A clay mineral-based composite material, and a method for preparing and using the same

Abstract

The present application belongs to the technical field of waste liquid treatment, and particularly relates to a clay mineral-based composite material and a preparation method and application thereof. The present application takes clay minerals as a base material, has the advantages of low cost, and has higher mechanical strength, which can further improve the structural stability of the composite material. By adding a pore-forming agent, a porous structure can be generated in the composite material, which increases the effective contact area between the composite material and pollutants, increases the mass transfer capacity of the composite material, and increases the effective active area of the composite material. By doping active nanometer carbon dots in the composite material, the composite material has the ability to catalyze the electrochemical oxidation of ammonia nitrogen, which can further improve the removal efficiency of ammonia nitrogen in wastewater. The composite material obtained by the present application not only has excellent mechanical properties and durability, but also has more excellent electric flocculation performance, and has a broad development prospect in the field of treating ammonia nitrogen and high-COD wastewater.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of waste liquid treatment, and particularly relates to a clay mineral-based composite material and a preparation method and application thereof. BACKGROUND

[0002] Electrocoagulation is an important water treatment technology commonly used for treating high chemical oxygen demand (COD) wastewater. In electrocoagulation systems, metal aluminum or iron is usually selected as the anode. Under the action of an electric field, the metal electrode generates metal cationic flocculants, and the flocculation of metal flocculants causes the coagulation and suspension of solid particles, suspended solids and colloidal substances in wastewater, thereby separating pollutants from the water body.

[0003] Electrocoagulation has many advantages. First, it is very effective in removing organic matter, colloids and heavy metals in high-COD wastewater. Second, this technology can achieve efficient purification in a short time and reduce the COD content. In addition, electrocoagulation can be used to treat different types of wastewater, including industrial wastewater and municipal wastewater, so it has a wide application prospect. However, traditional metal electrodes have the disadvantages of high cost, small effective active area and poor chemical stability. SUMMARY

[0004] The purpose of the present application is to provide a clay mineral-based composite material and a preparation method and application thereof. The clay mineral-based composite material provided by the present application has low cost, large effective active area and excellent chemical stability.

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

[0006] The present application provides a preparation method of a clay mineral-based composite material, comprising the following steps:

[0007] Electrochemically exfoliating biomass charcoal to obtain a nanometer carbon dot dispersion liquid;

[0008] Mixing the nanometer carbon dot dispersion liquid, clay mineral, conductive material, pore-forming agent dispersion liquid and water, and then granulating to obtain a pre-product;

[0009] Roasting the pre-product to obtain the clay mineral-based composite material.

[0010] Preferably, the process of electrochemical exfoliation comprises:

[0011] Placing two pieces of biomass charcoal in a liquid electrolyte for electrochemical exfoliation;

[0012] The liquid electrolyte comprises water;

[0013] The ratio of the amount of each piece of biomass charcoal to the liquid electrolyte is 50g: 700-1500mL.

[0014] The conditions of the electrochemical exfoliation include: the distance between the two pieces of biomass char is 3-8 cm; the voltage is 4-8 V, the current density is 0.8-1.2 mA / cm 2 , and the time is 4-6 days.

[0015] Preferably, the clay mineral includes one or more of shale powder, montmorillonite and illite.

[0016] Preferably, the conductive material includes a conductive fiber material.

[0017] The conductive fiber material includes a metal fiber or a non-metal fiber.

[0018] The length of the conductive fiber material is 3-5 mm, and the diameter is 8-13 μm.

[0019] Preferably, the preparation method of the pore-forming agent dispersion liquid includes:

[0020] Mixing the biomass and the alkali solution to perform a liquid phase reaction to obtain a reaction feed liquid;

[0021] Centrifuging the reaction feed liquid, and the obtained upper liquid is the pore-forming agent dispersion liquid.

[0022] The concentration of the alkali solution is 1.5-2 mol / L.

[0023] The mass ratio of the biomass to the alkali solution is 5:8.

[0024] The temperature of the liquid phase reaction is 50-80℃, and the time is 40-60 min.

[0025] The rotation speed of the centrifugation is 4000-5000 rpm, and the time is 15-20 min.

[0026] The mass concentration of the pore-forming agent dispersion liquid is 10-15%.

