CN113526648B - Method for removing coffee grounds, biochar and urea in water - Google Patents
Method for removing coffee grounds, biochar and urea in water Download PDFInfo
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- CN113526648B CN113526648B CN202111089951.7A CN202111089951A CN113526648B CN 113526648 B CN113526648 B CN 113526648B CN 202111089951 A CN202111089951 A CN 202111089951A CN 113526648 B CN113526648 B CN 113526648B
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- 235000013353 coffee beverage Nutrition 0.000 title claims abstract description 80
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 title claims abstract description 65
- 239000004202 carbamide Substances 0.000 title claims abstract description 65
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 43
- 238000000034 method Methods 0.000 title claims abstract description 30
- 238000003837 high-temperature calcination Methods 0.000 claims abstract description 49
- JRKICGRDRMAZLK-UHFFFAOYSA-L peroxydisulfate Chemical compound [O-]S(=O)(=O)OOS([O-])(=O)=O JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 claims abstract description 29
- 239000007864 aqueous solution Substances 0.000 claims abstract description 27
- 238000006243 chemical reaction Methods 0.000 claims abstract description 14
- 238000000227 grinding Methods 0.000 claims abstract description 12
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 8
- 230000010355 oscillation Effects 0.000 claims abstract description 8
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 8
- 239000001301 oxygen Substances 0.000 claims abstract description 8
- 238000002156 mixing Methods 0.000 claims abstract description 6
- 239000011888 foil Substances 0.000 claims description 8
- 238000010438 heat treatment Methods 0.000 claims description 8
- 238000001291 vacuum drying Methods 0.000 claims description 8
- 229910052751 metal Inorganic materials 0.000 claims description 5
- 239000002184 metal Substances 0.000 claims description 5
- LCPVQAHEFVXVKT-UHFFFAOYSA-N 2-(2,4-difluorophenoxy)pyridin-3-amine Chemical group NC1=CC=CN=C1OC1=CC=C(F)C=C1F LCPVQAHEFVXVKT-UHFFFAOYSA-N 0.000 claims description 4
- 150000001875 compounds Chemical class 0.000 claims description 4
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Substances [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 claims description 4
- 239000002245 particle Substances 0.000 claims description 3
- USHAGKDGDHPEEY-UHFFFAOYSA-L potassium persulfate Chemical compound [K+].[K+].[O-]S(=O)(=O)OOS([O-])(=O)=O USHAGKDGDHPEEY-UHFFFAOYSA-L 0.000 claims description 3
- 230000008929 regeneration Effects 0.000 claims 1
- 238000011069 regeneration method Methods 0.000 claims 1
- 238000002360 preparation method Methods 0.000 abstract description 8
- 229910021642 ultra pure water Inorganic materials 0.000 abstract description 7
- 239000012498 ultrapure water Substances 0.000 abstract description 7
- 239000000463 material Substances 0.000 abstract description 6
- 238000006555 catalytic reaction Methods 0.000 abstract description 4
- 230000004048 modification Effects 0.000 abstract description 2
- 238000012986 modification Methods 0.000 abstract description 2
- 239000000243 solution Substances 0.000 description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 239000002994 raw material Substances 0.000 description 6
- 238000001816 cooling Methods 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 4
- 239000004065 semiconductor Substances 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 238000002835 absorbance Methods 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 239000000919 ceramic Substances 0.000 description 3
- 239000000706 filtrate Substances 0.000 description 3
- 238000001179 sorption measurement Methods 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 2
- 230000003213 activating effect Effects 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000007717 exclusion Effects 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 238000001223 reverse osmosis Methods 0.000 description 2
- 239000002028 Biomass Substances 0.000 description 1
- 241000533293 Sesbania emerus Species 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 150000003384 small molecules Chemical class 0.000 description 1
- 239000008399 tap water Substances 0.000 description 1
- 235000020679 tap water Nutrition 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
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- 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
-
- 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
- B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
- B01J21/18—Carbon
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
- C02F2101/34—Organic compounds containing oxygen
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/30—Organic compounds
- C02F2101/38—Organic compounds containing nitrogen
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
Abstract
The invention provides a method for removing urea in water, which comprises the following steps: mixing the modified coffee grounds biochar, persulfate and an aqueous solution containing urea, and carrying out oscillation reaction to obtain a treated aqueous solution; the modified coffee grounds biochar is prepared by the following method: carrying out primary high-temperature calcination on the coffee grounds under the condition of limited oxygen, and grinding to obtain coffee grounds biochar; and carrying out secondary high-temperature calcination on the coffee grounds biochar to obtain the modified coffee grounds biochar. Compared with the prior art, the method has the advantages that the coffee grounds are used for preparing the biochar material, the modified biochar material is obtained through simple modification, and the activated persulfate of the modified biochar material is used for removing trace urea in the regenerated water under the catalysis of the activated persulfate, so that the stable operation of an ultrapure water preparation system is ensured, the supplied water TOC reaches the standard, and meanwhile, a foundation is provided for resource utilization.
