Method for high-value utilization of micro mineral powder solid waste

Abstract

The invention discloses a method for high-value utilization of micro mineral powder solid waste, which comprises the following steps of: naturally air-drying micro mineral powder, grinding and sieving to obtain a micro mineral powder raw material; uniformly mixing the micro mineral powder with biomass in different proportions, performing high-temperature oxygen-limited pyrolysis in a muffle furnace, and modifying by phosphoric acid, citric acid, CaCl2 and the like to obtain a micro mineral powder / biomass nano composite material; dispersing the micro mineral powder / biomass nano composite material and chitosan in water, and performing ultrasonic compounding for a period of time to obtain a chitosan / micro mineral powder / biomass nano composite material mixed solution; dispensing the mixed solution on the surface of a glassy carbon electrode to prepare a chemically modified electrode; the electrode is used for detecting dopamine and nitrite substances. The micro mineral powder nano material with high electrocatalytic activity can be prepared and can be used as an electrode material in the fields of batteries, electrochemical sensors, capacitors and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid waste, more particularly to a method for high-value utilization of micro-mineral powder solid waste. BACKGROUND

[0002] The micro-mineral powder is obtained by wet crushing and dissociating a carbon-containing material source to micron-level particle size before combustion / conversion using a micro-mineral separation technology, and then separating trace elements and minerals in the carbon-containing material source after surface modification and multiphase flow interface regulation, and obtaining clean solid fuel from low-quality coal, and then obtaining solid waste. A large amount of micro-mineral powder is produced in the process of extracting low-quality coal using the micro-mineral separation technology, and the micro-mineral powder is usually stacked in a tailings pond.

[0003] At present, the utilization of micro-mineral powder mainly focuses on concrete improvement, and the micro-mineral powder is a solid waste discharged after low-quality coal is extracted into clean solid fuel, and the chemical composition mainly includes iron, silicon, aluminum, calcium oxides, etc., which is an important solid secondary resource. Directly using the micro-mineral powder in concrete building materials cannot maximize its effective role. The present application prepares an electrocatalytic material for electrodes and capacitors by the way of micro-mineral powder and different biomass high-temperature limited oxygen pyrolysis carbonization and modification, which is a way to realize high-value utilization of micro-mineral powder. SUMMARY

[0004] Therefore, the present application provides a method for high-value utilization of micro-mineral powder solid waste, which can prepare micro-mineral powder nanomaterials with high electrocatalytic activity, and can be used as electrode materials in the fields of batteries, electrochemical sensors, capacitors, etc.

[0005] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0006] A method for high-value utilization of micro-mineral powder solid waste, comprising the following steps:

[0007] (1) The micro-mineral powder is naturally air-dried, ground, and sieved to obtain micro-mineral powder raw materials;

[0008] (2) The micro-mineral powder is mixed with different proportions of biomass, and then placed in a muffle furnace for high-temperature limited oxygen pyrolysis, and then modified by phosphoric acid, citric acid, or directly modified by CaCl2 to obtain a micro-mineral powder / biomass nanocomposite material;

[0009] (3) The micro-mineral powder / biomass nanocomposite material and chitosan are dispersed in water, and ultrasonic composite for a period of time to obtain a chitosan / micro-mineral powder / biomass nanocomposite material mixture;

[0010] (4) The mixture is drop-coated on the surface of a glassy carbon electrode to prepare a chemical modified electrode;

[0011] (5) The electrode is used for detecting dopamine and nitrite substances.

[0012] Preferably, the sieving in step (1) is sieving through a 40-mesh sieve.

[0013] Preferably, the biomass comprises one or more of ginger stems, tomato stems, eggplant stems, broccoli stems, enoki mushroom stems, walnut branches, and walnut shells.

[0014] Preferably, the mass ratio of the micro-mineral powder to the biomass is 10:1-1:10.

[0015] Preferably, the high-temperature limited-oxygen pyrolysis is high-temperature limited-oxygen pyrolysis at 500-1000℃ for 1-5h.

[0016] Preferably, the phosphoric acid modification is as follows: a certain amount of micro-mineral powder is weighed, 42% phosphoric acid (concentrated phosphoric acid mixed with water at a ratio of 1:1) is added, stirring is performed, room temperature soaking is performed for 12h, filtration and drying are performed, and then the product is placed in a muffle furnace for pyrolysis at 600℃ for 3h, is ground into a powder, and is sieved through a 100-mesh sieve, thereby obtaining the phosphoric acid modified micro-mineral powder biochar.

