CN111871362A - High-activity fly ash composite adsorbent and preparation method thereof - Google Patents
High-activity fly ash composite adsorbent and preparation method thereof Download PDFInfo
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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
- B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
- B01J20/103—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate comprising silica
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- B01J20/06—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group 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
- B01J20/06—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04
- B01J20/08—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04 comprising aluminium oxide or hydroxide; comprising bauxite
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- B01J2220/00—Aspects relating to sorbent materials
- B01J2220/40—Aspects relating to the composition of sorbent or filter aid materials
- B01J2220/48—Sorbents characterised by the starting material used for their preparation
- B01J2220/4875—Sorbents characterised by the starting material used for their preparation the starting material being a waste, residue or of undefined composition
- B01J2220/4887—Residues, wastes, e.g. garbage, municipal or industrial sludges, compost, animal manure; fly-ashes
Abstract
The invention discloses a high-activity fly ash composite adsorbent and a preparation method thereof. The preparation method of the high-activity fly ash composite adsorbent comprises the steps of sequentially carrying out flotation, acid washing, alkali dissolution, active iron loading and active aluminum coating on fly ash to obtain the high-activity fly ash composite adsorbent. According to the invention, the high-activity fly ash composite adsorbent is prepared by performing flotation, acid washing, alkali dissolution, active iron loading and active aluminum coating on fly ash, so that the resource utilization rate of the fly ash is improved; the high-activity fly ash composite adsorbent prepared by the invention fully exerts the synergistic effect of active iron and coated active aluminum on the surface of fly ash, has good adsorption effect, can be suitable for various pollutants, and has great application prospect.
Description
Technical Field
The invention relates to the technical field of comprehensive utilization of solid wastes, in particular to a high-activity fly ash composite adsorbent and a preparation method thereof.
Background
The fly ash is a solid waste generated in the operation of a coal-fired power plant, and the main component of the fly ash is SiO2And Al2O3The material has a porosity of about 70 percent, is a typical porous structure material, has a large specific surface area and has certain adsorption capacity. The treatment of heavy metals and organic pollutants in waste water and waste gas by utilizing the adsorption performance of the fly ash is one of important means for resource utilization of the fly ash. However, due to the powderThe coal ash has complex composition and few active adsorption points, and the effect is poor when the coal ash is directly used as an adsorbent to treat wastewater or waste gas.
In the prior art, the fly ash is generally subjected to modification treatment to improve the adsorption performance of the fly ash. Specifically, the fly ash can be treated by acid leaching, alkali leaching or high-temperature calcination and other means. However, the fly ash adsorbent modified by the above process has a good adsorption effect only on a single type of pollutant, and has a poor adsorption effect on other types of pollutants, which is not beneficial to the treatment of industrial wastewater containing various different pollutants.
Disclosure of Invention
The invention aims to overcome the technical defects, provides a high-activity fly ash composite adsorbent and a preparation method thereof, and solves the technical problem that the existing fly ash adsorbent in the prior art cannot simultaneously have a good adsorption effect on various pollutants.
In order to achieve the technical purpose, the first aspect of the invention provides a preparation method of a high-activity fly ash composite adsorbent, which comprises the steps of sequentially carrying out flotation, acid washing, alkali dissolution, active iron loading and active aluminum coating on fly ash to obtain the high-activity fly ash composite adsorbent; wherein the content of the first and second substances,
the step of loading active iron specifically comprises: mixing the fly ash dissolved out by alkali with a ferric iron solution and tetraethyl orthosilicate, stirring for 2-4 h, adjusting the pH value to be neutral, standing for 8-12 h, and washing and drying to obtain the fly ash loaded with active iron;
the step of coating the active aluminum specifically comprises the following steps: dispersing the fly ash loaded with the active iron in deionized water to form fly ash dispersion liquid loaded with the active iron; dispersing sodium metaaluminate and urea in deionized water to form an aluminum-containing dispersion liquid; and mixing the fly ash dispersion liquid loaded with the active iron with the aluminum-containing dispersion liquid, carrying out a second hydrothermal reaction, and washing and drying to obtain the high-activity fly ash composite adsorbent.
