Water treatment apparatus and method using photocatalytic reaction based on eutectic gallium indium nanoparticles

Abstract

By utilizing eutectic gallium–indium nanoparticles for wastewater treatment of contaminated water, holes (h+) generated through photocatalytic reactions in which the nanoparticles absorb light of specific wavelengths such as ultraviolet or visible light cause oxidation reactions that cleave bonds between carbon (C) and hydrogen (H), while electrons (e-) generated by the photocatalytic reactions cause reduction reactions that cleave bonds between carbon (C) and fluorine (F). As a result, the invention provides the advantage of decomposing and defluorinating perfluorinated compounds. Details of the project that supported this invention are as follows. [Project Identification Number] 1711189578 [Project Number] 2022R1A2C1007071 [Department Name] Ministry of Science and ICT [Project Management (Professional) Institution Name] Korea Research Foundation [Research Project Name] Personal Basic Research [Research Project Name] Dynamic Analysis on Binding and Clustering of Plasmonic Nanoparticles Through Multi-Bond Interaction [Contribution Rate] 1 / 2 [Project Performing Institution Name] Korean Foreign Language University [Research Period] 01 March 2023 to 29 February 2024. Details of another project that supported this invention are as follows. [Project Identification Number] 1485019432 [Project Number] ARQ201901019005 [Ministry Name] Ministry of Environment [Project Management (Professional) Institution Name ] Korea Environmental Industry Technology Institute [Research Project Name] Development of New Technology for Water and Sewage Treatment [Research Project Name] Development of technology for evaluating and removing trace and new pollutants in an oxidation process in a water treatment process [Contribution rate] 1 / 2 [Project Performing Institution Name] Seoul National University [Research Period] 01 March 2023 – 31 December 2023

Description

Water treatment device and method using photocatalytic reaction based on eutectic gallium indium nanoparticles

[0001] The present invention relates to a water treatment device and method using a photocatalytic reaction based on eutectic gallium-indium nanoparticles, and more particularly, to a water treatment device and method using a photocatalytic reaction based on eutectic gallium-indium nanoparticles, which can cause a photocatalytic reaction by irradiating light of a specific wavelength to eutectic gallium-indium (EGaIn, eutectic gallium-indium alloy) nanoparticles mixed in contaminated water, thereby enabling the decomposition and defluorination of perfluorinated compounds and further improving water treatment efficiency.

[0002] Water treatment devices are typically designed to remove aquatic pollutants. Perfluorinated compounds, one of these aquatic pollutants, are a group of substances in which hydrogen in the basic hydrocarbon skeleton is replaced by fluorine. They are chemically very stable, resisting degradation and accumulating in living organisms, resulting in toxicity.

[0003] Conventional water treatment devices primarily remove perfluorinated compounds through physical methods such as adsorption or filtration. However, due to limitations, interest in chemical decomposition is growing. However, even with chemical decomposition, the remaining carbon (C) and fluorine (F) bonds in the decomposition products can be ecologically toxic.

[0004] The purpose of the present invention is to provide a water treatment device and method using a photocatalytic reaction based on eutectic gallium indium nanoparticles, which can further improve water treatment efficiency by enabling water treatment without adding a separate oxidizing agent or reducing agent.

[0005] A water treatment device using a photocatalytic reaction based on eutectic gallium indium nanoparticles according to the present invention comprises: a reactor into which contaminated water containing perfluorinated compounds including per and poly fluoroalkyl substances (PFAS) in which a plurality of carbon (C) and fluorine (F) bonds exist in an alkyl group and fluorotelomer substances in which some of the carbons (C) in an alkyl group are not substituted with fluorine (F) but remain as hydrogen (H) is supplied; a light irradiation unit installed inside the reactor to irradiate the contaminated water with either ultraviolet light or visible light; a eutectic gallium indium suspension supply unit that supplies a eutectic gallium indium suspension in which eutectic gallium indium (EGaIn, eutectic gallium-indium alloy) nanoparticles and a dispersion solvent are mixed, to the reactor; It includes a stirrer installed in the reactor to mix the contaminated water and the eutectic gallium indium suspension, and inside the reactor, a hole (h) is formed by the photocatalytic reaction of the light irradiated from the light irradiation unit and the eutectic gallium indium nanoparticles. + ) and electrons (e - ) is generated, and the hole (h) + ) and the above electron (e - ) causes a reaction that decomposes the above perfluorinated compound.

[0006] Inside the above reactor, the electrons (e - ) can cause a reduction reaction that breaks the bond between carbon (C) and fluorine (F) of the perfluoroalkyl substance and decomposes it.

[0007] Inside the above reactor, the hole (h + ) can cause an oxidation reaction that breaks the bond between carbon (C) and hydrogen (H) of the above-mentioned fluorotelomer material or causes a chain reaction by binding to an electron-rich functional group, thereby causing decomposition.

