Preparation method and application of bagasse charcoal sodium alginate composite material

Abstract

The invention relates to the technical field of adsorption materials, in particular to a preparation method and application of a bagasse biochar and sodium alginate composite material, and a graphene structure biochar / sodium alginate composite material SKFC is constructed on the basis of biochar converted from bagasse through various strategies such as morphology regulation and control, sodium alginate doping and heteroatom compounding. The bagasse is rich in carbon element and has developed pores, so that the bagasse has relatively good adsorption capacity, and heteroatom doping enables the biochar material to have rich functional centers and active sites, and the biochar material can be applied to adsorption of antibiotics. And the sodium alginate is doped, so that a rapid adsorption effect is achieved. Therefore, the problem that the adsorption efficiency of the charcoal prepared by the existing preparation method on the furan antibiotics is low is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of adsorption materials, and particularly relates to a preparation method and application of a bagasse biochar sodium alginate composite material. Background Art

[0002] With the rapid development of human activities and society, as well as the increasing demand for life, the problem of antibiotic pollution in soil and water is becoming increasingly serious in pharmaceutical wastewater, medical wastewater and mixed sewage. Due to the characteristics of antibiotic water pollution such as bacteriostatic, lethal, persistent and difficult to degrade, there are also problems with food crop safety. The pollution of antibiotics in water has become an environmental problem that people attach great importance to.

[0003] The adsorption method has become the most promising method for removing antibiotics due to its low cost and high removal rate. And biochar materials are activated carbons prepared through specific processes, which have developed pores, a large specific surface area, contain a large number of surface active functional groups, are easy to dope and have strong adsorption ability. In addition, the adsorption performance of biochar mainly benefits from its unique pore structure and chemical properties. The porous structure and rich trace elements of biochar enable it to effectively improve soil aeration and water retention, and improve soil fertility. And these pore structures provide a large number of adsorption sites for adsorbates, enabling activated carbon to efficiently adsorb antibiotic pollutants. The mixing of iron and copper co-doping and sodium alginate endows the carbon material with excellent water solubility and a rapid adsorption effect.

[0004] Research shows that doping heteroatoms such as iron and copper in biochar materials can enhance their functionality. Carbon materials have low solubility in water, and the introduction of sodium alginate makes it have excellent water solubility. At present, there has been no report on preparing biochar materials using bagasse as the carbon material substrate, ferrous sulfate heptahydrate, copper chloride and sodium alginate.

[0005] Sugarcane is one of the main sugar crops in China. After sugar production, a large amount of bagasse will be generated. The high-value utilization of bagasse is a problem that must be solved in the future development of the sugar industry. If the agricultural waste bagasse is burned into charcoal, it not only realizes the effective utilization of waste, but also reduces environmental pollution. However, at present, the prepared biochar has poor effects on furan antibiotics and slow adsorption, and there is an urgent need for improvement. Summary of the Invention

[0006] The purpose of the present invention is to provide a preparation method and application of a bagasse biochar sodium alginate composite material, aiming to solve the problem of low adsorption efficiency of biochar prepared by existing preparation methods for furan antibiotics.

[0007] To achieve the above object, in the first aspect, the present invention provides a preparation method of a bagasse biochar sodium alginate composite material, including the following steps:

[0008] Wash the bagasse in clean water and then air-dry it. Crush it with a crusher to obtain a biomass material;

[0009] Grind and sieve the biomass material, and then calcine it under nitrogen protection to obtain a biochar material BC;

[0010] Mix the biochar material BC with KOH, grind them, and then calcine them under nitrogen protection to obtain a biochar material KBC;

[0011] Add sodium alginate to water, stir to dissolve it, and then add it to the biochar material KBC. Stir and ultrasonicate in sequence to obtain a sodium alginate-doped biochar material;

[0012] Add ferrous sulfate heptahydrate and copper chloride to water, stir to dissolve them, then add them to the sodium alginate-doped biochar material and stir for 24 hours. After the reaction ends, wash and dry in sequence to obtain a biochar material SKFC.