The second aspect of the invention provides a high-activity fly ash composite adsorbent, which is obtained by the preparation method of the high-activity fly ash composite adsorbent provided by the first aspect of the invention.
Compared with the prior art, the invention has the beneficial effects that:
according to the invention, the high-activity fly ash composite adsorbent is prepared by performing flotation, acid washing, alkali dissolution, active iron loading and active aluminum coating on fly ash, so that the resource utilization rate of the fly ash is improved; the high-activity fly ash composite adsorbent prepared by the invention fully exerts the synergistic effect of active iron and coated active aluminum on the surface of fly ash, has good adsorption effect, can be suitable for various pollutants, and has great application prospect.
Drawings
Fig. 1 is a process flow diagram of an embodiment of the preparation method of the high-activity fly ash composite adsorbent provided by the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Referring to fig. 1, a first aspect of the present invention provides a method for preparing a high-activity fly ash composite adsorbent, which includes steps of S1 flotation, S2 acid washing, S3 alkali dissolution, S4 loaded active iron, and S5 coated active aluminum, and each step is described in detail below.
The S1 flotation step specifically comprises the following steps: adding 0.5-2 ml of light diesel oil into 1kg of fly ash ore pulp, stirring for 5-10 min, then adding 0.2-0.5 ml of foaming agent, continuously stirring for 3-5 min, and after flotation, taking down mortar on the lower layer and drying to obtain the fly ash after flotation. In this embodiment, the solid-to-liquid ratio of fly ash to water in the fly ash slurry is 1: (2-4) carrying out tertiary flotation by adopting a flotation machine, wherein the rotating speed of the flotation machine is 2000-3000 r/min, and the air inflation is 0.2-0.3 m3/(m2Min), and the flotation time is 5-10 min each time. The fly ash has complex composition, partial components can influence the strength and the adsorption performance of the fly ash adsorbent, and the fly ash adsorbent is finally used in practiceIn the process, the service life is shortened, and the adsorption performance is reduced. The invention can remove the components which are unfavorable to the strength and the adsorption performance in the fly ash, such as carbon particles, floating beads and the like, and improve the strength and the adsorption performance of the residual fly ash by carrying out flotation on the fly ash, so that the prepared high-activity fly ash composite adsorbent has better wear resistance and compressive strength when being used for packing a column in the actual water treatment process, is not easy to damage and run off in use, and improves the service performance of the high-activity fly ash composite adsorbent.
The S2 pickling step specifically comprises the following steps: and (4) mixing the floated fly ash obtained in the step (S1) with an inorganic acid solution, stirring for 0.5-2 h at 90-95 ℃, and washing and drying to obtain the acid-washed fly ash. In the embodiment, the inorganic acid is one or more of hydrochloric acid, sulfuric acid and nitric acid, the concentration of the inorganic acid solution is 1-5 mol/L, and the solid-to-liquid ratio of the floated fly ash to the inorganic acid solution is 1g: (2-4) ml; and the washing process is to wash the fly ash with water until the pH value is 6.5-7.5 after the stirring process is finished. In the step, impurities which are not beneficial to synthesis can be removed through acid washing, the surface structure of the fly ash can be damaged, originally closed pores are opened, the surface pore number and the specific surface area are increased, and the adsorption performance of the fly ash adsorbent is improved.
After the acid washing process is finished, the coal ash after acid washing can be ground and sieved, and the particle size of the coal ash is controlled to be smaller than 200 meshes, so that the subsequent modification process can be smoothly carried out.