Description
Technical Field
The invention belongs to the technical field of water treatment, and particularly relates to a method for removing coffee grounds, biochar and urea in water.
Background
The semiconductor industry is a high water consumption industry, and especially under the condition of limited water resources, the operation of semiconductor production enterprises is greatly stressed by water limitation and water shortage. At present, more and more ultrapure water systems adopt reclaimed water as a water source, and the replacement of part of municipal water by the reclaimed water is a great trend and is an inevitable subject in the semiconductor industry.
However, compared with tap water, the content of organic matters in the regenerated water is often higher, and small molecular organic matters such as the small molecular organic matters are difficult to remove through a traditional ultrapure water preparation system, so that TOC (total organic carbon) of terminal water supply exceeds the standard. Therefore, an effective method for removing urea in the regenerated water is needed to be found so as to ensure the terminal water supply quality of the semiconductor industry while effectively utilizing water resources.
At present, in a traditional ultrapure water system, processes commonly used for removing organic matters are activated carbon adsorption, reverse osmosis, UV and the like. However, activated carbon adsorption can only remove some larger non-polar molecules, while some polar small molecules with high water solubility (such as isopropanol, urea, etc.) cannot be effectively adsorbed. It is also difficult to remove urea from water by reverse osmosis processes because urea is a small uncharged molecule that cannot be removed by either size exclusion or charge exclusion. In addition, urea has a weak absorption ability for UV radiation, and N bonds in urea cannot be broken by UV radiation alone, so that it is difficult to remove urea in water by UV.
Disclosure of Invention
In view of the above, the present invention provides a method for removing biochar from coffee grounds and urea in water, which can remove trace urea in water.
The invention provides a method for removing urea in water, which comprises the following steps:
mixing the modified coffee grounds biochar, persulfate and an aqueous solution containing urea, and carrying out oscillation reaction to obtain a treated aqueous solution;
the modified coffee grounds biochar is prepared by the following method:
carrying out primary high-temperature calcination on the coffee grounds under the condition of limited oxygen, and grinding to obtain coffee grounds biochar;
and carrying out secondary high-temperature calcination on the coffee grounds biochar to obtain the modified coffee grounds biochar.
Preferably, the coffee grounds are wrapped by aluminum foil after being dried in vacuum; the temperature of the vacuum drying is 100-110 ℃; the vacuum drying time is 20-30 h; and grinding to a particle size of 80 meshes or less.
Preferably, the oxygen-limiting condition is provided by a metal foil wrap; the temperature of the first high-temperature calcination is 800-1000 ℃; the time of the first high-temperature calcination is 1-3 h; the temperature rise rate of the first high-temperature calcination is 1-10 ℃/min.
Preferably, the temperature of the first high-temperature calcination is 900 ℃; the time of the first high-temperature calcination is 2 h; the heating rate of the first high-temperature calcination is 5 ℃/min.
Preferably, the temperature of the second high-temperature calcination is 500-600 ℃; the time of the second high-temperature calcination is 2-6 h; the temperature rise rate of the second high-temperature calcination is 1-5 ℃/min.
