CN116177687A - Filtering type electrocatalytic disinfection reactor and disinfection method - Google Patents

Abstract

The invention relates to a filtering type electrocatalytic disinfection reactor, which uses a novel filtering type antimony-nickel-doped tin dioxide electrode for disinfection, and belongs to a novel electrocatalytic disinfection reactor and a disinfection method. The invention prepares filter-type electrodes by optimizing the sol-gel method and dipping and pulling method. After the preparation is completed, the electrode is placed in a filter-type electrocatalytic reactor to play an electrode-filtering role. During the operation of the reactor, electrocatalysis is used to generate ozone to strengthen the electrode. Disinfection effect, at the same time, the characteristics of the thin boundary layer of the filter electrode can strengthen the organic matter and the disinfection effect. At the same time, the present invention can still detect a sufficient amount of oxidative substances in the water body after achieving a better disinfection effect, ensuring the water body is continuously protected. The need for disinfection effect.

Description

A filter-type electrocatalytic disinfection reactor and disinfection method

technical field

The invention belongs to the field of electrocatalytic electrode preparation and reactor design, in particular to a method for preparing a filter-type electrocatalytic reactor for disinfection and a corresponding filter-type electrode, and the application of the electrocatalytic disinfection method in water body disinfection.

Background technique

In recent years, with the improvement of people's living standards, the requirements and indicators for water disinfection have become more stringent. However, the traditional chlorination disinfection method has obvious disadvantages such as insufficient sterilization and high hazards of disinfection by-products. Therefore, new efficient and safe disinfection methods have attracted more and more attention, including electrocatalytic disinfection. Since the electrocatalytic disinfection method can generate oxidative substances in situ, it does not need to add disinfectants like traditional chlorination disinfection, avoiding secondary pollution of water bodies, and also reducing the capital cost brought by the use of chemicals.

There are obvious differences in the types and concentrations of oxidizing substances such as hypochlorous acid, ozone, and hydroxyl radicals produced by different electrode materials. As we all know, ozone is a greener and safer disinfectant than chlorine disinfection. The heterogeneous tin dioxide electrode has high electrocatalytic ozone efficiency, and when the electrode is applied to disinfection, its bactericidal efficiency is excellent and no obvious disinfection by-products are produced.

However, relevant studies all use parallel-plate antimony-nickel-doped tin dioxide electrode electrocatalysis system, which will not only expand the reaction area between bacteria and electrodes, but also seriously hinder the disinfection of electrodes and short-lived free radicals such as hydroxyl radicals and reduce organic matter in water. The mineralization efficiency, while the residual organic matter will consume the oxidative substances used for disinfection to further hinder the disinfection effect, and the organic matter will act as a precursor to promote the production of disinfection by-products. Therefore, it is of great significance to develop a filter-type antimony-nickel-doped tin dioxide electrode that can further improve the disinfection and mineralization effects of organic matter and suppress the production of disinfection by-products.

Contents of the invention

The purpose of the present invention is to provide a high-efficiency disinfection that can electrocatalyze ozone, and at the same time use the characteristics of the filter type to strengthen the disinfection effect, and can produce hypochlorous acid by electrocatalysis to ensure continuous disinfection. The present invention specifically includes a filter-type electrocatalytic disinfection reactor and Its electrode preparation method.

The present invention is a filter-type electrocatalytic disinfection reactor and a disinfection method, and its technical scheme is:

The filter-type disinfection reactor device includes an outer shell, a filter-type antimony-nickel-doped tin dioxide anode, and a stainless steel cathode; the cathode and the anode are parallel to each other and are located on the left and right sides of the outer shell, and there is a silicone ring at the contact position between the two and the outer shell Gasket; the upper part between the cathode and anode is the water outlet channel, and the rear part of the anode is the water collection tank and the water inlet channel; the upper part of the integral reactor shell is the water outlet pipe, and the water outlet pipe is connected with the circulating water tank, and the right side of the reactor shell is the water inlet pipe , the water inlet pipe communicates with the water pump.

In a further step, the size of the cathode and anode is (24mm×24mm×1mm), the distance between the cathode and the anode is 1cm, and the water pump controls the water inlet flow rate to be 0.9-5.4L/h.

