River and lake sediment dehydration electrode as well as preparation method and application thereof

Abstract

The invention discloses a river and lake sediment dehydration electrode and a preparation method and application thereof, and belongs to the technical field of environmental electrochemistry. The preparation method comprises the following steps: carrying out acid soaking treatment on plant-derived biomass charcoal to obtain modified biomass charcoal; and mixing the modified biomass charcoal, piezoelectric nanoparticles and an electrode, and carrying out hydrothermal reaction to obtain the river and lake sediment dehydration electrode. The invention also discloses the river and lake sediment dehydration electrode prepared by the method and application thereof. The river and lake sediment dehydration electrode can improve the deep dehydration efficiency, shorten the deep dehydration process flow and reduce the large-scale application cost, and has wide application prospects.

Description

Technical Field

[0001] This invention belongs to the field of environmental electrochemistry technology, specifically relating to a dewatering electrode for river and lake sediments, its preparation method, and its application. Background Technology

[0002] With rapid industrialization and urbanization, pollution of river and lake sediments has become increasingly serious. Currently, sediment dewatering mainly relies on mechanical dewatering, chemical conditioning, and thermal drying technologies. However, these methods generally suffer from low dewatering efficiency, high costs of exogenous chemicals, and high energy consumption. Therefore, the harmless treatment and resource utilization of sediments have become a key focus and challenge in urban water environment management and aquatic ecosystem restoration.

[0003] Piezoelectric technology, as an emerging method, has seen little reporting and application in the deep dewatering of river and lake sediments. Piezoelectric technology enhances electrode polarization, allows for the regulation of the zeta potential on the electrode surface, and strengthens the release of water molecules from the diffusion layer on sediment particles. However, the application of piezoelectric technology in sediment dewatering still faces several key challenges: 1) The activity of single piezoelectric materials is interfered with by coexisting components in the sediment, resulting in low charge utilization efficiency and unstable dewatering effects; 2) Composite piezoelectric materials have poor stability and are prone to separation during long-term operation; 3) The operating parameters of the piezoelectric dewatering process are difficult to control; 4) Powdered piezoelectric materials are difficult to recover. These factors severely restrict the engineering promotion of piezoelectric technology in sediment dewatering. How to improve the dewatering efficiency, anti-interference ability, interfacial stability, and process adaptability of piezoelectric catalytic materials, while reducing the cost of large-scale application, remains one of the problems that need to be solved in this field. Summary of the Invention

[0004] The problem to be solved by this invention is to provide an electrode for dewatering river and lake sediments, its preparation method and application, so as to solve the problems of low dewatering efficiency, complex process and harsh operating conditions of river and lake sediments.

[0005] The technical solution adopted to solve the technical problem is to provide a method for preparing a dewatering electrode for river and lake bottom sediment, including the following steps: (1) Plant-derived biochar was subjected to acid soaking treatment to obtain modified biochar; (2) The modified biochar, piezoelectric nanoparticles and electrodes are mixed and subjected to hydrothermal reaction to obtain the dewatering electrode for river and lake bottom sediment.

[0006] The beneficial effects of the above-mentioned technical solution of this invention are as follows: In this invention, acid immersion treatment precisely controls the pore size distribution by etching the surface and pores of plant-derived biochar, so that it forms a graded match with the particle size of piezoelectric nanoparticles. This graded structure forms a spatially confined micro-region in the composite material, inhibiting the aggregation of piezoelectric particles, while promoting charge transfer between the two interfaces, significantly improving the charge transfer efficiency caused by the piezoelectric effect; furthermore, when it is synergistically dehydrated with persulfate, the persulfate can be activated by the active sites on the surface of piezoelectric nanoparticles in the confined space, generating highly active free radicals, thereby achieving efficient dehydration of river and lake sediment.

[0007] Preferably, the plant-derived biochar is obtained by calcining at least one of straw, corn cob and rice straw; the particle size of the plant-derived biochar is >5 μm.

[0008] More preferably, the calcination includes the following steps: placing at least one of straw, corn cob and rice straw in a muffle furnace, heating to 800°C at a heating rate of 5°C / min in an air atmosphere, holding at that temperature for 2 hours, and then naturally cooling to room temperature.

