Preparation method of layered metal slow-release particle electrode

Abstract

The invention provides a preparation method of a layered metal slow-release particle electrode. The preparation materials comprise aggregate, an adhesive, a pore-forming agent and an active component. The layered metal sustained-release particle electrode is divided into a sustained-release layer and a sustained-release layer, the ratio of substances contained in the sustained-release layer and the sustained-release layer can be flexibly adjusted, the thicknesses and the number of layers of the sustained-release layer and the sustained-release layer can be flexibly adjusted according to requirements, and the types of the substances contained in the sustained-release layer and the sustained-release layer can be different and can be flexibly adjusted according to requirements. The slow-release particle electrode releases active components through the layered structure, the layered metal slow-release particle electrode has good catalytic property, adsorbability and conductivity, the problem that the generation rate of strong oxidizing active substances generated by a traditional particle electrode is low is solved, a precursor can be provided for biosynthesis of nano-particles, and the preparation method is simple and easy to implement. The problem of low interface electron transfer efficiency is solved, the degradation efficiency of the three-dimensional electro-catalysis biological membrane system is further improved, and a better treatment effect is achieved by using simpler and more convenient operation and lower cost.

Description

Technical Field

[0001] The invention belongs to the field of water treatment and provides a method for preparing a slow-release particle electrode, which is suitable for wastewater treatment by a three-dimensional electrocatalytic biofilm system. Background Art

[0002] The working principle of the three-dimensional electrocatalytic biofilm system is to fill the area between the cathode and anode of the traditional two-dimensional electrode with a particle electrode, so that each filled particle works independently as an electrolytic cell, and the rapid degradation of pollutants is achieved by the three effects of electrocatalytic oxidation, biodegradation, and adsorption. Among them, the electrocatalytic oxidation degradation of pollutants is mainly completed by strong oxidizing active substances such as H2O2 and OH, but H2O2 and OH are mainly produced in situ through the electrode plate. The output produced by the particle electrode is closely related to the performance of the particle electrode. The number of catalytic active sites in the traditional particle electrode is not enough, resulting in a small number of strong oxidizing substances, which reduces the treatment effect of the electrocatalytic biofilm system. Due to the low conductivity of the biofilm, the transmembrane electron transfer rate and the electron transfer efficiency between the organism and the electrode become low, resulting in low current utilization efficiency of the system and high treatment energy consumption.

[0003] For the above problems existing in the three-dimensional electrocatalytic biofilm system, the characteristics of particle electrodes and the efficiency of electron transfer between organisms and between organisms and non-organisms are the key to solving the problems of the three-dimensional electrocatalytic biofilm system. In recent years, research has focused on the development of new electrodes and particle electrode materials, and the improvement of their structures, so that they can add other properties on the basis of adsorption and electrocatalysis. The research objectives are mainly focused on increasing the specific surface area of ​​electrodes and electrocatalytic activity. At present, it is very common to use nanomaterials to improve the efficiency of biological electron transfer and thus increase the treatment efficiency of electrocatalytic biofilm systems. However, the synthesis steps of nanomaterials are complicated, the experimental configuration costs are high, and nanomaterials are not easy to recycle. Using particle electrodes to slowly release active ingredients can not only form nanoparticles in the microbial mineralization of metals in the three-dimensional electrocatalytic biofilm system to improve the interface electron transfer efficiency of the system, but also release metal ions in the system to induce the production of more strong oxidative reactive substances, provide the required metal source for microorganisms, and improve the degradation efficiency of the reaction system.