[0027] Preferably, the concentration of the nanometer carbon dot dispersion liquid is 10-18 mg / mL.

[0028] The mass ratio of the nanometer carbon dot dispersion liquid, the clay mineral, the conductive material, the pore-forming agent dispersion liquid and water is 2-4:4-7:2-3:1-2:3-5.

[0029] Preferably, the particle size of the pre-product is 1-2 cm.

[0030] Preferably, the temperature of the calcination is 600-800℃, the time is 80-120 min, and the pressure is 0.1-0.15 MPa.

[0031] The application further provides the clay mineral-based composite material prepared by the preparation method.

[0032] The application further provides application of the clay mineral-based composite material in treatment of ammonia-nitrogen waste liquid and high COD value waste liquid.

[0033] The application provides a preparation method of a clay mineral-based composite material, including the following steps: electrochemically peeling biomass charcoal to obtain a nano-carbon dot dispersion liquid; mixing the nano-carbon dot dispersion liquid, a clay mineral, a conductive material, a pore-forming agent dispersion liquid and water, and then granulating to obtain a pre-product; and roasting the pre-product to obtain the clay mineral-based composite material.

[0034] The application has the advantages of low cost and high mechanical strength, and can further improve the structural stability of the composite material; the addition of the pore-forming agent can generate a porous structure in the composite material, improve the effective contact area between the composite material and pollutants, increase the mass transfer capacity of the composite material, and increase the effective active area of the composite material; the doping of active nano-carbon dots in the composite material has the ability to catalyze the electrochemical oxidation of ammonia-nitrogen, and can further improve the removal efficiency of ammonia-nitrogen in wastewater. The composite material obtained by the application not only has excellent mechanical properties and durability, but also has excellent electric flocculation performance, and has a broad development prospect in the field of treatment of ammonia-nitrogen and high COD wastewater. Meanwhile, the preparation method provided by the application has the advantages of simple process, simple operation and high production efficiency, and is suitable for industrial production. DETAILED DESCRIPTION

[0035] The application provides a preparation method of a clay mineral-based composite material, including the following steps:

[0036] The biomass charcoal is electrochemically peeled to obtain a nano-carbon dot dispersion liquid.

[0037] The nano-carbon dot dispersion liquid, a clay mineral, a conductive material, a pore-forming agent dispersion liquid and water are mixed and then granulated to obtain a pre-product.

[0038] The pre-product is roasted to obtain the clay mineral-based composite material.

[0039] In the application, all the preparation raw materials are commercially available products well known to those skilled in the art, unless otherwise specified.

[0040] The biomass charcoal is electrochemically peeled to obtain a nano-carbon dot dispersion liquid.

[0041] In the present application, the biomass charcoal is preferably prepared by a preparation method, which preferably comprises: subjecting biomass to a carbonization treatment to obtain the biomass charcoal.

[0042] In the present application, the biomass preferably comprises residual sludge and / or straw. In the present application, the pressure of the carbonization treatment is preferably 0.1-0.15 MPa. In the present application, the temperature of the carbonization treatment is preferably 600-800℃; the heating rate for heating to the carbonization temperature is preferably 10-40℃ / min; and the holding time is preferably 80-120 min. In the present application, the carbonization treatment is preferably carried out in a nitrogen atmosphere. In the present application, the carbonization treatment is preferably carried out in a tube furnace; and the addition amount of the biomass is preferably 70-100 g.

[0043] In the present application, the process of the electrochemical exfoliation preferably comprises: electrochemically exfoliating two pieces of biomass charcoal in a liquid electrolyte.

[0044] In the present application, the liquid electrolyte preferably comprises water; and the ratio of the amount of each piece of biomass charcoal to the amount of liquid electrolyte is preferably 50 g: 700-1500 mL. In the present application, the conditions of the electrochemical exfoliation preferably comprise: a distance between the two pieces of biomass charcoal of 3-8 cm; a voltage of 4-8 V, a current density of 0.8-1.2 mA / cm 2 , and a time of 4-6 days.

[0045] After the electrochemical exfoliation, the present application further preferably comprises filtering and centrifuging the obtained slurry, and recording the supernatant obtained by centrifugation as a nanometer carbon dot dispersion liquid. In the present application, the centrifugation is preferably carried out at a speed of 4000-5000 rpm for 15-20 min.

