A water purifying element, a method for manufacturing the water purifying element, and a water purifier

Abstract

The present application belongs to the technical field of water treatment, and particularly relates to a water purification element, a preparation method of the water purification element and a water purifier. The water purification element is a porous elastic wooden base attached with Fe1Co3-MOFs nanoparticles. The preparation method of the water purification element comprises the following steps: 1) preparing a mixed aqueous solution of Co(NO3)2 and FeCl3; 2) soaking the porous elastic wooden base in the mixed aqueous solution of Co(NO3)2 and FeCl3 for 12-24 hours; 3) preparing a 2-MI aqueous solution with a certain concentration, adding the solution into which the porous elastic wooden base is soaked drop by drop, and stirring for a certain time of 12 hours to obtain a water purification element precursor; and 4) freeze-drying the water purification element precursor to obtain the water purification element, i.e. the porous elastic wooden base attached with Fe1Co3-MOFs nanoparticles. The water purifier is a water purification device in which the water purification element is installed in a five-labyrinth catalytic impeller stirrer. The water purification element has a degradation rate of no less than 92%, a water absorption rate of 40-80 g / g, and a Kobs of no less than 0.8 min ‑1 , and has a fast water purification speed, which can simultaneously meet the urgent needs of water treatment plants for the degradation rate and degradation rate of organic matters.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of water treatment, and particularly relates to a water purification element, a preparation method of the water purification element, and a water purifier using the water purification element. BACKGROUND

[0002] MOFs is a very promising precursor material, and has important application prospects in preparing high-efficiency catalysts for activating PMS. In this regard, it is very popular to develop sustainable, clean and renewable MOFs to activate PMS to remove organic pollutants. Therefore, designing and constructing low-cost MOFs with high catalytic activity and long-term stability is a challenging task in the field of AOPs. These MOFs materials in powder form limit their practical application in the industrial field. In order to solve these problems, many efforts have been made. On the other hand, Co / Fe-MOFs have high surface energy and are easy to aggregate. Therefore, it is necessary to disperse Co / Fe bimetallic MOFs on the scaffold to alleviate the aggregation phenomenon, while overcoming its shortcomings in recycling and practicality, we further grow Fe1Co3-MOFs in situ on biomass matrix to prepare Fe1Co3@BS, which directly integrates functional MOFs into stable, elastic and recyclable biomass-based substrates, which enables the production of 3D MOFs-based materials to maintain their crystallinity, hierarchical porous structure and stability. In particular, due to the special internal structure of the biomass material, functional MOFs can be uniformly dispersed in the internal pores, thereby greatly reducing the occurrence of MOFs aggregation and powder loss. SUMMARY

[0003] Based on the deficiencies of the prior art, the technical problem to be solved by the present application is to provide a water purification element which can overcome the aggregation of MOFs powder, realize easy recycling and strong practicability, and also provide a preparation method of the water purification element and a water purifier using the water purification element.

[0004] The technical scheme adopted by the present application to solve the above technical problems is as follows:

[0005] A water purification element is a porous elastic wood substrate attached with active components, and the active components are Fe1Co3-MOFs nanoparticles.

[0006] Further, the preparation method of the porous elastic wood substrate is as follows:

[0007] 1) An aqueous solution is prepared by using sodium hydroxide and sodium sulfite with a mass ratio of 1:1;

[0008] 2) The Larix gmelinii is cut into uniform cylindrical shape with a diameter of 1.5 cm and a height of 1 cm, 5 pieces are taken and soaked in 500 mL of the aqueous solution, and after soaking, the water is washed until the pH is neutral;

[0009] 3) freeze-drying the cleaned Larix gmelinii, to obtain a porous elastic wood matrix, which can also be referred to as a wood sponge.

