CN113289578A - Gasified slag-based composite ammonia nitrogen adsorbent, preparation method and regeneration method thereof, application thereof and method for treating ammonia nitrogen-containing wastewater - Google Patents
Gasified slag-based composite ammonia nitrogen adsorbent, preparation method and regeneration method thereof, application thereof and method for treating ammonia nitrogen-containing wastewater Download PDFInfo
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- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
- B01J20/20—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising free carbon; comprising carbon obtained by carbonising processes
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- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
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- B01J20/0203—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of metals not provided for in B01J20/04
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- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
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Abstract
The invention relates to the field of ammonia nitrogen adsorbents, and discloses a gasification slag-based composite ammonia nitrogen adsorbent, and a preparation method and a regeneration method thereof, wherein the method comprises the following steps: (1) separating carbon ash from the gasified slag to obtain carbon-rich slag, wherein the content of carbon elements in the carbon-rich slag is more than or equal to 15 weight percent, and the content of silicon elements in the carbon-rich slag is more than or equal to 40 weight percent; (2) and carrying out hydrothermal reaction on the carbon-rich slag, a sodium source substance and an aluminum source substance under alkaline conditions and in the presence of water, wherein the aluminum source substance is at least one selected from soluble metaaluminate and soluble aluminum salt. The gasified slag-based composite ammonia nitrogen adsorbent is prepared from the gasified slag, has good ammonia nitrogen adsorption performance on middle-low concentration ammonia nitrogen, and realizes good economic benefit and environmental protection benefit.
Description
Technical Field
The invention relates to the field of ammonia nitrogen adsorbents, in particular to a gasified slag-based composite ammonia nitrogen adsorbent, a preparation method and a regeneration method thereof, an application thereof and a method for treating ammonia nitrogen-containing wastewater.
Background
The gasified slag is produced by incomplete combustion of coal and oxygen or oxygen-enriched air to produce CO and H2In the process, inorganic mineral substances in the coal are subjected to different physical and chemical transformations, and solid residues formed along with residual carbon particles in the coal are carbon ash composite solid wastes generated in the modern coal chemical industry process. The reserves are huge, and the accumulation and the landfill occupy precious land resources and seriously damage the surrounding geological environment. Therefore, how to realize the resource utilization of the gasified slag solid waste to solve the serious ecological problem is a problem which needs to be solved urgently at present.
In addition, with the rapid development of industrialization and the improvement of environmental awareness of the people in China, the purification treatment of industrial wastewater is more and more concerned. The large amount of ammonia nitrogen in many industrial waste water can cause eutrophication of water bodies, wherein NH4N is one of the largest toxins to microorganisms in wastewater treatment processes.
The adsorption method is a common method for deeply treating low-concentration ammonia nitrogen wastewater, and has the advantages of small occupied area, low treatment cost and the like. However, although the common adsorbent has a good ammonia nitrogen adsorption amount, the regeneration of the common adsorbent is difficult, the cost is too high, and the application of the common adsorbent in ammonia nitrogen wastewater treatment is limited.
CN109046238A discloses a high-efficiency compound ammonia nitrogen adsorbent and a regeneration method thereof. The method is that one or more of diatomite, active carbon and zeolite are combined according to a certain proportion, and then the mixture is added with NH4 +、PO4 3+The solid mixture is suspended in the solution by stirring. A certain amount of magnesium salt solution is added dropwise, the pH is adjusted and the mixture is stirred. And filtering, drying and roasting the solid substances to obtain the high-efficiency compound ammonia nitrogen adsorbent. The adsorbent can be reused after being roasted, and can keep higher ammonia nitrogen removal rate. Although the method has high ammonia nitrogen removal rate, the raw materials of the diatomite, the activated carbon and the zeolite are expensive, and the loaded magnesium ions are easy to enter ammonia nitrogen wastewater when adsorbing ammonia nitrogen, so that secondary pollution is easy to cause.
Therefore, the method has important practical significance for providing the ammonia nitrogen adsorbent which has high ammonia nitrogen removal rate and low cost, can be regenerated and used and can realize effective utilization of gasification slag solid waste resources.
Disclosure of Invention
The invention aims to provide a method for preparing an ammonia nitrogen adsorbent from gasification slag, so that the ammonia nitrogen adsorbent which has good ammonia nitrogen adsorption performance and can be regenerated and used can be prepared at low cost while the gasification slag is effectively recycled, and the ammonia nitrogen adsorbent also has adsorption to COD and chromaticity.
