CN116282328B - Method for efficiently regenerating mineralized synergistic activated carbon by catalyzing perfluorinated compounds at low temperature - Google Patents
Method for efficiently regenerating mineralized synergistic activated carbon by catalyzing perfluorinated compounds at low temperature Download PDFInfo
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 265
- 150000001875 compounds Chemical class 0.000 title claims abstract description 58
- 238000000034 method Methods 0.000 title claims abstract description 52
- 230000001172 regenerating effect Effects 0.000 title claims abstract description 32
- 230000002195 synergetic effect Effects 0.000 title claims description 30
- 238000001179 sorption measurement Methods 0.000 claims abstract description 55
- 238000011069 regeneration method Methods 0.000 claims abstract description 31
- 230000003197 catalytic effect Effects 0.000 claims abstract description 26
- 230000008929 regeneration Effects 0.000 claims abstract description 20
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 32
- 229910052799 carbon Inorganic materials 0.000 claims description 24
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 21
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 21
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 16
- 239000000706 filtrate Substances 0.000 claims description 15
- 239000003245 coal Substances 0.000 claims description 10
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Substances [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 claims description 10
- 239000011261 inert gas Substances 0.000 claims description 9
- 238000010438 heat treatment Methods 0.000 claims description 8
- 239000007787 solid Substances 0.000 claims description 6
- 239000013078 crystal Substances 0.000 claims description 5
- 229910000027 potassium carbonate Inorganic materials 0.000 claims description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 claims description 4
- 238000000227 grinding Methods 0.000 claims description 4
- 235000013162 Cocos nucifera Nutrition 0.000 claims description 3
- 244000060011 Cocos nucifera Species 0.000 claims description 3
- 238000001035 drying Methods 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 3
- 238000005470 impregnation Methods 0.000 claims description 3
- 239000004570 mortar (masonry) Substances 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 2
- TYJJADVDDVDEDZ-UHFFFAOYSA-M potassium hydrogencarbonate Chemical compound [K+].OC([O-])=O TYJJADVDDVDEDZ-UHFFFAOYSA-M 0.000 claims 1
- 230000033558 biomineral tissue development Effects 0.000 abstract description 34
- 150000001447 alkali salts Chemical class 0.000 abstract description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 6
- 238000004064 recycling Methods 0.000 abstract description 5
- 230000001089 mineralizing effect Effects 0.000 abstract description 3
- 238000006555 catalytic reaction Methods 0.000 abstract description 2
- 238000006243 chemical reaction Methods 0.000 abstract description 2
- SNGREZUHAYWORS-UHFFFAOYSA-N perfluorooctanoic acid Chemical compound OC(=O)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)F SNGREZUHAYWORS-UHFFFAOYSA-N 0.000 description 29
- 229920006395 saturated elastomer Polymers 0.000 description 14
- 125000000524 functional group Chemical group 0.000 description 9
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 8
- 229910052731 fluorine Inorganic materials 0.000 description 8
- 239000011737 fluorine Substances 0.000 description 8
- 239000007789 gas Substances 0.000 description 8
- 239000007788 liquid Substances 0.000 description 7
- 229910021642 ultra pure water Inorganic materials 0.000 description 7
- 239000012498 ultrapure water Substances 0.000 description 7
- 239000002699 waste material Substances 0.000 description 7
- 230000004048 modification Effects 0.000 description 6
- 238000012986 modification Methods 0.000 description 6
- -1 perfluoro compound Chemical class 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- 238000000926 separation method Methods 0.000 description 6
- 239000000243 solution Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 239000011148 porous material Substances 0.000 description 4
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 description 4
- PUZPDOWCWNUUKD-UHFFFAOYSA-M sodium fluoride Chemical compound [F-].[Na+] PUZPDOWCWNUUKD-UHFFFAOYSA-M 0.000 description 4
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 4
- 231100000331 toxic Toxicity 0.000 description 4
- 230000002588 toxic effect Effects 0.000 description 4
- 238000007233 catalytic pyrolysis Methods 0.000 description 3
- 239000003153 chemical reaction reagent Substances 0.000 description 3
- 238000002425 crystallisation Methods 0.000 description 3
- 230000008025 crystallization Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 230000007935 neutral effect Effects 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000000967 suction filtration Methods 0.000 description 3
- 239000002023 wood Substances 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 150000004673 fluoride salts Chemical class 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 230000001699 photocatalysis Effects 0.000 description 2
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 description 2
- NROKBHXJSPEDAR-UHFFFAOYSA-M potassium fluoride Chemical compound [F-].[K+] NROKBHXJSPEDAR-UHFFFAOYSA-M 0.000 description 2
- 239000004323 potassium nitrate Substances 0.000 description 2
