Carbon material adsorbent prepared from biomass as raw material, preparation method of carbon material adsorbent and application of carbon material adsorbent in adsorption and solidification of heavy metal ions

Abstract

The invention relates to the technical field of adsorbents, and discloses a carbon material adsorbent prepared by taking biomass as a raw material, a preparation method of the carbon material adsorbent, and application of the carbon material adsorbent to adsorption and solidification of heavy metal ions. Comprising biomass carbon aerogel, after the biomass carbon aerogel is modified with tannic acid and a silane reagent, MOF grows in pores of the biomass carbon aerogel, and the carbon material adsorbent is obtained. The MOF material has the advantages of high selectivity to metal ions and larger adsorption capacity, so that the adsorption capacity of heavy metal ions is improved. By compounding the biomass carbon aerogel and the MOF material, the problems that the cost is high and the structure is easy to collapse in the adsorption process when the MOF material is singly adopted can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of adsorbents, and in particular to a carbon material adsorbent prepared from biomass as a raw material, a preparation method thereof, and an application thereof in adsorbing and solidifying heavy metal ions. Background Art

[0002] Heavy metals are persistent pollutants that are non-degradable. With the discharge of industrial wastewater from mining, metallurgy, chemical industry, battery and other industries, it has caused great harm to the water environment. Therefore, the removal of heavy metals in water is imperative.

[0003] Among the treatment methods of heavy metal wastewater, adsorption method has been increasingly used due to its advantages of simple operation, high efficiency, few side effects, easy regeneration and low cost. Biochar prepared from biomass contains a variety of surface functional groups, which makes it have good adsorption properties. However, for the adsorption of heavy metals, the selective adsorption capacity of biochar is weak, which limits its adsorption capacity. Summary of the invention

[0004] Technical problems solved by the present invention:

[0005] It is used to solve the problems of poor adsorption effect of heavy metal ions existing in existing carbon materials.

[0006] The technical solution adopted by the present invention is:

[0007] In view of the above technical problems, the object of the present invention is to provide a carbon material adsorbent prepared from biomass as raw material, a preparation method thereof, and an application thereof in adsorbing and solidifying heavy metal ions.

[0008] Based on this, the specific implementation plan is:

[0009] First, the present invention provides a carbon material adsorbent prepared using biomass as raw material, including biomass carbon aerogel. After the biomass carbon aerogel is modified with tannic acid and silane reagent, MOF is grown in the pores of the biomass carbon aerogel to obtain the carbon material adsorbent.

[0010] According to some preferred embodiments, the method for preparing biomass carbon aerogel is:

[0011] (1) After the biomass is crushed and cleaned, it is placed in a reactor (with polytetrafluoroethylene lining) for hydrothermal reaction to obtain an intermediate; hydrothermal reaction: 150-200° C., 10-20 h, natural cooling, collecting the product, and then washing it, specifically, washing it alternately with distilled water and ethanol to remove soluble matter.

[0012] (2) The intermediate is frozen at -30 to -10°C for 20 to 40 hours, and then placed in a freeze dryer for 30 to 50 hours to obtain a lyophilized product.

[0013] (3) The freeze-dried product is subjected to pyrolysis treatment under a nitrogen atmosphere to obtain biomass carbon aerogel; pyrolysis treatment: 700-950° C., 0.5-2 h.

[0014] In the above, the raw material of biomass includes at least one of bamboo chopsticks, rice husks, straw, rice straw, bagasse, wood blocks, and grass leaves.

[0015] According to some preferred embodiments, the silane reagent is γ-aminopropyltriethoxysilane.

[0016] According to some preferred embodiments, the modification method of biomass carbon aerogel with tannic acid and silane reagent is to dissolve tannic acid in Tris-HCl buffer with pH=8.5 to form a 2g / L tannic acid solution, and dissolve γ-aminopropyltriethoxysilane in ethanol to form a 10g / L silane solution. The tannic acid solution and the silane solution are blended in a volume ratio of 1:0.05-0.15 to obtain a modified solution.

[0017] The biomass carbon aerogel was dispersed in ethanol and subjected to ultrasonic treatment, and then removed, and then placed in a modified solution and oscillated at room temperature (25°C) for 8 to 20 hours. After the end, it was washed several times with deionized water, and then the product was dried (60 to 80°C) to obtain the modified biomass carbon aerogel.