[0008] The reactor may further include a nitrogen supply unit for supplying nitrogen gas to the interior of the reactor to remove dissolved oxygen in the contaminated water.

[0009] The method may further include a eutectic gallium indium nanoparticle synthesizer that introduces the above-described dispersion solvent and the eutectic gallium indium liquid metal, and uses ultrasonic waves to pulverize the eutectic gallium indium liquid metal into nanoparticles of a preset size, thereby synthesizing the eutectic gallium indium suspension in which the eutectic gallium indium nanoparticles are mixed with the dispersion solvent.

[0010] The above gallium indium suspension supply unit may be connected to a contaminated water supply unit that is connected to one side of the reactor and supplies the contaminated water.

[0011] The above oxidation reaction is carried out by the hole (h + ) decomposes water to generate OH radicals, and the OH radicals break the bonds between carbon (C) and hydrogen (H) and decompose them, and the hole (h) + ) may include reactions in which electrons bind to a functional group rich in electrons and decompose them through a chain reaction.

[0012] The reactor may further include a treated water discharge unit connected to the other side thereof and discharging treated water from the reactor, a water quality measuring unit for measuring the water quality of the treated water passing through the treated water discharge unit, and a treated water return unit for returning at least a portion of the treated water discharged to the treated water discharge unit to the reactor when the water quality measured by the water quality measuring unit exceeds a preset water quality standard.

[0013] According to another aspect of the present invention, a water treatment device using a photocatalytic reaction based on eutectic gallium indium nanoparticles comprises: a reactor; a contaminated water supply unit connected to one side of the reactor and supplying contaminated water to the reactor; a treated water discharge unit connected to the other side of the reactor and discharging treated water from the reactor; a light irradiation unit installed inside the reactor and irradiating the contaminated water with either ultraviolet light or visible light; a eutectic gallium indium nanoparticle synthesizer, into which a dispersion solvent and eutectic gallium indium liquid metal are introduced, and which crushes the eutectic gallium indium liquid metal into nanoparticles of a preset size using ultrasonic waves to synthesize a eutectic gallium indium suspension in which the eutectic gallium indium nanoparticles are mixed with the dispersion solvent; It includes a eutectic gallium indium suspension supply unit that supplies the eutectic gallium indium suspension synthesized in the nanoparticle synthesizer to the reactor, and inside the reactor, holes (h) are generated by the photocatalytic reaction of light irradiated from the light irradiation unit and the eutectic gallium indium nanoparticles. + ) and electrons (e - ) may occur, and a reaction may occur that decomposes the pollutants in the polluted water.

[0014] Inside the above reactor, the electrons (e - ) causes a reduction reaction in the contaminated water, and the hole (h + ) can cause an oxidation reaction in the contaminated water to decompose the contaminants in the contaminated water.

[0015] The reactor may further include a nitrogen supply unit for supplying nitrogen gas to the interior of the reactor to remove dissolved oxygen in the contaminated water.

[0016] A water treatment method using a photocatalytic reaction based on eutectic gallium indium nanoparticles according to the present invention comprises: a contaminated water supply step of supplying contaminated water containing perfluorinated compounds including per and poly fluoroalkyl substances (PFAS) in which a plurality of bonds of carbon (C) and fluorine (F) exist in an alkyl group, and fluorotelomer substances in which some of the carbons (C) in an alkyl group are not substituted with fluorine (F) but remain as hydrogen (H), to a reactor; a nitrogen supply step of injecting nitrogen gas into the reactor to remove dissolved oxygen in advance in the contaminated water accommodated in the reactor; a eutectic gallium indium nanoparticle supply step of supplying a eutectic gallium indium suspension, in which eutectic gallium indium nanoparticles and a dispersion solvent are mixed, to the contaminated water in the reactor from which dissolved oxygen has been removed; a light irradiation step of irradiating either ultraviolet light or visible light using a light irradiation unit to the contaminated water mixed with the eutectic gallium indium suspension in the reactor; Holes (h) are generated by the photocatalytic reaction between the light irradiated in the above light irradiation step and the gallium indium nanoparticles. + ) and electrons (e - ) is generated, and the electron (e) - ) causes a reduction reaction that breaks the bond between carbon (C) and fluorine (F) of the perfluoroalkyl substance and decomposes it, and the hole (h) + ) includes a water treatment step for decomposing and defluorinating perfluorinated compounds in the contaminated water by causing an oxidation reaction that breaks the bond between carbon (C) and hydrogen (H) of the fluorotelomer material or causes a chain reaction by binding to an electron-rich functional group to decompose it.

