Method for preparing porous carbon / hydrotalcite-like compound adsorbent from fine coal gasification slag

Abstract

The invention discloses a method for preparing a porous carbon / hydrotalcite-like compound adsorbent from fine coal gasification slag, which comprises the following steps: by taking the fine coal gasification slag as a raw material, sequentially carrying out alkali activation desiliconization and ion regulation, adding a pH regulator, stirring, and carrying out one-pot hydrothermal synthesis to obtain the porous carbon / hydrotalcite-like compound adsorbent. And carrying out solid-liquid separation and washing on the hydrothermal composition to obtain a solid phase, namely the porous carbon / hydrotalcite-like compound adsorbent. According to the invention, the pore structure of carbon is expanded while alkali activation desiliconization is carried out, so that the formation of porous carbon is ensured; the porous carbon / hydrotalcite-like compound adsorbent meets the requirement of forming a hydrotalcite-like compound with better crystallinity through ion regulation and control, provides an alkaline environment for synthesizing the hydrotalcite-like compound by adding a pH regulator, ensures the formation of the hydrotalcite-like compound through one-pot hydrothermal synthesis, and is obtained through solid-liquid separation and washing, the aggregation state in the hydrotalcite-like compound synthesis process is improved, and the stability and adsorption active sites of the composite adsorption material are increased.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of environmental functional materials, and particularly relates to a method for preparing a porous carbon / hydrotalcite-like composite adsorbent from coal gasification fine slag. BACKGROUND

[0002] The porous carbon / hydrotalcite-like composite material combines the high specific surface area of porous carbon and the characteristics of the rich active adsorption sites in hydrotalcite, and has broad application potential in the fields of wastewater treatment, gas adsorption and purification, medicine, photochemistry and the like.

[0003] The invention patent with the application number CN201811543004.9 discloses a carbon / hydrotalcite composite adsorbent, its preparation, application in heavy metal adsorption and regeneration method, which comprises the following steps: placing a raw material solution containing a carbon base, a cation source for synthesizing hydrotalcite, a carbonate source, and a hydroxyl source in a sealed container and aging at 90-130℃ to obtain the carbon / hydrotalcite composite adsorbent. The carbon base is at least one of biomass, activated carbon, and coal slime; the cation source for synthesizing hydrotalcite is a divalent metal and trivalent metal compound reagent; the carbonate source and the hydroxyl source are carbonate and sodium hydroxide. The raw material of hydrotalcite relies on high-purity metal salt chemical reagents, which is costly, and the preparation process of the porous carbon material / hydrotalcite-like composite material is complex, resulting in high cost and restricting its practical application.

[0004] With the increasing environmental problems caused by the large amount of coal gasification fine slag, a solid waste of the coal gasification industry, the rich residual carbon and metal elements contained in the coal gasification fine slag cannot be efficiently extracted and utilized, resulting in resource waste. Among them, the residual carbon has a developed pore structure, and the types of metal elements meet the composition requirements of hydrotalcite-like materials, which provides a natural composition and structural basis for preparing porous carbon / hydrotalcite-like composite materials.

[0005] Therefore, the method for preparing porous carbon / hydrotalcite-like composite adsorbents from gasification fine slag has not been formed yet, and it is necessary to prepare porous carbon / hydrotalcite-like composite materials from gasification fine slag, which can not only reduce the raw material cost of the composite material, but also realize the effective resource utilization of industrial solid waste, achieving a win-win situation. SUMMARY

[0006] The technical problem solved by the present application is to provide a method for preparing a porous carbon / hydrotalcite-like composite adsorbent from coal gasification fine slag in view of the above-mentioned deficiencies of the prior art.

[0007] To solve the above technical problem, the technical solution adopted by the present application is as follows: a method for preparing a porous carbon / hydrotalcite-like composite adsorbent from coal gasification fine slag, characterized in that the method uses coal gasification fine slag as raw material, and sequentially undergoes alkali activation desilication and ion regulation, and then a pH regulator is added for one-pot hydrothermal synthesis, and then the hydrothermal synthesis product is subjected to solid-liquid separation and washing to obtain the porous carbon / hydrotalcite-like composite adsorbent.

[0008] The present application reduces the influence of silicon through alkali activation desilication, expands the pore structure of carbon, ensures the formation of porous carbon, dissolves metal ions through ion regulation, makes the ratio of divalent metal cations to trivalent metal cations meet the requirements for forming a hydrotalcite-like compound with good crystallinity, provides an alkaline environment for synthesizing the hydrotalcite-like compound by adding a pH regulator, and ensures the formation of the hydrotalcite-like compound through one-pot hydrothermal synthesis, thereby obtaining the porous carbon / hydrotalcite-like composite adsorbent after solid-liquid separation and washing, wherein the porous carbon supports the hydrotalcite-like compound, improves the aggregation state during the synthesis of the hydrotalcite-like compound, and increases the stability and adsorption active sites of the composite adsorbent.