The step of alkali dissolution of S3 specifically comprises: and (4) mixing the coal ash obtained in the step (S2) after acid washing with an inorganic alkali solution and a nucleating agent, carrying out a first hydrothermal reaction, cooling to room temperature after the reaction is finished, and then washing and drying to obtain the coal ash dissolved out by alkali. In the embodiment, the inorganic alkali is one or more of sodium hydroxide and potassium hydroxide, the concentration of the inorganic alkali solution is 1-5 mol/L, and the solid-to-liquid ratio of the pulverized fuel ash after acid washing to the inorganic alkali solution is 1g: (1-5) ml; the nucleating agent is calcium sulfate, and the weight ratio of the pulverized fuel ash after acid washing to the nucleating agent is 1: (0.0005 to 0.002); the first hydrothermal reaction is carried out under the condition of stirring, the stirring speed is 200-300 rpm, the temperature of the first hydrothermal reaction is 80-120 ℃, and the time of the first hydrothermal reaction is 18-30 h; the washing process is that after the hydrothermal reaction is finished, the fly ash is washed by water until the pH value is 6.5-7.5. In the step, the nucleating agent is added, so that the dissolution of iron and aluminum in the fly ash can be accelerated, the reaction period is shortened, iron and aluminum crystals with a zeolite-like framework structure are formed in situ in the fly ash, and the adsorption performance is further improved.
After the alkali dissolution process is finished, the fly ash subjected to alkali dissolution can be ground and sieved, and the particle size of the fly ash is controlled to be smaller than 200 meshes, so that the subsequent modification process can be smoothly carried out.
The step of S4 loading active iron specifically comprises the following steps: and (4) mixing the alkali-dissolved fly ash obtained in the step (S3) with a ferric iron solution and tetraethyl orthosilicate, stirring for 2-4 h, adjusting the pH value to be neutral, standing for 8-12 h, and washing and drying to obtain the fly ash loaded with active iron. In this embodiment, the ferric iron solution is one or more of ferric chloride solution, ferric nitrate solution, and ferric sulfate solution, the concentration of the ferric iron solution is 0.1-0.5 mol/L, and the solid-to-liquid ratio of the fly ash dissolved out by the alkali to the ferric iron solution is 1g: (50-60) ml; the solid-to-liquid ratio of the fly ash dissolved out by the alkali to the tetraethyl orthosilicate is 1g: (0.5-1) ml. In the step, tetraethyl orthosilicate is added as a binder, so that the active iron and the fly ash matrix can be combined more tightly, and the active iron can be loaded on the surface of the fly ash more favorably. By loading active iron on the surface of the fly ash, the in-situ formation of Fe-O-Si (OH) in Fe and Si is facilitated3Etc. to increase the physical strength of the adsorbent; meanwhile, in an alkaline environment, the hydrated iron oxide can undergo deprotonation reaction, so that the surface of the hydrated iron oxide is negatively charged, and metal ions with positive charges are electrostatically adsorbed, thereby having a good adsorption effect on heavy metals such as Zn, Cu, Cd, Sr and the like in water.
The step of coating the activated aluminum by S5 specifically comprises the following steps: dispersing the fly ash loaded with the active iron obtained in the step S4 in deionized water to form fly ash dispersion liquid loaded with the active iron; dispersing sodium metaaluminate and urea in deionized water to form an aluminum-containing dispersion liquid; mixing the fly ash dispersion liquid loaded with active iron with the aluminum-containing dispersion liquid, carrying out a second hydrothermal reaction, washing and drying to obtain the high-purity ironAn active fly ash composite adsorbent. In the embodiment, in the fly ash dispersion liquid loaded with active iron, the mass concentration of the fly ash loaded with active iron is 0.005-0.01 g/mL; in the aluminum-containing dispersion liquid, the mass concentration of sodium metaaluminate is 0.01-0.05 g/mL, and the mass concentration of urea is 0.05-0.1 g/mL; the volume ratio of the fly ash dispersion liquid loaded with active iron to the aluminum-containing dispersion liquid is 1: (1-2); the temperature of the second hydrothermal reaction is 140-180 ℃, and the time of the second hydrothermal reaction is 8-16 h. In this step, the addition of urea can increase Al content3+The hydration activity of the sodium metaaluminate and the urea can enable the sodium metaaluminate to react with the urea to form an aluminate alumina sol, the alumina sol is usually composed of long-chain or cyclic-chain molecules, and the long-chain or cyclic-chain molecules are easy to crosslink to form a network structure so as to improve the physical adsorption performance of the adsorbent; meanwhile, partial active hydroxyl groups still exist in the hydrated alumina prepared by the method after drying and dehydration, the oxygen in the hydroxyl groups has non-bonding electrons and can be matched with the empty orbit of metal ions to form coordinate bond adsorption, and organic dye molecules can also form hydrogen bonds and chemical bonds in water to generate adsorption, so that the obtained high-activity fly ash composite adsorbent has a good adsorption effect on the metal ions and the organic dye.
