Catalytic ceramic membrane reactor and its application method

Abstract

The application discloses a catalytic ceramic membrane reaction device and an application method thereof. The catalytic ceramic membrane is used, and in a relatively closed reactor cavity, a nano disc type aerator is used to transport and disperse an oxidant and adjust the pressure in the reactor cavity. The catalytic ceramic membrane and the nano disc type aerator are arranged at intervals, and the catalytic ceramic membrane is uniformly mixed with the oxidant in a rotating state. The mass transfer distance of the oxidant after being mixed with a reaction liquid into membrane holes is shortened, the nano limited catalytic reaction efficiency and the catalytic degradation efficiency of pollutants are greatly improved, and therefore, pollutants in waste water can be efficiently removed.

Description

Technical Field

[0001] This invention relates to the field of membrane-based confined catalytic deep water treatment technology, and more particularly to a catalytic ceramic membrane reactor and its application method. Background Technology

[0002] Ceramic membranes are porous physical sieving materials, with structures including flat ceramic membranes, tubular ceramic membranes, and disc ceramic membranes. Through technological innovation and process improvement, the pore size of ceramic membranes can be controlled to range from 0.05 to 5 μm, and they have been widely used in solid-liquid separation, gas-solid separation, and liquid-liquid separation. In particular, the catalytic ceramic membrane technology developed in recent years loads high-performance catalysts inside the membrane pores. Utilizing the nanoscale confinement space of the membrane pores, it catalyzes the activation of oxidants to generate reactive oxygen species (ROS), confining ROS and target pollutants within the nanoscale space, further shortening the mass transfer distance, increasing reaction efficiency, and achieving highly efficient removal of pollutants.

[0003] Most existing catalytic ceramic membrane devices concentrate the catalytic ceramic membrane and oxidant in the same open reaction tank. During the mixing process of the oxidant and water, the pollutants are degraded through the membrane pores in a nano-confined catalytic manner. However, this method is limited by the uniformity of the mixing between the oxidant and water, especially for gaseous oxidants (such as ozone). In an open tank, the ozone emitted from the aeration head has low solubility in water, and it gradually forms large bubbles over time, eventually rising to the surface and bursting. This results in a problem of high ozone dosage and low utilization efficiency, which greatly limits the efficiency of membrane-based confined catalytic water treatment and also increases water treatment costs.

[0004] To address the challenge of low utilization efficiency of gaseous oxidants, existing technologies employ solid (persulfate-based) or liquid oxidants (hydrogen peroxide, peracetic acid, etc.) dissolved in water to form a high-concentration pre-prepared solution. During the catalytic reaction, this pre-prepared solution is then mixed with the target pollutant solution, and the pollutant is degraded through a nano-confined catalytic reaction within the pores of a catalytic ceramic membrane. While this method can improve oxidant utilization efficiency, the mixing process between the pre-prepared solution and the target pollutant solution is a static concentration equilibrium process with a slow mixing rate. Furthermore, the time it takes for the mixed solution to pass through the membrane pores is often on the order of milliseconds, making it difficult to ensure uniform mixing of the oxidant and the target pollutant solution before the catalytic reaction. This severely limits the efficiency of the nano-confined catalytic reaction within the membrane pores and the overall pollutant removal efficiency. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a catalytic ceramic membrane reactor. This reactor employs a catalytic disc ceramic membrane within a relatively sealed reactor chamber. A nanodisc aerator delivers and disperses the oxidant, and regulates the pressure within the reactor chamber, allowing the catalytic disc ceramic membrane to rotate and uniformly mix with the oxidant, thereby efficiently removing pollutants from wastewater. Another objective of this invention is to provide a method for applying the aforementioned catalytic ceramic membrane reactor.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] This invention provides a catalytic ceramic membrane reactor, comprising a reactor chamber, a catalytic disc ceramic membrane, a nano-disc aerator, a hollow tube, a variable speed motor, and a rotating shaft. The reactor chamber is a sealed container with a feed inlet. The three catalytic disc ceramic membranes are arranged in a triangle to form a catalytic ceramic membrane assembly. There are two or more nano-disc aerators arranged side by side in the reactor chamber. The catalytic ceramic membrane assembly is positioned between two adjacent nano-disc aerators, with the nano-disc aerators corresponding to the middle of the triangular region of the catalytic ceramic membrane assembly. One end of the hollow tube is connected to a nano-disc aerator, and the other end is an oxidant inlet. The variable speed motor drives the catalytic disc ceramic membrane to rotate via the rotating shaft. The rotating shaft is hollow and serves as a permeate channel, with one end connected to the permeate outlet in the middle of the catalytic disc ceramic membrane and the other end located outside the reactor chamber with a permeate discharge port.