[0046] In the present application, the concentration of the nanometer carbon dot dispersion liquid is preferably 10-18 mg / mL.

[0047] After obtaining the nanometer carbon dot dispersion liquid, the present application granulates a mixture of the nanometer carbon dot dispersion liquid, a clay mineral, an electrically conductive material, a pore-forming agent dispersion liquid, and water to obtain a pre-product.

[0048] In the present application, the clay mineral preferably comprises one or more of shale powder, montmorillonite, and illite.

[0049] In the present application, the conductive material preferably comprises a conductive fiber material; the conductive fiber material preferably comprises metal fibers or non-metal fibers; the metal fibers preferably comprise one or more of iron fibers, aluminum fibers and copper fibers; the non-metal fibers preferably comprise graphite fibers and / or lead oxide fibers. In the present application, the length of the conductive fiber material is preferably 3-5 mm, and the diameter is preferably 8-13 microns. In the present application, by blending metal fibers into clay minerals, a continuous conductive network can be formed in the composite material, not only ensuring the electrical conductivity of the composite material, but also further improving the mechanical properties and corrosion resistance of the composite material; in addition, the aluminum fibers or iron fibers therein can form an electric flocculation reaction system to further remove COD in wastewater.

[0050] In the present application, the pore-forming agent dispersion liquid is preferably prepared by a preparation method, which preferably comprises: mixing biomass and alkali liquor to perform liquid phase reaction to obtain a reaction liquor; centrifuging the reaction liquor to obtain the pore-forming agent dispersion liquid.

[0051] In the present application, the biomass preferably comprises residual sludge and / or straw. Before the mixing, the present application further preferably comprises pretreating the biomass, and the pretreatment preferably comprises crushing and dewatering. In the present application, the alkali liquor preferably comprises a NaOH solution; the concentration of the alkali liquor is preferably 1.5-2 mol / L. In the present application, the mass ratio of the biomass to the alkali liquor is preferably 5:8. In the present application, the temperature of the liquid phase reaction is preferably 50-80℃, and the time is preferably 40-60 min. In the present application, the rotation speed of the centrifugation is preferably 4000-5000 rpm, and the time is preferably 15-20 min.

[0052] In the present application, the mass concentration of the pore-forming agent dispersion liquid is preferably 10-15%.

[0053] In the present application, the mass ratio of the nanometer carbon dot dispersion liquid, the clay mineral, the conductive material, the pore-forming agent dispersion liquid and water is 2-4:4-7:2-3:1-2:3-5. In the present application, the volume of the nanometer carbon dot dispersion liquid is preferably 40-60% of the volume of water.

[0054] The present application does not have special limitations on the granulation process, and any process known to those skilled in the art can be used. In the present application, the particle size of the pre-product is preferably 1-2 cm.

[0055] After obtaining the pre-product, the present application calcines the pre-product to obtain the clay mineral-based composite material.

[0056] In the present application, the temperature of the calcination is preferably 600-800℃, the temperature rising rate to the calcination temperature is preferably 10-40℃ / min; the time is preferably 80-120min, and the pressure is preferably 0.1-0.15MPa. In the present application, the calcination is preferably carried out in a nitrogen atmosphere; the flow rate of the nitrogen is preferably 250-300mL / min. In the present application, the calcination is preferably carried out in a tube furnace; the addition amount of the pre-product is preferably 90-120g. In the present application, the clay-like substance produces ceramsite during the calcination.

[0057] The present application also provides a clay-like mineral-based composite material prepared by the preparation method described in the above technical solution, which comprises a clay-like mineral matrix and conductive material and nano-carbon dots loaded on the clay-like mineral matrix.

[0058] In the present application, the loading mass percentage of the conductive material is preferably 10-20%; and the loading mass percentage of the nano-carbon dots is preferably 20-30%.

[0059] The present application also provides the application of the clay-like mineral-based composite material described in the above technical solution as an electrode material in the treatment of ammonia-nitrogen waste liquid and high-COD-value waste liquid. The present application does not have special limitations on the specific implementation mode of the application, and the application of the present application is well known to those skilled in the art.

[0060] In order to further illustrate the present application, the clay-like mineral-based composite material, its preparation method and application provided by the present application are described in detail below in combination with examples, but they should not be understood as limitations on the protection scope of the present application.