[0009] The method for preparing a porous carbon / hydrotalcite-like composite adsorbent from coal gasification fine slag, characterized in that the raw material is coal gasification fine slag or high-carbon components or medium-carbon components separated from coal gasification fine slag carbon ash, the ignition loss of the high-carbon components is greater than 80%, and the ignition loss of the medium-carbon components is 20% to 50%.

[0010] The method for preparing a porous carbon / hydrotalcite-like composite adsorbent from coal gasification fine slag, characterized in that the process of alkali activation desilication is as follows: the alkali source is uniformly mixed with the raw material, then placed in a tube furnace for heating activation under an inert atmosphere, and then cooled to room temperature, followed by washing and filtration desilication to obtain the alkali activation desilication product; the alkali source is NaOH, KOH, CaO or Ca(OH)2; the alkali-to-carbon ratio of the alkali source to the raw material is 2 to 4:1; and the heating activation temperature is 350℃ to 700℃, and the holding time is 0.5h to 4h. The process and parameters of alkali activation desilication are controlled to sufficiently remove silicon and activate carbon, thereby expanding the pore structure of carbon, and the alkali-to-carbon ratio is a mass ratio.

[0011] The method for preparing porous carbon / hydrotalcite-like composite adsorbents from coal gasification fine slag, as described above, is characterized in that the ion regulation process is divided into two steps: ion dissolution and ratio regulation. This invention uses an acidic ion regulator to dissolve metal ions from the raw materials, facilitating the subsequent preparation of hydrotalcite-like compounds. The ratio regulation ensures that the ratio of dissolved divalent metal cations to trivalent metal cations meets the requirements for forming hydrotalcite-like compounds with good crystallinity.

[0012] The above-mentioned method for preparing porous carbon / hydrotalcite-like composite adsorbent from coal gasification fine slag is characterized in that the ion dissolution process involves adding an acidic ion regulator to the alkaline-activated desilication product for reaction; the acidic ion regulator is any one or a combination of at least two of HCl, HNO3, H2SO4, citric acid, acetic acid, formic acid, and tartaric acid; the concentration of the acidic ion regulator is 0.5 mol / L to 6 mol / L; the reaction time is 0.5 h to 5 h; and the liquid-to-solid ratio in the reaction process is 1 to 15:1. This invention ensures the quality of the porous carbon / hydrotalcite composite adsorbent by controlling the ion dissolution process to ensure sufficient dissolution of metal ions and thus guaranteeing the quality of the subsequently formed hydrotalcite-like material. Furthermore, by controlling the composition of the acidic ion regulator, a high dissolution rate is achieved when using a strong acid, while strong selectivity is achieved when using a weak acid, thereby regulating the types of metal ions dissolved.

[0013] The method for preparing porous carbon / hydrotalcite-like composite adsorbent from coal gasification fine slag, as described above, is characterized by the following proportion control process: determining the molar concentrations of divalent and trivalent metal cations in the solution after ion dissolution, and then adjusting the ion ratio by adding calcium or magnesium ions to ensure that the ratio of divalent and trivalent metal cations is within the range required for hydrotalcite formation. This invention, by controlling the proportion control process, ensures that the ratio of divalent to trivalent metal cations meets the requirements for forming hydrotalcite-like compounds with good crystallinity, thus guaranteeing the formation of hydrotalcite-like compounds.

[0014] It should be noted that the expression for the hydrotalcite-like substance in this invention is [M 2+ 1-x M 3+ x (OH)2] x+ (A n- ) x / n ·mH2O], where M 3+ It is a trivalent metal cation, M 2+ It is a divalent metal cation, A n- It is an anion that balances the interlayer charge, preferably Cl. - or OH - x is M 3+ / (M 3++M 2+ The ratio of the two is preferably 0.17-0.33, so as to control the formation of hydrotalcite-like compounds with better crystallinity.

[0015] The method for preparing the porous carbon / hydrotalcite-like composite adsorbent from coal gasification fine slag has the characteristics that the pH regulator is one or two of NaOH solution, KOH solution, urea and hexamethylenetetramine, and the dropping speed of the pH regulator is controlled to keep the pH value of the reaction system at 9-11.

[0016] The method for preparing the porous carbon / hydrotalcite-like composite adsorbent from coal gasification fine slag has the characteristics that the stirring time is 0.5-2 hours.

[0017] The method for preparing the porous carbon / hydrotalcite-like composite adsorbent from coal gasification fine slag has the characteristics that the one-pot hydrothermal synthesis condition is that the hydrothermal temperature is 80-180 DEG C and the hydrothermal time is 8-48 hours.