In order to achieve the above object, a first aspect of the present invention provides a method for preparing a gasified slag-based composite ammonia nitrogen adsorbent, the method comprising:
(1) separating carbon ash from the gasified slag to obtain carbon-rich slag, wherein the content of carbon elements in the carbon-rich slag is more than or equal to 15 weight percent, and the content of silicon elements in the carbon-rich slag is more than or equal to 40 weight percent;
(2) and carrying out hydrothermal reaction on the carbon-rich slag, a sodium source substance and an aluminum source substance in the presence of water under alkaline conditions, wherein the aluminum source substance is at least one selected from soluble metaaluminate and soluble aluminum salt.
The invention provides a gasification slag-based composite ammonia nitrogen adsorbent prepared by the method.
The third aspect of the invention provides a method for regenerating the gasified slag-based composite ammonia nitrogen adsorbent, which comprises the following steps:
and (3) contacting the gasification slag-based composite ammonia nitrogen adsorbent to be regenerated with a soluble sodium salt solution, and then sequentially carrying out solid-liquid separation and third drying on the contact product.
The invention provides the application of the gasified slag-based composite ammonia nitrogen adsorbent in ammonia nitrogen-containing wastewater treatment.
The fifth aspect of the invention provides a method for treating ammonia nitrogen-containing wastewater, which comprises the following steps:
and (3) contacting the ammonia-nitrogen-containing wastewater to be treated with a gasification slag-based composite ammonia-nitrogen adsorbent to perform adsorption treatment, wherein the gasification slag-based composite ammonia-nitrogen adsorbent is the gasification slag-based composite ammonia-nitrogen adsorbent in the second aspect.
Compared with the prior art, the invention has at least the following advantages:
(1) the gasification slag-based composite ammonia-nitrogen adsorbent provided by the invention has good ammonia-nitrogen adsorption performance on medium-and-low-concentration ammonia nitrogen, and has adsorption effects on COD (chemical oxygen demand), chromaticity and the like;
(2) the ammonia nitrogen adsorbent provided by the invention can be regenerated for use, the regeneration method is simple, and the regenerated ammonia nitrogen adsorbent still has good ammonia nitrogen adsorption performance;
(3) the method provided by the invention has the advantages that the gasified slag-based composite ammonia nitrogen adsorbent is prepared by utilizing the gasified slag, the process is simple, the preparation cost is low, the high value-added utilization of the gasified slag is realized, the purpose of treating wastes with wastes is realized, and the economic benefit and the environmental protection benefit are realized.
Additional features and advantages of the invention will be described in detail in the detailed description which follows.
Drawings
FIG. 1 shows the results of the color of the ammonia nitrogen adsorbent prepared in example 1 in the treatment of wastewater at different solid-to-liquid ratios.
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
As described above, the first aspect of the present invention provides a method for producing a gasified slag-based composite ammonia nitrogen adsorbent, comprising:
(1) separating carbon ash from the gasified slag to obtain carbon-rich slag, wherein the content of carbon elements in the carbon-rich slag is more than or equal to 15 weight percent, and the content of silicon elements in the carbon-rich slag is more than or equal to 40 weight percent;
(2) and carrying out hydrothermal reaction on the carbon-rich slag, a sodium source substance and an aluminum source substance in the presence of water under alkaline conditions, wherein the aluminum source substance is at least one selected from soluble metaaluminate and soluble aluminum salt.
According to the invention, the gasified slag refers to the gasified waste slag generated by coal gasification, and the source of the gasified slag is not limited by the invention. Preferably, the carbon element content in the gasified slag is more than 10 wt%, and the silicon element content is 30-70 wt%. The invention has no special limitation on the structural parameters of the gasified slag, such as specific surface area, particle size and the like, as long as the carbon-rich slag required by the invention can be obtained by carbon ash separation.
Preferably, in the carbon-rich slag, the content of carbon element is 15-35 wt%, and the content of silicon element is 50-70 wt%.
Preferably, the specific surface area of the carbon-rich slag is 150-300m2·g-1。
Preferably, the manner of separating the carbon ash is water medium cyclone gravity separation. The specific conditions for the water-medium cyclone reselection are not particularly limited, as long as carbon-rich slag with corresponding parameters such as carbon content and silicon element content can be obtained.