[0004] In order to solve the problems of low efficiency in producing electrocatalytic active substances and low current utilization efficiency in the above-mentioned three-dimensional electrocatalytic system, such as poor treatment effect and excessive energy consumption, the present invention proposes a method for preparing a layered metal slow-release particle electrode. The layered structure allows the slow-release particle electrode to release active ingredients. The layered metal slow-release particle electrode has good catalytic, adsorbent and conductive properties, which solves the problem of low production rate of strong oxidizing active substances produced by traditional particle electrodes. It can also provide precursors for biosynthetic nanoparticles, solve the problem of low interfacial electron transfer efficiency, further improve the current utilization efficiency of the three-dimensional electrocatalytic biofilm system, replace traditional means of improving electron transfer, and achieve better treatment effects with simpler operations and lower costs. Based on the above content, the present invention provides a method for preparing a layered metal slow-release particle electrode. Summary of the invention

[0005] The purpose of the present invention is to increase the yield of catalytically active substances and current utilization rate of a three-dimensional electrode biofilm system, thereby improving the treatment efficiency of the system. A method for preparing a layered metal slow-release particle electrode is proposed. The layered metal slow-release particle electrode has good catalytic, adsorbent, and electrical conductivity, and can provide precursors for biosynthetic nanoparticles. It is suitable for wastewater treatment by a three-dimensional electrocatalytic biofilm system. To achieve the above-mentioned purpose of the invention, the present invention provides the following technical solutions.

[0006] The present invention provides a method for preparing a layered metal slow-release particle electrode, wherein the preparation materials include aggregate, binder, pore former, and active ingredient. The layered metal slow-release particle electrode is divided into a slow-release layer and a resistive layer, the ratio of the substances contained in the slow-release layer and the resistive layer can be flexibly adjusted, the thickness and number of layers of the slow-release layer and the resistive layer can be flexibly adjusted according to demand, and the types of substances contained in the slow-release layer and the resistive layer can be different, which can be flexibly adjusted according to demand.

[0007] The aggregate is lithium slag, red mud and other industrial waste slag and tailings slag whose main components are SiO2, Al2O3 and some metals and their oxides; the binder is bentonite, montmorillonite, kaolin, clay and the like, which have adsorptive and adhesive properties; the pore-forming agent is starch, glucose and other materials that can be sintered into pores; the active ingredient is a solid material or liquid material of iron or copper, such as ferric oxide powder, copper oxide powder, ferric nitrate solution, ferric sulfate solution, copper nitrate solution, copper sulfate solution and the like.

[0008] The layered metal slow-release particle electrode can be a single layer, that is, the inside is a slow-release layer and the outside is a resistance-release layer. Its thickness can be flexibly adjusted so that the particle size of the inner slow-release layer before sintering is 2~5mm, and the particle size of the overall layered metal slow-release particle electrode after wrapping the outer resistance-release layer is 5~8mm before sintering.

[0009] The layered metal slow-release particle electrode can be multi-layered, that is, the innermost layer is a slow-release layer, which is wrapped with a resistance-release layer, then covered with a slow-release layer, and then wrapped with a resistance-release layer, and so on repeatedly; the innermost layer must be a slow-release layer, and the outermost layer must be a resistance-release layer; the thickness ratio of the slow-release layer to the resistance-release layer can be (1~1.5): (1~1.5), and the particle size of the multi-layer slow-release particle electrode before sintering can be 5~8mm.

[0010] In the sustained-release layer material of the layered metal sustained-release particle electrode, the mass ratio of aggregate, binder, pore former, and active ingredient can be (35-50): (20-30): (5-20): (15-35); in the barrier layer material of the layered metal sustained-release particle electrode, the mass ratio of aggregate, binder, pore former, and active ingredient can be (40-60): (30-40): (5-10): (5-10)

[0011] The present invention provides a technical solution 1, wherein the active ingredient is solid, comprising the following steps: S1: The aggregate is crushed in a crusher, washed in tap water to remove impurities, then washed with deionized water for more than three times, and dried in an oven at 110°C; S2: weighing the aggregate, binder, pore former and active ingredient in step 1 according to a certain mass percentage, putting them into a blender and mixing them evenly to obtain a slow-release raw material and a delayed-release raw material; S3: spraying water on the slow-release raw material in step 2 and rolling it into slow-release balls, sieving it according to the required particle size, and then uniformly wrapping it with the resisting raw material and spraying water on it and rolling it into raw material balls with larger particle size; S4: Place the raw material balls in step 3 in a muffle furnace, heat from room temperature to 200°C at a heating rate of 5°C / min, keep warm for 10 min, heat to 500°C, keep warm for 30 min, heat to 800°C, keep warm for 30 min, heat to 985°C, keep warm for 50 min. Cool naturally to room temperature to obtain a layered metal sustained-release particle electrode.