[0008] Furthermore, in the reaction device of the present invention, the reactor cavity is a cylinder with a diameter of 450-900 mm and a length of 150-800 mm; the nano-disc aerator is a disc ceramic membrane without catalytic function; the diameter of the support of the catalytic disc ceramic membrane and the nano-disc aerator is 200-400 mm, and the average pore size of the separation membrane layer is 50-200 nm and the thickness is 20-50 μm.

[0009] In the above scheme, the catalyst component in the catalytic disc ceramic membrane of the present invention accounts for 0.2 to 3 wt% of the matrix.

[0010] Another objective of this invention is achieved through the following technical solution:

[0011] The application method of the above-mentioned catalytic ceramic membrane reactor provided by the present invention includes a feed liquid with a pollutant concentration of 0.1-20 mg / L; a gaseous oxidant of ozone with a dosage of 0.5-10 mg / L; a liquid oxidant of persulfate, hydrogen peroxide, or peracetic acid with a concentration of 0.2-2.0 mM; a membrane flux of 80-120 LMH; continuous reaction at a rotation speed of 50-250 r / min for more than 5 hours; and a pollutant removal efficiency of 95-100% in the permeate.

[0012] The present invention has the following beneficial effects:

[0013] (1) This invention utilizes the rotation of the catalytic disc ceramic membrane to promote the formation of turbulence in the feed liquid, thereby improving the uniformity of mixing between the oxidant and the feed liquid. At the same time, the nano-disc aerators are evenly distributed on both sides of a catalytic ceramic membrane unit, shortening the mixing distance between the oxidant and the feed liquid and greatly improving the utilization efficiency of the oxidant.

[0014] (2) In this invention, the catalytic disc ceramic membrane and the nano-disc aerator are concentrated in a relatively closed reaction chamber. The pressure in the reaction chamber is controlled by adjusting the volume of the feed liquid, which improves the solubility of the oxidant, especially the gaseous oxidant, in water. The nano-disc aerator and the catalytic disc ceramic membrane are distributed at intervals, which shortens the mass transfer distance of the oxidant and the reaction liquid after they are mixed and enter the membrane pores, which greatly improves the efficiency of nano-confined catalytic reaction and the catalytic degradation efficiency of pollutants.

[0015] (3) The reaction device of the present invention can realize automated control, is adaptable to both gaseous and liquid oxidants, and can automatically adjust the mixing ratio of oxidant and feed liquid, effectively promoting the large-scale application of catalytic ceramic membrane. Attached Figure Description

[0016] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings:

[0017] Figure 1 This is a schematic diagram of the structure of the catalytic ceramic membrane reaction device according to Embodiment 1 of the present invention;

[0018] Figure 2 yes Figure 1 The illustrated embodiment shows a schematic diagram of the setup of the catalytic ceramic membrane assembly and the nanodisc aerator.

[0019] In the diagram: reactor chamber 1, feed liquid inlet 1a, catalytic disc ceramic membrane 2, nano-disc aerator 3, hollow tube 4, variable speed motor 5, rotating shaft 6, permeate discharge port 6a. Detailed Implementation

[0020] Example 1:

[0021] Figure 1 , Figure 2 The following is an embodiment of a catalytic ceramic membrane reaction device of the present invention, which includes a reactor chamber 1, a catalytic disc ceramic membrane 2, a nano-disc aerator 3, a hollow tube 4, a variable speed motor 5, and a rotating shaft 6.