[0013] Among them, in the step of "grinding and sieving the biomass material, and then calcining it under nitrogen protection to obtain a biochar material BC", the sieving uses a 120-mesh sieve, the calcination temperature is 350 °C, and the time is 1 h.

[0014] Among them, in the step of "mixing the biochar material BC with KOH, grinding them, and then calcining them under nitrogen protection to obtain a biochar material KBC", the mass ratio of the biochar material BC to KOH is 1:2.

[0015] Among them, in the step of "mixing the biochar material BC with KOH, grinding them, and then calcining them under nitrogen protection to obtain a biochar material KBC", the calcination temperature is 700 °C and the time is 2 h.

[0016] Among them, in the step of "adding ferrous sulfate heptahydrate and copper chloride to water, stirring to dissolve them, then adding them to the sodium alginate-doped biochar material and stirring for 24 hours. After the reaction ends, wash and dry in sequence to obtain a biochar material SKFC", the mass ratio of ferrous sulfate heptahydrate to copper chloride is 2:3.

[0017] In a second aspect, an application of a bagasse biochar sodium alginate composite material, based on the preparation method of the bagasse biochar sodium alginate composite material described in the first aspect, is applied to adsorb nitrofurazone in an aqueous solution for the protection of the water environment.

[0018] A preparation method of a bagasse biochar sodium alginate composite material of the present invention includes the following steps: washing bagasse in clean water and then drying it, crushing it through a crusher to obtain a biomass material; grinding and sieving the biomass material and then calcining it under nitrogen protection to obtain a biochar material BC; mixing the biochar material BC with KOH and grinding it, and then calcining it under nitrogen protection to obtain a biochar material KBC; adding sodium alginate into water, stirring and dissolving it, then adding it into the biochar material KBC, and successively stirring and ultrasonicating to obtain a sodium alginate-doped biochar material; adding ferrous sulfate heptahydrate and copper chloride into water, stirring and dissolving them, then adding them into the sodium alginate-doped biochar material and stirring for 24 hours, and successively washing and drying after the reaction ends to obtain a biochar material SKFC. Based on the biochar converted from sugarcane bagasse, the present invention constructs a graphene-structured biochar / sodium alginate composite material SKFC through various strategies such as morphology regulation, sodium alginate doping, and heteroatom compounding. Since sugarcane bagasse is rich in carbon elements and has well-developed pores, it has good adsorption capacity, and heteroatom doping makes this biochar material have rich functional centers and active sites, which can be applied to the adsorption of antibiotics. And the doping of sodium alginate achieves a rapid adsorption effect. The present invention provides a synthesis route for porous carbon materials, and the prepared porous carbon materials have high research significance as adsorbents for adsorbing pollutants in water, providing a broader idea for the research on the rapid adsorption of porous carbon materials. Thus, it solves the problem that the biochar prepared by the existing preparation methods has a low adsorption efficiency for furan antibiotics. Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 are the SEM images of BC and SKFC in Example 1; Figure 1 (a) is the SEM image of BC; Figure 1 (b) is the SEM image of SKFC.

[0021] Figure 2 is the X-ray diffraction pattern of SKFC.

[0022] Figure 3 is the Fourier infrared spectrum of SKFC.

[0023] Figure 4 is the nitrogen adsorption-desorption isotherm of SKFC; Figure 4 (a) is the nitrogen adsorption-desorption isotherm of BC; Figure 4(b) is the nitrogen adsorption - desorption curve of SKFC; Figure 4 (c) is the average pore size diagram of BC; Figure 4 The average pore size diagram of (d) SKFC.

[0024] Figure 5 is the adsorption efficiency of SKFC for nitrofurazone; Figure 5 (a) is the adsorption kinetic curve; Figure 5 (b) is the adsorption isotherm; Figure 5 (c) is the comparison diagram of adsorption efficiency.

[0025] Figure 6 are the adsorption isotherm curve and kinetic curve of SKFC; Figure 6 (a) is the pseudo - first - order curve; Figure 6 (b) is the pseudo - second - order curve; Figure 6 (c) is the Langmuir curve; Figure 6 (d) is the Freundlich curve.