[0017] Before the step of supplying the eutectic gallium indium nanoparticles, the method may further include a step of synthesizing eutectic gallium indium nanoparticles, including the steps of supplying a dispersion solvent and eutectic gallium indium liquid metal to a eutectic gallium indium nanoparticle synthesizer, the step of crushing the eutectic gallium indium liquid metal into eutectic gallium indium nanoparticles of a preset size using ultrasonic waves, and the step of removing nanoparticles exceeding the preset size deposited for a preset waiting time after the crushing to synthesize the eutectic gallium indium suspension in which the eutectic gallium indium nanoparticles of the preset size or less are mixed in the dispersion solvent.

[0018] The above oxidation reaction is carried out by the hole (h + ) decomposes water to generate OH radicals, and the OH radicals break the bonds between carbon (C) and hydrogen (H) and decompose them, and the hole (h) + ) may include reactions in which electrons bind to a functional group rich in electrons and decompose them through a chain reaction.

[0019] If the water quality measured by a water quality measuring device for the treated water discharged from the reactor after the water treatment step does not meet the preset water quality standard, the treated water may be returned to the reactor, and the light irradiation step may be performed again.

[0020] The present invention uses gallium indium nanoparticles in the treatment of contaminated water, thereby generating holes (h) through a photocatalytic reaction in which the nanoparticles absorb light of a specific wavelength, such as ultraviolet or visible light. + ) causes an oxidation reaction that breaks the bond between carbon (C) and hydrogen (H) and decomposes them, and electrons (e) generated by the photocatalytic reaction - ) has the advantage of enabling the decomposition and defluorination of perfluorinated compounds by causing a reduction reaction that breaks the bond between carbon (C) and fluorine (F) and decomposes them.

[0021] Additionally, electrons (e) generated by the photocatalytic reaction - ) and hole (h +) because both reduction and oxidation reactions occur, there is no need to add additional chemicals such as separate oxidizing agents, reducing agents, and pH adjusters, so there is an advantage in that the burden of environmental load and secondary treatment due to water treatment can be eliminated.

[0022] In addition, by mixing eutectic gallium indium liquid metal into a dispersion solvent and then pulverizing it into nanoparticles of a set size using ultrasonic waves to synthesize a eutectic gallium indium alloy suspension mixed with eutectic gallium indium nanoparticles, and mixing the eutectic gallium indium alloy suspension into contaminated water to use it for a photocatalytic reaction, there is an advantage in that the synthesis of eutectic gallium indium nanoparticles is easy and mixing into contaminated water is easy.

[0023] In addition, by removing dissolved oxygen in advance by aerating with nitrogen before mixing the eutectic gallium indium nanoparticle suspension into the contaminated water, the dissolved oxygen is converted into electrons (e). - ) can be prevented from interfering with the reduction reaction, so that water treatment efficiency can be further improved.

[0024] In addition, eutectic gallium indium nanoparticles have higher electrons excited by ultraviolet rays (e) than semiconductors such as gallium oxide (Ga2O3) or indium oxide (In2O3). - ) can be transferred to the lowest unoccupied molecular orbital more quickly, so water treatment efficiency can be further improved.

[0025] FIG. 1 is a schematic diagram of a water treatment device using a photocatalytic reaction based on eutectic gallium indium nanoparticles according to an embodiment of the present invention.

[0026] FIG. 2 is a schematic diagram of a eutectic gallium indium nanoparticle synthesizer according to an embodiment of the present invention.

[0027] Figure 3 is a flow chart showing a water treatment method using a photocatalytic reaction based on eutectic gallium indium nanoparticles according to an embodiment of the present invention.

[0028] Figure 4 is a graph showing the relationship between light wavelength and absorbance according to an embodiment of the present invention.

[0029] Figure 5 is a TEM photograph of a eutectic gallium nanoparticle according to an embodiment of the present invention.

[0030] Figure 6 schematically illustrates a chain reaction caused by a hole according to an embodiment of the present invention.

[0031] Hereinafter, embodiments of the present invention will be described with reference to the attached drawings.

[0032] A water treatment device using a photocatalytic reaction based on gallium indium nanoparticles according to an embodiment of the present invention is a device for treating water by decomposing perfluorinated compounds contained in contaminated water.

[0033] The above perfluorinated compounds include per and poly fluoroalkyl substances (PFAS) in which multiple bonds of carbon (C) and fluorine (F) exist in an alkyl group, and fluorotelomer substances in which some of the carbons (C) in the alkyl group are not replaced with fluorine (F) but remain as hydrogen (H).

[0034] However, the water treatment device according to the present invention is not limited thereto, and of course, it is also possible to treat water containing not only perfluorinated compounds but also pollutants including halogen elements, pesticides, pharmaceuticals, organic pollutants such as nitrosamines, etc.

[0035] FIG. 1 is a schematic diagram of a water treatment device using a photocatalytic reaction based on eutectic gallium indium nanoparticles according to an embodiment of the present invention.