- 235000010333 potassium nitrate Nutrition 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 239000011775 sodium fluoride Substances 0.000 description 2
- 235000013024 sodium fluoride Nutrition 0.000 description 2
- 239000004317 sodium nitrate Substances 0.000 description 2
- 235000010344 sodium nitrate Nutrition 0.000 description 2
- 159000000000 sodium salts Chemical class 0.000 description 2
- 239000002689 soil Substances 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000002156 adsorbate Substances 0.000 description 1
- 238000003556 assay Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 231100000693 bioaccumulation Toxicity 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 230000000875 corresponding effect Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 230000002939 deleterious effect Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 230000005518 electrochemistry Effects 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- 239000010903 husk Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 230000002045 lasting effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 238000007146 photocatalysis Methods 0.000 description 1
- 238000009832 plasma treatment Methods 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 150000003112 potassium compounds Chemical class 0.000 description 1
- 239000011698 potassium fluoride Substances 0.000 description 1
- 235000003270 potassium fluoride Nutrition 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- 210000002966 serum Anatomy 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000002336 sorption--desorption measurement Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000002352 surface water Substances 0.000 description 1
- 239000008399 tap water Substances 0.000 description 1
- 235000020679 tap water Nutrition 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Classifications
-
- 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
- C02F1/28—Treatment of water, waste water, or sewage by sorption
- C02F1/281—Treatment of water, waste water, or sewage by sorption using inorganic sorbents
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/30—Processes for preparing, regenerating, or reactivating
- B01J20/34—Regenerating or reactivating
- B01J20/3416—Regenerating or reactivating of sorbents or filter aids comprising free carbon, e.g. activated carbon
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/30—Processes for preparing, regenerating, or reactivating
- B01J20/34—Regenerating or reactivating
- B01J20/345—Regenerating or reactivating using a particular desorbing compound or mixture
- B01J20/3475—Regenerating or reactivating using a particular desorbing compound or mixture in the liquid phase
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/30—Processes for preparing, regenerating, or reactivating
- B01J20/34—Regenerating or reactivating
- B01J20/3483—Regenerating or reactivating by thermal treatment not covered by groups B01J20/3441 - B01J20/3475, e.g. by heating or cooling
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2303/00—Specific treatment goals
- C02F2303/16—Regeneration of sorbents, filters
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Analytical Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Hydrology & Water Resources (AREA)
- Water Supply & Treatment (AREA)
- Environmental & Geological Engineering (AREA)
- Materials Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- Inorganic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
Abstract
The invention discloses a method for efficiently regenerating activated carbon by mineralizing and cooperating perfluorinated compounds by low-temperature catalysis, and relates to the technical field of water treatment and recycling. The method adopts activated carbon to adsorb perfluorinated compounds, particularly uses alkali salt to modify and adsorb saturated activated carbon so as to increase surface alkaline catalytic sites, is then used for catalyzing the conversion of perfluorinated compounds at low temperature and is cooperated with the thermal regeneration of activated carbon, has good mineralization rate, and the regenerated activated carbon has good specific surface area and perfluorinated compound adsorption capacity.
Description
Technical Field
The invention belongs to the technical field of water treatment and recycling, and particularly relates to a method for efficiently regenerating mineralized synergistic activated carbon of a perfluoro compound by low-temperature catalysis.
Background
Perfluorinated compounds are a class of deleterious compounds that are of great concern worldwide. Perfluorooctanoic acid (PFOA) is a typical perfluorinated compound that is detected in groundwater, surface water, wastewater and tap water all over the world. PFOA has a half-life as long as 3.8 years in human serum and has strong bioaccumulation and toxic action. There is an increasing demand for efficient removal of PFOA from water. In recent years, application studies of advanced technologies such as plasma treatment, electrochemistry and photocatalysis have been greatly advanced, but these means remain only on a laboratory scale, and in actual practice, adsorption using Activated Carbon (AC) is the most widely used method for treating PFOA contaminated water. For the adsorption of saturated waste activated carbon, a convenient, green and environment-friendly recycling regeneration method is needed.