[0018] Second, the present invention provides a method for preparing the aforementioned carbon material adsorbent, comprising the following steps:

[0019] (1) Biomass carbon aerogel was modified by tannic acid and silane reagent;

[0020] (2) The modified biomass carbon aerogel and MOF precursor liquid are placed in a reactor to obtain a carbon material adsorbent through a thermal reaction.

[0021] According to some preferred embodiments, the MOF precursor liquid includes terephthalic acid, FeCl3·6H2O, and DMF.

[0022] According to some preferred embodiments, the thermal reaction is carried out at 80 to 110° C. for 10 to 18 hours.

[0023] The technical mechanism and beneficial effects adopted by the present invention are as follows:

[0024] (1) The carbon material adsorbent provided by the present invention utilizes the fact that biomass is widely available, cheap and easy to obtain, and contains rich active groups. It utilizes the porous structure and excellent adsorption capacity formed by it, so that it has a strong complexing ability with heavy metal ions, thereby increasing the adsorption capacity of the adsorbent.

[0025] (2) The carbon material adsorbent provided by the present invention forms a biomass carbon aerogel with rich pore structure and pore capacity, but has the problem of weak selective adsorption ability and low adsorption capacity. Based on this, we use the advantages of MOF materials with high selectivity for metal ions and greater adsorption capacity to improve the adsorption capacity of heavy metal ions.

[0026] (3) The carbon material adsorbent provided by the present invention can solve the problems of high cost and easy structural collapse during the adsorption process of using MOF materials alone by compounding biomass carbon aerogel with MOF materials. This is because biomass carbon aerogel has relatively low internal stress, so it can cope with more demanding application environments.

[0027] (4) The carbon material adsorbent provided by the present invention utilizes tannic acid and silane reagents to modify the biomass carbon aerogel: first, the use of tannic acid and silane reagents can enhance the mechanical strength and chemical stability of the biomass carbon aerogel, thereby avoiding structural collapse during the adsorption process; second, tannic acid and silane reagents can be used as nucleation sites for metal ions, thereby promoting the formation of MOF materials; third, the phenolic hydroxyl and carboxyl groups provided by tannic acid and the silane reagent as an amino donor can enhance the complexing ability for heavy metal ions and pollutants, thereby enhancing the adsorption capacity and metal ion selectivity of the carbon material adsorbent. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0029] Example 1

[0030] This embodiment provides a method for preparing a carbon material adsorbent:

[0031] (1) Sugarcane bagasse was used as the biomass raw material. After crushing and cleaning, it was placed in a polytetrafluoroethylene-lined reactor and hydrothermally treated at 180°C for 12 h. After the hydrothermal treatment, it was naturally cooled to room temperature and the hydrothermal product was collected. The hydrothermal product was then washed alternately with deionized water and ethanol.

[0032] (2) The washed hydrothermal product was then frozen at -30°C for 30 hours, and then placed in a freeze dryer for 40 hours to obtain a lyophilized product.

[0033] (3) The freeze-dried product was pyrolyzed at 800°C for 1 h under a nitrogen atmosphere to obtain biochar aerogel.

[0034] (4) Prepare 2 g / L tannic acid solution and 10 g / L silane solution respectively. Tannic acid solution: dissolve tannic acid in Tris-HCl buffer at pH = 8.5 to form a 2 g / L tannic acid solution; Silane solution: dissolve γ-aminopropyltriethoxysilane in ethanol to form a 10 g / L silane solution. Blend the tannic acid solution and the silane solution in a volume ratio of 1:0.1 to obtain a modified solution.

[0035] (5) The biomass carbon aerogel is dispersed in ethanol and ultrasonically dispersed. After the dispersion is completed, the filtered biomass carbon aerogel is placed in a modified solution and oscillated at room temperature for 10 hours. After the oscillation is completed, it is washed with deionized water for several times and then placed in an oven at 60°C to obtain a modified biomass carbon aerogel.

[0036] (6) Preparation of MOF precursor liquid: 6 mmol of terephthalic acid and 8.6 mmol of FeCl3·6H2O were dissolved in 150 mL of DMF, and after uniform stirring, 15 mL of 1 mol / L NaOH solution was dropped into the mixture, and after stirring, a MOF precursor liquid was obtained.

