Preparation method and application of saponin shell-based Fe / Mn-N co-doped hydrothermal carbon adsorption antibiotic material

Abstract

The invention relates to a preparation method and application of a gleditsia sinensis shell-based Fe / Mn-N co-doped hydrothermal carbon adsorption antibiotic material, gleditsia sinensis shells are cleaned, dried and ground, chitosan is added during grinding, and the mixture is sieved by a 80-mesh sieve to obtain gleditsia sinensis shell powder; the preparation method comprises the following steps: putting Chinese honeylocust fruit shell powder, a Fe source and a Mn source into a hydrothermal reaction kettle containing deionized water, carrying out hydrothermal reaction in an air blast drying box at 170-180 DEG C for 10-15 hours, carrying out suction filtration and cleaning with ultrapure water, transferring into a drying oven, drying to constant weight, grinding with an agate mortar, and sieving with a 100-mesh sieve to obtain hydrothermal carbon; and putting the hydrothermal carbon and urea into a ball mill, and carrying out ball milling treatment at the rotating speed of 500rpm for 4.5-5.5 hours to obtain the saponin shell-based Fe / Mn-N co-doped hydrothermal carbon adsorption antibiotic material. The preparation method is simple, the cost is low, the energy consumption is low, the prepared Fe / Mn co-doped hydrothermal carbon is loaded with nitrogen atoms after ball milling, the dispersity and stability of the hydrothermal carbon are improved, and metal agglomeration is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of hydrothermal carbon adsorption materials, and relates to a preparation method and application of a saponin shell-based Fe / Mn-N co-doped hydrothermal carbon adsorbing antibiotic material, in particular to a preparation method of a saponin shell-based Fe / Mn-N co-doped hydrothermal carbon and application of the same in treating tetracycline in water. Background Art

[0002] Tetracycline (TC) is widely used in medicine, animal husbandry and agriculture due to its antibacterial and bactericidal properties. The overuse of tetracycline has led to its widespread presence in aquaculture water, rivers and lakes. Long-term residual TC exposure can promote the development of antibiotic-resistant bacteria and genes, causing harmful effects on human health and ecological security. Currently, various materials have been developed for the removal of pollutants, such as zero-valent metals, metal oxides, biochars and metal-organic frameworks (MOFs). Metal oxides, especially Fe / Mn oxides, can participate in various pollutant removal technologies, including adsorption, redox and advanced oxidation, due to their specific nanoscale characteristics, high specific surface area, low cost, strong oxidation and adsorption capabilities.

[0003] Biochar (BC) is widely used as a carrier of metal oxides due to its high specific surface area, porous structure, low cost and environmental performance, which can improve their dispersibility and electron transfer ability. In particular, N-doped biochar can improve the stability and adsorption performance of the material. Therefore, bimetallic-loaded nitrogen-doped carbon materials can be used as promising adsorbents and oxidants. At present, the preparation procedure of metal-nitrogen co-doped biochar is complicated, usually solution impregnation followed by high-temperature calcination, and the main limitation is high energy consumption.

[0004] Agricultural waste adsorbents have attracted wide attention due to their high biomass, low cost, and environmental protection. Gleditsia sinensis, also known as soapberry, is a perennial woody plant of the Leguminosae family. It is widely distributed in my country and has high ecological and economic value. The soapberry shell contains saponins. Tea saponin and saponin are a natural non-compound surfactant and a pure natural cleaning product (shampoo, dishwashing liquid) that is biodegradable and less toxic. It can be used to stabilize hydrophobic compounds in different dispersed systems, and surfactant decoration helps prevent the aggregation and oxidation of Fe, while autoclave extraction of saponins has more suitable physical and chemical properties and better yields. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a preparation method and application of a saponin shell-based Fe / Mn-N co-doped hydrothermal carbon adsorbing antibiotic material to solve the problems of complex preparation procedures and high energy consumption of metal nitrogen-doped biochar.