According to a preferred embodiment of the invention, in the step (1), the method further comprises the steps of sequentially carrying out first drying, crushing and screening on the carbon-rich slag, and then carrying out the step (2).
Preferably, the conditions of the first drying include: the temperature is 80-120 ℃. The time of the first drying is not limited by the invention, as long as the carbon-rich slag can be completely dried.
Preferably, the particle size of the carbon-rich slag obtained through the crushing and the screening is 30-95 microns, and more preferably 65-95 microns.
The present invention is also not particularly limited in specific operations of the pulverization such as grinding and the screening such as screening with a sieve.
According to the invention, in the step (2), the water is distilled water and/or deionized water, the amount of the water is such that the solid content of the hydrothermal reaction system is 150-450g/L, wherein the solid content refers to the total content of the carbon-rich slag, the sodium source material and the aluminum source material in the hydrothermal reaction system.
Preferably, the sodium source is sodium hydroxide and/or sodium metaaluminate.
Preferably, the soluble aluminium salt is selected from at least one of aluminium chloride, aluminium nitrate and aluminium sulphate.
Preferably, the soluble metaaluminate is sodium metaaluminate and/or potassium metaaluminate, more preferably sodium metaaluminate.
According to a preferred embodiment of the present invention, the sodium source material is sodium hydroxide and the aluminum source material is sodium metaaluminate.
Preferably, in the step (2), the molar ratio of the carbon-rich slag, the aluminum source material and the sodium source material is (1.5-4.5): 1: (4.5-6.5).
More preferably, the molar ratio of the carbon-rich slag to the aluminum source material to the sodium source material is (2-4): 1: (5-6).
Further preferably, the molar ratio of the carbon-rich slag to the aluminum source material to the sodium source material is (2.5-3.5): 1: (5.5-6), more preferably 3: 1: 5.7.
according to the invention, the carbon-rich slag is calculated by the oxide (silicon dioxide) of silicon element contained in the slag, the aluminum source substance is calculated by the oxide (aluminum oxide) of aluminum element contained in the slag, and the sodium source substance is calculated by the oxide (sodium oxide) of sodium element contained in the slag.
According to a preferred embodiment of the present invention, in the step (2), before the hydrothermal reaction, the carbon-rich slag, the sodium source material and the aluminum source material are mixed, and then the mixture is subjected to the hydrothermal reaction.
Preferably, the mixing conditions include: the mixing time is 2-4h, and the mixing temperature is 20-30 ℃.
Preferably, the mixing is performed under stirring.
Preferably, in step (2), the conditions of the hydrothermal reaction include: the hydrothermal temperature is 100 ℃ and 250 ℃, the hydrothermal time is 12-36h, and the pH value is 10-13.
Preferably, the hydrothermal reaction is a constant temperature reaction.
Preferably, the hydrothermal reaction is carried out in a high temperature and high pressure resistant reaction kettle.
According to the present invention, in the step (2), the alkaline condition refers to the pH of the hydrothermal reaction system, and may be provided by the reaction raw material, such as the sodium source material and/or the aluminum source material, itself, or may be provided by other alkaline materials, and the present invention is not limited thereto, as long as the pH of the hydrothermal reaction system is satisfied.
According to a preferred embodiment of the invention, the method further comprises washing, solid-liquid separation and secondary drying the hydrothermal reaction product in sequence to obtain the gasified residue-based composite ammonia nitrogen adsorbent.
According to the present invention, the washing liquid to be washed is not limited and may be selected as required, for example, distilled water.
According to the present invention, the specific operation of the solid-liquid separation is not particularly limited, and the solid-liquid separation operation can be performed by the solid-liquid separation operation existing in the art.
Preferably, the solid-liquid separation is performed by filtration, and the filtration conditions comprise: filtering until the pH value of the filtrate is 6-8.
Preferably, the conditions of the second drying include: the temperature is 60-100 ℃. In the present invention, the time for the second drying is not particularly limited, as long as the product after the solid-liquid separation can be completely and sufficiently dried.
According to a particularly preferred embodiment of the invention, the method according to the invention comprises:
(1) carrying out carbon ash separation on the gasified slag to obtain carbon-rich slag, and sequentially carrying out primary drying, crushing and screening on the carbon-rich slag;
(2) under the alkaline condition and in the presence of water, mixing sodium hydroxide, sodium metaaluminate and carbon-rich slag obtained by screening, and then carrying out hydrothermal reaction on the mixed material;
(3) and washing, solid-liquid separation and secondary drying are sequentially carried out on the hydrothermal reaction product to obtain the gasified residue-based composite ammonia nitrogen adsorbent.