[0036] Referring to FIG. 1, a water treatment device using a photocatalytic reaction based on eutectic gallium indium nanoparticles according to an embodiment of the present invention includes a reactor (10), a nitrogen supply unit (20), a lamp (30), a eutectic gallium indium suspension supply unit (40), a eutectic gallium indium nanoparticle synthesizer (50), and a stirrer (60).

[0037] The above reactor (10) is formed to supply and receive contaminated water containing the perfluorinated compound. The above reactor (10) may be made of stainless steel or Pyrex glass, which are not deformed by ultraviolet rays.

[0038] The above reactor (10) is connected to a contaminated water supply unit (11) for supplying contaminated water on one upper side, and a treated water discharge unit (12) for discharging treated water from the reactor (10) is connected to the other upper side.

[0039] The above-mentioned treated water discharge unit (12) is equipped with a water quality measuring device (not shown) that measures the water quality of the treated water that is treated in the reactor (10) and discharged to the outside.

[0040] The above-mentioned treated water discharge unit (12) is provided with a treated water return unit (not shown) for returning at least a portion of the treated water to the reactor (10).

[0041] In this embodiment, the reactor (10) is described as a continuous stirred tank reactor (CSTR, Continuous Stirred Tank Reactor) by way of example. However, the invention is not limited thereto, and it is of course also possible to use a plug flow reactor (PFR, Plug Flow Reactor) as the reactor (10).

[0042] The above nitrogen supply unit (20) is connected to one side of the lower portion of the reactor (10) and is a device for supplying nitrogen gas into the interior of the reactor (10) to remove dissolved oxygen in the contaminated water.

[0043] The above lamp (30) is a light irradiation unit installed inside the reactor (10) to irradiate either ultraviolet light or visible light to the contaminated water from which dissolved oxygen has been removed. The lamp (30) is arranged lengthwise inside a quartz tube arranged vertically inside the reactor (10). A plurality of the lamps (30) are arranged at a predetermined interval from each other.

[0044] In this embodiment, the lamp (30) is described as irradiating ultraviolet rays with a short wavelength of about 254 nm. However, the present invention is not limited thereto, and the wavelength range of light that causes resonance can be adjusted and applied according to the nanoparticles by adjusting the size or shape of the eutectic gallium indium nanoparticles.

[0045] The eutectic gallium indium suspension supply unit (40) supplies the eutectic gallium indium suspension generated in the eutectic gallium indium nanoparticle synthesizer (50) to the inside of the reactor (10). In this embodiment, the eutectic gallium indium suspension supply unit (40) is described as being connected to the contaminated water supply unit (11), but is not limited thereto and may of course be provided separately from the contaminated water supply unit (11).

[0046] The eutectic gallium indium nanoparticle synthesizer (50), as shown in FIG. 2, is a device for producing a eutectic gallium indium suspension in which the eutectic gallium indium nanoparticles are mixed in a dispersion solvent, which is provided separately from the reactor (10). The dispersion solvent includes a polar solvent such as ethanol or water, and in this embodiment, an ethanol solvent (ethanol solution) is used as an example. The eutectic gallium indium nanoparticle synthesizer (50) includes a synthesis tank (51) into which the dispersion solvent and the eutectic gallium indium liquid metal are introduced, and an ultrasonic pulverizer (52) that uses ultrasonic waves in the synthesis tank (51) to pulverize the eutectic gallium indium liquid metal into nanoparticles of a preset size. In the eutectic gallium indium nanoparticle synthesizer (50),

[0047] The above stirrer (60) is a device that stirs to mix the contaminated water contained in the reactor (10) and the eutectic gallium indium suspension.

[0048] In this embodiment, the agitator (60) is described as being a propeller type that rotates the agitator blades, but is not limited thereto, and may utilize magnetic vibration or other various methods.

[0049] In addition, the water treatment device further includes a control unit (not shown) for controlling the operation of valves installed in the contaminated water supply unit (11), the treated water discharge unit (12), the nitrogen supply unit (20), the gallium indium suspension supply unit (40), and the treated water return unit (not shown).

[0050] In addition, the control unit (not shown) can control the supply amount supplied from the nitrogen supply unit (20), the gallium indium suspension supply unit (40), and the treated water recovery unit (not shown) according to the water quality measured by the water quality measuring device (not shown).

[0051] The water treatment method using a photocatalytic reaction based on eutectic gallium indium nanoparticles according to the embodiment of the present invention configured as described above is described as follows.

[0052] Figure 3 is a flow chart showing a water treatment method using a photocatalytic reaction based on eutectic gallium indium nanoparticles according to an embodiment of the present invention.