[0022] like Figure 1 As shown, the reactor chamber 1 is a closed container with a feed liquid inlet 1a. Three catalytic disc ceramic membranes 2 are arranged in a triangular pattern to form a catalytic ceramic membrane assembly (see...). Figure 2 Five nanodisc aerators 3 (without catalytic function) are arranged side-by-side in the reactor chamber 1; three catalytic ceramic membrane modules are respectively arranged between two adjacent nanodisc aerators 3, with the nanodisc aerators 3 and the catalytic ceramic membrane modules corresponding to the middle of their triangular regions (see...). Figure 2 One end of the hollow tube 4 is connected to the nano-disc aerator 3, and the other end is the inlet of the oxidant. The variable speed motor 5 drives the catalytic disc ceramic membrane 2 to rotate through the rotating shaft 6; and the rotating shaft 6 is hollow and serves as a permeate channel, one end of which is connected to the permeate outlet in the middle of the catalytic disc ceramic membrane 2, and the other end is located outside the reactor cavity 1 and is provided with a permeate discharge port 6a.

[0023] In this embodiment, the catalytic ceramic membrane reactor has a reaction chamber 1 that is a cylinder with a diameter of 500 mm and a length of 400 mm. The reactor also includes a catalytic disc ceramic membrane 2 and a nanodisc aerator 3. The support structure of the catalytic disc ceramic membrane 2 has a thickness of 2.5 mm and a diameter of 200 mm. The average pore size of the separation membrane layer is 100 nm and the thickness is 30 μm. The catalyst component in the catalytic disc ceramic membrane 2 accounts for 1.0 wt% of the matrix.

[0024] The application method is as follows: the feed liquid is sulfamethoxazole with a concentration of 20 mg / L; the dosage of the gaseous oxidant ozone is 6 mg / L; the membrane flux is 80 LMH; the reaction is carried out continuously for 12 h at a rotation speed of 150 r / min; and the removal efficiency of sulfamethoxazole in the permeate is 98.5%.

[0025] Example 2:

[0026] This embodiment of a catalytic ceramic membrane reactor differs from Embodiment 1 in that: there are three nanodisc aerators 3 and two catalytic ceramic membrane modules; the reaction chamber 1 is a cylinder with a diameter of 750 mm and a length of 300 mm; the catalytic ceramic membrane 2 and the nanodisc aerators 3 have a support diameter of 374 mm, an average pore size of 150 nm for the separation membrane layer, and a membrane thickness of 40 μm. The catalyst component in the catalytic ceramic membrane 2 accounts for 0.65 wt% of the matrix.

[0027] The application method in this embodiment is as follows: the feed solution is carbamazepine with a concentration of 10 mg / L; the concentration of liquid oxidant hydrogen peroxide is 1.5 mM; the membrane flux is 100 LMH; the reaction is carried out continuously for 10 h at a rotation speed of 80 r / min; and the removal efficiency of carbamazepine in the permeate is 100%.

[0028] The preparation method of the catalytic disc ceramic membrane 2 in this embodiment of the invention comprises the following steps:

[0029] (1) Preparation of dish-type ceramic membrane support

[0030] A dry-pressed powder was prepared by sieving and mixing 85 wt% alumina powder, 13 wt% aluminum sol (1.5 mol / L concentration), and 2 wt% hydroxypropyl methylcellulose. A semi-dry pressing method was used, with molding at 12 MPa for 20 seconds. After demolding, a disc-shaped ceramic membrane support green body I was obtained. Ribs (permeability flux) were added to the mold during the dry pressing process to create curved recesses inside the disc-shaped ceramic membrane support, resulting in a disc-shaped ceramic membrane support green body II. Disc-shaped ceramic membrane support green bodies I and II were aligned and bonded together (using a viscous slurry formed by adding 42% water to the above dry-pressed powder). After drying and calcination at 1350℃ for 2 hours, a disc-shaped ceramic membrane support was obtained.