[0017] The citric acid modification is as follows: the phosphoric acid modified micro-mineral powder biochar is taken, citric acid is added, stirring is performed for a certain time, filtration is performed, 60℃ drying is performed for 24h, the temperature is gradually increased to 120℃, and the temperature is maintained for 2h, the product is ground into a powder, and the powder is sieved through a 100-mesh sieve, thereby obtaining the phosphoric acid and citric acid modified micro-mineral powder biochar.

[0018] The CaCl2 modification is as follows: the micro-mineral powder biochar and a 0.05-0.5mol / L calcium chloride solution are placed in a constant-temperature oscillator in a solid-liquid ratio of 1g:15mL, and the product is shaken for 24h, filtered, washed with deionized water until the conductivity is stable, then placed in a 105℃ oven for drying for 5h, finally subjected to limited-oxygen pyrolysis at 200℃ for 1h, ground into a powder in a mortar, and sieved through a 100-mesh sieve, thereby obtaining the prepared calcium chloride modified micro-mineral powder biochar.

[0019] Preferably, the mass ratio of the micro-mineral powder / biomass nanocomposite to chitosan is 3:1-1:3.

[0020] Preferably, the ultrasonic compounding time is 1-4h.

[0021] According to the technical solutions described above, compared with the prior art, the present application has the following beneficial effects:

[0022] 1. The present application uses micro-mineral powder as a raw material to prepare an electrocatalytic material, reduces the damage of micro-mineral powder accumulation to the ecological environment, and realizes the reduction and high-value utilization of solid waste.

[0023] 2. The treatment process is simple and easy to implement, the electrocatalytic effect after modification is remarkable, and low-concentration rapid detection of electroactive substances such as nitrite and dopamine can be realized.

[0024] 3. The introduction of chitosan can not only improve the stability of the electrode, but also improve the electrocatalytic activity.

[0025] 4. The raw materials used in the method are easy to obtain, the cost is low, the operation is simple, and the added value is high. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only a part of the embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0027] Figure 1 The current-time of different concentrations of dopamine.

[0028] Figure 2 The cyclic voltammogram of 0.3mM sodium nitrite on the electrode modified by different materials;

[0029] Figure 3 The differential pulse voltammogram of different concentrations of sodium nitrite on the electrode modified by micro-powder / ginger rod biochar nanocomposite material (A);

[0030] Figure 4 The electrochemical response curve (A) and linear graph (B) of different concentrations of dopamine on the surface of the electrode modified by phosphoric acid+citric acid modified micro-powder nanomaterial;

[0031] Figure 5 The electrochemical response of different concentrations of dopamine on the surface of the electrode modified by phosphoric acid+citric acid modified micro-powder nanocomposite material.

[0032] Figure 6 The electrochemical response of different concentrations of dopamine on the surface of the electrode modified by CaCl2 modified micro-powder nanocomposite material. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0034] Embodiment 1

[0035] The micro-powder material is broken into small pieces with a crusher or hammer, and then placed in a sealed crucible with a cover after passing through a 40 mesh sieve. The crucible is placed in a muffle furnace set at 700°C, and the oxygen-limited pyrolysis is performed for 3h. The material is ground and passed through a 100 mesh sieve to obtain the micro-powder nanomaterial. 5-20mg of the above micro-powder nanomaterial is weighed, added to 5ml of ultrapure water, and ultrasonically shaken for 1h. 5-10μL of the dispersion liquid is dropped on the surface of a clean electrode using a pipette to obtain an electrode surface containing the modified material, which is dried under an incandescent lamp for use.

[0036] The micro-powder modified electrode has good electrocatalytic activity for dopamine in the working potential range of 0.30V. As the concentration of dopamine increases, the electrode shows a significantly enhanced response current signal, and the response speed is very fast, with a response time of less than 5s for 90% of the steady-state current. The concentration range is divided into two segments for linear fitting, with the equation y1=0.10797x+0.0782 and a correlation coefficient R2=0.9719, and the equation y2=0.00549x+0.2436 and a correlation coefficient R2=0.9875. The response sensitivity is 0.10797μA / (μmol / L).