[0018] The method for preparing the porous carbon / hydrotalcite-like composite adsorbent from coal gasification fine slag has the characteristics that the porous carbon / hydrotalcite-like composite adsorbent is used for adsorbing heavy metal ions in wastewater or capturing CO2.

[0019] Compared with the prior art, the present application has the following advantages: 1. The present application activates desilication by alkali, expands the pore structure of carbon, ensures the formation of porous carbon, meets the requirements of forming hydrotalcite-like compounds with better crystallinity through ion regulation, provides an alkaline environment for synthesizing hydrotalcite-like compounds by adding a pH regulator, ensures the formation of hydrotalcite-like compounds through one-pot hydrothermal synthesis, and obtains a porous carbon / hydrotalcite-like composite adsorbent through solid-liquid separation and washing, wherein the porous carbon loads the hydrotalcite-like compounds, improves the aggregation state in the synthesis process of the hydrotalcite-like compounds, and increases the stability and adsorption active sites of the composite adsorbent.

[0020] 2. The raw material of the porous carbon / hydrotalcite-like composite adsorbent of the present application is derived from coal gasification fine slag, which not only reduces the pollution of coal gasification fine slag to the ecological environment, but also realizes the resource utilization of coal-based solid waste, achieves the purpose of waste treatment with waste, is conducive to energy saving and emission reduction in the coal industry, and has good environmental and economic benefits.

[0021] 3. The application provides a high-value material utilization method of coal gasification fine slag, expands the high-value material utilization direction of the coal gasification fine slag, and prepares a composite adsorbent capable of compounding special structure-like hydrotalcite on the surface of porous carbon material, expands the raw material source of the multi-stage porous carbon / like hydrotalcite composite adsorbent, effectively reduces the raw material cost of the composite adsorbent and simplifies the process, and provides a reference method for preparing the multi-stage porous carbon / like hydrotalcite composite adsorbent from solid waste.

[0022] 4. The preparation method has low raw material source cost, convenient operation and good technical universality.

[0023] 5. The porous carbon / like hydrotalcite composite adsorbent has excellent adsorption capacity for CO2.

[0024] The technical solutions of the application are further described in detail below with the aid of drawings and examples. DESCRIPTION OF DRAWINGS

[0025] Figure 1 The figure is a preparation flowchart of the porous carbon / like hydrotalcite composite adsorbent.

[0026] Figure 2 The figure is a SEM image of the product after desilication by alkali activation in step one of Example 1 of the application.

[0027] Figure 3 The figure is a SEM image of the porous carbon / like hydrotalcite composite adsorbent obtained in Example 3 of the application.

[0028] Figure 4 The figure is an XRD image of the porous carbon / like hydrotalcite composite adsorbent obtained in Example 1, Example 4 and Example 6 of the application. DETAILED DESCRIPTION

[0029] Figure 1 The figure is a preparation flowchart of the porous carbon / like hydrotalcite composite adsorbent, which is prepared from coal gasification fine slag as a raw material, and sequentially subjected to alkali activation desilication and ion regulation, and then subjected to one-pot hydrothermal synthesis after stirring with a pH regulator. Figure 1 As can be seen from the figure, the application uses coal gasification fine slag as a raw material, and sequentially undergoes alkali activation desilication and ion regulation, and then undergoes one-pot hydrothermal synthesis after stirring with a pH regulator, and then the solid phase obtained after solid-liquid separation and washing of the hydrothermal synthesis product is the porous carbon / like hydrotalcite composite adsorbent.

[0030] Example 1 This example includes the following steps: Step one, taking the high-carbon component with a loss on ignition greater than 80% after the separation of the carbon ash from the coal gasification fine slag as the raw material, mixing 3g of the medium-carbon component uniformly with NaOH at a ratio of 4:1 of alkali to carbon, and then placing it in a tube furnace, passing nitrogen gas for 5 minutes, then heating to 700°C at a rate of 10°C / min under a nitrogen atmosphere, and maintaining the temperature for 2 hours, then cooling to room temperature under a nitrogen atmosphere, then closing the nitrogen valve, air cooling for 0.5 hours, then moving to a polytetrafluoroethylene beaker, adding 150 mL of deionized water, ultrasonic washing for 1 hour, and then filtering and desiliconizing, and then drying to obtain the product after alkali activation and desiliconization; Step two, taking 5g of the product after alkali activation and desiliconization obtained in step one, mixing it with 6 mol / L of HCl at a ratio of 1:1 of liquid to solid, and then placing it in an ultrasonic cleaner, and then reacting for 120 minutes at an ultrasonic power of 240 W and a temperature of 60°C to obtain the solution after ion dissolution; Step three, determining the amount-of-substance concentration of the divalent and trivalent metal ions in the solution after ion dissolution obtained in step two, then adding Mg(OH)2 to the solution after ion dissolution at a ratio of M 2+ / M 3+ =2, completely dissolving it, then adding 30 mL of deionized water to it, then adding 1.5 mol / L of NaOH solution as a pH adjuster to keep the pH value at 9, and then continuously stirring it for 1 hour, then transferring it to a 100 mL pressure reaction kettle lined with polytetrafluoroethylene, placing the reaction kettle in a 120°C constant-temperature drying box, taking out the reaction kettle after 24 hours, and then naturally cooling it to room temperature, and then washing the washed solid with deionized water by centrifugation until the supernatant is nearly neutral, and then drying the washed solid at 60°C under vacuum for 24 hours, and then grinding it to obtain the porous carbon / hydrotalcite-like composite adsorbent.