The second aspect of the invention provides a high-activity fly ash composite adsorbent, which is obtained by the preparation method of the high-activity fly ash composite adsorbent provided by the first aspect of the invention.
Example 1
(1) Flotation: adding 2ml of light diesel oil into 2kg of fly ash ore pulp, stirring for 7min, then adding 0.6ml of methyl isobutyl carbinol (MIBC), continuously stirring for 5min, carrying out three-time flotation by using a flotation machine, separating unburned carbon, washing a separation product, pouring out upper suspension, and repeating for 3 times; taking the lower layer mortar, and drying by using an electric heating constant temperature blast drying air box at 100 ℃ to obtain the coal ash subjected to flotation. Wherein the solid-liquid ratio of the fly ash to the water in the fly ash pulp is 1: 3, the rotating speed of the flotation machine is 2200r/min, and the aeration quantity is 0.25m3/(m2Min), each flotation time was 5 min.
(2) Acid washing: and mixing the floated fly ash with 2mol/L diluted hydrochloric acid according to a solid-to-liquid ratio of 1g:3ml, stirring for 1h at 90 ℃, washing with water until the pH value is 7, drying at 105 ℃, grinding and sieving with a 200-mesh sieve to obtain the washed fly ash.
(3) Alkali dissolution: adding 300g of the acid-washed fly ash and 3mol/L of NaOH solution into a stainless steel reaction kettle according to the solid-to-liquid ratio of 1g to 4ml, and then adding 0.3g of CaSO with the particle size of less than 40 mu m4Reacting the powder at 100 ℃ and 300rpm for 24h, cooling to room temperature after the reaction is finished, washing with water until the pH is 7, drying at 105 ℃, grinding, sieving by a 200-mesh sieve to obtain the fly ash dissolved out by alkali.
(4) Loading active iron: taking 8g FeCl3·6H2Dissolving O in 100ml of deionized water, fully stirring until the solution is clear, then adding 2g of the fly ash dissolved out by the alkali, then adding 1.2ml of tetraethyl orthosilicate, stirring for 4h, adjusting the pH to be neutral by using 2mol/L ammonia water, standing for 10h, removing supernatant, washing, and drying at 80 ℃ to obtain the fly ash loaded with active iron.
(5) Coating active aluminum: under the ultrasonic condition, 0.14g of the fly ash loaded with the active iron is dispersed in 20ml of deionized water to form fly ash dispersion liquid loaded with the active iron; under magnetic stirring, 0.68g of sodium metaaluminate and 1.92g of urea are dispersed in 30ml of deionized water to form an aluminum-containing dispersion liquid; mixing the fly ash dispersion liquid loaded with active iron and the aluminum-containing dispersion liquid, putting the mixture into a 70ml polytetrafluoroethylene-lined stainless steel high-pressure reaction kettle, reacting for 12h at 160 ℃, naturally cooling to room temperature, washing the product with deionized water and absolute ethyl alcohol for several times, and drying in a vacuum drying oven at 50 ℃ for 6h to obtain the high-activity fly ash composite adsorbent.
Example 2
(1) Flotation: adding 2ml of light diesel oil into 2kg of fly ash ore pulp, stirring for 7min, then adding 0.6ml of methyl isobutyl carbinol (MIBC), continuously stirring for 5min, carrying out three-time flotation by using a flotation machine, separating unburned carbon, washing a separation product, pouring out upper suspension, and repeating for 3 times; taking the lower layer mortar, and drying by using an electric heating constant temperature blast drying air box at 100 ℃ to obtain the coal ash subjected to flotation. Wherein the solid-liquid ratio of the fly ash to the water in the fly ash pulp is 1: 3, the rotating speed of the flotation machine is 2200r/min, and the aeration quantity is 0.25m3/(m2Min), each flotation time was 5 min.