[0012] The present invention provides a second technical solution, wherein the active ingredient is a liquid, comprising the following steps: S1: The aggregate is crushed in a crusher, washed in tap water to remove impurities, then washed with deionized water for more than three times, and dried in an oven at 110°C; S2: The aggregate, binder, pore former and active ingredient in step 1 are weighed according to a certain mass percentage, wherein the mass of the active ingredient is the mass of the metal ion, and the active ingredient is dissolved into a solution of a certain concentration so as to maximize the loading amount, and the material is impregnated by an impregnation method, and after a certain period of time, it is placed at 40-60°C for low temperature drying to obtain a slow-release raw material and a delayed-release raw material; S3: spraying water on the slow-release raw material in step 2 and rolling it into slow-release balls, sieving it according to the required particle size, and then uniformly wrapping it with the resisting raw material and spraying water on it and rolling it into raw material balls with larger particle size; S4: Place the raw material balls in step 3 in a muffle furnace, heat from room temperature to 200°C at a heating rate of 5°C / min, keep warm for 10 min, heat to 500°C, keep warm for 30 min, heat to 800°C, keep warm for 30 min, heat to 985°C, keep warm for 50 min. Cool naturally to room temperature to obtain a layered metal sustained-release particle electrode.

[0013] Compared with the prior art, the present invention has the following advantages: 1) The layered metal slow-release particle electrode can slowly release the metal source, so that the amount of strong oxidizing substances produced in the system is larger and the distribution is more uniform. The dissolution of metal ions has a catalytic effect, which further improves the catalytic oxidation degradation efficiency of the system, and increases the degradation efficiency of difficult-to-degrade organic matter such as tetracycline by 10%-30%; 2) Due to the different ratios of the inner and outer layer pore formers, active ingredients, etc., the layered metal sustained-release particle electrode has a higher porosity and catalytic active sites than ordinary particle electrodes while ensuring the hardness and strength of the particle electrode. It has stronger adsorption than natural minerals, and the release concentration is controllable with a certain degree of flexibility, which can maintain the dynamic balance of metal ion concentration in the solution for a long time; 3) Layered metal sustained-release particle electrodes can provide the metal source required for biomineralization, simplify material engineering, improve electron transfer means, improve biocompatibility, and enhance the system's electron transfer efficiency; 4) With the continuous release and utilization of metal ions, the pore structure of the material is further enriched, the specific surface area and adsorption capacity increase accordingly, and the space for microbial growth increases; 5) The preparation process, storage conditions, and recycling method of the layered metal sustained-release particle electrode are simple and have good performance; 6) The source of materials is easy to obtain, and waste can be treated by waste, which reduces the material cost in the preparation process of particle electrodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A single-layer three-view diagram of a layered metal sustained-release particle electrode of the present invention; Figure 2 A multi-layer three-view diagram of a layered metal sustained-release particle electrode of the present invention; Figure 3 A single-layer AA cross-sectional view of a layered metal sustained-release particle electrode of the present invention; Figure 4 A multi-layer BB cross-sectional view of a layered metal sustained-release particle electrode of the present invention; Figure 5 This is a diagram showing the sustained release effect of a layered metal sustained release particle electrode of the present invention; Figure 6 This is a diagram showing the degradation effect of a layered metal slow-release particle electrode of the present invention; Figure 7 The present invention is a layered metal sustained-release particle electrode biosynthesized nanoparticle Figure 1 ; Figure 8 The present invention is a layered metal sustained-release particle electrode biosynthesized nanoparticle Figure 2 . DETAILED DESCRIPTION