[0006] The present invention solves the technical problem by adopting the following technical solutions:

[0007] A method for preparing a saponin shell-based Fe / Mn-N co-doped hydrothermal carbon adsorbing antibiotic material comprises the following steps:

[0008] S1, washing and drying the soapberry shell, then grinding, adding chitosan during grinding, and passing through an 80-mesh sieve to obtain a soapberry shell powder; then placing the soapberry shell powder, Fe source, and Mn source in a hydrothermal reactor containing deionized water, and hydrothermally reacting in a 170-180° C. forced drying oven for 10-15 hours, filtering and washing with ultrapure water after the reaction, transferring to an oven and drying to constant weight, grinding with an agate mortar, passing through a 100-mesh sieve, and making hydrothermal charcoal;

[0009] S2. Place the hydrothermal carbon and urea in a ball mill and perform ball milling at a rotation speed of 500 rpm for 4.5-5.5 hours to obtain a saponin shell-based Fe / Mn-N co-doped hydrothermal carbon material for adsorbing antibiotics.

[0010] Moreover, the weight ratio of the sapodilla shell to chitosan is 15-35:1.

[0011] Moreover, the weight ratio of the soapberry shell powder:Fe source:Mn source is 25-35:15-25:1-5.

[0012] Moreover, the weight ratio of hydrothermal charcoal:urea is 2:1-2.

[0013] Moreover, the Fe source is FeSO 4 7H 2 O.

[0014] Furthermore, the Mn source is MnCl 2 ·4H 2 O.

[0015] Furthermore, the antibiotic is tetracycline.

[0016] A method for preparing a saponin shell-based Fe / Mn-N co-doped hydrothermal carbon adsorbing antibiotic material is used to treat tetracycline in a solution.

[0017] The advantages and positive effects of the present invention are:

[0018] 1. The Fe source and Mn source described in the present invention are abundant in nature and have environmental friendliness and redox properties. Gleditsia sinensis contains surfactants that can increase the hydrophobic effect between biochar and pollutants.

[0019] 2. The preparation method provided by the present invention is simple, low in cost and low in energy consumption. The prepared Fe / Mn co-doped hydrothermal carbon is loaded with nitrogen atoms after ball milling, and the dispersibility and stability of the Fe / Mn-N co-doped hydrothermal carbon are improved, and the agglomeration of the metal itself is reduced.

[0020] 3. The ball-milled Fe / Mn-N co-doped hydrothermal carbon of the present invention exhibits excellent adsorption capacity for tetracycline in water in terms of pH adaptability, ionic strength resistance and regeneration. In the adsorption isotherm model, the maximum adsorption capacity (q m ) is 409.07 mg / g. The present invention can be used as a promising environmentally friendly wastewater treatment adsorbent.

[0021] 4. The present invention adds chitosan when grinding the soap shell, the main purpose of which is to protect the surfactant in the soap shell. The soap shell contains saponin, tea saponin and other ingredients, which are natural non-compound surfactants, biodegradable and less toxic. During the grinding process, the activity of the surfactant may be damaged due to factors such as physical friction and temperature changes. Chitosan can play a protective role and maintain the performance of the surfactant.

[0022] 5. The present invention protects the surfactant in the soap locust shell by adding chitosan. By protecting the surfactant, chitosan indirectly improves the adsorption capacity of the material to tetracycline, so that the material can more effectively remove pollutants when treating water containing tetracycline. At the same time, chitosan itself has certain stability and viscosity. During the material preparation process, it can help maintain the structural stability of the material. In the subsequent hydrothermal reaction and ball milling treatment steps, the material can maintain good physical and chemical properties, reduce structural damage of the material during preparation and use, and improve the service life and reusability of the material.

[0023] 6. In the present invention, chitosan also helps to improve the dispersibility of the material. When the material comes into contact with solvents such as water, or is mixed with other ingredients during ball milling, chitosan can prevent the agglomeration of material particles, allowing the material to be more evenly dispersed in the system, thereby better exerting the adsorption effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a scanning electron microscope image of the Fe / Mn-BNHS of the present invention.