As described above, the second aspect of the present invention provides the gasification slag-based composite ammonia nitrogen adsorbent prepared by the foregoing method.
As described above, the third aspect of the present invention provides a method for regenerating the aforementioned gasified slag-based composite ammonia nitrogen adsorbent, the method comprising:
and (3) contacting the gasification slag-based composite ammonia nitrogen adsorbent to be regenerated with a soluble sodium salt solution, and then sequentially carrying out solid-liquid separation and third drying on the contact product.
Preferably, the soluble sodium salt is selected from at least one of sodium chloride, sodium sulfate, sodium nitrate and sodium carbonate, more preferably sodium chloride.
Preferably, the concentration of the soluble sodium salt solution is 1-3 mol/L.
Preferably, the soluble sodium salt solution is used in an amount of 0.02-0.1mol in terms of sodium element contained in the gasification slag-based composite ammonia nitrogen adsorbent to be regenerated, relative to 1g of the gasification slag-based composite ammonia nitrogen adsorbent to be regenerated.
Preferably, the conditions of the contacting include: the contact temperature is 20-40 ℃, and the contact time is 0.1-2 h.
In the third aspect of the present invention, the specific operation of the solid-liquid separation is not particularly limited, and the solid-liquid separation can be carried out by the solid-liquid separation operation known in the art, for example, by filtration.
In the third aspect of the present invention, the present invention further includes washing the product after the solid-liquid separation, and the washing liquid to be washed is not limited and may be selected as required, for example, distilled water.
Preferably, the third drying conditions include: the drying temperature is 60-100 ℃, and the drying time is 18-30 h.
The gasification slag-based composite ammonia nitrogen adsorbent provided by the invention can be regenerated and recycled, the regeneration method is simple, and ammonia nitrogen can be resolved from the gasification slag-based composite ammonia nitrogen adsorbent in the regeneration process and collected and utilized.
As described above, the fourth aspect of the present invention provides the use of the aforementioned gasified slag-based composite ammonia nitrogen adsorbent in the treatment of ammonia nitrogen-containing wastewater.
The specific operation of the application is not particularly limited, and the operation of removing ammonia nitrogen from the wastewater by using the ammonia nitrogen adsorbent in the prior art can be adopted.
As mentioned above, the fifth aspect of the present invention provides a method for treating wastewater containing ammonia nitrogen, which comprises:
and (3) contacting the ammonia-nitrogen-containing wastewater to be treated with a gasification slag-based composite ammonia-nitrogen adsorbent to perform adsorption treatment, wherein the gasification slag-based composite ammonia-nitrogen adsorbent is the gasification slag-based composite ammonia-nitrogen adsorbent in the second aspect.
Preferably, the conditions of the adsorption treatment include: the temperature is 20-40 deg.C, and the time is 2-10min, preferably 5-10 min.
Preferably, the concentration of ammonia nitrogen in the ammonia nitrogen-containing wastewater to be treated is 10-100mol/L, and more preferably 20-100 mol/L.
Ammonia nitrogen in the context of the present invention means nitrogen compounds present in the form of ammonia or ammonium ions in water, i.e. as free ammonia (NH)3) And ammonium ion (NH)4 +) Nitrogen in the form present.
Preferably, the dosage of the gasified slag-based composite ammonia nitrogen adsorbent is 10-20g relative to 1L of the ammonia nitrogen-containing wastewater to be treated.
According to a preferred embodiment of the invention, the method further comprises:
and regenerating the gasification slag-based composite ammonia nitrogen adsorbent subjected to adsorption treatment to obtain a regenerated gasification slag-based composite ammonia nitrogen adsorbent, and then recycling the regenerated gasification slag-based composite ammonia nitrogen adsorbent for the adsorption treatment, wherein the regeneration is performed according to the method of the third aspect.
The present invention will be described in detail below by way of examples.
In the following examples, all the raw materials used are commercially available ones unless otherwise specified.
In the following examples, room temperature means 25. + -. 2 ℃ unless otherwise specified.