[0026] Figure 7 is the flow chart of the preparation method of a bagasse biochar sodium alginate composite material provided by the present invention. Detailed implementation manners

[0027] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described by referring to the accompanying drawings are exemplary and are intended to explain the present invention, and should not be construed as a limitation to the present invention.

[0028] Please refer to Figures 1 to 7 , in the first aspect, the present invention provides a preparation method of a bagasse biochar sodium alginate composite material, including the following steps:

[0029] S1 Wash the bagasse in clean water and then air - dry it. Crush it with a crusher to obtain a biomass material;

[0030] Specifically, wash the bagasse in clean water 2 - 3 times, then place it outdoors to air - dry under light conditions, and finally crush it with a crusher to obtain a biomass material.

[0031] S2 Grind and screen the biomass material and then calcine it under nitrogen protection to obtain a biochar material BC;

[0032] The screening uses a 120 - mesh sieve, the calcination temperature is 350 °C, and the time is 1 h.

[0033] Specifically, grind the biomass material through a 120 - mesh sieve and calcine it under nitrogen protection to obtain a biochar material BC;

[0034] S3 mixes the biochar material BC with KOH, grinds them, and then calcines them under nitrogen protection to obtain the biochar material KBC;

[0035] The mass ratio of the biochar material BC to KOH is 1:2.

[0036] Specifically, mix the biochar material with KOH and grind them. Calcinate the ground mixture under nitrogen protection. Mix the obtained product with hydrochloric acid, stir magnetically for 19 h, and then wash the mixture until neutral and dry it to obtain the biochar material KBC.

[0037] S4 adds sodium alginate to water, stirs to dissolve it, then adds it to the biochar material KBC, and stirs and ultrasonifies in sequence to obtain the sodium alginate-doped biochar material;

[0038] The temperature of the calcination is 700 °C and the time is 2 h.

[0039] Specifically, add sodium alginate to water, stir to dissolve it, and then add the biochar material KBC. Ultrasonify for 1 h and stir magnetically for 2 h to obtain the sodium alginate-doped biochar material.

[0040] S5 adds ferrous sulfate heptahydrate and copper chloride to water, stirs to dissolve them, then adds them to the sodium alginate-doped biochar material and stirs for 24 hours. After the reaction ends, wash and dry in sequence to obtain the biochar material SKFC.

[0041] The mass ratio of the ferrous sulfate heptahydrate to the copper chloride is 2:3.

[0042] Specifically, add ferrous sulfate heptahydrate and copper chloride to water, stir to dissolve them, then add them to the sodium alginate-doped biochar material, stir for 24 h. After the reaction ends, wash and freeze-dry for 48 h to obtain the biochar / sodium alginate composite material SKFC.

[0043] Example 1 Biochar / sodium alginate composite material (SKFC), the preparation method includes the following steps

[0044] 1. Preparation of the biomass material

[0045] Wash the bagasse twice in clean water, then place it outdoors to dry naturally under light conditions, and finally crush it with a crusher, continue to grind and sieve it through 120 mesh to obtain the biomass material.

[0046] 2. Preparation of the precursor biochar material

[0047] Under nitrogen protection, heat at a heating rate of 5 °C / min to 350 °C and calcine for 1 hour to obtain the biochar material, labeled as BC.

[0048] By mass ratio, biochar material:KOH = 1:2. Take the biomass material obtained in step 1) and mix and grind it with KOH. The ground mixture is calcined at 700 °C for 2 hours under nitrogen protection with a heating rate of 5 °C / min. The obtained product is mixed with 1 moL / L -1 hydrochloric acid, magnetically stirred for 19 h, and then washed with ultrapure water and ethanol until neutral and dried to obtain a precursor biochar material, labeled as KBC.