Preferably, the temperature of the second high-temperature calcination is 550 ℃; the time of the second high-temperature calcination is 4 h; the temperature rise rate of the second high-temperature calcination is 2 ℃/min.
Preferably, the aqueous solution containing urea is regenerated water; the persulfate is selected from sodium persulfate and/or potassium persulfate; the mass ratio of the modified coffee grounds biochar to the persulfate is (0.05-0.8): (0.5 to 6).
Preferably, the ratio of the modified coffee grounds biochar to the urea-containing aqueous solution is (0.05-0.8) g: 1L; the ratio of the persulfate to the aqueous solution containing urea is (0.5-6) g: 1L of the compound.
Preferably, the ratio of the modified coffee grounds biochar to the aqueous solution containing urea is 0.4 g: 1L; the ratio of persulfate to aqueous solution containing urea is 2 g: 1L of the compound.
The invention also provides a preparation method of the modified coffee grounds biochar, which comprises the following steps:
carrying out primary high-temperature calcination on the coffee grounds under the condition of limited oxygen, and grinding to obtain coffee grounds biochar;
and carrying out secondary high-temperature calcination on the coffee grounds biochar to obtain the modified coffee grounds biochar.
The invention provides a method for removing urea in water, which comprises the following steps: mixing the modified coffee grounds biochar, persulfate and an aqueous solution containing urea, and carrying out oscillation reaction to obtain a treated aqueous solution; the modified coffee grounds biochar is prepared by the following method: carrying out primary high-temperature calcination on the coffee grounds under the condition of limited oxygen, and grinding to obtain coffee grounds biochar; and carrying out secondary high-temperature calcination on the coffee grounds biochar to obtain the modified coffee grounds biochar. Compared with the prior art, the method has the advantages that the coffee grounds are used for preparing the biochar material, the modified biochar material is obtained through simple modification, and the activated persulfate of the modified biochar material is used for removing trace urea in the regenerated water under the catalysis of the activated persulfate, so that the stable operation of an ultrapure water preparation system is ensured, the supplied water TOC reaches the standard, and meanwhile, a foundation is provided for resource utilization.
Drawings
FIG. 1 is a bar graph showing the influence of the persulfate addition amount on the urea removing effect in example 1 of the present invention;
FIG. 2 is a bar graph showing the influence of the amount of biochar added to the modified coffee grounds on the urea removal effect in example 2 of the present invention;
FIG. 3 is a bar graph of the effect of initial pH on urea removal in example 3 of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a preparation method of modified coffee grounds biochar, which comprises the following steps: carrying out primary high-temperature calcination on the coffee grounds under the condition of limited oxygen, and grinding to obtain coffee grounds biochar; and carrying out secondary high-temperature calcination on the coffee grounds biochar to obtain the modified coffee grounds biochar.
In the present invention, the sources of all raw materials are not particularly limited, and they may be commercially available.
The coffee grounds are residues left after coffee drinks are prepared by adopting coffee beans, and the coffee grounds are dried to obtain the raw materials of the coffee drink; in the present invention, it is preferred that the coffee grounds are first vacuum dried; the temperature of the vacuum drying is preferably 100-110 ℃, and more preferably 105 ℃; the vacuum drying time is preferably 20-30 h, more preferably 22-26 h, and still more preferably 24 h.
Carrying out vacuum drying and then carrying out first high-temperature calcination under the condition of oxygen limitation; the oxygen-limiting condition is preferably provided by a metal foil wrap; the metal foil is required to be prevented from melting under the condition of high-temperature calcination, and is preferably an aluminum foil in the invention; the temperature of the first high-temperature calcination is preferably 800-1000 ℃, more preferably 850-950 ℃, and further preferably 900 ℃; the time of the first high-temperature calcination, namely the heat preservation time, is preferably 1-3 h, more preferably 1.5-2.5 h, and further preferably 2 h; the heating rate of the first high-temperature calcination is preferably 1-10 ℃/min, more preferably 3-8 ℃/min, still more preferably 5-8 ℃/min, and most preferably 5 ℃/min.