[0061] Example 1

[0062] 100g of residual sludge was placed in a tube furnace, the gas cylinder pressure was adjusted to 0.1MPa, the temperature control program of the tube furnace was set, and the nitrogen atmosphere was maintained during carbonization, and the temperature was raised to 800℃ at a temperature rising rate of 10℃ / min, and the temperature was kept for 120min to obtain biomass charcoal;

[0063] Two pieces of 50g biomass charcoal were placed in 700mL water, the distance between the two pieces of biomass charcoal was 5cm, and the electrochemical stripping was carried out under the conditions of a voltage of 6V and a current density of 1.0mA / cm 2 for 5 days; then the obtained uniform dark yellow solution was filtered and centrifuged at a speed of 5000rpm for 15min, and the upper layer solution was taken as the nano-carbon dot dispersion liquid with a concentration of 10mg / mL;

[0064] The residual sludge was pretreated, mixed with 5:8 liquid-solid ratio and 1.5 mol / L NaOH solution, and then reacted in liquid phase at 50°C for 40 min. The obtained slurry was centrifuged at 5000 rpm for 15 min to remove the precipitate, and the supernatant was obtained as the pore-forming agent dispersion liquid with a concentration of 13%;

[0065] 50 g of shale powder, 30 g of aluminum fiber (length 5 mm, diameter 13 μm), 15 mL of pore-forming agent dispersion liquid, 40 mL of water, and 20 mL of nano-carbon point dispersion liquid were weighed and mixed. The mixed material was granulated by a granulator to obtain a pre-product with a particle size of 1 cm;

[0066] 120 g of the obtained pre-product was placed in a tube furnace, the gas cylinder pressure was adjusted to 0.1 MPa, the nitrogen flow was controlled at 300 mL / min, the temperature was raised to 600°C at a rate of 10°C / min, and the pre-product was calcined for 120 min to obtain the clay mineral composite material.

[0067] In the electrolytic cell, graphite plate was used as anode and copper plate as cathode, and the size of the electrode plate was 150 mm x 100 mm x 3 mm. 120 g of the clay mineral composite material and 800 mL of domestic sewage (the initial pollution index of domestic sewage was: COD = 313.15 mg / L, NH4 + -N = 42.28 mg / L) were added into the electrolytic cell. MS-603D type direct current stabilized power supply was used to provide 8V voltage for the electrolytic cell system, at this time, the current density of the electrolytic cell system was 0.83 mA / cm 2 After 60 min of treatment with the electrolytic system, the pollution index was measured as: COD = 78.24 mg / L, NH4 + -N = 16.79 mg / L. Therefore, the removal rate of COD was 75.01%, and the removal rate of NH4 + -N was 60.28%.

[0068] Example 2

[0069] 100 g of residual sludge was placed in a tube furnace, the gas cylinder pressure was adjusted to 0.1 MPa, the temperature control program of the tube furnace was set, and the nitrogen atmosphere was maintained during carbonization. The temperature was raised to 800°C at a rate of 10°C / min, and the biomass carbon was obtained after carbonization for 120 min;

[0070] Two pieces of 50 g of biomass carbon were placed in 700 mL of water, the distance between the two pieces of biomass carbon was 5 cm, the voltage was 6V, and the current density was 1.0 mA / cm 2Electrochemical stripping was performed under the following conditions for 5 days. The resulting uniform dark yellow solution was then filtered and centrifuged at 5000 rpm for 15 minutes. The supernatant solution was taken as the nano-carbon dot dispersion with a concentration of 10 mg / mL.

[0071] After pretreatment of activated sludge, it was mixed with a 1.5 mol / L NaOH solution at a liquid-to-solid ratio of 5:8. The mixture was then subjected to a liquid-phase reaction at 50°C for 40 min. The resulting liquid was then centrifuged at 5000 rpm for 15 min to remove the precipitate. The resulting supernatant was the pore-forming agent dispersion with a concentration of 13%.

[0072] Weigh out 80g of shale powder, 20g of iron fiber (5mm in length and 13μm in diameter), 15mL of pore-forming agent dispersion, 40mL of water and 20mL of nano carbon dot dispersion, mix them together, and granulate the mixture through a granulator to obtain a pre-product with a particle size of 2cm.