[0053] Referring to FIG. 4, a water treatment method according to an embodiment of the present invention includes a contaminated water supply step (S1), a nitrogen supply step (S2), a gallium indium nanoparticle supply step (S3), a light irradiation step (S4), a water treatment step (S5), a water quality judgment step (S6) (S7), a treated water discharge step (S8), and a treated water recovery step (S9).

[0054] First, in the contaminated water supply step (S1), contaminated water containing the perfluorinated compound is supplied to the reactor (10) through the contaminated water supply unit (11).

[0055] The above perfluorinated compounds include per and poly fluoroalkyl substances (PFAS) in which multiple bonds of carbon (C) and fluorine (F) exist in an alkyl group, and fluorotelomer substances in which some of the carbons (C) in the alkyl group are not replaced with fluorine (F) but remain as hydrogen (H).

[0056] Next, the nitrogen supply step (S2) injects nitrogen gas (N2) into the reactor (10) containing the contaminated water through the nitrogen supply unit (13).

[0057] When nitrogen gas (N2) is aerated in the contaminated water in the above reactor (10), all dissolved oxygen remaining in the contaminated water can be removed. The dissolved oxygen in the contaminated water is generated in the subsequent water treatment step (S5) by electrons (e). - ) to prevent the reduction reaction, so it is removed in advance using nitrogen gas. After injecting the nitrogen gas (N2), the dissolved oxygen is removed by waiting for a preset period of time. In the nitrogen supply step (S2), the injection amount or injection time of the nitrogen gas (N2) can be controlled according to the water quality or characteristics of the contaminated water.

[0058] When the above dissolved oxygen is removed, the eutectic gallium indium nanoparticle supply step (S3) is performed.

[0059] In the above eutectic gallium indium nanoparticle supply step (S3), a eutectic gallium indium suspension that has been synthesized in advance and contains the eutectic gallium indium nanoparticles is supplied into the reactor (10) through the eutectic gallium indium suspension supply unit (40).

[0060] Referring to Fig. 2, the method for synthesizing the eutectic gallium indium suspension is as follows.

[0061] First, as shown in Fig. 2a, a dispersion solvent and eutectic gallium indium liquid metal (EGaIn liquid metal) are supplied to the eutectic gallium indium nanoparticle synthesizer (51).

[0062] In the above eutectic gallium indium nanoparticle synthesizer (51), ultrasonic waves are generated using the ultrasonic grinder (probe sonicator) (52) to grind the eutectic gallium indium liquid metal into eutectic gallium indium nanoparticles of a preset size.

[0063] The above setting size can be set differently depending on the wavelength of light irradiated through the lamp (30). That is, the setting size can be set in advance through experiments, etc., to a size in which a photocatalytic reaction occurs better in the wavelength range of light irradiated through the lamp (30). In this embodiment, since it is explained by irradiating ultraviolet rays from the lamp (30) as an example, the size of the eutectic gallium indium nanoparticles can be set to a size that causes resonance in ultraviolet rays with a wavelength of about 254 nm. However, the present invention is not limited thereto, and if eutectic gallium indium nanoparticles that can react in the visible light range are synthesized, it is of course possible to utilize natural light in the process.

[0064] After the above grinding, the material is allowed to settle for a preset waiting time, as shown in Fig. 2b. Here, the waiting time is explained as being in the range of about 4 to 8 hours, for example.

[0065] Thereafter, as shown in Fig. 2c, nanoparticles exceeding the set size can be removed, thereby synthesizing the eutectic gallium indium suspension (EGaIn NP solution) in which the eutectic gallium indium nanoparticles having a size smaller than the set size are mixed in the dispersion solvent.

[0066] After the above eutectic gallium indium suspension is supplied to the reactor (10), the contaminated water and the eutectic gallium indium suspension are sufficiently mixed using the stirrer (60).

[0067] When the above contaminated water and the above gallium indium suspension are sufficiently mixed, the light irradiation step (S4) is performed.

[0068] In the above light irradiation step (S4), the lamp (30) is operated to irradiate ultraviolet rays with a wavelength of about 254 nm within the reactor (10).

[0069] When the above ultraviolet rays are irradiated, a water treatment step (S5) is performed in which the ultraviolet rays and the eutectic gallium indium nanoparticles react to perform water treatment.

[0070] In the above water treatment step (S5), holes (h) are formed by the photocatalytic reaction of the ultraviolet rays and the gallium indium nanoparticles. + ) and electrons (e - ) occurs.

[0071] The above photocatalytic reaction is a reaction that utilizes the localized surface plasmon resonance (LSPR) phenomenon, which causes collective vibration of a conductive electron cloud around the metal surface when nano-sized metal particles strongly absorb light of a specific wavelength.

[0072] The chemical formula 1 below shows the hole (h) in the eutectic gallium indium nanoparticles by the photocatalytic reaction. + ) and electrons (e - ) indicates that it occurs.