[0049] 3. Preparation of biochar / sodium alginate composite

[0050] Add sodium alginate (1 g) to 50 mL of water. After stirring and dissolving, add the precursor biochar material KBC (1 g), sonicate for 1 h, and magnetically stir for 2 h to obtain a homogeneous suspension complex of sodium alginate-doped biochar material. Add ferrous sulfate heptahydrate (0.4 g) and copper chloride (0.6 g) to 10 mL of water. After stirring and dissolving, use a dropper with a specification of 1 mL to take 10 mL of the sodium alginate-doped biochar material and drip it into 10 mL of the aqueous solution containing ferrous sulfate heptahydrate and copper chloride, stir for 24 h. After the reaction, wash with ultrapure water and ethanol until the solution in the filter flask is colorless and transparent, place it in the refrigerator and freeze for 12 h, and then freeze-dry for 48 h to obtain a biochar / sodium alginate composite, labeled as SKFC-11-23 (SKFC).

[0051] Comparative Example 1

[0052] Add sodium alginate (1 g) to 50 mL of water. After stirring and dissolving, add the precursor biochar material KBC (2 g), sonicate for 1 h, and magnetically stir for 2 h to obtain a homogeneous suspension complex of sodium alginate-doped biochar material. Labeled as SKFC-12-23.

[0053] Comparative Example 2

[0054] Add sodium alginate (1 g) to 50 mL of water. After stirring and dissolving, add the precursor biochar material KBC (0.5 g), sonicate for 1 h, and magnetically stir for 2 h to obtain a homogeneous suspension complex of sodium alginate-doped biochar material. Labeled as SKFC-21-23.

[0055] Comparative Example 3

[0056] Add ferrous sulfate heptahydrate (0.6 g) and copper chloride (0.6 g) to 10 mL of water. After stirring and dissolving, use a 1 mL pipette to take 10 mL of the sodium alginate-doped biochar material and drip it into the 10 mL aqueous solution containing ferrous sulfate heptahydrate and copper chloride. Stir for 24 h. After the reaction is completed, wash with ultrapure water and ethanol until the solution in the filter flask is colorless and transparent. Place it in the refrigerator and freeze for 12 h, and then freeze-dry for 48 h to obtain the biochar / sodium alginate composite material. Label it as SKFC-11-33.

[0057] Comparative Example 4

[0058] Add ferrous sulfate heptahydrate (0.4 g) and copper chloride (0.4 g) to 10 mL of water. After stirring and dissolving, use a 1 mL pipette to take 10 mL of the sodium alginate-doped biochar material and drip it into the 10 mL aqueous solution containing ferrous sulfate heptahydrate and copper chloride. Stir for 24 h. After the reaction is completed, wash with ultrapure water and ethanol until the solution in the filter flask is colorless and transparent. Place it in the refrigerator and freeze for 12 h, and then freeze-dry for 48 h to obtain the biochar / sodium alginate composite material. Label it as SKFC-11-22.

[0059] Comparative Example 5

[0060] Add ferrous sulfate heptahydrate (0.6 g) and copper chloride (0.4 g) to 10 mL of water. After stirring and dissolving, use a 1 mL pipette to take 10 mL of the sodium alginate-doped biochar material and drip it into the 10 mL aqueous solution containing ferrous sulfate heptahydrate and copper chloride. Stir for 24 h. After the reaction is completed, wash with ultrapure water and ethanol until the solution in the filter flask is colorless and transparent. Place it in the refrigerator and freeze for 12 h, and then freeze-dry for 48 h to obtain the biochar / sodium alginate composite material. Label it as SKFC-11-32.

[0061]

[0062] Table 1 Comparison Table of Adsorption Efficiency

[0063] Figure 1 These are the SEM images of SKFC-11-23 and BC prepared in Example 1. As can be seen from the figure, the surface of the directly calcined biochar before modification is relatively smooth, basically with irregular pores. After the modification treatment, its morphology has changed significantly. Different pore shapes and sizes are gradually etched on the surface of the carbon material, showing a honeycomb structure. It shows that after modification, the material exhibits pores of different sizes and an uneven multi-layer surface structure, which is a typical three-dimensional porous structure and can provide better adsorption performance for the material.