Preferably, the filter type antimony nickel doped tin dioxide electrode preparation method, the specific steps are as follows:

Step 1-1, fully clean the titanium foam substrate with a pore size of 20 μm, and then perform classification (120 mesh, 240 mesh, and 360 mesh successively) and polish to remove surface impurities and oxides, and then carry out alkali cleaning treatment of the substrate, and the foam Titanium is completely immersed in sodium hydroxide solution (mass concentration: 40%), and treated in an ultrasonic water bath at 80°C for 30 minutes. Wash the titanium foam several times with ultrasonic to remove the residual sodium hydroxide inside. Finally, the titanium foam was placed in a sufficient amount of 13% oxalic acid solution, and at the same time, it was etched with ultrasonic assistance for 30 minutes under the condition of a water bath at 80° C., and then etched under the condition of a water bath at 95° C. for 1.5 hours. After the substrate was etched, it was also ultrasonically cleaned several times with ultrapure water to remove the residual oxalic acid inside the titanium foam. Finally, the pretreated titanium foam substrate was stored in absolute ethanol for later use.

In step 1-2, the sol used for the electrode active coating is prepared by using the Pechini method. The specific steps are to stir and mix ethylene glycol and citric acid according to the molar ratio of ethylene glycol, citric acid, and total metals (tin, antimony, and nickel) in a ratio of 140:30:10 under the condition of a water bath at 65°C. After uniformity, raise the temperature of the water bath to 85°C, and then sequentially add metal compounds containing tin, antimony, and nickel (tin tetrachloride pentahydrate, antimony trioxide, nickel chloride hexahydrate) to dissolve and keep stirring for 45 minutes , and finally stop stirring, and age in a water bath at 60° C. for 2 hours. Tin tetrachloride pentahydrate, antimony trioxide and nickel chloride hexahydrate are prepared according to the proportioning ratio of tin, antimony and nickel metal molar ratios of 500:8:5 respectively to prepare the total metal (tin, antimony) of the sol. and nickel) content is 0.48mol/L. In step 1-3, immerse the pretreated titanium foam in sols with different nickel contents, and then use a vacuum drying oven under negative pressure (-0.08MPa) for 1 minute to fully infiltrate the solution into the titanium foam. Take the sol containing the impregnated matrix out of the vacuum box, and then use the dipping and pulling method to slowly pull out the soaked electrode matrix (conditions are dipping for 10 minutes, pulling 3mm/min), to ensure that the sol is evenly coated on the surface of the foamed titanium substrate with interior. Put the pulled substrate in a constant temperature drying oven at 120°C to dry for 10 minutes, and finally take it out and put it in a muffle furnace at 460°C for sintering for 10 minutes. And the active layer material that is not completely combined with the titanium foam. The above steps were repeated 12 times, and the last sintering in the muffle furnace was carried out with a temperature program at a sintering temperature of 500°C. After the sintering was completed, the electrodes were taken out and cooled naturally at room temperature.

Compared with the prior art, the present invention has significant advantages in that:

1. The filter-type antimony-nickel-doped tin dioxide electrode of the present invention is pretreated with alkali washing and acid under ultrasonic conditions, which can fully pretreat the interior of the foamed titanium substrate and strengthen the bonding effect between the subsequent active layer and the substrate At the same time, the influence of residual acids, bases and impurities on the performance of the electrode after preparation can be further reduced by multiple ultrasonic cleaning in the pretreatment process; the present invention uses vacuum conditions for impregnation, which can fully penetrate the sol into the foamed titanium. Promote the bonding effect of the subsequent electrode active layer and the foamed titanium substrate, and improve the stability of the electrode; the electrocatalytic disinfection reactor can not only efficiently perform electrocatalysis to generate ozone for disinfection, but also can effectively use the advantages of filter anodes to improve electrocatalysis The mass transfer efficiency of the system further enhances the electrocatalytic disinfection performance.

The invention prepares filter-type electrodes by optimizing the sol-gel method and dipping and pulling method. After the preparation is completed, the electrode is placed in a filter-type electrocatalytic reactor to play an electrode-filtering role. During the operation of the reactor, electrocatalysis is used to generate ozone to strengthen the electrode. Disinfection effect, at the same time, the characteristics of the thin boundary layer of the filter electrode can strengthen the organic matter and the disinfection effect. At the same time, the present invention can still detect a sufficient amount of oxidative substances in the water body after achieving a better disinfection effect, which ensures the water body is continuously protected. The need for disinfection effect.