[0015] The following are specific embodiments of the present invention and are combined with the attached Figure 1-8 , the technical solution of the present invention is further described, but the present invention is not limited to these embodiments. Specific implementation method (I) The present invention provides a single-layered metal slow-release particle electrode, comprising lithium slag as an aggregate, starch as a pore-forming agent, nano-bentonite as a binder, and ferric oxide powder as an active ingredient: 1. Crush the lithium slag into powder, wash it in tap water to remove impurities, then wash it three times with deionized water, and dry it in an oven at 110℃. Take out the dried lithium slag and crush it with a ball mill or a crusher, then put it in a box after drying it through 200 mesh. Purchase sodium bentonite with mesh size of 200 or above, analytical grade water-soluble starch, and high purity (99.9%) ferric oxide powder with mesh size of 200 or above; 2. The lithium slag, sodium bentonite, starch, and ferric oxide powder in step 1 are weighed according to a mass percentage of 45:25:10:20, mixed evenly by a blender, and prepared as a slow-release raw meal; they are weighed according to a mass percentage of 55:30:10:5, mixed evenly by a blender, and prepared as a resisted-release raw meal; 3. The slow-release raw material in step 2 is sprayed with water and rolled into a 5 mm slow-release ball 1, and then uniformly wrapped with the resisting-release raw material to form a resisting-release layer 2, and sprayed with water and rolled into a single-layer raw material ball with a particle size of 7 mm; 4. Put the raw material balls in step 3 into a 200ml ceramic crucible and place it in a muffle furnace. Heat the temperature from room temperature to 200℃ at a heating rate of 5℃ / min, keep it warm for 10min, then heat it to 500℃, keep it warm for 30min, heat it to 800℃, keep it warm for 30min, then heat it to 985℃, keep it warm for 45min. Cool it naturally to room temperature to obtain a single-layer metal sustained-release particle electrode (attached Figure 1 , 3 ). Specific implementation method (II) The present invention provides a multi-layered metal slow-release particle electrode, comprising lithium slag as an aggregate, starch as a pore-forming agent, nano-bentonite as a binder, and ferric oxide powder as an active ingredient: 1. Crush the lithium slag into powder, wash it in tap water to remove impurities, then wash it three times with deionized water, and dry it in an oven at 110°C. Take out the dried lithium slag and grind it in a ball mill or crusher, then pack it for use after passing through 200 mesh and drying. Purchase sodium bentonite with mesh size of 200 or above, analytical grade water-soluble starch, and high purity (99.9%) ferric oxide powder with mesh size of 200 or above; 2. The lithium slag, sodium bentonite, starch, and ferric oxide powder in step 1 are weighed according to a mass percentage of 45:25:10:20, mixed evenly by a blender, and prepared as a slow-release raw meal; they are weighed according to a mass percentage of 55:30:10:5, mixed evenly by a blender, and prepared as a resisted-release raw meal; 3. Spray water on the slow-release raw material in step 2 and roll it into a 2 mm slow-release ball 1, then evenly wrap it with the slow-release raw material to form a slow-release layer 2, spray water and roll it into a particle size of 4 mm, then wrap it with the slow-release raw material to form a slow-release layer 1, to 6 mm, and finally wrap the slow-release raw material to form a slow-release layer 2 to 8 mm, forming a multi-layer raw material ball; 4. Put the raw material balls in step 3 into a 200ml ceramic crucible and place it in a muffle furnace. Heat the temperature from room temperature to 200℃ at a heating rate of 5℃ / min, keep it warm for 10min, then heat it to 500℃, keep it warm for 30min, then heat it to 800℃, keep it warm for 30min, then heat it to 990℃, keep it warm for 50min. Cool it naturally to room temperature to obtain a multilayered metal sustained-release particle electrode (attached Figure 2 , 4 ). Specific implementation method (III) The present invention provides a single-layered metal slow-release particle electrode, including red mud as an aggregate, starch as a pore-forming agent, nano-bentonite as a binder, and ferric sulfate solution as an active ingredient: 1. Crush the blocky red mud into powder, wash it in tap water to remove impurities, then wash it three times with deionized water, and dry it in an oven at 110°C. Take out the dried red mud and grind it in a ball mill or pulverizer, pass it through 200 mesh, and then pack it for use after drying. Purchase sodium bentonite with a mesh size of more than 200, analytical grade water-soluble starch, and ferric sulfate solution; 2. The red mud, sodium bentonite, starch, and ferric sulfate solution in step 1 are weighed according to the mass percentage of 42.5:22.5:15:20, the solid materials are mixed evenly by a stirrer, and impregnated into the ferric sulfate solution to maximize its load. After the impregnation is completed, it is placed in a 55° oven for drying to prepare a slow-release raw meal; according to the mass percentage of 55:30:10:5, the solid materials are mixed evenly by a stirrer, impregnated into the ferric sulfate solution, and after the impregnation is completed, it is placed in a 55° oven for drying to prepare a resisted-release raw meal; 3. The slow-release raw material in step 2 is sprayed with water and rolled into 3 mm slow-release balls 1, and then uniformly wrapped with the resisting-release raw material to form a resisting-release layer 2, and sprayed with water and rolled into single-layer raw material balls with a particle size of 7 mm; 4. The raw material balls in step 3 were placed in a 200 ml ceramic crucible and placed in a muffle furnace. The temperature was raised from room temperature to 200°C at a heating rate of 5°C / min, and kept for 10 min. The temperature was then raised to 500°C and kept for 30 min. The temperature was then raised to 800°C and kept for 30 min. The temperature was then raised to 985°C and kept for 45 min. The mixture was naturally cooled to room temperature to obtain a monolayer metal sustained-release particle electrode.