[0031] Figure 2 The SEM image of the product after alkali activation and desiliconization obtained in step one of this example is shown in FIG. 1, and the product after alkali activation and desiliconization is porous carbon. Figure 2 As can be seen from FIG. 1, after alkali activation and desiliconization, the surface of the porous carbon has relatively obvious etching marks, and there are a large number of irregular pore structures, which provide good adsorption space for CO2.

[0032] The acidic ion adjuster in this example can also be any one or a combination of at least two of HCl, HNO3, H2SO4, citric acid, acetic acid, formic acid, and tartaric acid; and the pH adjuster in this example can also be one or two of KOH solution, urea, and hexamethylenetetramine.

[0033] Example 2 This example includes the following steps: Step one, 10g of coal gasification fine slag sample was mixed with NaOH at a ratio of 3 and then placed in a tube furnace, nitrogen was passed for 5min, then heated to 620℃ at a rate of 10℃ / min under nitrogen atmosphere and kept for 4h, then cooled to room temperature under nitrogen atmosphere, then the nitrogen valve was closed, air-cooled for 0.5h, finally moved to a Teflon beaker, 150mL of deionized water was added and ultrasonic washing was carried out for 1h and desilication was carried out by filtration, and the product after alkali activation and desilication was obtained after drying; Step two, 5g of the product after alkali activation and desilication obtained in step one was mixed with 2mol / L HCl at a ratio of 10:1 and then placed in an ultrasonic cleaner, ultrasonic power was 240W, temperature was 60℃, reaction time was 30min, and the solution after ion dissolution was obtained; Step three, the concentration of divalent and trivalent metal ions in the solution after ion dissolution obtained in step two was determined, then Mg(OH)2 was added to the solution after ion dissolution at a ratio of M 2+ / M 3+ =2, after complete dissolution, 30mL of deionized water was added, then 1.5mol / L NaOH solution was added as a pH regulator to keep the pH value at 10, and stirring was continued for 1h, then the solution was transferred to a 100mL pressure reactor lined with polytetrafluoroethylene, the reactor was placed in a 120℃ constant temperature drying box, after 24h, the reactor was taken out and naturally cooled to room temperature, finally the washed solid was centrifuged with deionized water until the supernatant was nearly neutral, the washed solid was dried at 60℃ under vacuum for 24h, and then ground to obtain a porous carbon / hydrotalcite-like composite adsorbent.

[0034] The acidic ion regulator in this embodiment can also be any one or a combination of at least two of HCl, HNO3, H2SO4, citric acid, acetic acid, formic acid and tartaric acid; the pH regulator in this embodiment can also be one or two of NaOH solution, KOH solution, urea and hexamethylenetetramine.

[0035] Example 3 This embodiment includes the following steps: Step one, 10g of the medium carbon component with loss on ignition of 20%-50% after separation of coal gasification fine slag carbon ash was mixed with KOH at a ratio of 2 and then placed in a tube furnace, nitrogen was passed for 5min, then heated to 620℃ at a rate of 10℃ / min under nitrogen atmosphere and kept for 0.5h, then cooled to room temperature under nitrogen atmosphere, then the nitrogen valve was closed, air-cooled for 0.5h, finally moved to a Teflon beaker, 150mL of deionized water was added and ultrasonic washing was carried out for 1h and desilication was carried out by filtration, and the product after alkali activation and desilication was obtained after drying; Step two, take 5g of the product after alkali-activated desilication in step one, mix with 2mol / L HNO3 according to the ratio of 15:1, and then put it into the ultrasonic cleaner, with ultrasonic power of 240W, temperature of 60℃, and reaction time of 90min, to obtain the solution after ion dissolution; Step three, determine the concentration of divalent and trivalent metal ions in the solution after ion dissolution in step two, then add Mg(OH)2 to the solution according to the ratio of M 2+ / M 3+ =2, completely dissolve it, then add 30mL deionized water, and then add 1.5mol / L KOH solution as pH regulator to keep the pH value at 10, and continue to stir for 1h, then transfer it to a 100mL pressure reactor with inner liner of polytetrafluoroethylene, put the reactor into a 120℃ constant temperature drying oven, take out the reactor after 24h, and then cool it to room temperature naturally, finally wash the washed solid with deionized water by centrifugation until the supernatant is close to neutral, dry the washed solid at 60℃ under vacuum for 24h, grind it, and then obtain the porous carbon / hydrotalcite-like composite adsorbent.