[0037] Example 2

[0038] The crushed ginger stem powder and micro-powder are mixed in proportions of 1:0, 0:1, 1:1, 1:2, 2:1, 1:3, 3:1, 2:3, and 3:2, respectively, and then subjected to oxygen-limited pyrolysis at 700°C for 3h. The material is ground and passed through a 100 mesh sieve to prepare ginger stem / micro-powder biochar nanocomposite materials. 5-20mg of each of the nine micro-powder nanomaterials is weighed, added to 3mL of ultrapure water, and ultrasonically dispersed for 1h to obtain a suspension containing the modified material. 5-10μL of the dispersion liquid is dropped on the surface of a clean electrode using a pipette, and the electrode is dried under an infrared lamp for use.

[0039] Figure 2 The effect of the mass ratio of ginger stem to micro-powder on the electrochemical performance of the micro-powder / ginger stem biochar nanocomposite material is shown in Figure 2 It can be seen that when the ratio of ginger stem to micro-powder is 2:3, the prepared nanocomposite material has the smallest oxidation peak potential value and the highest oxidation peak current for sodium nitrite, which is more conducive to the detection of sodium nitrite.

[0040] Compared with the bare electrode, pure micro-powder, pure ginger stem, and micro-powder / ginger stem biochar materials can all enhance the detection performance for sodium nitrite, among which the micro-powder / ginger stem biochar nanocomposite material has the best effect as shown in Figure 3 .

[0041] The current response of different concentrations of nitrite on the electrode surface was measured by differential pulse voltammetry as shown in Figure 4 A.Figure 4 B can be known that its linear range is wide, sodium nitrite (5 μM ~ 1000 μM) concentration and peak current presents good linear relationship, its linear correlation coefficient R2 is 0.9980, linear equation is ipa = 0.00566χ + 0.11565. The detection limit of sodium nitrite is low, and the detection limit can reach 2 μM.

[0042] Example 3

[0043] The micro-powder material is broken into small pieces by a crusher or a hammer, and then placed in a sealed crucible after being passed through a 40 mesh sieve. The crucible is placed in a muffle furnace at 600 DEG C for 3 hours of limited oxygen pyrolysis. The micro-powder nanomaterial is obtained by grinding and passing through a 100 mesh sieve. 100 g of the micro-powder is weighed, 100 mL of 42% phosphoric acid (concentrated phosphoric acid mixed with water at a ratio of 1:1) is added, and a rotor is stirred. The mixture is soaked at room temperature for 12 hours, and then filtered and dried. The dried mixture is placed in a crucible and compacted, and then placed in a muffle furnace for pyrolysis at 600 DEG C for 3 hours. After cooling, the mixture is ground into powder in a mortar, and then passed through a 100 mesh sieve. The micro-powder biochar modified by phosphoric acid is obtained. 10 g of the micro-powder biochar modified by phosphoric acid is taken, 200 mL of 1 mol / L citric acid is added, and stirred for 2 hours. The mixture is filtered and dried in an oven at 60 DEG C for 24 hours, and then gradually heated to 120 DEG C and kept for 2 hours. After cooling, the mixture is ground into powder in a mortar, and then passed through a 100 mesh sieve. The micro-powder biochar modified by phosphoric acid and citric acid is obtained.

[0044] 5-20 mg of different micro-powder nanomaterials are weighed and mixed with chitosan, and then 5-20 ml of ultrapure water is added and ultrasonically dispersed for 1 hour to obtain a suspension containing different micro-powder nanomaterials. 5-10 μL of the dispersion is taken by a pipette and dropped on the surface of a clean electrode, and then dried under an infrared lamp for use.

[0045] The current response of 0.1, 0.5, 1, 5, 10, 50, and 100 μM dopamine on the surface of the micro-powder nanomaterial modified by phosphoric acid and citric acid is measured by cyclic voltammetry, as shown in Figure 5 .

[0046] Example 4

[0047] The micro-powder material is broken into small pieces by a crusher or a hammer, and then placed in a sealed crucible with a cover after passing through a 40 mesh sieve. The crucible is placed in a muffle furnace at 600°C for 3 hours of limited oxygen pyrolysis. The micro-powder nanomaterial is obtained by grinding and passing through a 100 mesh sieve. The micro-powder nanomaterial and a 0.05-0.5 mol / L calcium chloride solution are placed in a constant temperature oscillator at a solid-liquid ratio of 1 g:15 mL for 24 hours of oscillation, and then filtered, washed with deionized water until the conductivity is stable, and then placed in an oven at 105°C for 5 hours of drying. Finally, the CaCl2 modified micro-powder biochar is obtained by grinding into powder in a mortar and passing through a 100 mesh sieve. 5-20 mg of CaCl2 modified micro-powder nanocomposite is weighed and mixed with chitosan, and then 5-20 ml of ultrapure water is added and ultrasonic dispersed for 1 hour to obtain a CaCl2 modified micro-powder nanocomposite suspension. 5-10 μL of the dispersion is dropped on the surface of a clean electrode with an infrared lamp for drying.