China is the largest active carbon producing country worldwide. As an excellent adsorption material, activated carbon is widely used in various fields such as food, chemical industry, environment, etc., and has to be replaced frequently because the activated carbon is easily saturated and loses adsorption capacity in the use process. The regeneration methods of the ineffective active carbon aiming at different application fields are numerous, and common methods comprise a thermal regeneration method, a solvent regeneration method, a chemical regeneration method, an electrochemical regeneration method, a wet air oxidation method, a catalytic oxidation regeneration method, an ultrasonic regeneration method, a photocatalytic regeneration method and the like.
Among these, the thermal regeneration method is one of the most widely developed and used activated carbon regeneration methods. The principle is that under the high temperature condition, the adsorbate adsorbed in the saturated activated carbon is desorbed from the pores of the activated carbon and separated from the saturated activated carbon, so that the pores of the activated carbon which are originally blocked are opened, and the adsorption performance of the activated carbon is recovered. However, the temperature of the existing thermal regeneration technology is generally higher than 950 ℃, the mineralization rate of the perfluorinated compounds is low, and toxic and harmful fluorine-containing organic gases are generated and discharged into the atmosphere, so that the perfluorinated compounds are infinitely circulated in the water-air soil and permanently pollute the environment.
The invention aims at the waste activated carbon which is saturated by adsorbing the perfluorinated compounds, and aims at blocking the lasting circulation of the perfluorinated compounds in the water, gas and soil, simultaneously ensuring the resource regeneration in the heat treatment process, reducing the heat regeneration temperature, improving the heat regeneration efficiency, and simultaneously realizing the regeneration and the utilization of the activated carbon and the resource recovery of fluoride salt generated in the heat treatment process. The invention provides a method for regenerating activated carbon by mineralizing and synergetically catalyzing perfluorinated compounds at low temperature, which aims at waste activated carbon which is saturated by adsorbing perfluorinated compounds, achieves complete regeneration of the activated carbon and complete mineralization of perfluorinated compounds under the condition of not exceeding 600 ℃, reduces pollution of toxic and harmful products to the environment, reduces the possibility of circulating fluorine-containing substances in the environment, and has great prospect in the fields of water treatment and recycling.
Disclosure of Invention
The invention aims to provide a method for efficiently regenerating a low-temperature catalytic perfluoro compound mineralization synergistic active carbon, which has good mineralization rate, and the regenerated active carbon has good specific surface area and perfluoro compound adsorption capacity.
The technical scheme adopted by the invention for achieving the purpose is as follows:
a method for efficiently regenerating mineralized synergistic activated carbon by catalyzing perfluorinated compounds at low temperature comprises the following steps:
1) Obtaining adsorption saturated activated carbon;
2) Constructing alkaline sites on the surface of the adsorption saturated activated carbon by using alkali salt to obtain modified adsorption saturated activated carbon;
3) Under the protection of inert gas, carrying out thermal regeneration on the modified adsorption saturated activated carbon at 400-700 ℃, and filtering to obtain regenerated activated carbon;
4) Crystallizing the filtrate to obtain fluoride crystals;
the specific surface area of the regenerated active carbon is 850-1100m 2 /g。
The invention adopts a mode of constructing alkaline sites to assist the mineralization of the thermocatalytic perfluorinated compounds to cooperatively regenerate the waste activated carbon, so that the waste activated carbon can recover the adsorption capacity at low temperature and can be recycled, and meanwhile, the mineralization rate of the perfluorinated compounds is close to 100%, thereby greatly reducing the possibility of toxic and harmful products entering the environment. In addition, in the process of constructing alkaline sites on waste active carbon, the method adopts grinding, mixing and impregnating construction modes, so that the active carbon absorbing the perfluorinated compounds in the thermal regeneration process is fully contacted with the alkaline reagent, the use amount of the alkaline reagent is obviously reduced, the cost is reduced, and in addition, on the premise of ensuring the use amount, the corrosion effect of the alkaline reagent on active carbon micropores is reduced.