[0010] The freeze-drying can directly vaporize the frozen water between the wood molecules and form pores in situ, which not only simplifies the preparation process, but also increases the wood pores and interconnected channels. By adjusting the soaking time and concentration of the solution, the porosity of the porous channel elastic wood matrix can be adjusted. The mixed solution concentration is preferably 10 g / L, and the soaking time is 3 h. If the solution concentration and soaking time are further increased, the lignin and cellulose in the wood are excessively damaged, resulting in that the wood matrix does not have a sufficient support skeleton, and cannot form a wood matrix with good elasticity, resulting in a decrease in the deformation performance. If the solution concentration and soaking time are further reduced, although the final porous channel elastic wood matrix has a good support skeleton, the specific surface area of the internal pores and channel walls is low, the loading capacity of the MOFs powder is reduced, and the treatment efficiency of the water purification element is reduced. In addition, since the water absorption capacity of the porous channel elastic wood matrix is closely related to the porosity and deformation performance, therefore, too high or too low solution concentration will reduce the water absorption rate of the porous channel elastic wood matrix, and accordingly reduce the treatment rate.

[0011] Further, the concentration of the aqueous solution is 10 g / L, and the soaking time is 3 h.

[0012] Further, the pore size of the porous elastic wood matrix is 10-200 nm, and the porosity is 60-85%.

[0013] A preparation method of a water purification element, comprising the following steps:

[0014] 1) preparing a mixed aqueous solution of Co(NO3)2 and FeCl3;

[0015] 2) soaking the porous elastic wood matrix in the mixed aqueous solution of Co(NO3)2 and FeCl3 for 12-24 h;

[0016] 3) preparing a 2-MI aqueous solution with a certain concentration, adding the solution drop by drop into the solution in which the porous elastic wood matrix is soaked, stirring for a certain time of 12 h, to obtain a water purification element precursor;

[0017] 4) freeze-drying the water purification element precursor, to obtain a water purification element, i.e., a porous elastic wood matrix with Fe1Co3-MOFs nanoparticles attached thereto.

[0018] Further, the molar ratio of Co(NO3)2 to FeCl3 in the mixed aqueous solution of Co(NO3)2 and FeCl3 is 1-4:1.

[0019] Further, the concentration of the 2-MI aqueous solution is 3.36 mol / L, and the dosage is 40 mL.

[0020] Further, the average particle size of the Fe1Co3-MOFs nanoparticles is 2-50 nm.

[0021] Under the above process, the water purification element has excellent deformation performance, degradation rate, water absorption capacity and degradation speed. The ratio of Co(NO3)2 and FeCl3 can change the catalytic activity of the formed MOFs particles, and too high or too low ratio will reduce the processing rate of the catalytic stirring device. This design uses in-situ growth method to load uniform MOFs nanoparticles on the pore surface of the porous elastic wood matrix, which can make the nanoparticles more stable and adhere to the lignin and cellulose.

[0022] A water purifier comprises a five-cage catalytic impeller stirrer mounted on a stirring rod, and according to the depth of the treated water, the stirring rod is provided with several layers of five-cage catalytic impeller stirrers, the five-cage catalytic impeller stirrer has five loading cages, the water purification element is loaded in the loading cage, and the size of the water purification element is matched with the size of the loading cage. Among them, the shape of the water purification element can be changed at will, and the corresponding shape of the water purification element can be prepared according to the specific shape of the existing water purifier equipment, and the process is simple and the cost is low.

[0023] Further, the loading cage is made of nylon material and is prepared by 3D printing.

[0024] Compared with the prior art, the beneficial effects of the present application are:

[0025] 1. The water purification element has the following advantages: 1) the MOFs powder itself has strong PMS activation ability, and the porous elastic wood matrix itself also has certain adsorption, and the superposition of the two can significantly improve the organic matter removal rate of the water purification element; 2) by controlling the loading amount of Fe1Co3-MOFs nanoparticles and the direction of the flow channel, the catalytic performance of the Fe1Co3@BS filter can be adjusted; 3) the Fe1Co3@BS filter pool can well recover and degrade even under high MB concentration within a wide pH range (3-11); 4) the porous cells on the porous elastic wood matrix and the inner walls of the interconnected channels can effectively disperse the MOFs powder, reduce the powder agglomeration phenomenon, and significantly improve the water purification efficiency; 5) the water absorption capacity of the porous elastic wood matrix can significantly improve the water purification efficiency.