[0025] Figure 2 Element distribution diagram of Fe / Mn-BNHS of the present invention.

[0026] Figure 3 Graphs showing contact angles of Fe / Mn-HS, Fe / Mn-BHS and Fe / Mn-BNHS of the present invention.

[0027] Figure 4 This is a diagram showing the removal effect of tetracycline by Fe / Mn-HS, Fe / Mn-BHS and Fe / Mn-BNHS of the present invention.

[0028] Figure 5 This is a graph showing the removal of tetracycline by Fe / Mn-HS and Fe / Mn-BNHS at different time points of the present invention.

[0029] Figure 6 This is a pseudo-first-order kinetic fitting curve diagram of the adsorption of tetracycline by Fe / Mn-BNHS of the present invention.

[0030] Figure 7 This is a pseudo-second-order kinetic fitting curve diagram of the adsorption of tetracycline by Fe / Mn-BNHS of the present invention.

[0031] Figure 8 The Freundlich isotherm diagram of the adsorption of tetracycline by Fe / Mn-BNHS of the present invention.

[0032] Fig. 9 This is the Langmuir isotherm diagram of tetracycline adsorption by Fe / Mn-BNHS of the present invention.

[0033] Fig.10 The diagram of the adsorption of tetracycline in solution by Fe / Mn-BNHS of the present invention at different pH values.

[0034] Fig.11 This is a diagram of the adsorption of tetracycline in solution by Fe / Mn-BNHS of the present invention at different ion concentrations.

[0035] Fig.12 This is a diagram showing the effect of Fe / Mn-BNHS of the present invention on tetracycline removal after multiple cycles of use. DETAILED DESCRIPTION

[0036] The present invention is further described in detail below through specific examples. The following examples are only illustrative and not restrictive, and the protection scope of the present invention cannot be limited thereto.

[0037] A method for preparing a saponin shell-based Fe / Mn-N co-doped hydrothermal carbon adsorbing antibiotic material comprises the following steps:

[0038] S1, washing and drying the soapberry shell, then grinding, adding chitosan during grinding, and passing through an 80-mesh sieve to obtain a soapberry shell powder; then placing the soapberry shell powder, Fe source, and Mn source in a hydrothermal reactor containing deionized water, and hydrothermally reacting in a 170-180° C. forced drying oven for 10-15 hours, filtering and washing with ultrapure water after the reaction, transferring to an oven and drying to constant weight, grinding with an agate mortar, passing through a 100-mesh sieve, and making hydrothermal charcoal;

[0039] S2. Place the hydrothermal carbon and urea in a ball mill and perform ball milling at a rotation speed of 500 rpm for 4.5-5.5 hours to obtain a saponin shell-based Fe / Mn-N co-doped hydrothermal carbon material for adsorbing antibiotics.

[0040] Example 1

[0041] Preparation of antibiotic adsorption materials

[0042] A method for preparing a saponin shell-based Fe / Mn-N co-doped hydrothermal carbon adsorbing antibiotic material comprises the following steps:

[0043] S1. Wash and dry the soapberry shell, then grind it, add 1.6g chitosan during grinding, and pass it through an 80-mesh sieve to obtain soapberry shell powder; mix 6g of soapberry shell powder, 4g of FeSO 4 7H 2 O and 0.6 g MnCl 2 ·4H 2 O was placed in a hydrothermal reactor containing 45 ml of deionized water, and hydrothermally reacted in a 180°C forced air drying oven for 12 h. After the reaction, it was filtered and washed with ultrapure water and transferred to a 70°C oven for drying to constant weight. It was ground with an agate mortar and passed through a 100-mesh sieve to obtain Fe / Mn-HS.