The source of the gasified slag used in the following examples was Ningxia coal industry, Inc. (carbon content 20 wt%, silicon content 40.07 wt%, specific surface area 200 m)2·g-1)。
Preparation example
Carrying out water-medium cyclone gravity separation on the gasified slag to respectively obtain carbon-rich slag and high ash slag, wherein:
carbon-rich slag: the carbon content was 30.7% by weight, the silicon content was 49.5% by weight, and the specific surface area was 279m2·g-1For subsequent examples 1-3 and comparative example 2 below;
high ash content: the carbon content was 3% by weight, the silicon content was 57% by weight, and the specific surface area was 10.94m2·g-1For subsequent comparative example 1 described below.
Example 1
(1) Sequentially carrying out first drying (at the drying temperature of 100 ℃) and grinding on the carbon-rich slag, and screening by using a 200-mesh sieve to obtain the carbon-rich slag with the grain diameter of 63-76 microns;
(2) in a reaction kettle, in the presence of distilled water, stirring and mixing the carbon-rich slag obtained in the step (1), sodium hydroxide and sodium metaaluminate (the total solid content is 400g/L) at room temperature for 3 hours, and then carrying out hydrothermal reaction on the mixed material, wherein the hydrothermal reaction temperature is 160 ℃, the hydrothermal reaction time is 24 hours, and the pH value is 10.23; the molar ratio of the carbon-rich slag to the sodium metaaluminate to the sodium hydroxide is 3: 1: 5.7, the dosage of the carbon-rich slag is calculated by silicon dioxide, the dosage of the sodium metaaluminate is calculated by aluminum oxide, and the dosage of the sodium hydroxide is calculated by sodium oxide;
(3) and washing the hydrothermal reaction product with excess distilled water, filtering until the pH value of the filtrate is 7, and drying at 80 ℃ to obtain the gasified residue-based composite ammonia nitrogen adsorbent.
Example 2
(1) Sequentially carrying out first drying (at the drying temperature of 80 ℃) and grinding on the carbon-rich slag, and screening by using a 300-mesh sieve to obtain the carbon-rich slag with the particle size of 48-54 micrometers;
(2) in a reaction kettle, in the presence of distilled water, stirring and mixing the carbon-rich slag obtained in the step (1), sodium hydroxide and sodium metaaluminate (the total solid content is 380g/L) at room temperature for 2 hours, and then carrying out hydrothermal reaction on the mixed material, wherein the hydrothermal reaction temperature is 140 ℃, the hydrothermal reaction time is 24 hours, and the pH value is 11.01; the molar ratio of the carbon-rich slag to the sodium metaaluminate to the sodium hydroxide is 2.5: 1: 5.5, the dosage of the carbon-rich slag is calculated by silicon dioxide, the dosage of the sodium metaaluminate is calculated by aluminum oxide, and the dosage of the sodium hydroxide is calculated by sodium oxide;
(3) and washing the hydrothermal reaction product with excess distilled water, filtering until the pH value of the filtrate is 7, and drying at 60 ℃ to obtain the gasified residue-based composite ammonia nitrogen adsorbent.
Example 3
(1) Sequentially carrying out first drying (at the drying temperature of 120 ℃) and grinding on the carbon-rich slag, and screening by using a 400-mesh sieve to obtain the carbon-rich slag with the particle size of 31-39 microns;
(2) in a reaction kettle, in the presence of distilled water, stirring and mixing the carbon-rich slag obtained in the step (1), sodium hydroxide and sodium metaaluminate (the total solid content is 410g/L) at room temperature for 4 hours, and then carrying out hydrothermal reaction on the mixed material, wherein the hydrothermal reaction temperature is 240 ℃, the hydrothermal reaction time is 24 hours, and the pH value is 12.03; the molar ratio of the carbon-rich slag to the sodium metaaluminate to the sodium hydroxide is 3.2: 1: 6, the dosage of the carbon-rich slag is calculated by silicon dioxide, the dosage of sodium metaaluminate is calculated by aluminum oxide, and the dosage of sodium hydroxide is calculated by sodium oxide;
(3) and washing the hydrothermal reaction product with excess distilled water, filtering until the pH value of the filtrate is 7, and drying at 60 ℃ to obtain the gasified residue-based composite ammonia nitrogen adsorbent.