[0048] The current response of 0.1, 0.5, 1, 5, 10, and 100 μM dopamine on the surface of the CaCl2 modified micro-powder nanocomposite modified electrode is measured by cyclic voltammetry as shown in Figure 6 .

[0049] The embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and the related parts can be referred to the method part.

[0050] The above description of the disclosed embodiments enables a person skilled in the art to implement or use the present application. Various modifications to the embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for high-value utilization of micro-fine powder solid waste, characterized by, The method comprises the following steps: (1) grinding and sieving the micro-mineral powder after natural air-drying to obtain a micro-mineral powder raw material; (2) mixing the micro-mineral powder with different proportions of biomass uniformly, placing in a muffle furnace for high-temperature limited-oxygen pyrolysis, and then modifying the micro-mineral powder / biomass nanocomposite material by phosphoric acid, citric acid modification or directly by CaCl2 modification; (3) dispersing the micro-mineral powder / biomass nanocomposite material and chitosan in water, and ultrasonic compounding for a period of time to obtain a chitosan / micro-mineral powder / biomass nanocomposite material mixture; (4) drop-coating the mixture on the surface of a glassy carbon electrode to prepare a chemical modified electrode; (5) using the electrode for detection of dopamine and nitrite substances.

2. The method for high value utilization of micro-fine mineral powder solid waste according to claim 1, characterized in that, The sieving in step (1) is sieving through a 40-mesh sieve.

3. The method for high value utilization of micro-fine mineral powder solid waste according to claim 1, characterized in that, The biomass comprises one or more of ginger stems, tomato stems, eggplant stems, broccoli stems, shiitake mushroom stems, walnut branches and walnut shells.

4. The method for high value utilization of micro-fine mineral powder solid waste according to claim 1, characterized in that, The mass ratio of the micro-mineral powder to the biomass is 10:1-1:

10.

5. The method for high value utilization of micro-fine mineral powder solid waste according to claim 1, characterized in that, The high-temperature limited-oxygen pyrolysis is high-temperature limited-oxygen pyrolysis at 500-1000 DEG C for 1-5 h.

6. The method for high value utilization of micro-fine mineral powder solid waste according to claim 1, characterized in that, The phosphoric acid modification is as follows: taking a certain amount of micro-mineral powder, adding 42% phosphoric acid, stirring, room temperature soaking for 12 h, filtering and drying, and then placing in a muffle furnace for pyrolysis at 600 DEG C for 3 h, grinding into powder, and sieving through a 100-mesh sieve to obtain the phosphoric acid modified micro-mineral powder biochar; The citric acid modification is as follows: taking the phosphoric acid modified micro-mineral powder biochar, adding citric acid, stirring for a certain period of time, filtering, drying at 60 DEG C for 24 h, gradually heating to 120 DEG C and keeping for 2 h, grinding into powder, and sieving through a 100-mesh sieve to obtain the micro-mineral powder biochar modified by phosphoric acid and citric acid; The CaCl2 modification is as follows: placing the micro-mineral powder biochar and a 0.05-0.5 mol / L calcium chloride solution in a constant-temperature shaker at a solid-liquid ratio of 1 g:15 mL, oscillating for 24 h, filtering, washing with deionized water until the conductivity is stable, then placing in a 105 DEG C oven for drying for 5 h, finally limiting-oxygen pyrolysis at 200 DEG C for 1 h, grinding into powder in a mortar, and sieving through a 100-mesh sieve to obtain the prepared calcium chloride modified micro-mineral powder biochar.

7. The method for high value utilization of micro-fine mineral powder solid waste according to claim 1, characterized in that, The mass ratio of the micro-mineral powder / biomass nanocomposite material to chitosan is 3:1-1:

3.

8. The method for high value utilization of micro-fine mineral powder solid waste according to claim 1, characterized in that, The ultrasonic compounding time is 1-4 h.

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