[0073]

[0074] Here, the above hole (h + ) is an electron (e) in the above eutectic gallium indium nanoparticles - ) is the part that has fallen out, and is also called a hole.

[0075] Electrons (e) generated by the above photocatalytic reaction - ) causes a reduction reaction to occur, breaking the bond between carbon (C) and fluorine (F) of the perfluoroalkyl substance and decomposing it. In other words, the bond between carbon (C) and fluorine (F) can be broken to cause defluorination.

[0076] The holes (h) generated by the above photocatalytic reaction + ) causes an oxidation reaction that breaks the bond between carbon (C) and hydrogen (H) of the above fluorotelomer material and decomposes it.

[0077] At this time, the oxidation reaction is carried out by the hole (h + ) decomposes water to generate OH radicals, and the generated OH radicals (·OH) break the bonds between carbon (C) and hydrogen (H) and decompose them, and the hole (h) + ) can include all reactions in which the bond is directly bonded to an electron-rich functional group, such as an oxygen atom or a carboxyl group, causing a chain reaction and decomposition.

[0078] For example, referring to Figure 6, the chain reaction is as follows. Perfluorooctanoic acid (PFOA, C7F), a type of perfluorinated compound 15 COOH) is C7F in water 15 It exists in the COO- state, C7F 15 The electron of COO- is a hole (h + ) is removed by C7F 15 COO· radical is generated. Then, unstable C7F 15 COO· radical undergoes Kolbe decarboxylation reaction and loses CO2 to form C7F 15 · Transformed into a radical. C7F 15 · The radical reacts rapidly with ·OH or HOO· radicals to form thermodynamically unstable C7F 15 OH is formed. After that, C7F 15 OH undergoes hydrolysis and HF removal to form C6F 13 COO- is formed. Similarly, C6F 13 COO- repeats the same process to C5F 11 COO- and is ultimately mineralized into CO2 and fluoride ion (F-). In this stepwise decomposition process, the major intermediate is perfluoroheptanoic acid (PFHpA, C6F 13COOH), perfluorohexanoic acid (PFHxA, C5F 11 COOH), perfluoropentanoic acid (PFPeA, C4F9COOH), perfluorobutanoic acid (PFBA, C3F7COOH), and trifluoroacetic acid (TFA, CF3COOH) are produced.

[0079] That is, the oxidation reaction is carried out by the hole (h + ) and the above OH radicals.

[0080] After the above water treatment step (S5), the water quality judgment step (S6)(S7) is performed.

[0081] The above water quality judgment step (S6)(S7) includes a process (S6) in which the water quality measuring device (not shown) measures the water quality of the treated water discharged from the reactor (10) after treatment, and a process (S7) in which the water quality measured by the water quality measuring device (not shown) is compared with a preset water quality standard.

[0082] If the water quality measured by the water quality measuring device (not shown) satisfies the water quality standard, the treated water discharge step (S8) is performed to discharge the treated water from the reactor (10) to the outside.

[0083] If the water quality measured by the water quality measuring device (not shown) does not satisfy the water quality standard, the treated water recovery step (S9) is performed to return the treated water to the reactor (10).

[0084] After the above-mentioned treated water is returned to the reactor (10), the light irradiation step (S4) can be performed again. However, the present invention is not limited thereto, and it is also possible to increase the supply amount of the eutectic gallium suspension by performing the eutectic gallium nanoparticle supply step (S3) again according to the water quality measured by the water quality measuring device (not shown).

[0085] Meanwhile, Fig. 4 is a graph showing the relationship between light wavelength and absorbance according to an embodiment of the present invention.

[0086] Referring to Fig. 4, the change in absorbance of the eutectic gallium indium nanoparticles according to the wavelength of light irradiated from the lamp (30) is shown.

[0087] It can be seen that the absorbance of the eutectic gallium nanoparticles is maximum when the wavelength of light is approximately 254 nm.

[0088] Figure 5 is a TEM photograph of a eutectic gallium nanoparticle according to an embodiment of the present invention.

[0089] Referring to Fig. 5, the eutectic gallium nanoparticles have a smooth spherical shape, and the eutectic gallium nanoparticles are distributed in a size range of about 10 to 200 nm. The size of the eutectic gallium nanoparticles varies depending on the output and time of the ultrasonic pulverizer (52), and can be pulverized with different distributions in a range of about 5 to 500 nm.

[0090] The higher the uniformity of the size of the eutectic gallium nanoparticles, the narrower the width of the absorption band, and the wavelength of maximum absorbance can be controlled by changing the shape of the eutectic gallium nanoparticles.

[0091] In the present invention as described above, the holes (h) generated by the photocatalytic reaction of the ultraviolet rays and the gallium indium nanoparticles + ) and the above electron (e - ) can achieve complete decomposition and defluorination of the perfluorinated compound by allowing the reduction reaction and oxidation reaction to occur simultaneously.