[0026] 2. The degradation rate of the water purification element is ≥92%, the water absorption rate is 40-80 g / g, and the Kobs is ≥0.8 min -1 , the water purification speed is fast, and the urgent needs of water treatment plants for organic matter degradation rate and degradation rate can be met at the same time. Attached Figure Description

[0027] Figure 1 A schematic diagram of a five-cage catalytic impeller agitator;

[0028] Figure 2 High-magnification scanning electron microscope image of a porous elastic wood matrix;

[0029] Figure 1 The components are: 1. Loading cage, 2. Stirring rod, and 3. Water purification element. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] The water purifier of the present invention, such as Figure 1 As shown, the device includes a five-cage catalytic impeller agitator, which is mounted on a stirring rod 2. Depending on the depth of the water to be treated, the stirring rod 2 has several layers of five-cage catalytic impeller agitators. Each five-cage catalytic impeller agitator has five loading cages 1, and the water purification element 3 is installed in one of these loading cages 1. The size of the water purification element 3 is adapted to the size of the loading cage 1. The loading cage 1 is 3D printed from nylon material. The preparation of the water purification element 3 is described in Examples 1-5.

[0032] Example 1

[0033] The water purification element in this embodiment is prepared using the following steps:

[0034] A. Preparation of porous elastic wood matrix: 1) Prepare an aqueous solution with a concentration of 10 g / L using sodium hydroxide and sodium sulfite in a 1:1 mass ratio; 2) Soak five uniform cylindrical pieces of balsa wood, each 1.5 cm in diameter and 1 cm in height, in 500 mL of the aqueous solution for three hours, then remove and wash until the pH is neutral; 3) Freeze-dry the washed wood to obtain the porous elastic wood matrix; the obtained porous elastic wood matrix has a pore size of 10-200 nm and a porosity of 60-85%. Figure 2 As shown;

[0035] B, preparation of water purification element: 1) dilute 4 mL of cobalt nitrate aqueous solution (0.8 mol / L) to a volume of 24 mL; 2) immerse 5 porous elastic wood matrixes in the Co(NO3)2 aqueous solution and soak for 24 h; 3) prepare 40 mL of 2-MI aqueous solution with a concentration of 3.36 mol / L, and add the solution soaked by the wood matrixes drop by drop, and stir for 12 h to obtain a water purification element precursor; 4) freeze-dry the water purification element precursor to obtain the water purification element.

[0036] Example 2

[0037] The preparation of the water purification element in this example adopts the following steps:

[0038] A, preparation of porous elastic wood matrix: 1) prepare an aqueous solution with a concentration of 10 g / L by using sodium hydroxide and sodium sulfite with a mass ratio of 1:1; 2) immerse 5 pieces of uniform cylindrical barred cedar with a diameter of 1.5 cm and a height of 1 cm in 500 mL of the aqueous solution, and take them out after three hours and wash to neutral pH; 3) freeze-dry the cleaned wood to obtain the porous elastic wood matrix;

[0039] B, preparation of water purification element: 1) mix 2 mL of cobalt nitrate aqueous solution (0.8 mol / L) with 16 mL of ferric chloride aqueous solution (0.1 mol / L), and dilute to a volume of 24 mL; 2) immerse 5 porous elastic wood matrixes in the mixed Co(NO3)2 and FeCl3 aqueous solution and soak for 24 h; 3) prepare 40 mL of 2-MI aqueous solution with a concentration of 3.36 mol / L, and add the solution soaked by the wood matrixes drop by drop, and stir for 12 h to obtain a water purification element precursor; 4) freeze-dry the water purification element precursor to obtain the water purification element.