Description of drawings

Fig. 1 is a device diagram of a filter-type electrocatalytic reactor and a device diagram of a non-filter-type electrocatalyst reactor of the present invention. Schematic diagram of filter-type electrocatalytic disinfection reactor (left), device diagram of non-filter-type electrocatalytic reactor (right).

Fig. 2 is a physical diagram of the electrode after pretreatment and preparation in Example 1 of the present invention. Titanium foam before pretreatment (A); titanium foam after pretreatment (B); electrode after preparation (C).

Fig. 3 is an SEM image of the filter-type antimony-nickel-doped tin dioxide electrode prepared in Example 1 of the present invention.

Fig. 4 is a comparison chart of the ozone generation effect and the disinfection effect of the electrocatalytic disinfection reactor under the filter type and the non-filter condition in Comparative Example 1 of the present invention.

Fig. 5 is an effect diagram of the filter type electrocatalytic disinfection reactor in Experimental Example 1 of the present invention, using simulated swimming pool water as the target water body for disinfection and an effect diagram of electrocatalysis to generate oxidative substances.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

Example 1

After sanding the two sides with 120-mesh, 240-mesh, and 360-mesh sandpaper in sequence, the pore size is 20 μm (that is, the filtration accuracy, which is the pore size with through holes on the substrate, and the size of the largest particle that is allowed to pass through when the impurity solution passes through the substrate. ) titanium foam substrate (length × width × thickness: 24mm × 24mm × 1mm) using an ultrasonic cleaner to fully wash away the impurities inside the voids of titanium foam to reduce the impact of subsequent impurities on the electrode preparation and use process; completely immerse the titanium foam Sodium solution (mass concentration: 40%), treated in an ultrasonic water bath at 80°C for 30 minutes to fully remove the oil stains on the surface and interior of the titanium foam. Residual sodium hydroxide inside. Finally, place the foamed titanium in a 13% oxalic acid solution with a mass concentration, and at the same time use ultrasonic-assisted pickling and etching in a water bath of 80°C for 30 minutes, and then etch it in a water bath of 95°C for another 1.5 hours, and then fully etch the foamed titanium. Inside and outside. The titanium foam before and after pretreatment is shown in Figure A and Figure B in Figure 2;

Adopt Pechini method to prepare the used sol of electrode active coating: concrete step is under 65 ℃ of water bath conditions, according to the molar ratio of ethylene glycol, citric acid, total metal (tin, antimony and nickel) be the compounding of 140:30:10 First, stir and mix ethylene glycol and citric acid evenly, raise the temperature of the water bath to 85°C, and then add compounds containing tin, antimony, and nickel in sequence (tin tetrachloride pentahydrate, antimony trioxide, chlorine hexahydrate, etc.) Nickel chloride) was dissolved and reacted with constant stirring for 45 minutes, and finally the stirring was stopped, and aging was carried out in a water bath at 60° C. for 2 hours. Tin tetrachloride pentahydrate, antimony trioxide and nickel chloride hexahydrate are prepared in a ratio of 500:8:5 according to the mol ratio of metal tin, antimony and nickel, and the total metal (tin, antimony) of the sol is obtained. and nickel) content is 0.48mol/L.

Using a vacuum drying oven, impregnate the pretreated foamed titanium for 15 minutes under the conditions of a vacuum degree of 0.07 MPa and a vacuum time of 1 minute, so that the sol can fully penetrate into the foamed titanium, and then use a pulling machine to take out the foamed titanium and pull it The speed is 3mm/min. The completed substrate was dried in a constant temperature drying oven at 120°C for 20 minutes, and finally it was taken out and placed in a muffle furnace at 500°C for sintering for 20 minutes. After the sintering was completed, a short ultrasonic cleaning was performed to fully remove the loose and incomplete interior of the titanium foam. active layer material combined with titanium foam;

According to the above steps, cycle back and forth 12 times, and the last muffle furnace sintering is carried out by temperature program (rise from room temperature at 15 °C/min to 200 °C, stay for 15 min, then increase at 20 °C/min to 400 °C, stay for 20 min, and finally 20°C/min to 500°C, stay for 40min for sintering), after the sintering is completed, take out the electrode and cool it naturally at room temperature, and finally make a filter-type antimony-nickel-doped tin dioxide electrode, as shown in Figure C in Figure 2.