[0092] In addition, since both oxidation and reduction reactions occur through the photocatalytic reaction, there is no need to add separate chemicals such as oxidizing or reducing agents, and there is no need to use separate chemicals such as pH adjusters for the reduction reaction, so the environmental load generated during the water treatment process and the burden of secondary treatment can be minimized.

[0093] In addition, the above eutectic gallium indium nanoparticles are gallium oxide (G a 2 O3) When using semiconductors such as indium oxide (In2O3), electrons excited by ultraviolet rays (e) are more - ) can be transferred to the lowest unoccupied molecular orbital more quickly, thereby improving water treatment efficiency.

[0094] In addition, by controlling the size and shape of the gallium indium nanoparticles, it is possible to achieve a water treatment process that reacts to various wavelengths of ultraviolet light or visible light, thereby reducing energy and costs for the water treatment process.

[0095] While the present invention has been described with reference to the embodiments illustrated in the drawings, these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible. Therefore, the true scope of technical protection of the present invention should be determined by the technical spirit of the appended claims.

[0096] According to the present invention, a water treatment device capable of decomposing and defluorinating perfluorinated compounds can be manufactured.

Claims

1. A reactor supplied with contaminated water containing perfluorinated compounds, including per and poly fluoroalkyl substances (PFAS) in which multiple bonds of carbon (C) and fluorine (F) exist in an alkyl group, and fluorotelomer substances in which some of the carbons (C) in an alkyl group are not replaced with fluorine (F) but remain as hydrogen (H); A light irradiation unit installed inside the reactor and irradiating the contaminated water with either ultraviolet light or visible light; A eutectic gallium-indium alloy (EGaIn) suspension supply unit for supplying a eutectic gallium-indium suspension containing eutectic gallium-indium alloy (EGaIn) nanoparticles and a dispersion solvent to the reactor; A stirrer is installed in the above reactor and mixes the contaminated water and the gallium indium suspension, Inside the above reactor, Holes (h) are generated by the photocatalytic reaction between the light irradiated from the above light irradiation unit and the eutectic gallium indium nanoparticles. + ) and electrons (e - ) is generated, and the hole (h) + ) and the above electron (e - ) causes a reaction that decomposes the above perfluorinated compound, Water treatment device using photocatalytic reaction based on gallium indium nanoparticles.

2. In claim 1, Inside the above reactor, The above electron (e) - ) causes a reduction reaction that breaks the bond between carbon (C) and fluorine (F) of the perfluoroalkyl substance and decomposes it. Water treatment device using photocatalytic reaction based on gallium indium nanoparticles.

3. In claim 2, Inside the above reactor, The above hole (h + ) causes an oxidation reaction that breaks the bond between carbon (C) and hydrogen (H) of the above fluorotelomer substance or causes a chain reaction by binding to an electron-rich functional group, thereby causing decomposition. Water treatment device using photocatalytic reaction based on gallium indium nanoparticles.

4. In claim 1, Further comprising a nitrogen supply unit for supplying nitrogen gas into the interior of the reactor to remove dissolved oxygen in the contaminated water. Water treatment device using photocatalytic reaction based on gallium indium nanoparticles.

5. In claim 1, A eutectic gallium indium nanoparticle synthesizer is further included, which inputs the dispersion solvent and the eutectic gallium indium liquid metal, and uses ultrasonic waves to crush the eutectic gallium indium liquid metal into nanoparticles of a preset size, thereby synthesizing the eutectic gallium indium suspension in which the eutectic gallium indium nanoparticles are mixed with the dispersion solvent. Water treatment device using photocatalytic reaction based on gallium indium nanoparticles.

6. In claim 1, The above gallium indium suspension supply unit is, Connected to one side of the above reactor and connected to a contaminated water supply unit that supplies the contaminated water, Water treatment device using photocatalytic reaction based on gallium indium nanoparticles.

7. In claim 3, The above oxidation reaction is, The above hole (h + ) decomposes water to produce OH radicals, and the OH radicals break the bonds between carbon (C) and hydrogen (H) and cause decomposition, The above hole (h + ) involves a reaction in which the electron-rich functional group binds to it and decomposes it through a chain reaction. Water treatment device using photocatalytic reaction based on gallium indium nanoparticles.

8. In claim 1, A treated water discharge unit connected to the other side of the above reactor and discharging the treated water from the above reactor, A water quality measuring device that measures the water quality of the treated water passing through the above-mentioned treated water discharge unit, If the water quality measured by the water quality measuring device exceeds the preset water quality standard, the system further includes a treated water recovery unit for recovering at least a portion of the treated water discharged to the treated water discharge unit to the reactor. Water treatment device using photocatalytic reaction based on gallium indium nanoparticles.