[0040] Example 3

[0041] The preparation of the water purification element in this example adopts the following steps:

[0042] A, preparation of porous elastic wood matrix: 1) prepare an aqueous solution with a concentration of 10 g / L by using sodium hydroxide and sodium sulfite with a mass ratio of 1:1; 2) immerse 5 pieces of uniform cylindrical barred cedar with a diameter of 1.5 cm and a height of 1 cm in 500 mL of the aqueous solution, and take them out after three hours and wash to neutral pH; 3) freeze-dry the cleaned wood to obtain the porous elastic wood matrix;

[0043] B. Preparation of water purification element: 1) Mix 2.68 mL of cobalt nitrate aqueous solution (0.8 mol / L) with 10.72 mL of ferric chloride aqueous solution (0.1 mol / L) and dilute to a volume of 24 mL; 2) Immerse 5 porous elastic wood matrix pieces in a mixed aqueous solution of Co(NO3)2 and FeCl3 for 24 h; 3) Prepare 40 mL of 3.36 mol / L 2-MI aqueous solution and add it dropwise to the solution in which the wood matrix is ​​immersed, and stir for 12 h to obtain the water purification element precursor; 4) Freeze-dry the water purification element precursor to obtain the water purification element.

[0044] Example 4

[0045] The water purification element in this embodiment is prepared using the following steps:

[0046] A. Preparation of porous elastic wood matrix: 1) Prepare an aqueous solution with a concentration of 10 g / L using sodium hydroxide and sodium sulfite in a mass ratio of 1:1; 2) Soak 5 pieces of balsa wood cut into uniform cylindrical shapes with a diameter of 1.5 cm and a height of 1 cm in 500 mL of aqueous solution, and wash them after three hours until the pH is neutral; 3) Freeze-dry the washed wood to obtain the porous elastic wood matrix.

[0047] B. Preparation of water purification element: 1) Mix 3 mL of cobalt nitrate aqueous solution (0.8 mol / L) and 8 mL of ferric chloride aqueous solution (0.1 mol / L), and dilute to a volume of 24 mL; 2) Immerse 5 porous elastic wood matrix pieces in a mixed aqueous solution of Co(NO3)2 and FeCl3 for 24 h; 3) Prepare 40 mL of 3.36 mol / L 2-MI aqueous solution, add it dropwise to the solution in which the wood matrix is ​​immersed, and stir for 12 h to obtain the water purification element precursor; 4) Freeze-dry the water purification element precursor to obtain the water purification element.

[0048] Example 5

[0049] The water purification element in this embodiment is prepared using the following steps:

[0050] A. Preparation of porous elastic wood matrix: 1) Prepare an aqueous solution with a concentration of 10 g / L using sodium hydroxide and sodium sulfite in a mass ratio of 1:1; 2) Soak 5 pieces of balsa wood cut into uniform cylindrical shapes with a diameter of 1.5 cm and a height of 1 cm in 500 mL of aqueous solution, and wash them after three hours until the pH is neutral; 3) Freeze-dry the washed wood to obtain the porous elastic wood matrix.

[0051] B. Preparation of water purification element: 1) Mix 3.2 mL of cobalt nitrate aqueous solution (0.8 mol / L) and 6.4 mL of ferric chloride aqueous solution (0.1 mol / L), and dilute to a volume of 24 mL; 2) Immerse 5 porous elastic wood matrix pieces in a mixed aqueous solution of Co(NO3)2 and FeCl3 for 24 h; 3) Prepare 40 mL of 3.36 mol / L 2-MI aqueous solution, add it dropwise to the solution in which the wood matrix is ​​immersed, and stir for 12 h to obtain the water purification element precursor; 4) Freeze-dry the water purification element precursor to obtain the water purification element.

[0052] The structural parameters of the water purification elements prepared in Examples 1-5 above and the corresponding organic matter catalytic degradation performance test results are shown in Table 1. Here, the specific surface area of ​​MOF nanoparticles refers to the surface area per unit mass of MOF nanoparticles; the pore size refers to the average pore size per gram of MOF surface; the reaction rate constant refers to the organic matter degradation concentration per unit time during the catalytic degradation of organic matter by different MOF nanoparticles; the degradation rate refers to the ratio of the decrease in organic matter concentration to the initial concentration after 10 minutes; and whether PMS is added refers to whether PMS is added to the reaction solution during the reaction process. Comparative Example 1 is a control example of Example 3, the only difference being that PMS was not added to the solution in Comparative Example 1. Comparative Example 2 is also a control example of Example 3, the difference being that the water purification element in Comparative Example 2 does not have MOF nanoparticles.