[0036] The acidic ion regulator in this embodiment can also be any one or a combination of at least two of HCl, H2SO4, citric acid, acetic acid, formic acid and tartaric acid; and the pH regulator in this embodiment can also be one or two of NaOH solution, urea and hexamethylenetetramine.

[0037] Example 4 This embodiment includes the following steps: Step one, take 3g of high-carbon component with loss on ignition greater than 80% after separation of coal gasification fine slag carbon ash as raw material, mix it uniformly with NaOH according to the ratio of 4:1, then put it into a tube furnace, pass nitrogen gas for 5min, then heat it to 500℃ at a rate of 10℃ / min under nitrogen atmosphere, and keep it at this temperature for 2h, then cool it to room temperature under nitrogen atmosphere, then close the nitrogen valve, and air cool it for 0.5h, finally transfer it to a polytetrafluoroethylene beaker, add 150mL deionized water, ultrasonic wash for 1h, and then filter and desilicate, and dry to obtain the product after alkali-activated desilication; Step two, take 5g of the product after alkali-activated desilication in step one, mix it with 1.0mol / L H2SO4 according to the ratio of 10:1, and then put it into the ultrasonic cleaner, with ultrasonic power of 240W, temperature of 60℃, and reaction time of 90min, to obtain the solution after ion dissolution; Step three, determine the concentration of divalent and trivalent metal ions in the solution after ion dissolution in step two, then add Mg(OH)2 to the solution according to the ratio of M 2+ / M 3+=2, Mg(OH)2was added into the solution after ion leaching, after complete dissolution, 30 mL of deionized water was added, then the solution was transferred into a 100 mL pressure reactor with polytetrafluoroethylene lining, the reactor was placed in a constant temperature drying oven at 80℃, after 48 h, the reactor was taken out and naturally cooled to room temperature, finally, the washed solid was dried at 60℃ under vacuum for 24 h, and then grinded to obtain the porous carbon / hydrotalcite-like composite adsorbent.

[0038] Figure 3 The SEM image of the porous carbon / hydrotalcite-like composite adsorbent obtained in this example is shown in the left side of the figure, and the right side of the figure is an enlarged view of the left side of the figure. Figure 3 As can be seen from the figure, the porous carbon / hydrotalcite-like composite adsorbent obtained in this example has clear nanosheet-like hydrotalcite on the substrate of porous carbon, indicating the successful preparation of the porous carbon / hydrotalcite-like composite adsorbent.

[0039] In this example, the acidic ion regulator can also be any one or a combination of at least two of HCl, HNO3, citric acid, acetic acid, formic acid and tartaric acid; and the pH regulator can also be one or both of NaOH solution and KOH solution.

[0040] Example 5 This example includes the following steps: Step one, 3 g of high-carbon components with a loss on ignition of more than 80% after separation of coal gasification fine slag carbon ash were mixed with NaOH at a ratio of 4:1, and then placed in a tube furnace, nitrogen was passed for 5 min, then heated to 500℃ at a rate of 10℃ / min under nitrogen atmosphere, and kept for 2 h, then cooled to room temperature under nitrogen atmosphere, then the nitrogen valve was closed, and air-cooled for 0.5 h, finally transferred to a polytetrafluoroethylene beaker, 150 mL of deionized water was added and ultrasonic washed for 1 h, and then desilicated by filtration, and dried to obtain the product after alkali activation and desilication; Step two, 5 g of the product after alkali activation and desilication obtained in step one was mixed with 1.5 mol / L of HCl at a ratio of 10:1, and then placed in an ultrasonic cleaner, and reacted for 90 min under ultrasonic power of 240 W and temperature of 60℃, to obtain a solution after ion leaching; Step three, the molar concentration of divalent and trivalent metal ions in the solution after ion leaching obtained in step two was determined, then Mg(OH)2was added into the solution at a ratio of 2:1, after complete dissolution, 30 mL of deionized water was added, then the solution was transferred into a 100 mL pressure reactor with polytetrafluoroethylene lining, the reactor was placed in a constant temperature drying oven at 80℃, after 48 h, the reactor was taken out and naturally cooled to room temperature, finally, the washed solid was dried at 60℃ under vacuum for 24 h, and then grinded to obtain the porous carbon / hydrotalcite-like composite adsorbent. 2+ / M 3+=5 of CaCl2, after complete dissolution, 1.5 mol / L NaOH solution was added as pH regulator to make the solution pH to 10, and continuously stirred for 0.5 h, then transferred to a 100 mL pressure reactor lined with polytetrafluoroethylene, the reactor was put into a constant temperature drying oven at 120℃, after 12 h, the reactor was taken out, and naturally cooled to room temperature, finally washed with deionized water by centrifugation until the supernatant was close to neutral, the washed solid was vacuum dried at 60℃ for 24 h, and then grinded to obtain the porous carbon / hydrotalcite-like composite adsorbent.