[0044] S2. 1.2 g of hydrothermal carbon and 1.6 g of urea were placed in a ball mill and ball-milled at 500 rpm for 5 h to obtain Fe / Mn-BNHS. Fe / Mn-BHS was obtained according to the above method without adding urea and chitosan.

[0045] Characterization of adsorption materials

[0046] Figure 1-2 The surface morphology of Fe / Mn-BNHS is shown. According to the EDX spectrum ( Figure 1 ) shows that Fe, Mn and N elements have been successfully introduced into the hydrochar. After ball milling, the hydrochar forms a dense stacking structure and the particle surface becomes smooth ( Figure 2 ).

[0047] Figure 3 The hydrophobicity of Fe / Mn-HS, Fe / Mn-BHS and Fe / Mn-BNHS was shown. Compared with the contact angle of Fe / Mn-HS, ball milling increased the hydrophobicity of Fe / Mn hydrothermal carbon. In addition, the addition of urea and chitosan during ball milling introduced nitrogen, and the hydrophobicity of hydrothermal carbon was further increased by adding these two substances.

[0048] Example 2

[0049] This example evaluates the adsorption capacity of Fe / Mn-HS and Fe / Mn-BNHS for tetracycline in solution.

[0050] The adsorbent materials (Fe / Mn-HS and Fe / Mn-BNHS) prepared in Example 1 were added to the TC solution with an initial concentration of 50 mg / L, respectively, with an addition amount of 1 g / L, the reaction temperature was set to 25°C, the shaking box speed was 180 rpm, and 3 parallel experiments were set for each group of experiments. After 24 hours, samples were taken through a 0.45 μm filter membrane to determine the residual TC concentration. Figure 4-5 The diagram shows the adsorption effect of Fe / Mn-HS and Fe / Mn-BNHS on tetracycline in water.

[0051] The removal rates of TC by Fe / Mn-HS were 33.07%, and the removal rates of TC by Fe / Mn-BHS increased (54.2%) after ball milling. After the introduction of nitrogen during ball milling, the removal rates of TC by Fe / Mn-BNHS were further increased (92.2%). Figure 4 ). In the first 30 minutes, the adsorption capacity of Fe / Mn-BNHS for TC increased rapidly, then increased slowly, and reached equilibrium after 780 minutes. In the rapid removal stage, the removal efficiency of TC was 76.8% ( Figure 5 This result can be attributed to the increase of oxygen-containing functional groups and surface active sites after ball milling. This indicates that the combination of Fe / Mn-N doped hydrochar and ball milling is an effective strategy to improve TC removal efficiency.

[0052] Example 3

[0053] In order to explain the mechanism of TC adsorption on Fe / Mn-BNHS, pseudo-first-order and pseudo-second-order models were applied to fit the removal kinetics results.

[0054] Fe / Mn-BNHS was added to the above TC solution, the reaction temperature was set to 25°C, the dosage was 1g / L, the oscillation box speed was 180rpm, and 3 parallel experiments were set for each group of experiments. Samples were taken and filtered at 1, 2, 3, 4, 5, 10, 30, 60, 110, 190, 300, 570, 780 and 1200min, and the residual concentration of TC was determined. The adsorption kinetics experimental data were fitted using the pseudo-first-order kinetic model, the pseudo-second-order kinetic model and the intraparticle diffusion model, respectively. The relevant equations are shown below: The pseudo-first-order kinetic model

[0055]

[0056] Pseudo-second-order kinetic model

[0057]

[0058] where q t (μg / g) and q e (μg / g) are the adsorption amount of the adsorbent on the adsorbate at time t (min) and equilibrium, respectively; k1 (min -1 ) and k 2 (min -1 ) are the adsorption rate constants of the pseudo-first-order kinetic model and the pseudo-second-order kinetic model, respectively.