[0053] As shown in Table 1, compared with the prior art, the water purification elements of Examples 1-5 all exhibit excellent degradation performance, specifically manifested in higher specific surface area, higher reaction rate constant, and higher degradation rate of the MOF nanoparticles. Among them, when the molar ratio of Co(NO3)2 to FeCl3 is 3:1, the resulting water purification element has the highest reaction rate constant and degradation rate. This is because different ratios of Co(NO3)2 and FeCl3 lead to different catalytic PMS activities of the MOFs. The porous structure of the elastic wood matrix supporting the MOFs allows for continuous transport of the organic pollutant solution and promotes the interaction between organic pollutant molecules and MOFs by increasing the residence time, thus resulting in excellent degradation performance of the obtained water purification element. As the molar ratio of Co(NO3)2 to FeCl3 increases, the specific surface area and pore size of the MOF nanoparticles decrease to some extent, but the degradation rate increases, indicating that the specific surface area and pore size of the MOF nanoparticles have a much smaller impact on the catalytic performance of MOFs than the Fe / Co molar ratio. A suitable Fe / Co molar ratio has a significant impact on the catalytic degradation performance of the water purification element. Comparing Comparative Example 1 with Example 3, it can be seen that the adsorption effect of MOF nanoparticles is much smaller than their catalytic effect. Comparing Comparative Example 2 with Example 3, it can be seen that the synergistic effect of the three-dimensional network structure of the wood-based elastic sponge and the MOF nanoparticles significantly improves the degradation effect of the water purification element.

[0054] Table 1. Structural parameters of the water purification elements prepared in Examples 1-5 and corresponding organic matter catalytic degradation performance test results.

[0055]

[0056] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A water purification element for catalytically enhancing the degradation rate and degradation percentage of organic pollutants using PMS, characterized in that, The water purification element is a porous elastic wood matrix with active components attached, the active components being Fe1Co3-MOF nanoparticles; The method for preparing the porous elastic wood matrix is ​​as follows: 1) Prepare an aqueous solution using sodium hydroxide and sodium sulfite in a 1:1 mass ratio; 2) Cut the balsa wood into uniform cylindrical pieces with a diameter of 1.5cm and a height of 1cm. Take 5 pieces and soak them in 500mL of aqueous solution. After soaking, take them out and wash them with water until the pH is neutral. 3) Freeze-dry the cleaned balsa wood to obtain a porous, elastic wood matrix; The concentration of the aqueous solution is 10 g / L, and the soaking time is 3 hours. The porous elastic wood matrix has a pore size of 10-200 nm and a porosity of 60-85%. The method for preparing the water purification element includes the following steps: 1) Prepare a mixed aqueous solution of Co(NO3)2 and FeCl3; 2) Immerse the porous elastic wood matrix in a mixed aqueous solution of Co(NO3)2 and FeCl3 for 12-24 hours; 3) Prepare a 2-MI aqueous solution of a certain concentration and add it dropwise to the solution in which the porous elastic wood matrix is ​​soaked. Stir for 12 hours to obtain the precursor of the water purification element. 4) Freeze-dry the water purification element precursor to obtain the water purification element, which is a porous elastic wood matrix with Fe1Co3-MOFs nanoparticles attached. The molar ratio of Co(NO3)2 to FeCl3 is 3:1; The concentration of the 2-MI aqueous solution was 3.36 mol / L; The average particle size of the Fe1Co3-MOF nanoparticles is 2-50 nm.

2. A water purifier, characterized in that, The water purifier includes a five-cage catalytic impeller agitator, which is mounted on a stirring rod. Depending on the depth of the water to be treated, the stirring rod has several layers of five-cage catalytic impeller agitators. The five-cage catalytic impeller agitator has five loading cages. The water purification element as described in claim 1 is loaded in the loading cage, and the size of the water purification element is adapted to the size of the loading cage.

3. The water purifier according to claim 2, characterized in that, The loading cage is made of nylon using 3D printing.

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