Specifically, the method for efficiently regenerating the mineralized synergistic activated carbon of the low-temperature catalytic perfluorinated compounds comprises the following steps:
1) The activated carbon is used for adsorbing perfluorinated compounds, and after the activated carbon is saturated in adsorption, the activated carbon is dried for 12-24 hours at the temperature of 30-50 ℃ to obtain the activated carbon saturated in adsorption;
2) Adding alkali salt into the adsorption saturated activated carbon, fully grinding the adsorption saturated activated carbon by using a mortar or a ball mill until white alkali salt solid disappears, and obtaining modified adsorption saturated activated carbon by using a mechanochemical method;
3) Under the protection of inert gas, the modified adsorption saturated active carbon is heated to 400-700 ℃ from room temperature at a heating rate of 5-10 ℃/min under the protection of the inert gas with continuous gas flow of 100-200mL/min, and is kept at the constant temperature for 30-40min, then cooled to the room temperature, added with ultrapure water, subjected to suction filtration, subjected to solid-liquid separation, and subjected to solid cleaning to be neutral, so as to obtain regenerated active carbon;
4) Recovering filtrate, crystallizing the filtrate to obtain fluoride crystals;
or alternatively, the first and second heat exchangers may be,
1) The activated carbon is used for adsorbing perfluorinated compounds, and after the activated carbon is saturated in adsorption, the activated carbon is dried for 12-24 hours at the temperature of 30-50 ℃ to obtain the activated carbon saturated in adsorption;
2) Preparing an alkali salt solution with the concentration of 0.961-3.844mol/L, adding adsorption saturated activated carbon by adopting an isovolumetric impregnation method at normal temperature, and then heating to 40-80 ℃ and drying for 10-20min to obtain modified adsorption saturated activated carbon;
3) Under the protection of inert gas, the modified adsorption saturated active carbon is heated to 400-700 ℃ from room temperature at a heating rate of 5-10 ℃/min under the protection of the inert gas with continuous gas flow of 100-200mL/min, and is kept at the constant temperature for 30-40min, then cooled to the room temperature, added with ultrapure water, subjected to suction filtration, subjected to solid-liquid separation, and subjected to solid cleaning to be neutral, so as to obtain regenerated active carbon;
4) The filtrate is recovered, and then the filtrate is crystallized to obtain fluoride crystals.
According to the embodiment of the invention, the mass volume ratio of the active carbon to the ultrapure water is as follows: 1g, 400-450mL.
According to an embodiment of the present invention, the activated carbon is selected from any one of coconut husk, wood, and coal.
According to an embodiment of the present invention, the alkali salt is selected from one of sodium salt and potassium salt.
According to an embodiment of the present invention, the sodium salt is selected from one of sodium nitrate, sodium hydroxide or sodium carbonate.
According to an embodiment of the present invention, the potassium salt is selected from one of potassium nitrate, potassium hydroxide and potassium carbonate.
According to an embodiment of the present invention, in the filtrate crystallization, evaporation crystallization is used for the filtrate of sodium fluoride; the filtrate of potassium fluoride adopts cooling crystallization.
According to an embodiment of the invention, the ratio of the alkali salt to the activated carbon is 9.61-19.22mmol/g.
The beneficial effects of the invention include:
the invention obtains a method for efficiently regenerating the mineralized synergistic activated carbon of the low-temperature catalytic perfluorinated compounds, which adopts the activated carbon to adsorb the perfluorinated compounds, is then used for mineralizing the low-temperature catalytic perfluorinated compounds and efficiently regenerating the synergistic activated carbon, has good mineralization rate, and the regenerated activated carbon has good specific surface area and perfluorinated compounds adsorption capacity; in addition, the invention realizes the mineralization rate of the perfluorinated compound close to 100% and the resource recovery of the fluoride salt and the activated carbon with lower alkali-carbon ratio and thermal regeneration temperature.
Therefore, the invention provides a method for efficiently regenerating the mineralized synergistic activated carbon of the low-temperature catalytic perfluorinated compounds, which has good mineralization rate, and the regenerated activated carbon has good specific surface area and perfluorinated compounds adsorption capacity.