After the first high-temperature calcination is finished, natural cooling is preferably carried out, and grinding is carried out to obtain the coffee grounds biochar; the grinding is preferably carried out to a particle size of 80 mesh or less.
Carrying out secondary high-temperature calcination on the coffee grounds biochar; the temperature of the second high-temperature calcination is preferably 500-600 ℃, and more preferably 550 ℃; the time of the second high-temperature calcination, namely the heat preservation time, is preferably 2-6 h, more preferably 3-5 h, and further preferably 4 h; the heating rate of the second high-temperature calcination is preferably 1-5 ℃/min, more preferably 2-4 ℃/min, still more preferably 2-3 ℃/min, and most preferably 3 ℃/min.
After the second high-temperature calcination, natural cooling is preferably carried out, and the modified coffee grounds biochar can be obtained.
The invention adopts the coffee grounds with wide sources as the raw materials, has easily obtained and wide sources, reduces the treatment pressure of the waste coffee grounds, has simple preparation method, changes waste into valuable, realizes resource utilization, and realizes low cost and high profit.
The invention also provides an application of the modified coffee grounds biochar in water treatment; the water treatment is preferably a treatment of urea in water.
The invention also provides a method for removing urea in water, which comprises the following steps: mixing the modified coffee grounds biochar, persulfate and an aqueous solution containing urea, and carrying out oscillation reaction to obtain a treated aqueous solution; the modified coffee grounds biochar is prepared by the following method: carrying out primary high-temperature calcination on the coffee grounds under the condition of limited oxygen, and grinding to obtain coffee grounds biochar; and carrying out secondary high-temperature calcination on the coffee grounds biochar to obtain the modified coffee grounds biochar.
Wherein, the invention has no special limitation to the raw materials of all the raw materials, and the raw materials are available on the market; the modified coffee grounds biochar is prepared according to the method, and is not described herein again.
Mixing the modified coffee grounds biochar, persulfate and an aqueous solution containing urea, and carrying out oscillation reaction to obtain a treated aqueous solution; the persulfate is preferably sodium persulfate and/or potassium persulfate; the mass ratio of the modified coffee grounds biochar to the persulfate is (0.05-0.8): (0.5 to 6), more preferably (0.1 to 0.8): (0.5-4), and more preferably (0.2-0.6): (1-3), most preferably 0.5: 2; the ratio of the modified coffee grounds biochar to the urea-containing aqueous solution is preferably (0.05-0.8) g: 1L, more preferably (0.1 to 0.8) g: 1L, and preferably (0.2 to 0.6) g: 1L, most preferably 0.4 g: 1L; the ratio of the persulfate to the aqueous solution containing urea is preferably (0.5-6) g: 1L, more preferably (0.5 to 4) g: 1L, and preferably (1-3) g: 1L, most preferably 2 g: 1L; the content of urea in the aqueous solution containing urea is preferably less than or equal to 1 mg/L; the pH value of the aqueous solution containing urea is preferably 3-10, more preferably 3-9, still more preferably 3-8, and most preferably 3-7; the aqueous solution containing urea is not particularly limited as long as it is a waste water containing urea, which is well known to those skilled in the art, and is preferably a regenerated water in the present invention; the shaking reaction is preferably carried out at room temperature; the rotation speed of the oscillation reaction is preferably 100-300 r/min, more preferably 100-250 r/min, still more preferably 150-200 r/min, and most preferably 180 r/min; the oscillation reaction time is preferably 3-10 h, more preferably 4-8 h, and still more preferably 5-6 h.
The method for removing urea in water, especially removing trace urea in regenerated water by using the process of activating persulfate by using the modified coffee grounds and the biochar is an environment-friendly, economical and feasible method, realizes the reutilization of coffee grounds wastes, improves the utilization efficiency of biomass resources, improves the foundation for resource utilization, ensures the effluent quality of an ultrapure water system, ensures the stable operation of the ultrapure water preparation system, and ensures that the TOC (total organic carbon) of supplied water reaches the standard.