Figure 3 is an SEM image of the antimony-nickel-doped tin dioxide electrode prepared in Example 1 of the present invention. It can be clearly seen that the electrode gaps are numerous and uniform, and no obvious cracks are found in the active layer, which can be clearly seen at a magnification of 5000 times. The granular structure indicates that the growth or agglomeration of coating grains is better, which is beneficial to the electrocatalytic oxidation.

Experimental example 1

As shown in Figure 1 (left) (filtering type), the hollow airtight reactor cavity that outer casing 1 forms is surrounded, is provided with flat anode 4 (being the filter type antimony-nickel-doped di tin oxide electrode) and a flat cathode 3 (stainless steel cathode), the cathode 3 and the anode 4 are arranged in parallel on the left and right sides of the outer casing 1, on the outer edge of the flat anode 4 and the flat cathode 3 (ie, the periphery of the flat plate) Silicone ring-shaped gaskets 5 are respectively provided at the contact positions with the inner wall of the outer shell 1 to make them airtightly connected with the inner wall of the outer shell; The side chamber serves as a water collection tank 6 , and the outer shell 1 is provided with a water inlet pipe communicating with the water collection tank 6 and a water outlet pipe 2 communicating with the chamber where the cathode 3 is located. The water outlet pipe 2 communicates with the circulating water tank through the pipeline; the water inlet pipe 7 is arranged on the right side wall of the reactor shell 1, and the water inlet pipe 7 is connected with the water tank containing the water body to be treated through the water pump; when the valve of the water inlet pipe 7 is opened, the reaction The filter plays the filtering role of the electrode, and the reactor behaves as a filter electrocatalytic system;

As shown in Fig. 1 (right side) (non-filtering type), the hollow airtight reactor cavity that outer casing 1 forms is surrounded, is provided with flat anode 4 (being the filtering type antimony-nickel doped of the embodiment 1 preparation) in cavity Tin dioxide electrode) and flat cathode 3 (stainless steel cathode), cathode 3 and anode 4 are arranged in parallel on the left and right sides in the outer casing 1, on the outer edge of flat anode 4 and flat cathode 3 (i.e. the periphery of the flat plate ) and the inner wall surface of the outer casing 1 are respectively provided with a silicone ring gasket 5, so that they are airtightly connected with the inner wall surface of the outer casing; the lower part of the outer casing 1 is provided with a connected water inlet pipe B8 and connected to the chamber where the cathode 3 is located Through the outlet pipe 2. The outlet pipe 2 is connected with the circulating water tank through the pipeline; the water inlet pipe B8 is connected with the water tank containing the water body to be treated through the water pump; the valve of the water inlet pipe B8 connected with the water tank at the lower part of the reactor is opened, which is a traditional non-filtered parallel plate electrocatalysis system.

The distance between the anode 4 and the cathode 3 is 1 cm, the cathode 3 is rectangular (length × width × thickness: 24mm × 24mm × 1mm), the anode 4 and the cathode 3 are connected to the positive and negative poles of the DC power supply; the concentration of the sodium nitrate electrolyte in the water tank is adjusted to 6mM/L, The circulation flow rate is 1.8L/h, the electrode current density is 10mA/cm ² , turn on the power and turn on the water pump, and at the same time adjust the valve as mentioned above, the reactor filter type electrocatalytic reaction and non-filter type electrocatalytic ozone reaction can be carried out respectively .

As shown in Figure A in Figure 4, it is the electrocatalytic ozone effect and comparison chart under the filter type and non-filter type conditions in Experimental Example 1 of the present invention. It can be clearly found that ozone can be generated more effectively under filter conditions, and the current efficiency of its electrocatalytic ozone is higher.

Adjust the electrolyte concentration of sodium nitrate in the water tank to 6mM/L, the circulation flow rate to 1.8L/h, the electrode current density to 7.5mA/cm ² , and the concentration of Escherichia coli to 10 ⁶ CFU/mL. The valve is adjusted to carry out filter type electrocatalytic reaction and non-filter type electrocatalytic disinfection reaction of the reactor.