Drawings
FIG. 1 is a graph showing the results of tests of the mineralization rate of PFOA adsorption by different activated carbons in relation to basic functional groups;
FIG. 2 shows the degree of mineralization of PFOA under different conditions.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clear and clear, the technical solutions of the present invention are described in further detail below with reference to the specific embodiments:
example 1:
a method for efficiently regenerating mineralized synergistic activated carbon by catalyzing perfluorinated compounds at low temperature comprises the following steps:
1) Coal activated carbon (purchased from Shandong south Corp., code: coal-1) was used for adsorbing PFOA, and after saturation of the adsorption, the activated carbon was dried at 40℃for 15 hours to obtain an adsorption-saturated activated carbon;
2) Adding sodium carbonate into the adsorption saturated activated carbon, fully grinding by using a mortar until white alkali salt solid disappears, and obtaining modified adsorption saturated activated carbon by using a mechanochemical method;
3) Under the protection of inert gas, the modified adsorption saturated activated carbon is heated to 600 ℃ from room temperature at a heating rate of 5 ℃/min under the protection of the inert gas with the continuous gas flow of 100mL/min, and is kept at the constant temperature for 30min, then the temperature is reduced to the room temperature, ultrapure water is added into the room temperature, solid-liquid separation is carried out after suction filtration, and the solid is cleaned to be neutral, so that regenerated activated carbon is obtained;
4) Recovering filtrate, and then evaporating and crystallizing the filtrate to obtain sodium fluoride crystals;
wherein, the mass volume ratio of the active carbon to the ultrapure water is as follows: 1g:400mL; the ratio of sodium carbonate to activated carbon was 9.61mmol/g.
Example 2:
the method for efficiently regenerating the mineralized synergistic activated carbon of the low-temperature catalytic perfluorinated compounds is different from that of the embodiment 1: the mass volume ratio of the active carbon to the ultrapure water is as follows: 450mL of 1 g; the ratio of sodium carbonate to activated carbon was 19.22mmol/g.
Example 3:
the method for efficiently regenerating the mineralized synergistic activated carbon of the low-temperature catalytic perfluorinated compounds is different from that of the embodiment 1: the mass volume ratio of the active carbon to the ultrapure water is as follows: 1g:430mL; the ratio of sodium carbonate to activated carbon was 12mmol/g.
Example 4:
the method for efficiently regenerating the mineralized synergistic activated carbon of the low-temperature catalytic perfluorinated compounds is different from that of the embodiment 1: sodium carbonate was not added.
Example 5:
the method for efficiently regenerating the mineralized synergistic activated carbon of the low-temperature catalytic perfluorinated compounds is different from that of the embodiment 1: potassium hydroxide is used instead of sodium carbonate.
Example 6:
the method for efficiently regenerating the mineralized synergistic activated carbon of the low-temperature catalytic perfluorinated compounds is different from that of the embodiment 1: sodium hydroxide is used instead of sodium carbonate.
Example 7:
the method for efficiently regenerating the mineralized synergistic activated carbon of the low-temperature catalytic perfluorinated compounds is different from that of the embodiment 1: potassium carbonate is used instead of sodium carbonate.
Example 8:
the method for efficiently regenerating the mineralized synergistic activated carbon of the low-temperature catalytic perfluorinated compounds is different from that of the embodiment 1: sodium nitrate is used instead of sodium carbonate.
Example 9:
the method for efficiently regenerating the mineralized synergistic activated carbon of the low-temperature catalytic perfluorinated compounds is different from that of the embodiment 1: potassium nitrate is used instead of sodium carbonate.
Example 10:
the method for efficiently regenerating the mineralized synergistic activated carbon of the low-temperature catalytic perfluorinated compounds is different from that of the embodiment 1: wood activated carbon (available from Guangdong Korean Co., ltd., number Wood-1) was used instead of Coal activated carbon Coal-1.
Example 11:
the method for efficiently regenerating the mineralized synergistic activated carbon of the low-temperature catalytic perfluorinated compounds is different from that of the embodiment 1: wood activated carbon (AR) Shanghai (available from national medicine group, number Wood-2) was used instead of Coal activated carbon Coal-1.
Example 12:
the method for efficiently regenerating the mineralized synergistic activated carbon of the low-temperature catalytic perfluorinated compounds is different from that of the embodiment 1: coco-1 was replaced with Coconut activated carbon (available from Shandong south Corp., number Cocout).
Example 13:
the method for efficiently regenerating the mineralized synergistic activated carbon of the low-temperature catalytic perfluorinated compounds is different from that of the embodiment 1: coal activated carbon F400 (available from Karl Co., ltd., code Coal-2) was used instead of Coal activated carbon Coal-1.
Example 14:
the method for efficiently regenerating the mineralized synergistic activated carbon of the low-temperature catalytic perfluorinated compounds is different from that of the embodiment 6: step 1) -step 2) are not performed.
The thermal regeneration treatment was started directly from step 3) with PFOA (PFOA amount equal to that of the coal-based activated carbon adsorbed PFOA of example 6).