In order to further illustrate the present invention, the following will describe in detail a method for removing biochar from coffee grounds and urea from water, which is provided by the present invention, with reference to examples.
The reagents used in the following examples are all commercially available.
Example 1
The preparation of the modified coffee grounds biochar and the removing effect of the modified coffee grounds biochar on low-concentration urea under different sodium persulfate adding amounts comprise the following steps:
1.1, placing the dried coffee grounds in a vacuum drying oven at 105 ℃ for drying for 24 hours;
1.2 placing the coffee grounds in a ceramic crucible, wrapping aluminum foil paper, covering a cover, placing in a muffle furnace, heating to 900 ℃ at the heating rate of 5 ℃/min, keeping for 2 hours, naturally cooling, opening the furnace and taking out;
1.3 grinding the cooled biochar through a sieve of 80 meshes to obtain a coffee grounds biochar product;
1.4, placing the coffee grounds biochar in a ceramic crucible, placing the ceramic crucible in a muffle furnace, heating to 550 ℃ at the heating rate of 2 ℃/min, keeping the temperature for 4 hours, naturally cooling, opening the furnace and taking out the biochar to obtain a final modified coffee grounds biochar product;
1.5A 500 mL Erlenmeyer flask was charged with 400 mL of the prepared 1 mg/L urea solution without adjusting the initial pH of the solution. Then, 0.2 g/L of modified biochar is added into the urea solution, and persulfate with different concentrations (0.8, 1, 2, 4 and 6 g/L) is added to induce reaction. The flask was placed in a constant temperature shaker (180 r/min, 25 ℃ C.), and the reaction was stopped after 5 hours. The obtained sample was passed through a 45 μm filter, and then absorbance of the filtrate was measured by UV, and the concentration was converted from a standard curve of urea and recorded, and the results are shown in fig. 1. All experiments were done in triplicate and the results averaged.
As shown in figure 1, the urea in the regenerated water can be effectively removed by activating the persulfate through the modified biochar, the best removal effect can be achieved when the adding amount of the persulfate is 2 g/L, and the removal rate reaches 91.4%.
Example 2
The modified biochar prepared in the embodiment 1 of the invention is put into a urea solution for catalysis in different adding amounts.
A500 mL Erlenmeyer flask was charged with 400 mL of the prepared 1 mg/L urea solution without adjusting the initial pH of the solution. Thereafter, each of the biochar samples (0.05, 0.1, 0.2, 0.4, 0.8 g/L) prepared in Experimental example 1 was accurately weighed in a 500 mL Erlenmeyer flask, and 2 g/L persulfate was added to induce reaction. The flask was placed in a constant temperature shaker (180 r/min, 25 ℃ C.), and the reaction was stopped after 5 hours. The obtained sample was passed through a 45 μm filter, and then absorbance of the filtrate was measured by UV, and the concentration was converted from a standard curve of urea and recorded, and the result is shown in fig. 2. All experiments were done in triplicate and the results averaged.
As shown in FIG. 2, the urea in the regenerated water can be effectively removed by using the modified biochar to activate persulfate, the best removal effect can be achieved when the adding amount of the modified biochar is 0.4 g/L, and the removal rate reaches 94.4%.
Example 3
The modified biochar prepared in the embodiment 1 of the invention is placed in urea solutions with different pH values for catalysis.
400 mL of a prepared 1 mg/L urea solution was put into a 500 mL Erlenmeyer flask, and the pH of the solution was adjusted to 3, 4, 5, 6, 7, 8, 9, and 10 with 0.1 mol/L hydrochloric acid and sodium hydroxide. Then, 0.2 g/L of the biochar sample prepared in experiment case 1 is accurately weighed and added into a 500 mL conical flask, and 2 g/L of persulfate is added to induce reaction. The flask was placed in a constant temperature shaker (180 r/min, 25 ℃ C.), and the reaction was stopped after 5 hours. The obtained sample was passed through a 45 μm filter, and then absorbance of the filtrate was measured by UV, and the concentration was converted from a standard curve of urea and recorded, and the result is shown in fig. 3. All experiments were done in triplicate and the results averaged.
