CN105858965B - Method and device for advanced treatment of nitrobenzene wastewater by high-gravity enhanced nano-zero-valent iron-ozone method - Google Patents

Abstract

The invention belongs to the technical field of nitrobenzene wastewater treatment, and specifically relates to a method and device for advanced treatment of nitrobenzene wastewater by supergravity enhanced nano-zero-valent iron-ozone method, which solves the complicated preparation process of nano-zero-valent iron and directly uses When ozone acts on nitrobenzene wastewater, the utilization rate of ozone is not high, and the dosage is large. Its steps: the ferrous iron salt nitrobenzene wastewater solution and the _KBH4 or _NaBH4 aqueous solution react in the impinging flow-rotating packed bed to form aniline-containing wastewater; the aniline-containing wastewater reacts with ozone in the rotating packed bed. The device includes impinging flow-rotating packed bed, and the rotating packed bed is equipped with upper and lower reaction zones, the upper reaction zone is a liquid-liquid reaction zone, the lower reaction zone is a gas-liquid reaction zone, and a liquid receiving device is set between the upper and lower reaction zones , a gas outlet is set at the top of the lower reaction zone. The utilization rate of the nanometer zero-valent iron in the invention is more sufficient, the ozone utilization rate and oxidation efficiency are improved, and the invention is suitable for treating nitrobenzene wastewater with large batches and heavy processing tasks.

Description

Method and device for advanced treatment of nitrobenzene wastewater by high-gravity enhanced nano-zero-valent iron-ozone method

technical field

The invention belongs to the technical field of nitrobenzene wastewater treatment, and in particular relates to a method and device for advanced treatment of nitrobenzene wastewater by supergravity enhanced nanometer zero-valent iron-ozone method.

Background technique

Nitrobenzene wastewater is a kind of wastewater that is extremely difficult to degrade. Due to its wide source and high toxicity, it has been included in the list of priority pollutants in my country. In recent years, research on the treatment of nitrobenzene wastewater has attracted much attention.

Nanoscaled Zerovalent Iron (NZVI) has the characteristics of large specific surface area and high reactivity. It has great application potential in wastewater treatment fields such as the removal of heavy metal ions, organic wastewater degradation, and groundwater pollution remediation. Studies have shown that nano-zero-valent iron can quickly and efficiently reduce refractory nitrobenzene compounds to easily biodegradable aniline compounds. However, in the existing research on the application of nano-zero-valent iron, the preparation process of nano-zero-valent iron is usually: under nitrogen protection and continuous stirring, add strong The reducing agent is separated and washed by several times of centrifugation or magnetic separation, and finally dried or stored in ethanol or acetone solution. The above-mentioned preparation process has complicated steps and harsh conditions, and it is inevitable that some nanoparticles will be oxidized and inactivated during the drying and storage process. In the process of preparing nanoparticles, traditional stirring reactors often have problems such as long mixing time (5-50 ms), uneven mixing, and uneven particle size distribution, which are difficult to meet the needs of mass production.

Ozone is a green, efficient, and non-secondary pollution oxidizing agent. The oxidation of ozone on pollutants can be divided into direct oxidation by ozone molecules directly attacking pollutants and indirect oxidation by indirect attacking pollutants by catalyzed hydroxyl radicals. The direct oxidation and indirect oxidation of ozone can effectively mineralize organic matter into small molecular substances, thereby improving the biodegradability of wastewater. As a strong oxidizing group, hydroxyl radicals can non-selectively degrade organic matter in wastewater into small molecular compounds. It is reported in the literature that both nano-zero-valent iron and Fe ²⁺ can catalyze ozone to generate free hydroxyl groups, thereby degrading pollutants. However, the current application of ozone oxidation technology has problems such as poor water solubility of ozone. For the refractory nitrobenzene wastewater, direct treatment with ozone also has problems such as low utilization rate of ozone and large amount of ozone.

As a new type of process intensification technology, High Gravity Technology (Higee) has the advantages of short mixing time and uniform mixing. The high-gravity technology uses a high-speed rotating packing bed to simulate a high-gravity field. During the high-speed rotating process of the packing, it has the effects of crushing, shearing, and tearing on the liquid, which greatly increases the contact area between the phases and accelerates the renewal rate of the phase interface. Greatly increase the mass transfer rate at the phase boundary and strengthen the microscopic mixing process. Regardless of the microscopic mixing, mass transfer, and reaction between liquid-liquid two-phase or gas-liquid two-phase flow, the high-gravity rotating packed bed has incomparable advantages over traditional agitators.

Contents of the invention

Aiming at the current problems such as complicated preparation process of nanometer zero-valent iron, difficulty in scale-up, low utilization rate of ozone and large dosage when directly using ozone to act on nitrobenzene wastewater, the present invention aims to provide a continuous and easy-to-engineer scale-up super Gravity-enhanced nano-zero-valent iron-ozone method for advanced treatment of nitrobenzene wastewater.

