，随着超声时间的增加，四氯酚的去除率和氯离子释放随之增加，反应时间2小时后，四氯酚的去除率和脱氯分别达到96.3％和45.7％左右。而在没有PTFE的体系中，四氯酚的去除率和脱氯仅有6.1％和3.2％左右。
实施例9
将浓度分别为0.25g/L的PTFE粉末和5mg/L的甲基橙共1mL混合液放入10mL的试管中，然后将试管放置于超声波治疗仪上，超声波治疗仪的功率密度为2.5W/cm 2，超声频率为1MHz，占空比为30％，超声2min后，测定甲基橙的吸光度，具体结果见图6中(A)。
对比例9
与实施例9相同，只是在烧杯中不加PTFE微粉；超声2min后，测定甲基橙的吸光度，具体结果见图6中(A)。
结果显示，在1MHz的超声波作用下，有PTFE微粉体系比未加PTFE的体系有明显的污染物去除效果。
实施例10
将浓度分别为0.25g/L的PTFE和5mg/L的甲基橙共1mL混合液放入10mL的试管中，然后将试管放置于B超机的探头上，B超机的频率分别设置为8、10、12MHz，能量为50％，脉冲长度为2，超声10min后测定甲基橙的吸光度，具体结果见图6中(B)。
对比例10
与实施例10相同，只是在试管中不加PTFE微粉；超声10min后，测定甲基橙的吸光度。具体结果见图6中(B)。
结果显示，在8、10、12MHz的超声波作用下，有PTFE微粉体系比未加PTFE的体系有明显的污染物去除效果，说明PTFE在高频的超声波作用下也具有压电催化效果。
实施例11
在100mL丝口瓶中加入50mL去离子水和50mg PTFE微粉，通入氩气(流速为0.6L/min)，通气时间为30min，完全密封丝口瓶。然后将含有PTFE微粉的丝口瓶放置于超声清洗机中，超声清洗机的功率密度为0.3W/cm 2，超声频率为40kHz，超声2小时后，取丝口瓶中的顶空气体，用气相色谱测定氢气的含量，结果测得氢气的含量为2.23×10^ -4mmol。具体结果见图7。
对比例11
与实施例11相同，只是在密封的丝口瓶中不加PTFE微粉；超声2小时后，几乎没有测到氢气的存在。
以上实施例的结果可得，在实施例1中，PTFE膜对甲基橙的去除率达71.3±0.3％。在实施例2-3中，相比未经过超声处理的PTFE膜，经过超声处理后的PTFE膜可以明显看到铁电畴的存在，且通过在膜表面施加一定压力后可以明显检测到电压的存在。在实施例4-6中，PTFE粉末在超声波的活化过程中可以产生·OH、·O 2 -、 1O 2和·H；而在对照实施例4-6中(未加PTFE)，反应体系中未检测到·OH、·O 2 -、和·H，只检测到微弱的 1O 2。在实施例7-8中，PTFE微粉在超声波的作用下可以对甲基橙和四氯酚的去除率分别达到89.7±0.01和96.3±1.3％，而未加PTFE粉末，甲基橙和四氯酚的去除率只有1.1±0.3％和6.1±0.9％。在实施例9-10中，PTFE微粉也能在兆赫兹的频率下被激发产生压电催化性能。根据实施例11和其对照组，PTFE在超声波的作用下可以实现产氢。
综上所述，PTFE在超声波的作用下可以被活化，持续作用时能够产生氧化和还原活性物种，可以实现环境污染物的降解去除以及清洁能源氢气的产生。
以上所述实施例仅表达了本发明的几种实施方式，其描述较为具体和详细， 但并不能因此而理解为对发明专利范围的限制。应当指出的是，对于本领域的普通技术人员来说，在不脱离本发明构思的前提下，还可以做出若干变形和改进，这些都属于本发明的保护范围。因此，本发明专利的保护范围应以所附权利要求为准。

Claims (16)

  1. 活化聚四氟乙烯的方法，其特征在于，包括：对聚四氟乙烯材料进行超声处理。
  2. 根据权利要求1所述的活化聚四氟乙烯的方法，其特征在于，对所述聚四氟乙烯材料进行超声处理时，超声频率范围为20kHz～15MHz。
  3. 根据权利要求2所述的活化聚四氟乙烯的方法，其特征在于，所述超声频率优选为40kHz～1MHz。
  4. 根据权利要求1所述的活化聚四氟乙烯的方法，其特征在于，对所述聚四氟乙烯材料进行超声处理时，超声的功率密度范围为0.1～400W/cm 2。
  5. 根据权利要求4所述的活化聚四氟乙烯的方法，其特征在于，所述功率密度优选为0.1～5W/cm 2。
  6. 根据权利要求1所述的活化聚四氟乙烯的方法，其特征在于，所述聚四氟乙烯材料的形状可以为颗粒状、薄膜状或者块状中的一种或任意组合。
  7. 采用聚四氟乙烯产电的方法，其特征在于，包括：对聚四氟乙烯材料如权利要求1至5任一项所述的活化聚四氟乙烯的方法进行活化处理时或者活化处理后，在所述聚四氟乙烯材料的上下两面分别连接正负电极，并对所述电极施加压力。
  8. 根据权利要求7所述的采用聚四氟乙烯产电的方法，其特征在于，所述聚四氟乙烯材料的形状为薄膜状。
  9. 根据权利要求8所述的采用聚四氟乙烯产电的方法，其特征在于，所述聚四氟乙烯材料的厚度范围为10nm～500μm。
  10. 根据权利要求9所述的采用聚四氟乙烯产电的方法，其特征在于，所述压力范围为0～100kPa。
  11. 根据权利要求7所述的采用聚四氟乙烯产电的方法，其特征在于，所 述聚四氟乙烯材料在空气或者水环境中进行超声处理。
  12. 采用聚四氟乙烯产氢的方法，其特征在于，包括：将聚四氟乙烯材料置于水环境中，采用如权利要求1至6任一项所述的活化聚四氟乙烯的方法进行超声处理，收集超声过程中产生的氢气。
  13. 采用聚四氟乙烯净化废水的方法，其特征在于，包括：将聚四氟乙烯材料置于废水环境中采用如权利要求1至6任一项所述的活化聚四氟乙烯的方法进行超声处理，获得具有强氧化能力的物质或者具有强还原能力的物质，所述具有强氧化能力的物质可用于氧化废水中的污染物，所述具有强还原能力的物质可用于还原废水中的污染物。
  14. 根据权利要求13所述的采用聚四氟乙烯净化废水的方法，其特征在于，所述具有强氧化能力的物质包括羟基自由基、超氧自由基和单线态氧中的一种或多种。
  15. 根据权利要求13所述的采用聚四氟乙烯净化废水的方法，其特征在于，所述具有强还原能力的物质为活性氢自由基。
  16. 根据权利要求13所述的采用聚四氟乙烯净化废水的方法，其特征在于，所述聚四氟乙烯材料的投加量为10～2000mg/L。
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