As can be seen from fig. 3, the initial pH of the solution has less influence on the adsorption of urea, and urea can be effectively removed in a wider pH range. Wherein, the removal of urea is more facilitated under the conditions of neutral pH and acidity, and more than 90 percent of urea can be removed.
Claims (7)
1. A method for removing urea from water, comprising:
mixing the modified coffee grounds biochar, persulfate and an aqueous solution containing urea, and carrying out oscillation reaction to obtain a treated aqueous solution;
the modified coffee grounds biochar is prepared by the following method:
carrying out primary high-temperature calcination on the coffee grounds under the condition of limited oxygen, and grinding to obtain coffee grounds biochar;
performing secondary high-temperature calcination on the coffee grounds biochar to obtain modified coffee grounds biochar;
the oxygen-limiting condition is provided by a metal foil wrap; the temperature of the first high-temperature calcination is 800-1000 ℃; the time of the first high-temperature calcination is 1-3 h; the temperature rise rate of the first high-temperature calcination is 1-10 ℃/min;
the temperature of the second high-temperature calcination is 500-600 ℃; the time of the second high-temperature calcination is 2-6 h; the temperature rise rate of the second high-temperature calcination is 1-5 ℃/min.
2. The removal method according to claim 1, wherein the coffee grounds are vacuum-dried and then wrapped with a metal foil; the temperature of the vacuum drying is 100-110 ℃; the vacuum drying time is 20-30 h; and grinding to a particle size of 80 meshes or less.
3. The removal method according to claim 1, wherein the temperature of the first high-temperature calcination is 900 ℃; the time of the first high-temperature calcination is 2 h; the heating rate of the first high-temperature calcination is 5 ℃/min.
4. The removal method according to claim 1, wherein the temperature of the second high-temperature calcination is 550 ℃; the time of the second high-temperature calcination is 4 h; the temperature rise rate of the second high-temperature calcination is 2 ℃/min.
5. The removal method according to claim 1, wherein the aqueous solution containing urea is regeneration water; the persulfate is selected from sodium persulfate and/or potassium persulfate; the mass ratio of the modified coffee grounds biochar to the persulfate is (0.05-0.8): (0.5 to 6).
6. The removal method according to claim 1, wherein the ratio of the modified coffee grounds biochar to the aqueous solution containing urea is (0.05-0.8) g: 1L; the ratio of the persulfate to the aqueous solution containing urea is (0.5-6) g: 1L of the compound.
7. The removal method according to claim 1, wherein the ratio of the modified coffee grounds biochar to the aqueous solution containing urea is 0.4 g: 1L; the ratio of persulfate to aqueous solution containing urea is 2 g: 1L of the compound.
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| CN104129841B (en) * | 2014-08-22 | 2016-04-27 | 中国科学院南京土壤研究所 | A kind of method of activator matrix material activation persulphate degraded Organic Pollutants In Water |
| CN104371748B (en) * | 2014-10-24 | 2017-02-15 | 东华大学 | Preparation method of high-yield biochar |
| CN106045002B (en) * | 2016-07-11 | 2020-06-26 | 华中科技大学 | Method for catalyzing persulfate degradation of organic matter or ammonia nitrogen in sewage by sludge biochar |
| CN106882852A (en) * | 2017-03-14 | 2017-06-23 | 华南农业大学 | A kind of method of charcoal Adsorption of Heavy Metals Cr (VI) prepared by utilization coffee grounds |
| CN109607740A (en) * | 2018-12-19 | 2019-04-12 | 大连理工大学 | A kind of biochar material containing environmentally persistent free radicals and preparation method thereof |
| US11352271B2 (en) * | 2019-06-26 | 2022-06-07 | Central South University | Method and device for sewage treatment |
| CN112536036B (en) * | 2020-11-13 | 2021-10-01 | 中国科学院南京土壤研究所 | A kind of carbon-based metal single-atom composite material and its preparation method and application |
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