[0059] The kinetic parameters were fitted as Figure 6 and as shown in Table 1. Compared with the pseudo-first-order model (R 2 =0.8916)( Figure 6 ), the quasi-secondary model showed a higher correlation coefficient (R 2 =0.9997)( Figure 7 ). The adsorption amount q obtained from the pseudo-second-order model e,cal (mg / g) is closer to the experimental value (q e,exp ). Therefore, the pseudo-second-order model can more accurately describe the dynamic process of TC removal by biochar. The results show that the adsorption reaction of biochar on TC is chemical adsorption, involving electron sharing or exchange between TC and biochar.

[0060] Table 1 Fitting parameters of adsorption kinetics and adsorption isotherm models

[0061]

[0062] Example 4

[0063] In order to further evaluate the removal performance of Fe / Mn-BNHS for TC (tetracycline) and its adsorption mechanism, two commonly used isotherm models were used to fit the experimental data.

[0064] Fe / Mn-BNHS was added to TC solutions with concentrations of 20, 50, 80, 100, 120, 150, 180, 200 and 250 mg / L, with a dosage of 1 g / L. The reaction temperature was 25 °C, the oscillation box speed was 180 rpm, and samples were taken and filtered at the equilibrium time to determine the residual concentration of TC. The adsorption isotherm experimental data were fitted using the Langmuir and Freundlich models, respectively. The Langmuir isotherm model assumes that adsorption is mainly a monolayer chemical adsorption occurring on the surface of a homogeneous adsorbent, and that there are no lateral or longitudinal forces between the adsorbed molecules; the Freundlich isotherm model assumes that adsorption is a multi-molecular layer physical adsorption and that the surface of the adsorbent is non-uniform. The specific equations are shown below:

[0065] Langmuir isotherm model:

[0066]

[0067] Freundlich isotherm model:

[0068]

[0069] Among them, q m (μg / g) is the theoretical maximum adsorption capacity, K L (L / μg) is the Langmuir constant related to the adsorption energy, C 0 (μg / L) and Ce (μg / L) are the concentrations of the adsorbate at the initial and adsorption equilibrium, respectively. F (L / μg) and n are the Freundlich constants related to the adsorption capacity and adsorption strength of the adsorbent, respectively.

[0070] Compared with the Freundlich model (R 2 =0.95573)( Figure 8 ), the Langmuir model can fit the experimental data better (R 2 =0.9808)( Fig. 9 ), indicating that the adsorption of TC on biochar follows a monolayer chemical adsorption mechanism. In the Langmuir model, the maximum adsorption amount of TC on Fe / Mn-BNHS (q m ) was 409.07 mg / g, which was much higher than that of other adsorbents (Table 2).

[0071] Table 2 Comparison of adsorption capacity of metal-based adsorption materials

[0072]

[0073] Example 5

[0074] Application of Fe / Mn-BNHS in the adsorption of tetracycline in solutions at different pH values

[0075] Fe / Mn-BNHS was added to a TC solution with a concentration of 50 mg / L, with a dosage of 1 g / L. The solution pH was set to 3, 5, 7, 9 and 11, respectively. The temperature was set to 25°C, the oscillation box speed was 180 rpm, and samples were taken and filtered at the equilibrium time to determine the residual concentration of TC.

[0076] The adsorption capacity of TC at different pH values ​​is shown in Figure 2. Fig.10 As shown. The adsorption amount of TC decreases as the pH increases. When the pH is 5, 7, and 9, the adsorption amount of TC by Fe / Mn-BNHS remains at a high level, all up to 40 mg / g. The results show that the Fe / Mn-BNHS hydrothermal carbon provided by the present invention has good adaptability in a wide pH range.

[0077] Example 6

[0078] Application of Fe / Mn-BNHS in the adsorption of tetracycline in solution at different ion concentrations

[0079] Fe / Mn-BNHS was added to NaCl and CaCl 2 A TC solution with a concentration of 50 mg / L (C0 = 0.001, 0.01 and 0.1 mol / L) was prepared. The temperature was set to 25°C and the speed of the oscillating box was 180 rpm. Samples were taken and filtered at the equilibrium time to determine the residual concentration of TC.