Comparative example 1
(1) Sequentially carrying out first drying (at the drying temperature of 100 ℃) and grinding on the high ash slag, and screening by using a 200-mesh sieve;
(2) stirring and mixing the high ash residue obtained by screening in the step (1), sodium hydroxide and sodium metaaluminate for 2 hours at room temperature in a reaction kettle in the presence of distilled water, and then carrying out hydrothermal reaction on the mixed material, wherein the hydrothermal reaction temperature is 160 ℃, the hydrothermal reaction time is 24 hours, and the pH value is 10.23; the molar ratio of the high ash, sodium metaaluminate and sodium hydroxide is 3.2: 1: 6, the dosage of the high ash is calculated by silicon dioxide, the dosage of the sodium metaaluminate is calculated by aluminum oxide, and the dosage of the sodium hydroxide is calculated by sodium oxide;
(3) and washing the hydrothermal reaction product with excess distilled water, filtering until the pH value of the filtrate is 7, and drying at 60 ℃ to obtain the gasified residue amino nitrogen adsorbent.
Comparative example 2
(2) Calcining the carbon-rich slag under the conditions comprising: the calcination temperature is 550 ℃, the calcination time is 10 hours, and gasified slag ash is obtained, wherein the content of carbon element in the gasified slag ash is 0.3 weight percent, the content of silicon element in the gasified slag ash is 69 weight percent, and the specific surface area is 9m2·g-1；
(3) Stirring and mixing the gasified slag ash obtained in the step (2), sodium hydroxide and sodium metaaluminate for 2 hours at room temperature in a reaction kettle in the presence of distilled water, and then carrying out hydrothermal reaction on the mixed material, wherein the hydrothermal reaction temperature is 160 ℃, the hydrothermal reaction time is 24 hours, and the pH value is 10.23;
the molar ratio of the use amount of the gasification slag ash to the use amount of the sodium metaaluminate to the use amount of the sodium hydroxide is 3.2: 1: 6, the dosage of the high ash is calculated by silicon dioxide, the dosage of the sodium metaaluminate is calculated by aluminum oxide, and the dosage of the sodium hydroxide is calculated by sodium oxide;
(4) and washing the hydrothermal reaction product with excess distilled water, filtering until the pH value of the filtrate is 7, and drying at 60 ℃ to obtain the ammonia nitrogen adsorbent.
Test example
(1) Ammonia nitrogen adsorption performance test
The ammonia nitrogen adsorbents obtained in the above examples and comparative examples were tested for ammonia nitrogen removal, and the specific test results are shown in table 1.
The test process is as follows: contacting the ammonia nitrogen-containing wastewater to be treated (the concentration of ammonia nitrogen is 65mol/L and is recorded as the initial concentration of ammonia nitrogen) with the gasification slag-based composite ammonia nitrogen adsorbent to perform adsorption treatment, wherein the adsorption treatment conditions comprise: the temperature is room temperature, and the time is 2 min; the dosage of the gasified slag-based composite ammonia nitrogen adsorbent is 10g relative to 1L of the ammonia nitrogen-containing wastewater to be treated.
And after adsorption treatment, testing the ammonia nitrogen concentration in the treated wastewater (recorded as the treated ammonia nitrogen concentration), wherein the ammonia nitrogen concentration is obtained by taking the supernatant of the wastewater to pass through a 0.45-micrometer filter membrane, testing the filtered filtrate by using a national standard Nashin's reagent spectrophotometry for measuring ammonia nitrogen in water (HJ535-2009), and calculating by using the following formula to obtain the ammonia nitrogen removal rate.
Ammonia nitrogen removal rate/% (ammonia nitrogen initial concentration-ammonia nitrogen concentration after treatment)/ammonia nitrogen initial concentration 100
Wherein the ammonia nitrogen initial concentration refers to the ammonia nitrogen concentration in the ammonia nitrogen-containing wastewater before adsorption treatment, and the mol/L;
the ammonia nitrogen concentration after treatment refers to the ammonia nitrogen concentration, mol/L, in the ammonia nitrogen-containing wastewater after adsorption treatment.
TABLE 1
| Example numbering | Ammonia nitrogen removal per mol% |
| Example 1 | 72.89 |
| Example 2 | 69.32 |
| Example 3 | 68.23 |
| Comparative example 1 | 32.03 |
| Comparative example 2 | 41.42 |
(2) Test for regeneration Performance
Respectively regenerating the ammonia nitrogen adsorbent after the adsorption performance test, wherein the specific process is as follows:
and (3) contacting the gasification slag-based composite ammonia nitrogen adsorbent to be regenerated with a sodium chloride solution (the concentration is 2mol/L) at room temperature (the solid-liquid ratio is 20g/L), wherein the contact time is 2 h. And then sequentially filtering the contact products, washing by using excessive distilled water, and drying at the drying temperature of 80 ℃ for 24h to obtain a regenerated ammonia nitrogen adsorbent, wherein ammonia nitrogen is resolved from the adsorbent in the regeneration process and can be collected and utilized.