[0041] In this embodiment, the acidic ion regulator can also be any one or a combination of at least two of HCl, HNO3, H2SO4, citric acid, acetic acid, formic acid and tartaric acid; and the pH regulator can also be one or two of KOH solution, urea and hexamethylenetetramine.

[0042] Example 6 This embodiment includes the following steps: Step one, 3 g of high-carbon component with loss on ignition greater than 80% after separation of coal gasification fine slag carbon ash was mixed with NaOH at a ratio of 4:1, and then put into a tube furnace, nitrogen was passed for 5 min, then heated to 500℃ at a rate of 10℃ / min under nitrogen atmosphere, and kept for 2 h, then cooled to room temperature under nitrogen atmosphere, then the nitrogen valve was closed, and air-cooled for 0.5 h, finally transferred to a polytetrafluoroethylene beaker, 150 mL of deionized water was added and ultrasonic washed for 1 h, and then desilicated by filtration, and dried to obtain the product after alkali activation and desilication; Step two, 5 g of the product after alkali activation and desilication obtained in step one was mixed with 1 mol / L citric acid at a ratio of 10:1, and then put into an ultrasonic cleaner, ultrasonic power was 240 W, temperature was 60℃, and reaction time was 5 h, to obtain the solution after ion leaching; Step three, the amount-of-substance concentration of divalent and trivalent metal ions in the solution after ion leaching obtained in step two was determined, then CaCl2 was added to the solution after ion leaching at a ratio of M 2+ / M 3+ =3 of CaCl2, after complete dissolution, 1.5 mol / L NaOH solution was added as pH regulator to make the solution pH to 11, and continuously stirred for 2 h, then transferred to a 100 mL pressure reactor lined with polytetrafluoroethylene, the reactor was put into a constant temperature drying oven at 180℃, after 8 h, the reactor was taken out, and naturally cooled to room temperature, finally washed with deionized water by centrifugation until the supernatant was close to neutral, the washed solid was vacuum dried at 60℃ for 24 h, and then grinded to obtain the porous carbon / hydrotalcite-like composite adsorbent.

[0043] Figure 4The XRD pattern of the porous carbon / hydrotalcite-like composite adsorbent obtained in Example 1, Example 4 and Example 6 can be seen from Figure 4 It can be seen from the XRD pattern of the porous carbon / hydrotalcite-like composite adsorbent that the porous carbon / hydrotalcite-like composite adsorbent is successfully prepared.

[0044] The acidic ion regulator in the present embodiment can also be any one or a combination of at least two of HCl, HNO3, H2SO4, citric acid, acetic acid, formic acid and tartaric acid; the pH regulator in the present embodiment can also be one or two of KOH solution, urea and hexamethylenetetramine.

[0045] Example 7 The present embodiment comprises the following steps: Step 1: Take 3g of high-carbon components with a loss on ignition greater than 80% after separation of the carbon ash of coal gasification fine slag as raw material, mix 3g of high-carbon components uniformly with NaOH at a ratio of 4:1 of alkali to carbon, then put into a tube furnace, pass nitrogen for 5min, then heat to 500℃ at a rate of 10℃ / min under nitrogen atmosphere, and keep for 2h, then cool to room temperature under nitrogen atmosphere, then close the nitrogen valve, air cool for 0.5h, finally move to a polytetrafluoroethylene beaker, add 150mL of deionized water, ultrasonic washing for 1h and desilication by filtration, then dry to obtain the product after alkali activation and desilication; Step 2: Take 5g of the product after alkali activation and desilication obtained in Step 1, mix with 0.5moL / L of HCl at a ratio of 10:1 of liquid to solid, then put into an ultrasonic cleaner, ultrasonic power is 240W, temperature is 60℃, reaction for 90min, to obtain the solution after ion dissolution; Step 3: Determine the amount of concentration of divalent and trivalent metal ions in the solution after ion dissolution obtained in Step 2, then add Mg(OH)2 to the solution after ion dissolution at a ratio of M 2+ / M 3+ =2, after complete dissolution, add 30mL of deionized water, then add 1.5mol / L of NaOH solution as a pH regulator to keep the pH at 10, and continue to stir for 1h, then transfer to a 100mL pressure reaction kettle lined with polytetrafluoroethylene, put the reaction kettle into a 80℃ constant temperature drying box, take out the reaction kettle after 48h, and naturally cool to room temperature, finally wash with deionized water by centrifugation until the supernatant is close to neutral, dry the washed solid at 60℃ under vacuum for 48h, then grind to obtain the porous carbon / hydrotalcite-like composite adsorbent.