[0009] More preferably, plant-derived biochar is obtained by calcining corn cobs.

[0010] More preferably, the acid soaking time in step (1) is 10~30 min; the acid soaking is carried out with hydrochloric acid with a molar concentration of 0.05~0.20 M.

[0011] More preferably, the acid soaking time in step (1) is 30 min; the acid soaking treatment is carried out with hydrochloric acid with a molar concentration of 0.10M.

[0012] Preferably, the piezoelectric nanoparticles are at least one of MoS2, BaTiO3 and PbTiO3; the particle size of the piezoelectric nanoparticles is <500 nm.

[0013] More preferably, the piezoelectric nanoparticles are PbTiO3.

[0014] More preferably, in step (2), the mass ratio of modified biochar to piezoelectric nanoparticles is 100:1~20; and the total mass of modified biochar and piezoelectric nanoparticles loaded per square centimeter electrode is 0.5~1.0 g.

[0015] More preferably, in step (2), the mass ratio of modified biochar to piezoelectric nanoparticles is 100:15; and the electrode is loaded with a total mass of 0.8 g of modified biochar and piezoelectric nanoparticles per square centimeter.

[0016] Preferably, the hydrothermal reaction temperature in step (2) is 160℃~220℃ and the time is 6~10 h.

[0017] More preferably, in step (2), the ratio of the narrowest pore radius of the modified biochar to the diameter of the piezoelectric nanoparticles after the hydrothermal reaction is 1:1.3~1.7.

[0018] More preferably, the ratio of the diameter of the modified biochar pores at their narrowest point to the diameter of the piezoelectric nanoparticles after hydrothermal reaction in the composite material obtained in step (2) is 1:1.6.

[0019] Preferably, the electrode is a titanium-based ruthenium-iridium electrode with dimensions of 80×80×0.1 mm. 3 .

[0020] The present invention also provides a dewatering electrode for river and lake sediment prepared by the above preparation method.

[0021] This invention also provides the application of the above-mentioned river and lake sediment dewatering electrode in river and lake sediment dewatering.

[0022] Preferably, the application of the river and lake sediment dewatering electrode in river and lake sediment dewatering includes the following steps: Using a dewatering electrode for river and lake sediment as the anode and cathode, and a mixture of river and lake sediment to be treated and persulfate aqueous solution as the electrolyte, voltage is applied to efficiently dewater the river and lake sediment.

[0023] The beneficial effects of the above-mentioned technical solution of this invention are as follows: This invention utilizes the pore size distribution of modified biochar and piezoelectric nanoparticles in the dewatering electrode of river and lake sediment to enhance the piezoelectric effect of piezoelectric nanoparticles in a high water content environment, while enhancing the activation efficiency of persulfate, destroying extracellular polymers in the sediment, releasing bound water, and regulating the Zeta potential on the surface of the composite material in the dewatering electrode of river and lake sediment to remove interstitial water, thereby achieving the purpose of deep dewatering of river and lake sediment and solving the technical problem of low dewatering efficiency of river and lake sediment.

[0024] More preferably, the distance between the anode and cathode plates is 1-5 cm; the water content of the river and lake sediment is >85%; the mass ratio of the river and lake sediment to the persulfate in the persulfate aqueous solution is 100:1-5; the voltage intensity is 0.8-1.6 V; and the dehydration time is 2-10 min.

[0025] More preferably, the distance between the anode and cathode plates is 1 cm; the mass ratio of river / lake sediment to persulfate in the persulfate aqueous solution is 100:3; the voltage intensity is 1.4 V; and the dehydration time is 4 min.