[0080] Fig.11 It shows that with the Na + The increase in concentration of Na + strength did not affect the adsorption capacity of biochar. However, when Ca 2+ When the concentration reached 0.1 mol / L, the adsorption of TC by Fe / Mn-BNHS decreased. This indicates that Fe / Mn-BNHS can maintain a high adsorption capacity for TC in solutions with different ion types, indicating that the adsorbent is a promising material for purifying actual wastewater.

[0081] Example 7

[0082] Evaluation of the regeneration performance of Fe / Mn-BNHS

[0083] Fe / Mn-BNHS was added to a TC solution with a concentration of 50 mg / L, with a dosage of 1 g / L, the temperature was set to 25°C, the speed of the oscillating box was 180 rpm, and samples were taken and filtered at the equilibrium time to determine the residual concentration of TC. The adsorbed biochar was filtered and then regenerated with ethanol solution. After filtration and drying, the adsorption experiment was continued and repeated 5 times to determine the regeneration adsorption capacity of Fe / Mn-BNHS.

[0084] like Fig.12 As shown in the figure, Fe / Mn-BNHS exhibited high adsorption capacity in both the first and second cycles. It continued to decline after the second cycle experiment, and after five cycles, the removal rate of TC was still as high as 73%. This shows that Fe / Mn-BNHS can obtain good regeneration stability and has certain application value in actual processing.

[0085] Although the embodiments of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments.

Claims

1. A method for preparing a saponin shell-based Fe / Mn-N co-doped hydrothermal carbon adsorbing antibiotic material, characterized in that: The method comprises the following steps: S1, washing and drying the soapberry shell, then grinding, adding chitosan during grinding, and passing through an 80-mesh sieve to obtain a soapberry shell powder; then placing the soapberry shell powder, Fe source, and Mn source in a hydrothermal reactor containing deionized water, and hydrothermally reacting in a 170-180° C. forced drying oven for 10-15 hours, filtering and washing with ultrapure water after the reaction, transferring to an oven and drying to constant weight, grinding with an agate mortar, passing through a 100-mesh sieve, and making hydrothermal charcoal; S2. Place the hydrothermal carbon and urea in a ball mill and perform ball milling at a rotation speed of 500 rpm for 4.5-5.5 hours to obtain a saponin shell-based Fe / Mn-N co-doped hydrothermal carbon material for adsorbing antibiotics.

2. The method for preparing the saponin shell-based Fe / Mn-N co-doped hydrothermal carbon adsorbing antibiotic material according to claim 1, characterized in that: The weight ratio of the sapodilla shell to chitosan is 15-35:

1.

3. The method for preparing the saponin shell-based Fe / Mn-N co-doped hydrothermal carbon adsorbing antibiotic material according to claim 1, characterized in that: The weight ratio of the soapberry shell powder:Fe source:Mn source is 25-35:15-25:1-5.

4. The method for preparing the saponin shell-based Fe / Mn-N co-doped hydrothermal carbon adsorbing antibiotic material according to claim 1, characterized in that: The weight ratio of hydrothermal charcoal:urea is 2:1-2.

5. The method for preparing the saponin shell-based Fe / Mn-N co-doped hydrothermal carbon adsorbing antibiotic material according to claim 1, characterized in that: The Fe source is FeSO4·7H2O.

6. The method for preparing the saponin shell-based Fe / Mn-N co-doped hydrothermal carbon adsorbing antibiotic material according to claim 1, characterized in that: The Mn source is MnCl2·4H2O.

7. The method for preparing the saponin shell-based Fe / Mn-N co-doped hydrothermal carbon adsorbing antibiotic material according to claim 1, characterized in that: The antibiotic is tetracycline.

8. Use of the preparation method of the saponin shell-based Fe / Mn-N co-doped hydrothermal carbon adsorption antibiotic material according to claim 1 in treating tetracycline in a solution.

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