[0073] 120g of the obtained preproduct was placed in a tube furnace, the gas cylinder pressure was adjusted to 0.1MPa, the nitrogen flow rate was controlled at 300mL / min, and the temperature was raised to 800℃ at a heating rate of 10℃ / min for calcination. The temperature was held for 120min to obtain the clay mineral composite material.

[0074] Graphite plates were used as the anode and copper plates as the cathode in the electrolytic cell. The electrode plates were both 150mm × 100mm × 3mm in size. 120g of clay-based mineral composite material and 800mL of domestic sewage (initial pollution indicators for the domestic sewage were: COD = 313.15mg / L, NH4+) were added to the electrolytic cell. + -N = 42.28 mg / L). An MS-603D DC regulated power supply was used to provide 8V to the electrolytic cell system. At this voltage, the current density of the electrolytic cell system was 0.74 mA / cm². 2 After treatment with this electrolysis system for 60 minutes, the pollution indicators were measured as follows: COD = 90.27 mg / L, NH4+ = 0.27 mg / L. + -N = 19.09 mg / L. Therefore, the COD removal rate is 73.17%, and NH4+... + -N removal rate was 54.85%.

[0075] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for producing a clay mineral-based composite material, characterized by, The method comprises the following steps: The biomass charcoal is subjected to electrochemical exfoliation to obtain a nanometer carbon dot dispersion liquid; the concentration of the nanometer carbon dot dispersion liquid is 10-18 mg / mL; The nanometer carbon dot dispersion liquid, clay mineral, conductive material, pore-forming agent dispersion liquid and water are mixed to obtain a pre-product; The conductive material is metal fiber; The pore-forming agent dispersion liquid is prepared by mixing biomass and alkali liquor to perform liquid phase reaction to obtain a reaction liquid; the reaction liquid is subjected to centrifugation, and the obtained upper liquid is the pore-forming agent dispersion liquid; the mass ratio of the nanometer carbon dot dispersion liquid, clay mineral, conductive material, pore-forming agent dispersion liquid and water is 2-4:4-7:2-3:1-2:3-5; The pre-product is subjected to calcination to obtain the clay mineral-based composite material; the calcination temperature is 600-800 DEG C, the time is 80-120 min, and the pressure is 0.1-0.15 MPa; The loading mass percentage of nanometer carbon dots on the clay mineral-based composite material is 20-30%; The clay mineral-based composite material is used as electrode material for electrocoagulation to treat ammonia-nitrogen waste liquid and high COD value waste liquid.

2. The production method according to claim 1, characterized by, The process of electrochemical exfoliation comprises: Two pieces of biomass charcoal are placed in a liquid electrolyte to perform electrochemical exfoliation; The liquid electrolyte comprises water; The dosage ratio of each piece of biomass charcoal to liquid electrolyte is 50 g:700-1500 mL; The conditions of the electrochemical exfoliation include: the distance between the two pieces of biomass char is 3-8 cm; the voltage is 4-8 V, the current density is 0.8-1.2 mA / cm 2 , and the time is 4-6 days.

3. The preparation method according to claim 1, characterized in that, The clay mineral comprises one or more of shale powder, montmorillonite and illite.

4. The method of claim 1, wherein, The length of the conductive material is 3-5 mm, and the diameter is 8-13 μm.

5. The preparation method according to claim 1, characterized in that, The concentration of the alkali liquor is 1.5-2 mol / L; The mass ratio of biomass to alkali liquor is 5:8; The temperature of the liquid phase reaction is 50-80 DEG C, and the time is 40-60 min; The rotation speed of the centrifugation is 4000-5000 rpm, and the time is 15-20 min; The mass concentration of the pore-forming agent dispersion liquid is 10-15%.

6. The method of claim 1, wherein, The particle size of the pre-product is 1-2 cm.

7. The clay mineral-based composite material produced by the production process according to any one of claims 1 to 6, characterized by The clay mineral-based composite material comprises a clay mineral matrix and conductive material and nanometer carbon dots loaded on the clay mineral matrix.

8. The use of the clay mineral-based composite material of claim 7 as electrode material for treating ammonia-nitrogen waste liquid and high COD value waste liquid.