[0019] The sustained-release experiment showed that the layered metal sustained-release particle electrode in Example 1 released iron ions slowly in 0-21 hours. In 0-9 hours, the iron ion concentration in the solution increased at a rate of 0.15 mg / L·h; in 9-21 hours, the iron ion concentration in the solution increased at a rate of 0.03 mg / L·h; after 24 hours, the total iron ion concentration fluctuated around 2.0 mg / L, reaching a dynamic-adsorption-slow-release equilibrium (attached Figure 5 ). The layered metal slow-release particle electrodes of Examples 2 and 3 have the same change trend. With the changes in the pore-forming agent and the content of active ingredients, the concentration of the slowly released metal ions is 0.2-6.5 mg / L. According to the adsorption experiment test, the equilibrium adsorption capacity of the layered metal slow-release particle electrode component for tetracycline is about 0.5-1.4 mg / g without the addition of adsorbent. The particle electrode is replaceable, and the dosage of the particle electrode can be adjusted according to the required metal ion concentration. The layered metal slow-release particle electrode of Example 1 was put into the three-dimensional electrocatalytic biofilm system and started to run for a total of 15 days. The average removal rate of tetracycline hydrochloride reached 43.71%, which was 18.74% higher than the average removal rate of the system with ordinary particle electrodes, and the average removal rate in 20 days was increased by 27.66% (see Appendix). Figure 6 The nanoparticles synthesized in the system were characterized by SEM and TEM (attached Figure 7 , 8 ), the measurement using an electrochemical workstation showed that the system's electron transfer efficiency was improved and the layered metal sustained-release particle electrode had good electrocatalytic properties.

[0020] The above contents are further detailed descriptions of the present invention in combination with specific implementations, but do not mean that the specific implementations of the present invention are limited to these examples. For ordinary technicians in the field of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A method for preparing a layered metal slow-release particle electrode, characterized in that: The preparation materials include aggregate, binder, pore former and active ingredient. The layered metal slow-release particle electrode is divided into a slow-release layer and a resistive layer. The ratio of the materials contained in the slow-release layer and the resistive layer can be flexibly adjusted. The thickness and number of layers of the slow-release layer and the resistive layer can be flexibly adjusted according to demand. The types of materials contained in the slow-release layer and the resistive layer can be different and can be flexibly adjusted according to demand.

2. The method for preparing a layered metal slow-release particle electrode according to claim 1, characterized in that: The aggregates are lithium slag, red mud and other industrial waste slag and tailings slag whose main components are SiO2, Al2O3 and some metals and their oxides; the binders are bentonite, montmorillonite, kaolin, clay and the like, which have adsorptive and adhesive properties; the pore-forming agents are starch, glucose and other materials that can be sintered into pores; the active ingredients are solid or liquid materials of iron or copper, such as ferric oxide powder, copper oxide powder, ferric nitrate solution, ferric sulfate solution, copper nitrate solution, copper sulfate solution and the like.