As shown in Figure B in Figure 4, it is the electrocatalytic disinfection effect and comparison chart under the filter type and non-filter type conditions in Experimental Example 1 of the present invention. It can be clearly found that the disinfection under the filter type conditions is more rapid and sufficient.

Experimental example 2

Prepare simulated swimming pool water and add it to the water tank so that the TOC concentration is 10mg/L. At the same time, adjust the circulation flow to 1.8L/h, the electrode current density to 7.5mA/cm ² , and the concentration of E. coli to 10 ⁶ CFU/mL, and turn on the power And turn on the water pump, and use the filter-type electrocatalytic system prepared in Experimental Example 1 above to carry out electrocatalytic disinfection of the reactor to simulate swimming pool water reaction.

As shown in Figure 5, even in the simulated swimming pool water containing organic matter, the electrocatalytic disinfection effect is still excellent, and after achieving a high disinfection effect and difficult to detect Escherichia coli, the relatively stable presence of ozone and active chlorine can still be detected continuously , indicating that the electrocatalytic reactor can guarantee the continuous disinfection effect of the water body after disinfection, and can reduce the possibility of microbial recurrence.

Claims (10)

1. a filter-type electrocatalytic disinfection reactor, comprising a hollow airtight reactor cavity surrounded by an outer casing (1), in which a flat anode (4) and a flat cathode (3) are provided in the cavity, and the cathode ( 3) The anode (4) is arranged on the left and right sides of the outer shell (1) in parallel, and the outer edge of the anode (4) is airtightly connected with the inner wall of the cavity, and the cavity is separated into two mutually independent and interconnected ones by the anode (4). The disconnected chamber is used as the sump (6) on the side of the anode (4) away from the cathode (3), and the outer casing (1) is respectively provided with water inlet pipes communicating with the sump (6) (7) and the outlet pipe (2) that communicates with the chamber where the cathode (3) is located; The anode (4) is titanium foam with an antimony-nickel-doped tin dioxide coating on the outer surface and the surface of the channel, forming a filter-type antimony-nickel-doped tin dioxide anode (4), and water can be fed by the flat anode (4 ) from one side surface of the anode to its other side surface. 2. filter type electrocatalytic disinfection reactor according to claim 1, is characterized in that: The cathode (3) is a stainless steel cathode (3); Silicone ring gaskets (5) are respectively provided at the contact positions of the outer edge of the flat anode (4) and the flat cathode (3) (that is, the peripheral edge of the flat plate) and the inner wall of the outer shell (1), so that they are in contact with the inner wall of the outer shell. closed connection; The upper part of the chamber outer shell (1) between the cathode and the anode is sealed with a water outlet pipe (2), and the water outlet pipe (2) communicates with the circulating water tank through a pipeline; the water inlet pipe (7) is arranged on the outer shell of the reactor (1 ) on the right side wall, the water inlet pipe (7) communicates with the water outlet of the water pump through the pipeline, and the water inlet of the water pump is connected with the water body to be treated. 3. filter type electrocatalytic disinfection reactor according to claim 1 or 2, is characterized in that: The anode (4) and the cathode (3) are respectively electrically connected to the positive and negative poles of the DC power supply outside the cavity through wires. 4. The filter-type electrocatalytic disinfection reactor according to claim 1 or 2, characterized in that: the electrode preparation process of the filter-type antimony-nickel-doped tin dioxide comprises the following steps: Step 1-1, fully clean the foamed titanium substrate with a pore size of 20-50 μm, and then perform grading (120-mesh, 180 mesh, greater than 180 mesh-240 mesh, greater than 240 mesh-360 mesh sandpaper sequentially) and polish; then base Alkali washing treatment, the foamed titanium is completely immersed in a sodium hydroxide solution (mass concentration of 35-45%), and treated for 25-35min under the condition of an ultrasonic water bath at 70-80°C; finally, the foamed titanium is placed in a mass concentration of 10- In 15% oxalic acid solution, at the same time use ultrasonic assisted acid etching for 20-30min under the condition of 70-80℃ water bath, and then etch for 1.5-2 hours under the condition