[0031] (2) Preparation of separation membrane

[0032] A separation membrane layer was prepared on the surface of a disc ceramic membrane support by dip coating. After drying at 90℃, the membrane was calcined at 1200℃ and held for 2 hours to obtain a disc ceramic membrane with a separation membrane layer and a pore size of 50-200 nm.

[0033] (3) Preparation of catalytic disc ceramic membrane

[0034] The above-mentioned disc-shaped ceramic membrane with separation membrane layer is immersed in a 0.02-1.5 mol / L metal nitrate solution. After the ceramic membrane is fully saturated in the solution by vacuum pressure, it is taken out and vacuum dried (vacuum degree of 0.8 MPa, temperature of 90℃). The completely dried ceramic membrane loaded with metal precursor is placed in a muffle furnace and calcined at 550℃ for 3-6 hours to obtain the catalytic disc-shaped ceramic membrane.

[0035] The nitrates mentioned above can be one or a combination of ferric nitrate (Fe(NO3)3·9H2O), cobalt nitrate (Co(NO3)2·6H2O), nickel nitrate (Ni(NO3)2), manganese nitrate (Mn(NO3)2·6H2O), silver nitrate (AgNO3), and copper nitrate (Cu(NO3)2).

[0036] The nano-disc aerator 3 in this embodiment of the invention is a disc ceramic membrane with a separation membrane layer obtained in step (2) of the above-mentioned method for preparing catalytic disc ceramic membrane 2, that is, a disc ceramic membrane without catalytic function.

Claims

1. A catalytic ceramic membrane reaction device, characterized in that: The reactor includes a reactor chamber (1), a catalytic disc ceramic membrane (2), a nano-disc aerator (3), a hollow tube (4), a variable speed motor (5), and a rotating shaft (6). The reactor chamber (1) is a closed container with a feed liquid inlet (1a). The three catalytic disc ceramic membranes (2) are arranged in a triangular pattern to form a catalytic ceramic membrane assembly. There are two or more nano-disc aerators (3) arranged side by side in the reactor chamber (1). The catalytic ceramic membrane assembly is arranged between two adjacent nano-disc aerators (3). Between the nano-disc aerator (3) and the triangular region of the catalytic ceramic membrane assembly, one end of the hollow tube (4) is connected to the nano-disc aerator (3), and the other end is the inlet of the oxidant; the variable speed motor (5) is connected to drive the catalytic disc ceramic membrane (2) to rotate through the rotating shaft (6); and the rotating shaft (6) is hollow and serves as a permeate channel, one end of which is connected to the permeate outlet in the middle of the catalytic disc ceramic membrane (2), and the other end is located outside the reactor cavity (1) and is provided with a permeate discharge port (6a).

2. The catalytic ceramic membrane reactor according to claim 1, characterized in that: The reactor chamber (1) is a cylinder with a diameter of 450-900 mm and a length of 150-800 mm; the nano-disc aerator (3) is a disc ceramic membrane without catalytic function; the diameter of the support of the catalytic disc ceramic membrane (2) and the nano-disc aerator (3) is 200-400 mm, and the average pore size of the separation membrane layer is 50-200 nm and the thickness is 20-50 μm.

3. The catalytic ceramic membrane reactor according to claim 1, characterized in that: The catalyst component in the catalytic disc ceramic membrane (2) accounts for 0.2 to 3 wt% of the matrix.

4. The method of using the catalytic ceramic membrane reactor according to any one of claims 1-3, characterized in that: The pollutant concentration of the feed liquid is 0.1-20 mg / L; a gaseous oxidant or a liquid oxidant is added from one end of the hollow tube (4) as the oxidant inlet; the gaseous oxidant is ozone, and the dosage is 0.5-10 mg / L; the liquid oxidant is persulfate, hydrogen peroxide, or peracetic acid, and the concentration is 0.2-2.0 mM; the membrane flux of the catalytic disc ceramic membrane (2) is 80-120 LMH, and the reaction is carried out continuously for more than 5 hours at a rotation speed of 50-250 r / min, and the removal efficiency of pollutants in the permeate is 95-100%.

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