Example 15:
the method for efficiently regenerating the mineralized synergistic activated carbon of the low-temperature catalytic perfluorinated compounds is different from that of the embodiment 6: step 1) is not performed.
PFOA (PFOA amount equal to that of the coal-based activated carbon adsorbed PFOA of example 6) is directly mixed with sodium hydroxide starting from step 2) and then subjected to a thermal regeneration treatment.
Example 16:
the method for efficiently regenerating the mineralized synergistic activated carbon of the low-temperature catalytic perfluorinated compounds is different from that of the embodiment 6: step 2) is not performed.
After the Coal activated carbon Coal-1 is saturated by adsorbing PFOA, directly starting the heat regeneration treatment of the activated carbon saturated by adsorption from the step 3).
Example 17:
the method for efficiently regenerating the mineralized synergistic activated carbon of the low-temperature catalytic perfluorinated compounds is different from that of the embodiment 1: step 2) is different.
Step 2) of the present embodiment includes the following processes: preparing sodium carbonate solution with the concentration of 0.961mol/L, adding adsorption saturated activated carbon by adopting an equal volume impregnation method at normal temperature, and then heating to 40-80 ℃ and drying for 10-20min to obtain the modified adsorption saturated activated carbon.
Test example 1:
specific surface area test
N was performed on a specific surface area and porosity analyzer (ASAP 2420, micromeritics, USA) 2 Adsorption-desorption test, degassing temperature is 300 ℃, and specific surface area is calculated by micro active software.
Table 1 results of specific surface area test of samples
| Experimental grouping | Specific surface area (m) 2 /g） |
| Activated carbon | 1009.7 |
| Example 1 | 891.1 |
| Example 2 | 893.6 |
| Example 3 | 891.3 |
| Example 4 | 862.7 |
| Example 5 | 1061.0 |
| Example 6 | 930.6 |
| Example 7 | 925.2 |
| Example 8 | 968.0 |
| Example 9 | 884.1 |
| Example 17 | 892.7 |
The above-described test was performed on the regenerated activated carbon prepared in example 1-example 9 and example 17, and the results are shown in table 1. As can be seen from table 1, the specific surface area of example 5 is increased compared with that of activated carbon, probably because the potassium compound generated by potassium hydroxide at high temperature etches carbon to form carbon dioxide and carbon monoxide gas, and a pore structure is generated, thereby achieving the purposes of expanding pores and increasing specific surface area; compared with the embodiment 4, the specific surface area of the regenerated active carbon is improved to a certain extent in the embodiment 1, which shows that the construction of the alkaline site improves the specific surface area of the regenerated active carbon, and is more beneficial to the recycling or reutilization of the regenerated active carbon; example 17 showed little difference in specific surface area from example 1, indicating that the regenerated activated carbon obtained by thermal regeneration after alkali salt modification of the adsorption saturated activated carbon by two different methods had little difference in specific surface area.
Test example 2:
mineralization rate test
Detecting fluorine content in the filtrate after solid-liquid separation by adopting an Ion Chromatograph (IC);
S/%=(F1/F0)×100%
wherein S is mineralization rate; f0 is the fluorine content adsorbed by the activated carbon; f1 is the fluorine content in the filtrate after solid-liquid separation.
TABLE 2 mineralization rate test results
| Experimental grouping | Mineralization rate/% |
| Example 1 | 88.3 |
| Example 2 | 90.8 |
| Example 3 | 89.4 |
| Example 4 | 65.51 |
| Example 5 | 99.35 |
| Example 6 | 99.57 |
| Example 7 | 84.39 |
| Example 8 | 91.10 |
| Example 9 | 83.07 |
| Example 17 | 88.58 |
The above-described test was conducted on the fluorine content in the filtrate after the solid-liquid separation of examples 1 to 9 and 17, and the results are shown in Table 2. As can be seen from table 2, the mineralization rate of example 1 is also significantly increased compared with example 4, which demonstrates that the use of alkali salt modification to assist in catalytic pyrolysis of the perfluorinated compounds can achieve higher mineralization rate and reduce the production of short-chain perfluorinated compounds and fluorine-containing gas; compared with example 1, the mineralization rate of example 17 is not greatly different, which shows that the higher mineralization rate can be realized by performing alkali salt modification on the activated carbon saturated by adsorption by two different methods and then performing catalytic pyrolysis on the perfluorinated compounds.