(2) Acid washing: and mixing the floated fly ash with 2mol/L diluted hydrochloric acid according to a solid-to-liquid ratio of 1g:3ml, stirring for 1h at 90 ℃, washing with water until the pH value is 7, drying at 105 ℃, grinding and sieving with a 200-mesh sieve to obtain the washed fly ash.
(3) Alkali dissolution: adding 300g of the acid-washed fly ash and 3mol/L of NaOH solution into a stainless steel reaction kettle according to the solid-to-liquid ratio of 1g to 4ml, and then adding 0.3g of CaSO with the particle size of less than 40 mu m4Reacting the powder at 100 ℃ and 300rpm for 24h, cooling to room temperature after the reaction is finished, washing with water until the pH is 7, drying at 105 ℃, grinding, sieving by a 200-mesh sieve to obtain the fly ash dissolved out by alkali.
(4) Loading active iron: taking 3g FeCl3·6H2Dissolving O in 100ml of deionized water, fully stirring until the solution is clear, then adding 2g of the fly ash dissolved out by the alkali, then adding 1ml of tetraethyl orthosilicate, stirring for 2 hours, adjusting the pH to be neutral by using 2mol/L ammonia water, standing for 8 hours, removing supernatant, washing, and drying at 80 ℃ to obtain the fly ash loaded with active iron.
(5) Coating active aluminum: under the ultrasonic condition, 0.1g of the fly ash loaded with the active iron is dispersed in 20ml of deionized water to form fly ash dispersion liquid loaded with the active iron; under magnetic stirring, 0.3g of sodium metaaluminate and 1.5g of urea are dispersed in 30ml of deionized water to form an aluminum-containing dispersion liquid; mixing the fly ash dispersion liquid loaded with active iron and the aluminum-containing dispersion liquid, putting the mixture into a 70ml polytetrafluoroethylene-lined stainless steel high-pressure reaction kettle, reacting for 16h at 140 ℃, naturally cooling to room temperature, washing the product with deionized water and absolute ethyl alcohol for several times, and drying in a vacuum drying oven at 50 ℃ for 6h to obtain the high-activity fly ash composite adsorbent.
Example 3
(1) Flotation: adding 2ml of light diesel oil into 2kg of fly ash ore pulp, stirring for 7min, then adding 0.6ml of methyl isobutyl carbinol (MIBC), continuously stirring for 5min, carrying out three-time flotation by using a flotation machine, separating unburned carbon, washing a separation product, pouring out upper suspension, and repeating for 3 times; taking off the mortar in the lower layer, drying with 100 deg.C electrothermal constant temperature blast drying bellows to obtain the final productAnd (5) selecting the fly ash. Wherein the solid-liquid ratio of the fly ash to the water in the fly ash pulp is 1: 3, the rotating speed of the flotation machine is 2200r/min, and the aeration quantity is 0.25m3/(m2Min), each flotation time was 5 min.
(2) Acid washing: and mixing the floated fly ash with 2mol/L diluted hydrochloric acid according to a solid-to-liquid ratio of 1g:3ml, stirring for 1h at 90 ℃, washing with water until the pH value is 7, drying at 105 ℃, grinding and sieving with a 200-mesh sieve to obtain the washed fly ash.
(3) Alkali dissolution: adding 300g of the acid-washed fly ash and 3mol/L of NaOH solution into a stainless steel reaction kettle according to the solid-to-liquid ratio of 1g to 4ml, and then adding 0.3g of CaSO with the particle size of less than 40 mu m4Reacting the powder at 100 ℃ and 300rpm for 24h, cooling to room temperature after the reaction is finished, washing with water until the pH is 7, drying at 105 ℃, grinding, sieving by a 200-mesh sieve to obtain the fly ash dissolved out by alkali.