[0026] The present invention has the following beneficial effects: The dewatering electrode for river and lake sediments of this invention is a composite electrode with adjustable pore size distribution, enhanced piezoelectric effect, and activation of persulfate. The electrode uses piezoelectric nanoparticles as its core, supplemented by porous plant-derived biochar with optimized pore size, and a titanium-based ruthenium-iridium electrode as its carrier. By adjusting the pore size of the biochar and the diameter of the piezoelectric nanoparticles, the deformation of the piezoelectric nanoparticles within the carrier pores under an electric field is enhanced, improving piezoelectric performance and avoiding the problem of reduced piezoelectric performance due to limited deformation capacity in high-water-content river and lake sediment environments. The positive charge generated by the electrode is used to regulate the zeta potential on the electrode surface, enhancing the release of water molecules from the diffusion layer on the sediment particle surface; the negative charge is used to activate persulfate, promoting the generation of active species, disrupting the extracellular polymer structure of the sediment particles, releasing bound water, and improving the dewatering and volume reduction efficiency of the sediment. After dewatering using the electrode and method of this invention, the overall water content of the river and lake sediment is reduced from >85% to <40%, with a dewatering rate >45%. Using the river and lake sediment dewatering electrode of the present invention for river and lake sediment dewatering has a low risk of secondary pollution, and the device is simple and easy to implement, providing an efficient solution for efficient dewatering of river and lake sediment. Attached Figure Description

[0027] Figure 1 This is a surface morphology diagram of the composite material in this invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments.

[0029] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but only to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0030] Unless otherwise specified, the methods used in the following embodiments are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following embodiments are commercially available.

[0031] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0032] Example 1 A method for preparing a dewatering electrode for river and lake sediment includes the following steps: (1) Place the corn cob in a muffle furnace and heat it to 800°C at a heating rate of 5°C / min under an air atmosphere. Hold it for 2 hours and let it cool naturally to room temperature. After sieving, plant-derived biochar with a particle size >5 μm is obtained. (2) Plant-derived biochar was soaked in hydrochloric acid with a molar concentration of 0.10 M for 30 min to obtain modified biochar; (3) Modified biochar and PbTiO3 with a particle size <500 nm were mixed evenly at a mass ratio of 100:15 to obtain a composite material. The ratio of the narrowest pore radius of the modified biochar in the composite material to the diameter of the PbTiO3 after hydrothermal reaction was 1:1.6. Then, 0.8 g of the composite material was weighed per square centimeter of titanium-based ruthenium-iridium electrode. The composite material was then compared with a material with a size of 80×80×0.1 mm. 3 The titanium-based ruthenium-iridium electrode is mixed and then subjected to a hydrothermal reaction at 220℃ for 10 h to obtain a dewatering electrode for river and lake bottom sediment.

[0033] In the preparation method of this embodiment, the surface morphology of the composite material obtained in step (3) is as follows: Figure 1 As shown.

[0034] Example 2 A method for preparing a dewatering electrode for river and lake sediment includes the following steps: (1) Place the corn cob in a muffle furnace and heat it to 800°C at a heating rate of 5°C / min under an air atmosphere. Hold it for 2 hours and let it cool naturally to room temperature. After sieving, plant-derived biochar with a particle size >5 μm is obtained. (2) Plant-derived biochar was soaked in hydrochloric acid with a molar concentration of 0.10 M for 10 min to obtain modified biochar; (3) Modified biochar and PbTiO3 with a particle size <500 nm were mixed uniformly at a mass ratio of 100:1 to obtain a composite material. The ratio of the narrowest pore radius of the modified biochar in the composite material to the diameter of the PbTiO3 after hydrothermal reaction was 1:1.3. Then, 0.5 g of the composite material was weighed per square centimeter of titanium-based ruthenium-iridium electrode. The composite material was then compared with a material with a size of 80×80×0.1 mm. 3 The titanium-based ruthenium-iridium electrode is mixed and then subjected to a hydrothermal reaction at 200℃ for 8 hours to obtain a dewatering electrode for river and lake bottom sediment.

[0035] Example 3 A method for preparing a dewatering electrode for river and lake sediment includes the following steps: (1) Place the corn cob in a muffle furnace and heat it to 800°C at a heating rate of 5°C / min under an air atmosphere. Hold it for 2 hours and let it cool naturally to room temperature. After sieving, plant-derived biochar with a particle size >5 μm is obtained. (2) Plant-derived biochar was soaked in hydrochloric acid with a molar concentration of 0.10 M for 20 min to obtain modified biochar; (3) Modified biochar and PbTiO3 with a particle size <500 nm were mixed evenly at a mass ratio of 100:20 to obtain a composite material. The ratio of the narrowest pore radius of the modified biochar in the composite material to the diameter of the PbTiO3 after hydrothermal reaction was 1:1.7. Then, 1 g of the composite material was weighed per square centimeter of titanium-based ruthenium-iridium electrode. The composite material was then combined with a electrode with dimensions of 80×80×0.1 mm. 3 The titanium-based ruthenium-iridium electrode is mixed and then subjected to a hydrothermal reaction at 220℃ for 10 h to obtain a dewatering electrode for river and lake bottom sediment.