3. The method for preparing a layered metal slow-release particle electrode according to claim 1, characterized in that: The layered metal slow-release particle electrode can be single-layered, that is, the inside is a slow-release layer and the outside is a resistance-release layer, and its thickness can be flexibly adjusted so that the particle size of the inner slow-release layer before sintering is 2~5mm, and the particle size of the outer resistance-release layer is wrapped. The overall layered metal slow-release particle electrode particle size before sintering is 5~8mm; the layered metal slow-release particle electrode can be multi-layered, that is, the innermost layer is a slow-release layer, which is wrapped with a resistance-release layer, then covered with a slow-release layer, and then wrapped with a resistance-release layer, and so on; the innermost layer must be a slow-release layer, and the outermost layer must be a resistance-release layer; the thickness ratio of the slow-release layer to the resistance-release layer can be (1~1.5): (1~1.5), and the particle size of the multi-layered slow-release particle electrode before sintering can be 5~8mm.

4. The method for preparing a layered metal slow-release particle electrode according to claim 1, characterized in that: In the sustained-release layer material of the layered metal sustained-release particle electrode, the mass ratio of aggregate, binder, pore former and active ingredient can be (35-50): (20-30): (5-20): (15-35); in the barrier-release layer material of the layered metal sustained-release particle electrode, the mass ratio of aggregate, binder, pore former and active ingredient can be (40-60): (30-40): (5-10): (5-10).

5. The method for preparing a layered metal sustained-release particle electrode according to claim 1, when the active ingredient is solid, the preparation method comprises the following steps: S1: The aggregate is crushed in a crusher, washed in tap water to remove impurities, then washed with deionized water for more than three times, and dried in an oven at 110°C; S2: weighing the aggregate, binder, pore former and active ingredient in step 1 according to a certain mass percentage, putting them into a blender and mixing them evenly to obtain a slow-release raw material and a delayed-release raw material; S3: spraying water on the slow-release raw material in step 2 and rolling it into slow-release balls, sieving it according to the required particle size, and then uniformly wrapping it with the resisting raw material and spraying water on it and rolling it into raw material balls with larger particle size; S4: Place the raw material balls in step 3 in a muffle furnace, heat from room temperature to 200°C at a heating rate of 5°C / min, keep warm for 10 min, heat to 500°C, keep warm for 30 min, heat to 800°C, keep warm for 30 min, heat to 985°C, keep warm for 50 min. Cool naturally to room temperature to obtain a layered metal sustained-release particle electrode.

6. The method for preparing a layered metal sustained-release particle electrode according to claim 1, when the active ingredient is a liquid, the preparation method comprises the following steps: S1: The aggregate is crushed in a crusher, washed in tap water to remove impurities, then washed with deionized water for more than three times, and dried in an oven at 110°C; S2: The aggregate, binder, pore former and active ingredient in step 1 are weighed according to a certain mass percentage, wherein the mass of the active ingredient is the mass of the metal ion, and the active ingredient is dissolved into a solution of a certain concentration so as to maximize the loading amount, and the material is impregnated by an impregnation method, and after a certain period of time, it is placed at 40-60°C for low temperature drying to obtain a slow-release raw material and a delayed-release raw material; S3: spraying water on the slow-release raw material in step 2 and rolling it into slow-release balls, sieving it according to the required particle size, and then uniformly wrapping it with the resisting raw material and spraying water on it and rolling it into raw material balls with larger particle size; S4: Place the raw material balls in step 3 in a muffle furnace, heat from room temperature to 200°C at a heating rate of 5°C / min, keep warm for 10 min, heat to 500°C, keep warm for 30 min, heat to 800°C, keep warm for 30 min, heat to 985°C, keep warm for 45 min. Cool naturally to room temperature to obtain a layered metal sustained-release particle electrode.

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