[0064] Figure 2It is an X-ray diffraction pattern. As can be seen from the figure, BC has a crystalline and amorphous phase structure, while SKFC only has an amorphous phase structure. The modified carbon material exhibits a broad peak centered at 2θ = 23.8° and a weak diffraction peak at 2θ = 43.9°. This may be due to the increase in the interlayer spacing of some graphitized carbon materials (such as the insertion of oxygen-containing functional groups or amorphization), resulting in the diffraction peak of the (002) crystal plane shifting towards a lower angle. Broad peaks are observed at around 2θ = 25° and 44°, which are typical characteristics of graphite carbon structure and amorphous structure. This indicates that the material is a typical graphene carbon material.

[0065] Figure 3 It is a Fourier transform infrared spectrum. At 3406 cm -1 the peak is significantly enhanced, indicating a significant enhancement of the hydroxyl bending vibration. And a new infrared absorption peak appears at 1423 cm -1 corresponding to the -CH2 peak, indicating the presence of carboxyl groups in the carbon material. Also, since sodium alginate itself contains a large number of oxygen-containing functional groups such as hydroxyl and carboxyl, it indicates that the doping of sodium alginate is successful. At the same time, two new infrared absorption peaks appear at 592 and 573 cm -1 representing the stretching vibrations of Fe-O and Cu-O. On the one hand, this is due to the formation of inorganic oxides (such as iron oxide and ferrous oxide) during the pyrolysis process. On the other hand, this is due to the cross-linking of iron salts, copper salts with alginate to form -COO-Fe, etc. The above results show that a biochar carbon material rich in oxygen-containing functional groups and metal oxides has been successfully prepared in this experiment. It indicates that iron and copper have been successfully doped, further confirming the successful synthesis of SKFC.

[0066] Figure 4 It is the nitrogen adsorption-desorption isotherms of the prepared SKFC-11-23 and BC. As can be seen from the figure, the specific surface area has increased significantly, and SKFC-11-23 shows a type IV isotherm and an H3 hysteresis loop, indicating mesoporous characteristics with irregular pore structures. This shows that the modified carbon material is mainly a mesoporous material and contains a large number of micropores, providing more active sites.

[0067]

[0068] Table 2 Physicochemical properties of adsorbents

[0069] Example 2 Adsorption of antibiotics in aqueous solution by biochar / sodium alginate composite material (SKFC)

[0070] In this experimental example, furacilin (NF) was selected as the adsorption research object. Furacilin does not limit the present invention.

[0071] The method is as follows: In a solution containing NF, add SKFC. The adsorption method is magnetic stirring adsorption, and the parameters are 35 °C and 400 rpm. After the adsorption, the instrument used is an ultraviolet spectrophotometer.

[0072] Adsorption performance test of NF by different adsorbents

[0073] Respectively take 11 groups of 10 mL working solutions (single adsorption system, 800 mg L -1 NF; PH 6.2), and add 0.02 g of adsorbents (BC, SA, SA-KBC, SA-FeCu, KBC, SKFC-12-23, SKFC-21-23, SKFC-11-22, SKFC-11-32, SKFC-11-33, SKFC-11-23) to them respectively. Under 35 °C and 400 rpm, perform magnetic stirring adsorption for 60 min.

[0074] Figure 5 (a-c) are the adsorption efficiencies of the prepared adsorbents for NF. As Figure 5 shown in (c), compared with BC etc., the SKFC-11-23 composite material prepared by the present invention exhibits excellent adsorption performance, and the adsorption efficiency for NF is 94.4%.

[0075] Adsorption kinetics experiment

[0076] The method is as follows:

[0077] Add 0.02 g of adsorbent SKFC-11-23 to 10 mL of working solution (single adsorption system, 800 mg L -1 NF; PH 6.2), and conduct experiments within the time range of 5 min - 180 min.

[0078] Figure 6 (a-b) are the adsorption kinetics curves of the prepared SKFC-11-23 for NF. As can be seen from the figure, the pseudo-second-order adsorption kinetic constant (R 2 = 0.999) is greater than the pseudo-second-order adsorption kinetic constant (R 2 = 0.974), and the adsorption kinetics curve of SKFC-11-23 conforms to the pseudo-second-order kinetic model. It shows that chemical adsorption is the main one.