And (4) repeatedly carrying out the ammonia nitrogen adsorption performance test on the regenerated ammonia nitrogen adsorbent, and testing the ammonia nitrogen adsorption performance of the regenerated ammonia nitrogen adsorbent.
The present invention cyclically performs the adsorption-regeneration process, specifically, the process is adsorption (zero regeneration) -regeneration-adsorption (primary regeneration) -regeneration-adsorption (secondary regeneration) -regeneration-adsorption (tertiary regeneration), so as to test the regeneration adsorption stability of the ammonia nitrogen adsorbent provided by the present invention, and the specific results are shown in table 2.
TABLE 2
(3) COD test
The ammonia nitrogen adsorbent prepared in the above example was contacted with actual coking wastewater (initial COD was about 6850mg/L after ammonia distillation treatment) to perform adsorption treatment under the following conditions: the temperature is room temperature and the time is 2 hours; the dosage of the gasified residue-based composite ammonia nitrogen adsorbent is 10g relative to 1L of actual coking wastewater.
COD of the actual coking wastewater after the treatment is tested, the COD test is obtained by HJ/T399-2007 fast digestion spectrophotometry for determination of chemical oxygen demand of water quality, and the test result is shown in the following table 3.
TABLE 3
(4) Color test
The ammonia nitrogen adsorbent prepared in the above example is used for treating actual coking wastewater respectively, and the chromaticity of the wastewater is tested to change along with different solid-liquid ratios (namely different adding amounts of the adsorbent);
specifically, the method comprises the following steps: the ammonia nitrogen adsorbent prepared in the above example was contacted with actual coking wastewater (initial COD was about 6850mg/L after ammonia distillation treatment) to perform adsorption treatment under the following conditions: the temperature is room temperature and the time is 2 hours; the dosage of the gasified residue-based composite ammonia nitrogen adsorbent is 0-20g relative to 1L of actual coking wastewater.
The invention exemplarily provides the chromaticity changes of the coking wastewater when the ammonia nitrogen adsorbent prepared in the example 1 is added in the amount of 0g/L, 1g/L, 2g/L, 5g/L, 10g/L, 15g/L and 20g/L respectively, and the specific results are shown in FIG. 1. from FIG. 1, the chromaticity of the wastewater is obviously reduced when the ammonia nitrogen adsorbent is used for treating the coking wastewater, and the chromaticity reduction degree of the wastewater is increased along with the increase of the added amount.
In conclusion, the results show that the gasified slag-based composite ammonia nitrogen adsorbent prepared by the gasified slag has good ammonia nitrogen adsorption capacity on medium-and-low-concentration ammonia nitrogen, and also has certain adsorption effect on COD, chromaticity and the like.
In addition, the gasification slag-based composite ammonia nitrogen adsorbent provided by the invention can be regenerated and recycled, the regeneration method is simple, the regeneration rate is high, the ammonia nitrogen removal rate is good after regeneration, and ammonia nitrogen is resolved from the adsorbent in the regeneration process and can be collected and utilized.
In addition, the method for preparing the gasified slag-based composite ammonia nitrogen adsorbent by utilizing the gasified slag has the advantages of simple process and low cost, realizes high value-added utilization of the gasified slag, and achieves the purpose of treating wastes with processes of wastes against one another.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (13)
1. A method for preparing a gasified slag-based composite ammonia nitrogen adsorbent is characterized by comprising the following steps:
(1) separating carbon ash from the gasified slag to obtain carbon-rich slag, wherein the content of carbon elements in the carbon-rich slag is more than or equal to 15 weight percent, and the content of silicon elements in the carbon-rich slag is more than or equal to 40 weight percent;
(2) and carrying out hydrothermal reaction on the carbon-rich slag, a sodium source substance and an aluminum source substance in the presence of water under alkaline conditions, wherein the aluminum source substance is at least one selected from soluble metaaluminate and soluble aluminum salt.
2. The method according to claim 1, wherein in the step (1), in the carbon-rich slag, the content of carbon element is 15-35 wt%, and the content of silicon element is 50-70 wt%;
preferably, the carbon ash separation mode is water medium cyclone reselection;
preferably, the step (1) further comprises the steps of sequentially carrying out first drying, crushing and screening on the carbon-rich slag, and then carrying out the step (2);
preferably, the conditions of the first drying include: the temperature is 80-120 ℃;
preferably, the particle size of the carbon-rich slag obtained by screening is 30-95 microns.