[0036] Example 4 A method for preparing a dewatering electrode for river and lake sediments, which differs from the method for preparing a dewatering electrode for river and lake sediments in Example 1, is as follows: corn cobs in step (1) are replaced with straw; the remaining steps and parameters are the same as in Example 1.

[0037] Example 5 A method for preparing a dewatering electrode for river and lake sediments, which differs from the method for preparing a dewatering electrode for river and lake sediments in Example 1, is as follows: the corn cob in step (1) is replaced with rice husk; the remaining steps and parameters are the same as in Example 1.

[0038] Example 6 A method for preparing a dewatering electrode for river and lake sediments, which differs from the method for preparing a dewatering electrode for river and lake sediments in Example 1, is as follows: PbTiO3 in step (3) is replaced with MoS2; the remaining steps and parameters are the same as in Example 1.

[0039] Example 7 A method for preparing a dewatering electrode for river and lake sediments, which differs from the method for preparing a dewatering electrode for river and lake sediments in Example 1, is as follows: PbTiO3 in step (3) is replaced with BaTiO3; the remaining steps and parameters are the same as in Example 1.

[0040] Comparative Example 1 A method for preparing a dewatering electrode for river and lake sediment includes the following steps: (1) Place the corn cob in a muffle furnace and heat it to 800°C at a heating rate of 5°C / min under an air atmosphere. Hold it for 2 hours and let it cool naturally to room temperature. After sieving, plant-derived biochar with a particle size >5 μm is obtained. (2) Plant-derived biochar and PbTiO3 with a particle size <500 nm were mixed evenly at a mass ratio of 100:15 to obtain a composite material; then, 0.8 g of the composite material was weighed per square centimeter of titanium-based ruthenium-iridium electrode, and the composite material was combined with a electrode with dimensions of 80×80×0.1 mm. 3 The titanium-based ruthenium-iridium electrode is mixed and then subjected to a hydrothermal reaction at 220℃ for 10 h to obtain a dewatering electrode for river and lake bottom sediment.

[0041] Experimental Example 1. Analysis of the dewatering effect of different dewatering electrodes on river and lake sediments A persulfate aqueous solution was prepared using a dual-electrode system in a single reaction chamber. The dewatering electrodes for river and lake sediment prepared in Examples 1-7 and Comparative Example 1 were used simultaneously as the cathode and anode, respectively, with a plate spacing of 1 cm. The river and lake sediment to be treated, with a water content of 93.4%, was mixed with the persulfate aqueous solution as the electrolyte. The mass ratio of persulfate in the river and lake sediment to be treated to that in the persulfate aqueous solution was 100:3. The river and lake sediment to be treated originated from Taihu Lake. A voltage of 1.4 V was applied to dewater the river and lake sediment. The dewatering efficiency was analyzed according to CJ / T 221-2005, "Test Method for Sludge from Urban Wastewater Treatment Plants," and the results are shown in Table 1.

[0042] Table 1. Dewatering effect of different dewatering electrodes for river and lake sediments

[0043] As can be seen from the results in Table 1, the dewatering effect of the river and lake sediment dewatering electrode of the present invention reaches its best at 4 min, with high overall dewatering efficiency. This is because the river and lake sediment dewatering electrode of the present invention uses piezoelectric nanoparticles as the core, supplemented by porous plant-derived biochar with optimized pore size, and titanium-based ruthenium-iridium electrode as the carrier. By controlling the pore size of biochar and the diameter of piezoelectric nanoparticles, the deformation of piezoelectric nanoparticles in the carrier pores under electric field drive is enhanced, thereby improving piezoelectric performance and avoiding the problem of reduced piezoelectric performance due to limited deformation ability in high water content river and lake sediment environments. In contrast, the unmodified biochar and piezoelectric nanoparticles fail to form a pore size match, and the dewatering electrode prepared by it has a lower dewatering efficiency.