[0046] The acidic ion regulator in the present embodiment can also be any one or a combination of at least two of HCl, HNO3, H2SO4, citric acid, acetic acid, formic acid and tartaric acid; the pH regulator in the present embodiment can also be one or two of KOH solution, urea and hexamethylenetetramine.

[0047] Example 8 This example includes the following steps: Step one, taking the high-carbon component with a loss on ignition greater than 80% after separation of the carbon ash of the coal gasification fine slag as raw material, 3g of the medium-carbon component is mixed with Ca(OH)2 at a ratio of 4:1 and then placed in a tube furnace, nitrogen is passed for 5 minutes, then the temperature is raised to 350°C at a rate of 10°C / min under a nitrogen atmosphere, and the temperature is maintained for 2 hours, then the temperature is cooled to room temperature under a nitrogen atmosphere, then the nitrogen valve is closed, air cooling is performed for 0.5 hours, then the product is moved to a Teflon beaker, 150 mL of deionized water is added, ultrasonic washing is performed for 1 hour, and desilication is performed by filtration, and then the product is dried to obtain an alkali-activated desilicated product; Step two, 5g of the alkali-activated desilicated product obtained in step one is mixed with 6 mol / L HCl at a ratio of 1:1, then placed in an ultrasonic cleaner, ultrasonic power is 240W, temperature is 60°C, and reaction is performed for 90 minutes to obtain an ion leached solution; Step three, the amount-of-substance concentration of divalent and trivalent metal ions in the ion leached solution obtained in step two is determined, then CaO is added to the ion leached solution at a ratio of M 2+ / M 3+ =2, after complete dissolution, 30 mL of deionized water is added, then 1.5 mol / L NaOH solution is added as a pH adjuster to maintain the pH value at 10, and stirring is continued for 1 hour, then the solution is transferred to a 100 mL pressure reactor lined with polytetrafluoroethylene, the reactor is placed in a 120°C constant temperature drying oven, after 24 hours the reactor is removed, allowed to cool to room temperature, then washed with deionized water by centrifugation until the supernatant is nearly neutral, the washed solid is dried in a vacuum at 60°C for 24 hours, then ground to obtain a porous carbon / hydrotalcite-like composite adsorbent.

[0048] In this example, the acidic ion adjuster can also be any one or a combination of at least two of HNO3, H2SO4, citric acid, acetic acid, formic acid, and tartaric acid; in this example, the pH adjuster can also be one or two of KOH solution, urea, and hexamethylenetetramine.

[0049] Example 9 This example includes the following steps: Step one, 10g of a coal gasification fine slag sample is mixed with CaO at a ratio of 3:1 and then placed in a tube furnace, nitrogen is passed for 5 minutes, then the temperature is raised to 400°C at a rate of 10°C / min under a nitrogen atmosphere and maintained for 4 hours, then the temperature is cooled to room temperature under a nitrogen atmosphere, then the nitrogen valve is closed, air cooling is performed for 0.5 hours, then the product is moved to a Teflon beaker, 150 mL of deionized water is added, ultrasonic washing is performed for 1 hour, and desilication is performed by filtration, and then the product is dried to obtain an alkali-activated desilicated product; Step two, taking 5g of the desilicated product from step one, mixing with 2mol / L HCl at a liquid-solid ratio of 10:1, and then placing in an ultrasonic cleaner at an ultrasonic power of 240W and a temperature of 60℃ for 90min to obtain an ion leached solution; Step three, determining the amount of concentration of divalent and trivalent metal ions in the ion leached solution from step two, and then adding CaO to the ion leached solution at a ratio of M 2+ / M 3+ =2, completely dissolving, then adding 30mL of deionized water, and then adding 1.5mol / L NaOH solution as a pH regulator to keep the pH value at 10, and continuously stirring for 1h, and then transferring to a 100mL pressure reactor lined with polytetrafluoroethylene, placing the reactor in a 120℃ constant temperature drying oven, taking out the reactor after 24h, and naturally cooling to room temperature, and finally washing with deionized water by centrifugation until the supernatant is nearly neutral, and grinding the washed solid at 60℃ under vacuum for 24h to obtain a porous carbon / hydrotalcite-like composite adsorbent.