3. The method according to claim 1 or 2, wherein, in the step (2), the carbon-rich slag, the sodium source material and the aluminum source material are mixed before the hydrothermal reaction, and then the mixed materials are subjected to the hydrothermal reaction;
preferably, the conditions of the hydrothermal reaction include: the hydrothermal temperature is 100 ℃ and 250 ℃, the hydrothermal time is 12-36h, and the pH value is 10-13.
4. A process according to any one of claims 1 to 3, wherein in step (2), the sodium source is sodium hydroxide and/or sodium metaaluminate;
preferably, the soluble aluminum salt is selected from at least one of aluminum chloride, aluminum nitrate and aluminum sulfate;
preferably, the soluble metaaluminate is sodium metaaluminate and/or potassium metaaluminate, more preferably sodium metaaluminate;
more preferably, the sodium source material is sodium hydroxide, and the aluminum source material is sodium metaaluminate.
5. The method as claimed in any one of claims 1 to 4, wherein, in the step (2), the carbon-rich slag, the aluminum source material and the sodium source material are used in a molar ratio of (1.5-4.5): 1: (4.5-6.5), wherein the carbon-rich slag is calculated by silicon dioxide, the aluminum source substance is calculated by aluminum oxide, and the sodium source substance is calculated by sodium oxide.
6. The method of any of claims 1-5, wherein the method further comprises: washing, solid-liquid separation and secondary drying are sequentially carried out on the hydrothermal reaction product to obtain the gasified residue-based composite ammonia nitrogen adsorbent;
preferably, the conditions of the second drying include: the temperature is 60-100 ℃.
7. The gasification slag-based composite ammonia nitrogen adsorbent prepared by the method of any one of claims 1 to 6.
8. The method for regenerating the gasification slag-based composite ammonia nitrogen adsorbent according to claim 7, is characterized by comprising the following steps:
and (3) contacting the gasification slag-based composite ammonia nitrogen adsorbent to be regenerated with a soluble sodium salt solution, and then sequentially carrying out solid-liquid separation and third drying on the contact product.
9. Regeneration process according to claim 8, wherein the soluble sodium salt is selected from at least one of sodium chloride, sodium sulphate, sodium nitrate and sodium carbonate, preferably sodium chloride;
preferably, the concentration of the soluble sodium salt solution is 1-3 mol/L;
preferably, the conditions of the contacting include: the contact temperature is 20-40 ℃, and the contact time is 0.1-2 h;
preferably, the third drying conditions include: the drying temperature is 60-100 ℃, and the drying time is 18-30 h.
10. The use of the gasification slag-based composite ammonia nitrogen adsorbent of claim 7 in the treatment of wastewater containing ammonia nitrogen.
11. A method for treating wastewater containing ammonia nitrogen is characterized by comprising the following steps:
and (3) contacting the ammonia-nitrogen-containing wastewater to be treated with a gasification slag-based composite ammonia-nitrogen adsorbent to perform adsorption treatment, wherein the gasification slag-based composite ammonia-nitrogen adsorbent is the gasification slag-based composite ammonia-nitrogen adsorbent according to claim 7.
12. The method of claim 11, wherein the conditions of the adsorption process comprise: the temperature is 20-40 deg.C, and the time is 2-10 min;
preferably, the concentration of ammonia nitrogen in the wastewater containing ammonia nitrogen to be treated is 20-100 mol/L;
preferably, the dosage of the gasified slag-based composite ammonia nitrogen adsorbent is 10-20g relative to 1L of the ammonia nitrogen-containing wastewater to be treated.
13. The method of claim 11 or 12, wherein the method further comprises:
regenerating the gasification slag-based composite ammonia nitrogen adsorbent subjected to adsorption treatment to obtain a regenerated gasification slag-based composite ammonia nitrogen adsorbent, and then recycling the regenerated gasification slag-based composite ammonia nitrogen adsorbent for treating ammonia nitrogen-containing wastewater, wherein the regeneration is carried out by adopting the method of claim 8 or 9.
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| CN115869908A (en) * | 2022-12-09 | 2023-03-31 | 山西大学 | Method for preparing adsorption-catalysis functional material from coal gasification ash |
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