of 90-95℃ water bath; Ultrasonic cleaning, and finally the foamed titanium substrate after pretreatment is stored in absolute ethanol for later use; Step 1-2, tin tetrachloride pentahydrate, antimony trioxide, nickel chloride hexahydrate are respectively 500:(6-10):(1-8) according to tin, antimony, nickel metal molar ratio Prepare sol; Step 1-3, sol coating by dipping and pulling method, the conditions are dipping for 10-20min, pulling 2-3mm/min, and then drying and sintering, and the substrate after pulling is placed at a constant temperature of 120-160°C Dry it in a drying oven for 10-15 minutes, and finally take it out and put it in a muffle furnace at 460-500°C for sintering for 10-15 minutes. Active layer substances; According to the above steps, cycle back and forth 10-12 times for dipping and pulling sintering. During the last muffle furnace sintering process, the temperature is programmed to sintering temperature at a rate of 15°C/min-20°C/min. The sintering temperature is 450-550°C, and the sintering is 40- After 60 minutes, the electrode was taken out and cooled naturally at room temperature, and finally a tin dioxide electrode doped with antimony and nickel was prepared. 5. The filter-type electrocatalytic disinfection reactor according to claim 1 or 2, characterized in that: the inner cavity of the outer casing is a square circular symmetrical hollow cylindrical structure in cross section, and the distance between the opposite surfaces of the cathode and anode is 1-2cm, the water pump controls the water inlet flow rate to 0.9-5.4L/h. 6. The filter-type electrocatalytic disinfection reactor according to claim 4, characterized in that: in the preparation step 1-1 of the tin dioxide anode doped with antimony and nickel, each pretreatment step is carried out before and after completion. Ultrasonic cleaners are used for sufficient cleaning, and the alkali cleaning and pickling processes are all carried out under ultrasonic conditions; In the preparation steps 1-3, the electrodes after each sintering were ultrasonically cleaned. 7. The filter-type electrocatalytic disinfection reactor according to claim 1, characterized in that: in the preparation step 1-2 of the tin dioxide anode doped with antimony and nickel, Under the condition of 60-70°C, the molar ratio of ethylene glycol, citric acid, and total metals (tin, antimony, and nickel) is (130-150):(25-35):(5-15), Stir and mix ethylene glycol and citric acid evenly, raise the temperature of the water bath to 80-90°C, then add tin tetrachloride, antimony trioxide, and nickel chloride to dissolve and keep stirring for 40-50 minutes, and finally Stop stirring, and age under water bath conditions at 55-65°C for 2-3h; tin tetrachloride pentahydrate, antimony trioxide, and nickel chloride hexahydrate are respectively 500:(6-10):(1-8) proportioning preparation tin, antimony and nickel mixed sol, and according to the coating situation of sol on foamed titanium, determine the metal (tin, antimony) of optimal viscosity sol and nickel) content is 0.46-0.5mol/L. 8. The filter-type electrocatalytic disinfection reactor according to claim 1, characterized in that: before the electrode is lifted described in the preparation step, the sol that is not soaked in foamed titanium is placed in a vacuum desiccator, and the vacuum degree is 0.06- 0.08MPa, the vacuum time is 1-2min. 9. A disinfection method in water disinfection using the filter-type electrocatalytic disinfection reactor described in any one of claims 1-8, characterized in that: the treatment process is to open the water outlet pipe (2) and the water inlet pipe (7). valve; the outlet pipe (2) is connected with the circulating water tank through the pipeline; the water inlet pipe (7) is connected with the water tank containing the water body to be treated through the water pump; the anode (4) and the cathode (3) are connected with the positive and negative poles of the DC power supply , the current density is set to 5-10mA/cm ² , and the circulation flow rate is adjusted to 1.5-2L/h at the same time. 10. disinfection method according to claim 9, is characterized in that: use filter type antimony nickel doped tin dioxide anode (4) in this electrocatalytic disinfection reactor not only can efficiently carry out electrocatalysis to produce ozone to carry out disinfection while , and can effectively use the advantages of filter anodes to improve the mass transfer efficiency of the electrocatalytic system, further enhance the electrocatalytic disinfection performance, and can be used to treat various water samples (such as swimming pool water disinfection).

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