9. Reactor and; A contaminated water supply unit connected to one side of the reactor and supplying contaminated water to the reactor; A treated water discharge unit connected to the other side of the reactor and discharging the treated water from the reactor; A light irradiation unit installed inside the reactor and irradiating the contaminated water with either ultraviolet light or visible light; A eutectic gallium indium nanoparticle synthesizer that synthesizes a eutectic gallium indium suspension in which a dispersion solvent and a eutectic gallium indium liquid metal are introduced, the eutectic gallium indium liquid metal is crushed into nanoparticles of a preset size using ultrasonic waves, and the eutectic gallium indium nanoparticles are mixed with the dispersion solvent; It includes a eutectic gallium indium suspension supply unit that supplies the eutectic gallium indium suspension synthesized in the nanoparticle synthesizer to the reactor, Inside the above reactor, Holes (h) are generated by the photocatalytic reaction between the light irradiated from the above light irradiation unit and the eutectic gallium indium nanoparticles. + ) and electrons (e - ) occurs, and a reaction occurs that decomposes the pollutants in the polluted water. Water treatment device using photocatalytic reaction based on gallium indium nanoparticles.

10. In claim 9, Inside the above reactor, The above electron (e) - ) causes a reduction reaction in the contaminated water, and the hole (h + ) causes an oxidation reaction in the contaminated water to decompose the contaminants in the contaminated water. Water treatment device using photocatalytic reaction based on gallium indium nanoparticles.

11. In claim 9, Further comprising a nitrogen supply unit for supplying nitrogen gas into the interior of the reactor to remove dissolved oxygen in the contaminated water. Water treatment device using photocatalytic reaction based on gallium indium nanoparticles.

12. A contaminated water supply step for supplying contaminated water containing perfluorinated compounds, including per and poly fluoroalkyl substances (PFAS) in which multiple bonds of carbon (C) and fluorine (F) exist in an alkyl group, and fluorotelomer substances in which some of the carbons (C) in an alkyl group are not replaced with fluorine (F) but remain as hydrogen (H), to a reactor; A nitrogen supply step for removing dissolved oxygen in contaminated water contained in the reactor in advance by injecting nitrogen gas into the reactor; A eutectic gallium indium nanoparticle supply step for supplying a eutectic gallium indium suspension, in which eutectic gallium indium nanoparticles and a dispersion solvent are mixed, to contaminated water from which dissolved oxygen has been removed in the above reactor; A light irradiation step of irradiating either ultraviolet light or visible light using a light irradiation unit to the contaminated water mixed with the eutectic gallium indium suspension in the reactor; Holes (h) are generated by the photocatalytic reaction between the light irradiated in the above light irradiation step and the gallium indium nanoparticles. + ) and electrons (e - ) is generated, and the electron (e) - ) causes a reduction reaction that breaks the bond between carbon (C) and fluorine (F) of the perfluoroalkyl substance and decomposes it, and the hole (h) + ) includes a water treatment step for decomposing and defluorinating perfluorinated compounds in the contaminated water by causing an oxidation reaction that breaks the bond between carbon (C) and hydrogen (H) of the fluorotelomer material or causes a chain reaction by binding to an electron-rich functional group, Water treatment method using photocatalytic reaction based on eutectic gallium indium nanoparticles.

13. In claim 11, Before the above eutectic gallium indium nanoparticle supply step, A process of supplying a dispersion solvent and eutectic gallium indium liquid metal to a eutectic gallium indium nanoparticle synthesizer, A process of crushing the eutectic gallium indium liquid metal into eutectic gallium indium nanoparticles of a preset size using ultrasound, A eutectic gallium indium nanoparticle synthesis step further comprises a process of synthesizing the eutectic gallium indium suspension in which the eutectic gallium indium nanoparticles having a size smaller than the set size are mixed in the dispersion solvent by removing nanoparticles exceeding the set size deposited for a preset waiting time after the above pulverization. Water treatment method using photocatalytic reaction based on eutectic gallium indium nanoparticles.

14. In claim 12, The above oxidation reaction is, The above hole (h + ) is a reaction in which water is decomposed to generate OH radicals, and the OH radicals break the bonds between carbon (C) and hydrogen (H) and cause decomposition, The above hole (h + ) involves a reaction in which the electron-rich functional group binds to it and decomposes it through a chain reaction. Water treatment method using photocatalytic reaction based on eutectic gallium indium nanoparticles.

15. In claim 12, If the water quality measured by the water quality meter for the treated water discharged from the reactor after the above water treatment step does not meet the preset water quality standards, The above-mentioned treatment water is returned to the above-mentioned reactor, and the above-mentioned light irradiation step is performed again. Water treatment method using photocatalytic reaction based on eutectic gallium indium nanoparticles.

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