Test example 3:
perfluorochemical adsorption Capacity test
50mL of PFOA solution with the concentration of 5mg/L is respectively added into 6 polyethylene bottles, then 0.01g, 0.03g, 0.05g, 0.07g, 0.10g and 0.15g of active carbon are respectively added, the mixture is placed into a constant temperature shaking table for reaction for 48 hours at the temperature of 25 ℃ and the rpm of 200rpm, a disposable needle filter (0.22 mu m) is adopted for filtering, filtrate is taken, the residual PFOA concentration in the solution is measured by an ultra-high performance liquid chromatography-triple quadrupole tandem mass spectrometer, an adsorption isotherm is made, and then the PFOA adsorption capacity corresponding to the residual PFOA concentration after the experiment of the thermal regeneration treatment device is completed is obtained according to the adsorption isotherm.
The experimental data were fitted using the Freundlich nonlinear isotherm model as shown in the equation below:
q e =K F ×(C e ) 1/n
q in e For equilibrium adsorption quantity (mmol/g), C e Concentration of PFOA in solution at equilibrium (mmol/L), K F Is the Freundlich adsorption capacity parameter (ng/mg)/(ng/L) 1/n N is the Freundlich index associated with affinity of the adsorption energy distribution.
TABLE 3 PFOA adsorption Capacity test results
| Experimental grouping | PFOA adsorption capacity q e90% （mg/g） |
| Example 1 | 198.56 |
| Example 2 | 203.94 |
| Example 3 | 200.37 |
| Example 4 | 187.80 |
| Example 5 | 267.95 |
| Example 6 | 211.74 |
| Example 7 | 221.19 |
| Example 8 | 282.02 |
| Example 9 | 214.03 |
The above-described test was performed on the regenerated active carbon prepared in example 1-example 9, and the results are shown in table 3. As can be seen from Table 3, the PFOA adsorption capacity of examples 1-3 and examples 5-9 is obviously improved compared with that of example 4, which shows that the alkali salt modification has an effect of thermal regeneration on the activated carbon, so that the alkali functional groups on the surface of the activated carbon are increased, the adsorption capacity of the regenerated activated carbon on the perfluorinated compounds is enhanced, and the superiority of the alkali salt modification in assisting thermal regeneration is reflected.
Test example 4:
basic functional group amount assay
And (3) measuring the content of the oxygen-containing functional groups on the surface of the activated carbon by using a Boehm titration method.
The above-described test was performed on the activated carbon samples of example 1 and examples 10 to 13, and the results are shown in fig. 1. As can be seen from fig. 1, the amount of basic functional groups on the surface of each activated carbon sample is different; and the mineralization rate of the activated carbon sample with lower alkaline functional group content is also lower, which shows that the alkaline functional group content on the surface of the activated carbon sample has an influence on the mineralization rate, namely, the alkaline functional group content on the surface of the activated carbon is positively correlated with the thermal regeneration mineralization degree of the adsorbed PFOA. Therefore, the auxiliary catalytic pyrolysis of the perfluorinated compounds under the low-temperature condition can be realized by constructing alkaline sites on the waste activated carbon saturated by the perfluorinated compounds, and almost hundred percent mineralization rate is ensured.
Test example 5:
influence test of alkali salt modified activated carbon on PFOA mineralization rate
The mineralization rate test method is the same as in test example 3. Activated carbon is noted as GAC; the experimental grouping included: example 6 is noted as: activated carbon adsorption PFOA+alkali modification; example 14 is noted as: PFOA; example 15 is noted as: PFOA+base; example 16 is noted as: activated carbon adsorbs PFOA.
Mineralization rates were measured in examples 6, 14-16, and the results are shown in FIG. 2. As can be seen from FIG. 2, the mineralization rate in example 15 was not significantly increased compared with example 14, indicating that the addition of the simple alkali salt had little effect on the mineralization rate; compared with the example 16, the example 6 has obvious mineralization rate increase, which shows that the alkali salt modified activated carbon has obvious improvement effect on the mineralization rate; compared with the examples 14 and 6 and 15, the mineralization rate of the activated carbon is obviously increased, which indicates that the basic functional groups on the surface of the activated carbon have obvious promotion effect on the mineralization rate; and the alkali salt is adopted to modify the modified activated carbon, so that the surface alkaline site is increased, the activated carbon can be further assisted to catalyze and pyrolyze the perfluorinated compounds, the mineralization rate of nearly hundred percent can be realized, and the generation of fluorine-containing gas is reduced.