(4) Loading active iron: taking 13g FeCl3·6H2Dissolving O in 100ml of deionized water, fully stirring until the solution is clear, then adding 2g of the fly ash dissolved out by the alkali, adding 2ml of tetraethyl orthosilicate, stirring for 4 hours, adjusting the pH to be neutral by using 2mol/L ammonia water, standing for 12 hours, removing supernatant, washing, and drying at 80 ℃ to obtain the fly ash loaded with active iron.
(5) Coating active aluminum: under the ultrasonic condition, 0.2g of the fly ash loaded with the active iron is dispersed in 20ml of deionized water to form fly ash dispersion liquid loaded with the active iron; under magnetic stirring, dispersing 1.5g of sodium metaaluminate and 3g of urea in 30ml of deionized water to form an aluminum-containing dispersion liquid; mixing the fly ash dispersion liquid loaded with active iron and the aluminum-containing dispersion liquid, putting the mixture into a 70ml polytetrafluoroethylene-lined stainless steel high-pressure reaction kettle, reacting for 8h at 180 ℃, naturally cooling to room temperature, washing the product with deionized water and absolute ethyl alcohol for several times, and drying in a vacuum drying oven at 50 ℃ for 6h to obtain the high-activity fly ash composite adsorbent.
Comparative example 1
Comparative example 1 is the alkali-digested fly ash obtained in example 1.
Comparative example 2
Comparative example 2 is the fly ash loaded with active iron obtained in example 1.
Comparative example 3
(1) Flotation: adding 2ml of light diesel oil into 2kg of fly ash ore pulp, stirring for 7min, then adding 0.6ml of methyl isobutyl carbinol (MIBC), continuously stirring for 5min, carrying out three-time flotation by using a flotation machine, separating unburned carbon, washing a separation product, pouring out upper suspension, and repeating for 3 times; taking the lower layer mortar, and drying by using an electric heating constant temperature blast drying air box at 100 ℃ to obtain the coal ash subjected to flotation. Wherein the solid-liquid ratio of the fly ash to the water in the fly ash pulp is 1: 3, the rotating speed of the flotation machine is 2200r/min, and the aeration quantity is 0.25m3/(m2Min), each flotation time was 5 min.
(2) Acid washing: and mixing the floated fly ash with 2mol/L diluted hydrochloric acid according to a solid-to-liquid ratio of 1g:3ml, stirring for 1h at 90 ℃, washing with water until the pH value is 7, drying at 105 ℃, grinding and sieving with a 200-mesh sieve to obtain the washed fly ash.
(3) Alkali dissolution: adding 300g of the acid-washed fly ash and 3mol/L of NaOH solution into a stainless steel reaction kettle according to the solid-to-liquid ratio of 1g to 4ml, and then adding 0.3g of CaSO with the particle size of less than 40 mu m4Reacting the powder at 100 ℃ and 300rpm for 24h, cooling to room temperature after the reaction is finished, washing with water until the pH is 7, drying at 105 ℃, grinding, sieving by a 200-mesh sieve to obtain the fly ash dissolved out by alkali.
(4) Coating active aluminum: under the ultrasonic condition, 0.14g of the fly ash dissolved out by the alkali is dispersed in 20ml of deionized water to form fly ash dispersion liquid dissolved out by the alkali; under magnetic stirring, 0.68g of sodium metaaluminate and 1.92g of urea are dispersed in 30ml of deionized water to form an aluminum-containing dispersion liquid; mixing the fly ash dispersion liquid dissolved out by alkali with the aluminum-containing dispersion liquid, putting the mixture into a 70ml polytetrafluoroethylene-lined stainless steel high-pressure reaction kettle, reacting for 12h at 160 ℃, naturally cooling to room temperature, washing the product for several times by deionized water and absolute ethyl alcohol, and drying in a vacuum drying oven for 6h at 50 ℃ to obtain the fly ash coated with the active aluminum.
Test group 1
The fly ash adsorbents obtained in examples 1 to 3 and comparative examples 1 to 3 were subjected to Cu-containing treatment2+Simulated adsorption experiment and coagulation of wastewaterThe results are shown in Table 1.