[0037] (7) The MOF precursor liquid was blended with the modified biomass carbon aerogel and subjected to ultrasonic treatment. It was then transferred to a high-pressure reactor and reacted at 100°C for 15 hours. After the reaction was completed, it was cooled to room temperature to obtain a carbon material adsorbent.

[0038] Comparative Example 1

[0039] The difference between this comparative example and Example 1 is that the biomass carbon aerogel is directly used as the carbon material adsorbent.

[0040] Comparative Example 2

[0041] The difference between this comparative example and Example 1 is that the MOF precursor liquid is directly treated in a high-pressure reactor, and the obtained MOF material is used as a carbon material adsorbent.

[0042] Comparative Example 3

[0043] The difference between this comparative example and Example 1 is that the biochar is not treated with the modification solution.

[0044] Test example

[0045] The carbon material adsorbent prepared in Example 1 and Comparative Examples 1-3 was used as a sample for testing. Specifically, the adsorption performance was tested by adding it to wastewater with consistent heavy metal content (the concentration of copper wastewater and lead wastewater was 200 mg / L) at room temperature, with an addition amount of 2 g / L. After 2 hours of addition, the removal rates of copper and lead were measured. Then, the adsorbed carbon material adsorbent was added to a solution containing a desorbent EDTA, and after oscillation, filtration, and drying, it was added to pulmonary edema to test the heavy metal adsorption removal rate. The test results are shown in Table 1.

[0046] Table 1 Measurement results

[0047]

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A carbon material adsorbent prepared from biomass as raw material, characterized in that: The invention comprises a biomass carbon aerogel. After the biomass carbon aerogel is modified by tannic acid and a silane reagent, MOF is grown in the pores of the biomass carbon aerogel to obtain a carbon material adsorbent.

2. The carbon material adsorbent prepared from biomass as raw material according to claim 1, characterized in that: The biomass raw material includes at least one of bamboo chopsticks, rice husks, straw, rice straw, bagasse, wood blocks, and grass leaves.

3. The carbon material adsorbent prepared from biomass as raw material according to claim 1, characterized in that: The silane reagent was γ-aminopropyltriethoxysilane.

4. The carbon material adsorbent prepared from biomass as raw material according to any one of claims 1 to 3, characterized in that: The preparation method of biomass carbon aerogel comprises the following steps: (1) After the biomass is crushed and cleaned, it is placed in a reactor for hydrothermal reaction to obtain an intermediate; (2) freezing the intermediate at -30 to -10°C for 20 to 40 hours, and then placing it in a freeze dryer for 30 to 50 hours to obtain a lyophilized product; (3) The freeze-dried product is subjected to pyrolysis treatment under a nitrogen atmosphere to obtain biomass carbon aerogel.

5. The carbon material adsorbent prepared from biomass as raw material according to claim 4, characterized in that: (1), hydrothermal reaction: 150-200°C, 10-20h.

6. The carbon material adsorbent prepared from biomass as raw material according to claim 4, characterized in that: (3) Pyrolysis treatment: 700-950°C, 0.5-2h.

7. A method for preparing a carbon material adsorbent using biomass as raw material as claimed in any one of claims 1 to 6, characterized in that: The steps include: S1 biomass carbon aerogel was modified by tannic acid and silane reagent; S2 places the modified biomass carbon aerogel and MOF precursor liquid in a reactor to obtain a carbon material adsorbent through a thermal reaction.

8. The method for preparing a carbon material adsorbent using biomass as raw material according to claim 7, characterized in that: In S1, modification treatment: the biomass carbon aerogel is placed in a modification solution and shaken to obtain the modified biomass carbon aerogel; the modification solution is a mixture of a tannic acid solution and a silane reagent solution.

9. The method for preparing a carbon material adsorbent using biomass as raw material according to claim 7, characterized in that: In S2, the MOF precursor liquid includes terephthalic acid, FeCl3·6H2O, and DMF; thermal reaction: 80-110°C, 10-18h.

10. Use of a carbon material adsorbent prepared from biomass as a raw material as claimed in any one of claims 1 to 6, or a carbon material adsorbent obtained by the preparation method as claimed in any one of claims 7 to 9 in adsorbing and solidifying heavy metal ions.

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