[0079] Adsorption isotherm experiment

[0080] The method is as follows:

[0081] Series of working solutions of NF: single adsorption system, with initial concentrations of 200 mg L -1 、400 mg L -1 、600 mg L -1 、800 mg L-1 、 1000 mg / L -1 、 1200 mg / L -1 of the NF series solution, with pH = 6.2.

[0082] Take 10 mL of different series of working solutions respectively, add 0.02 g of adsorbent SKFC-11-23, and stir magnetically at 400 rmp for 60 min.

[0083] Figure 6 (c-d) is the adsorption isotherm of the prepared SKFC-11-23 for NF (35 °C, pH = 6.2).

[0084] As can be seen from the figure, the adsorption capacity changes. The correlation coefficient (R 2 ) of the Langmuir model fitting for the adsorption of NF by SKFC is 0.989, showing a good fit. The correlation coefficient (R 2 ) of the Freundlich model fitting is 0.912. The R 2 of the Langmuir model is higher than that of the Freundlich model, which better describes the behavior of SKFC for NF, indicating that the observed adsorption behavior is mainly monolayer adsorption, involving chemical and physical adsorption.

[0085] In the second aspect, an application of a bagasse biochar sodium alginate composite material, based on the preparation method of the bagasse biochar sodium alginate composite material described in the first aspect, is applied to the protection of the water environment.

[0086] The above-disclosed is only a preferred embodiment of the preparation method and application of a bagasse biochar sodium alginate composite material of the present invention. Of course, the scope of the rights of the present invention cannot be limited thereby. Those of ordinary skill in the art can understand all or part of the processes of implementing the above embodiments, and the equivalent changes made according to the claims of the present invention still fall within the scope covered by the invention.

Claims

1. A preparation method of a bagasse biochar sodium alginate composite material, characterized in that, It includes the following steps: Wash the bagasse in clean water and then dry it, and crush it through a crusher to obtain a biomass material; Grind and sieve the biomass material and then calcine it under nitrogen protection to obtain a biochar material BC; Mix the biochar material BC with KOH, grind them, and then calcine them under nitrogen protection to obtain a biochar material KBC; Add sodium alginate into water, stir to dissolve it, and then add it to the biochar material KBC, and stir and ultrasonicate in sequence to obtain a sodium alginate-doped biochar material; Add ferrous sulfate heptahydrate and copper chloride into water, stir to dissolve them, then add them to the sodium alginate-doped biochar material and stir for 24 hours. After the reaction ends, wash and dry in sequence to obtain a biochar material SKFC.

2. The preparation method of the bagasse biochar sodium alginate composite material according to claim 1, characterized in that, In "Grind and sieve the biomass material and then calcine it under nitrogen protection to obtain a biochar material BC", the sieving uses a 120-mesh sieve, the calcination temperature is 350 °C, and the time is 1 h.

3. The preparation method of the bagasse biochar sodium alginate composite material according to claim 1, characterized in that, In "Mix the biochar material BC with KOH, grind them, and then calcine them under nitrogen protection to obtain a biochar material KBC", the mass ratio of the biochar material BC to KOH is 1:

2.

4. The preparation method of the bagasse biochar sodium alginate composite material according to claim 3, characterized in that, In "Mix the biochar material BC with KOH, grind them, and then calcine them under nitrogen protection to obtain a biochar material KBC", the calcination temperature is 700 °C, and the time is 2 h.

5. The preparation method of the bagasse biochar sodium alginate composite material according to claim 1, characterized in that, In "Add ferrous sulfate heptahydrate and copper chloride into water, stir to dissolve them, then add them to the sodium alginate-doped biochar material and stir for 24 hours. After the reaction ends, wash and dry in sequence to obtain a biochar material SKFC", the mass ratio of ferrous sulfate heptahydrate to copper chloride is 2:

3.

6. Application of a bagasse biochar sodium alginate composite material, based on the preparation method of the bagasse biochar sodium alginate composite material according to any one of claims 1-6, characterized in that, It is applied to adsorb nitrofurazone in an aqueous solution for the protection of the water environment.

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