Containing Cu2+The wastewater simulated adsorption experiment process comprises the following steps: copper sulfate is dispersed into deionized water to prepare 6 parts of simulated Cu-containing material with the mass concentration of 500mg/L2+Wastewater, the pH of the wastewater is adjusted to 8, 1g of the fly ash adsorbents obtained in examples 1-3 and comparative examples 1-3 are respectively added into each part of the copper-containing wastewater, the wastewater is oscillated at normal temperature by using a constant-temperature water bath oscillator, the oscillation is stopped once every 10min, the mixture is kept stand for 5min, 1ml of supernatant is taken and taken for 5 times in total, and a full-spectrum plasma emission spectrometer is used for measuring Cu2+Residual concentration calculation of adsorption Material vs Cu2+The maximum adsorption capacity of.
TABLE 1 different kinds of fly ash sorbents to Cu2+Maximum adsorption capacity of
As can be seen from the test group 1, the high-activity fly ash composite adsorbents obtained in the embodiments 1 to 3 of the invention are all for Cu2+Has better adsorption effect. Example 1 vs. Cu, compare to comparative examples 1-32+The adsorption capacity is remarkably improved because the synergistic effect of the active iron and the active aluminum can be fully exerted by simultaneously loading the active iron and the coated active aluminum in the example 1, so that the high-activity fly ash composite adsorbent obtained in the example 1 can be used for treating Cu2+Has larger adsorption capacity.
Test group 2
Methyl orange wastewater simulated adsorption experiments were performed on the fly ash adsorbents obtained in the above examples 1 to 3 and comparative examples 1 to 3, and the results are shown in table 2.
The simulated adsorption experiment process of the methyl orange wastewater comprises the following steps: dispersing methyl orange into deionized water, preparing 6 parts of simulated methyl orange-containing wastewater with the mass concentration of 500mg/L, adding 1g of the fly ash adsorbent obtained in the examples 1-3 and the comparative examples 1-3 into each part of methyl orange-containing wastewater respectively, oscillating at normal temperature by using a constant-temperature water bath oscillator, stopping oscillating once every 20min, performing centrifugal separation, taking 1ml of supernatant, continuously oscillating the rest liquid, taking 5 times in total, measuring the concentration of residual methyl orange by using an IS-7220 type spectrophotometer, and calculating the maximum adsorption capacity of the adsorption material on the methyl orange.
TABLE 2 maximum adsorption capacity of different kinds of fly ash adsorbents for methyl orange
| Maximum adsorption capacity (mg.g) for methyl orange-1) | |
| Example 1 | 203.6 |
| Example 2 | 186.3 |
| Example 3 | 193.8 |
| Comparative example 1 | 81.3 |
| Comparative example 2 | 112.1 |
| Comparative example 3 | 158.3 |
As can be seen from the test group 2, the high-activity fly ash composite adsorbent obtained in the embodiments 1 to 3 of the invention has a good adsorption effect on methyl orange. Compared with comparative examples 1-3, the adsorption capacity of the high-activity fly ash composite adsorbent obtained in example 1 for methyl orange is remarkably improved, because the synergistic effect of active iron and active aluminum can be fully exerted by simultaneously loading active iron and coating active aluminum in example 1, so that the high-activity fly ash composite adsorbent obtained in example 1 has larger adsorption capacity for methyl orange.
Compared with the prior art, the invention has the beneficial effects that:
according to the invention, the high-activity fly ash composite adsorbent is prepared by performing flotation, acid washing, alkali dissolution, active iron loading and active aluminum coating on fly ash, so that the resource utilization rate of the fly ash is improved; the high-activity fly ash composite adsorbent prepared by the invention fully exerts the synergistic effect of active iron and coated active aluminum on the surface of fly ash, has good adsorption effect, can be suitable for various pollutants, and has great application prospect.