[0050] The acidic ion regulator in this embodiment can also be any one or a combination of at least two of HNO3, H2SO4, citric acid, acetic acid, formic acid and tartaric acid; and the pH regulator in this embodiment can also be one or two of NaOH solution, KOH solution, urea and hexamethylenetetramine.

[0051] The porous carbon / hydrotalcite-like composite adsorbents obtained in Examples 1-9 were tested for specific surface area and CO2 adsorption capacity, and the results are shown in Table 1.

[0052] Table 1

[0053] As can be seen from Table 1, the porous carbon / hydrotalcite-like composite adsorbents prepared by coal gasification fine slag in Examples 1-9 have the characteristics of large specific surface area and high adsorption capacity.

[0054] The porous carbon / hydrotalcite-like composite adsorbents prepared in Examples 1-9 can also be used for heavy metal ion adsorption in wastewater.

[0055] The above is only a preferred embodiment of the present application, and does not limit the present application in any way. Any simple modification, change and equivalent change to the above embodiment according to the technical essence of the present application are still within the protection scope of the technical solution of the present application.

Claims

1. A method for preparing porous carbon / hydrotalcite-like composite adsorbent from coal gasification fine slag, characterized in that, This method uses coal gasification fine slag as raw material, which undergoes alkali activation and desilication and ion regulation, followed by the addition of a pH adjuster and stirring before being synthesized in a one-pot hydrothermal process. The solid phase obtained after solid-liquid separation and washing of the hydrothermal synthesized product is the porous carbon / hydrotalcite-like composite adsorbent.

2. The method for preparing porous carbon / hydrotalcite-like composite adsorbent from coal gasification fine slag according to claim 1, characterized in that, The raw material is coal gasification fine slag or high-carbon or medium-carbon components after carbon and ash separation of coal gasification fine slag, wherein the loss on ignition of the high-carbon component is greater than 80% and the loss on ignition of the medium-carbon component is 20% to 50%.

3. The method for preparing porous carbon / hydrotalcite-like composite adsorbent from coal gasification fine slag according to claim 1, characterized in that, The alkaline activation desilication process is as follows: the alkaline source and the raw material are mixed evenly, then placed in a tube furnace and heated for activation under an inert atmosphere. After cooling to room temperature, the mixture is washed and filtered for desilication to obtain the alkaline activated desilication product. The alkaline source is NaOH, KOH, CaO, or Ca(OH)2. The alkaline-to-carbon ratio of the alkaline source to the raw material is 2~4:

1. The heating activation temperature is 350℃~700℃, and the holding time is 0.5h~4h.

4. The method for preparing porous carbon / hydrotalcite-like composite adsorbent from coal gasification fine slag according to claim 1, characterized in that, The ion regulation process is divided into two processes: ion dissolution and ratio regulation.

5. The method for preparing porous carbon / hydrotalcite-like composite adsorbent from coal gasification fine slag according to claim 4, characterized in that, The ion dissolution process is as follows: an acidic ion regulator is added to the product after alkaline activation and desilication to carry out the reaction; the acidic ion regulator is any one or a combination of at least two of HCl, HNO3, H2SO4, citric acid, acetic acid, formic acid and tartaric acid; the concentration of the acidic ion regulator is 0.5 mol / L to 6 mol / L; the reaction time is 0.5 h to 5 h; and the liquid-solid ratio of the reaction process is 1 to 15:

1.

6. The method for preparing porous carbon / hydrotalcite-like composite adsorbent from coal gasification fine slag according to claim 4, characterized in that, The process of ratio control is as follows: the molar concentrations of divalent and trivalent metal cations in the solution after ion dissolution are measured, and then the ion ratio is adjusted by adding calcium or magnesium ions so that the ratio of divalent and trivalent metal cations is within the range required by the hydrotalcite-like solution.

7. The method for preparing porous carbon / hydrotalcite-like composite adsorbent from coal gasification fine slag according to claim 1, characterized in that, The pH adjuster is one or two of NaOH solution, KOH solution, urea, and hexamethylenetetramine. When adding the pH adjuster, the dropping rate of the pH adjuster is controlled to maintain the pH value of the reaction system at 9-11.

8. The method for preparing porous carbon / hydrotalcite-like composite adsorbent from coal gasification fine slag according to claim 1, characterized in that, The stirring time is 0.5h to 2h.

9. The method for preparing porous carbon / hydrotalcite-like composite adsorbent from coal gasification fine slag according to claim 1, characterized in that, The conditions for the one-pot hydrothermal synthesis are: hydrothermal temperature of 80℃~180℃ and hydrothermal time of 8h~48h.

10. The method for preparing porous carbon / hydrotalcite-like composite adsorbent from coal gasification fine slag according to claim 1, characterized in that, The porous carbon / hydrotalcite-like composite adsorbent is used for the adsorption of heavy metal ions or the capture of CO2 in wastewater.

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