The conventional technology in the above embodiments is known to those skilled in the art, and thus is not described in detail herein.
The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any person skilled in the art will readily recognize that variations or substitutions are within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (4)
1. A method for efficiently regenerating mineralized synergistic activated carbon by catalyzing perfluorinated compounds at low temperature comprises the following steps:
step 1) obtaining adsorption saturated activated carbon;
step 2) constructing alkaline sites on the surface of the adsorption saturated activated carbon by using one of sodium hydroxide, sodium carbonate, potassium hydroxide or potassium carbonate to obtain modified adsorption saturated activated carbon;
step 3) under the protection of inert gas, carrying out thermal regeneration on the modified adsorption saturated activated carbon at 400-600 ℃, and filtering to obtain regenerated activated carbon;
step 4) crystallizing the filtrate to obtain fluoride crystals;
the method is characterized in that: the specific surface area of the regenerated active carbon is 850-1100m 2 /g；
The specific operation method of the step 2) comprises the following steps:
adding one of sodium hydroxide, sodium carbonate, potassium hydroxide or potassium carbonate into the adsorption saturated activated carbon, fully grinding the mixture by using a mortar or a ball mill until white solid disappears, and obtaining the modified adsorption saturated activated carbon by using a mechanochemical method;
or alternatively, the first and second heat exchangers may be,
preparing sodium hydroxide, sodium carbonate, potassium hydroxide or potassium carbonate solution with the concentration of 0.961-3.844mol/L, adding adsorption saturated activated carbon by adopting an isovolumetric impregnation method at normal temperature, and then heating to 40-80 ℃ and drying for 10-20min to obtain modified adsorption saturated activated carbon;
the ratio of the sodium hydroxide, the sodium carbonate, the potassium hydroxide or the potassium carbonate to the activated carbon is 9.61-19.22mmol/g.
2. The method for efficiently regenerating the mineralized synergistic activated carbon by using the low-temperature catalytic perfluorinated compounds, which is disclosed in claim 1, is characterized in that: the activated carbon in the step 1) is selected from any one of coconut shells, woody or coal.
3. The method for efficiently regenerating the mineralized synergistic activated carbon by using the low-temperature catalytic perfluorinated compounds, which is disclosed in claim 1, is characterized in that: the time of the thermal regeneration in the step 3) is 30-40min.
4. The method for efficiently regenerating the mineralized synergistic activated carbon by using the low-temperature catalytic perfluorinated compounds, which is disclosed in claim 1, is characterized in that: the flow rate of the inert gas in the step 3) is 100-200mL/min.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1369213A (en) * | 1963-09-13 | 1964-08-07 | Teijin Ltd | Activated carbon regeneration process |
| JP2013184132A (en) * | 2012-03-09 | 2013-09-19 | Swing Corp | Regeneration method for used activated carbon and activated carbon and method for manufacturing the same |
| CN106512974A (en) * | 2016-11-10 | 2017-03-22 | 中南大学 | Regeneration method of activated carbon |
| CN115193428A (en) * | 2021-04-14 | 2022-10-18 | 上海交通大学 | Regeneration method of waste activated carbon containing perfluorinated compounds |
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| EP3646946A1 (en) * | 2018-10-30 | 2020-05-06 | Helmholtz-Zentrum für Umweltforschung GmbH-UFZ | Method for the removal of polyfluorinated organic compounds from water by means of an adsorbent and regeneration thereof |
| US20200306726A1 (en) * | 2019-03-25 | 2020-10-01 | Battelle Memorial Institute | Systems and Methods of Regenerating Activated Carbon |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1369213A (en) * | 1963-09-13 | 1964-08-07 | Teijin Ltd | Activated carbon regeneration process |
| JP2013184132A (en) * | 2012-03-09 | 2013-09-19 | Swing Corp | Regeneration method for used activated carbon and activated carbon and method for manufacturing the same |
| CN106512974A (en) * | 2016-11-10 | 2017-03-22 | 中南大学 | Regeneration method of activated carbon |
| CN115193428A (en) * | 2021-04-14 | 2022-10-18 | 上海交通大学 | Regeneration method of waste activated carbon containing perfluorinated compounds |
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