The above description is only exemplary of the present invention and should not be taken as limiting the invention, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A preparation method of a high-activity fly ash composite adsorbent is characterized by comprising the steps of sequentially carrying out flotation, acid washing, alkali dissolution, active iron loading and active aluminum coating on fly ash to obtain the high-activity fly ash composite adsorbent; wherein the content of the first and second substances,
the step of loading active iron specifically comprises the following steps: mixing the fly ash dissolved out by alkali with a ferric iron solution and tetraethyl orthosilicate, stirring for 2-4 h, adjusting the pH value to be neutral, standing for 8-12 h, and washing and drying to obtain the fly ash loaded with active iron;
the step of coating the active aluminum specifically comprises the following steps: dispersing the fly ash loaded with the active iron in deionized water to form fly ash dispersion liquid loaded with the active iron; dispersing sodium metaaluminate and urea in deionized water to form an aluminum-containing dispersion liquid; and mixing the fly ash dispersion liquid loaded with the active iron with the aluminum-containing dispersion liquid, carrying out a second hydrothermal reaction, and washing and drying to obtain the high-activity fly ash composite adsorbent.
2. The preparation method of the high-activity fly ash composite adsorbent according to claim 1, wherein the concentration of the ferric iron solution is 0.1-0.5 mol/L, and the solid-to-liquid ratio of the fly ash dissolved out by alkali to the ferric iron solution is 1g: (50-60) ml; the solid-to-liquid ratio of the fly ash dissolved out by the alkali to the tetraethyl orthosilicate is 1g: (0.5-1) ml.
3. The preparation method of the high-activity fly ash composite adsorbent according to claim 1, wherein in the fly ash dispersion liquid loaded with the active iron, the mass concentration of the fly ash loaded with the active iron is 0.005-0.01 g/mL;
in the aluminum-containing dispersion liquid, the mass concentration of sodium metaaluminate is 0.01-0.05 g/mL, and the mass concentration of urea is 0.05-0.1 g/mL;
the volume ratio of the fly ash dispersion liquid loaded with the active iron to the aluminum-containing dispersion liquid is 1: (1-2).
4. The preparation method of the high-activity fly ash composite adsorbent according to claim 1, wherein the temperature of the second hydrothermal reaction is 140-180 ℃, and the time of the second hydrothermal reaction is 8-16 h.
5. The preparation method of the high-activity fly ash composite adsorbent according to claim 1, wherein the flotation step specifically comprises: adding 0.5-2 ml of light diesel oil into 1kg of fly ash ore pulp, stirring for 5-10 min, then adding 0.2-0.5 ml of foaming agent, continuously stirring for 3-5 min, and after flotation, taking down mortar on the lower layer and drying to obtain the fly ash after flotation.
6. The preparation method of the high-activity fly ash composite adsorbent according to claim 1, wherein the acid washing step specifically comprises: and mixing the floated fly ash with an inorganic acid solution, stirring for 0.5-2 hours at 90-95 ℃, and washing and drying to obtain the acid-washed fly ash.
7. The method for preparing the high-activity fly ash composite adsorbent according to claim 1, wherein the alkali dissolution step specifically comprises: mixing the coal ash after acid washing with an inorganic alkali solution and a nucleating agent, carrying out a first hydrothermal reaction, cooling to room temperature after the reaction is finished, and then washing and drying to obtain the coal ash after alkali dissolution.
8. The preparation method of the high-activity fly ash composite adsorbent according to claim 7, wherein the concentration of the inorganic alkali solution is 1-5 mol/L, and the solid-to-liquid ratio of the acid-washed fly ash to the inorganic alkali solution is 1g: (1-5) ml;
the nucleating agent is calcium sulfate, and the weight ratio of the pulverized fuel ash after acid washing to the nucleating agent is 1: (0.0005-0.002).
9. The preparation method of the high-activity fly ash composite adsorbent according to claim 7, wherein the first hydrothermal reaction is carried out under a stirring condition, the stirring speed is 200-300 rpm, the temperature of the first hydrothermal reaction is 80-120 ℃, and the time of the first hydrothermal reaction is 18-30 h.
10. A high-activity fly ash composite adsorbent is characterized by being obtained by the preparation method of the high-activity fly ash composite adsorbent according to any one of claims 1-9.
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