[0044] 2. Analysis of the dewatering effect of river and lake sediment dewatering electrodes on river and lake sediment under different conditions A persulfate aqueous solution was prepared using a dual-electrode system in a single reaction chamber. The river and lake sediment dewatering electrodes prepared in Examples 1-7 and Comparative Example 1 were used simultaneously as the cathode and anode, respectively, with the electrode spacing controlled at 1 cm. The river and lake sediment to be treated with a water content of 93.4% was mixed with the persulfate aqueous solution as the electrolyte. The mass ratio of persulfate in the river and lake sediment to be treated to that in the persulfate aqueous solution was 100:3. The river and lake sediment to be treated originated from Taihu Lake. Voltages of different intensities were applied to dewater the river and lake sediment for 4 min. The dewatering efficiency was analyzed according to CJ / T 221-2005, "Test Method for Sludge from Urban Wastewater Treatment Plants". The results are shown in Table 2.

[0045] Table 2. Dewatering effect of different dewatering electrodes for river and lake sediments

[0046] As can be seen from the results in Table 2, the dewatering effect of the river and lake sediment dewatering electrode of the present invention can be best at a voltage of 1.4 V, which can achieve efficient dewatering of river and lake sediment and is easy to implement; while the unmodified biochar and piezoelectric nanoparticles failed to form a pore size match, the piezoelectric nanoparticles had a large degree of deformation in the carrier pores, and the dewatering electrode prepared by it had a low dewatering efficiency.

[0047] The present invention has been described according to the above embodiments. It should be understood that the above embodiments do not limit the present invention in any way. All technical solutions obtained by equivalent substitution or equivalent transformation fall within the scope of the present invention.

Claims

1. A method for preparing a dewatering electrode for river and lake bottom sediment, characterized in that, Includes the following steps: (1) Plant-derived biochar was subjected to acid soaking treatment to obtain modified biochar; (2) The modified biochar, piezoelectric nanoparticles and electrodes are mixed and subjected to hydrothermal reaction to obtain the dewatering electrode for river and lake bottom sediment.

2. The method for preparing the dewatering electrode for river and lake sediment as described in claim 1, characterized in that, The plant-derived biochar is obtained by calcining at least one of straw, corn cob, and rice straw; the particle size of the plant-derived biochar is >5μm.

3. The method for preparing the dewatering electrode for river and lake sediment as described in claim 2, characterized in that, The acid soaking time in step (1) is 10~30 min; the acid soaking treatment is carried out with hydrochloric acid with a molar concentration of 0.05~0.20 M.

4. The preparation method of the river and lake sediment dewatering electrode as described in claim 1, characterized in that, The piezoelectric nanoparticles are at least one of MoS2, BaTiO3 and PbTiO3; the particle size of the piezoelectric nanoparticles is <500 nm.

5. The method for preparing the dewatering electrode for river and lake sediment as described in claim 1, characterized in that, In step (2), the mass ratio of modified biochar to piezoelectric nanoparticles is 100:1~20; the electrode load per square centimeter contains 0.5~1.0 g of modified biochar and piezoelectric nanoparticles.

6. The method for preparing the dewatering electrode for river and lake sediment as described in claim 1, characterized in that, In step (2), the hydrothermal reaction temperature is 160℃~220℃ and the time is 6~10 h.

7. A dewatering electrode for river and lake sediment prepared by any one of claims 1 to 6.

8. The application of the river and lake sediment dewatering electrode according to claim 7 in the dewatering of river and lake sediment.

9. The application as described in claim 8, characterized in that, Includes the following steps: Using the river and lake sediment dewatering electrode as described in claim 7 as the anode plate and cathode plate, and using a mixture of river and lake sediment to be treated and persulfate aqueous solution as the electrolyte, voltage is applied to efficiently dewater the river and lake sediment.

10. The application as described in claim 9, characterized in that, The distance between the anode and cathode plates is 1-5 cm; the water content of the river / lake sediment is >85%; the mass ratio of the river / lake sediment to the persulfate in the persulfate aqueous solution is 100:1-5; the voltage intensity is 0.8-1.6 V; and the dehydration time is 2-10 min.

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