In order to achieve the above object, the technical scheme adopted in the present invention is:

The method for the advanced treatment of nitrobenzene wastewater by high-gravity enhanced nanometer zero-valent iron-ozone method comprises the following steps:

1) First dissolve the soluble ferrous salt in the nitrobenzene wastewater to prepare a ferrous ferrous salt-containing nitrobenzene wastewater solution;

2) Take KBH ₄ or NaBH ₄ aqueous solution;

3) Two liquids, nitrobenzene wastewater solution containing ferrous iron salt and KBH ₄ or NaBH ₄ aqueous solution, collide, mix and react in the impinging flow-rotating packed bed, and reduce nitrobenzene while preparing nanometer zero-valent iron into aniline to form aniline-containing wastewater;

4) The aniline-containing wastewater is in countercurrent or cross-current contact with ozone in the rotating packed bed to undergo oxidative degradation reaction. After degradation, the wastewater is discharged and the ozone tail gas is discharged.

The reaction formula for preparing nanometer zero-valent iron is:

The reaction formula for the reduction of nitrobenzene by nanometer zero-valent iron is:

Nano zero-valent iron and Fe ²⁺ catalyze the reaction formula of ozone to generate hydroxyl radicals:

The concentration of the nitrobenzene wastewater is 50-500 mg·L ^-1 , and the concentration of ferrous iron in the soluble ferrous salt nitrobenzene wastewater solution is 20-30 times the concentration of nitrobenzene in the nitrobenzene wastewater The concentration of the KBH ₄ or NaBH ₄ aqueous solution is 2 to 4 times the concentration of ferrous iron in the selected soluble ferrous salt nitrobenzene wastewater solution, and the gas phase ozone concentration is 10 to 100 mg·L ^-1 , the The volume flow ratio of aniline-containing wastewater to ozone is 500-2000 L·m ^-3 , the soluble ferrous salt is ferrous chloride, ferrous nitrate or ferrous sulfate, and the ferrous salt-containing nitrobenzene wastewater solution The initial pH value is 2.0-9.0.

The two liquids of the ferrous salt-containing nitrobenzene wastewater solution and the KBH ₄ or NaBH ₄ aqueous solution are equal-volume fluids, and the initial impact velocity of the two equal-volume fluids is 1-25 m·s ^-1 . The rotating speed of the supergravity device is 100-3000 rpm. The reaction temperature is 10-30°C.

The device for completing the above-mentioned high-gravity enhanced nano-zero-valent iron-ozone method for advanced treatment of nitrobenzene wastewater includes impingement flow-rotating packed bed I and rotating packed bed II, and impinging flow-rotating packed bed I includes an impinging flow device and Rotating packed bed Ⅰ, impinging flow device includes feeding pipe Ⅰ and feeding pipe Ⅱ with opposite nozzles at the bottom, feeding pipe Ⅰ and feeding pipe Ⅱ respectively pass through pump Ⅰ and pump Ⅱ and liquid storage tank Ⅰ and liquid storage Tank II is connected, and liquid flowmeters are installed between feed pipe I and feed pipe II and pump I and pump II, and a liquid outlet is set at the bottom of the impingement flow-rotary packed bed and leads to liquid storage tank III; rotary packing The bed II and the liquid storage tank III are connected by the pump III and the liquid flow meter III; the inlet port of the rotary packed bed II is connected with the ozone generator through the gas flow meter, and the ozone generator is connected with the oxygen cylinder; the gas outlet of the rotary packed bed II It is connected with the exhaust gas treatment device, and the liquid outlet is connected with the liquid storage tank IV.

Based on the above-mentioned high-gravity enhanced nano-zero-valent iron-ozone method for advanced treatment of nitrobenzene wastewater, the high-gravity enhanced nano-zero-valent iron-ozone method for advanced treatment of nitrobenzene wastewater contains ferrous iron salts. Nitrobenzene waste The aqueous solution and KBH ₄ or NaBH ₄ aqueous solution are measured by pump Ⅰ and pump Ⅱ respectively through liquid flow meter Ⅰ and flow meter Ⅱ, and then pumped into the impinging flow-rotating packed bed from feed pipe Ⅰ and feed pipe Ⅱ. Impingement flow - collision, mixing and reaction in the rotating packed bed, reducing nitrobenzene to aniline while preparing nano-zero-valent iron, and then the aniline-containing wastewater is thrown out and discharged into the liquid storage tank III; the aniline-containing wastewater is pumped by pump III Enter the rotary packed bed II to contact with the ozone generated by the ozone generator in countercurrent or crossflow to carry out the oxidation degradation reaction. After degradation, the waste water is discharged into the liquid storage tank IV, and the ozone tail gas is discharged to the tail gas treatment device.

Another device for completing the method for the advanced treatment of nitrobenzene wastewater by the supergravity-enhanced nano-zero-valent iron-ozone method includes an impingement flow-rotating packed bed, and the impinging flow-rotating packed bed includes an impinging flow device and a rotating packed bed , the shell of the rotating packed bed is provided with a liquid inlet, a liquid outlet, an air inlet and an air outlet, and the impinging flow device enters the rotating packed bed from the top liquid inlet, and the rotating packed bed is provided with an upper reaction zone and a lower reaction zone, and the upper reaction zone The area is a liquid-liquid reaction area containing ferrous salt nitrobenzene wastewater solution and KBH ₄ or NaBH ₄ aqueous solution, the lower reaction area is a gas-liquid reaction area containing aniline wastewater and ozone, and the upper and lower reaction areas are respectively set Coaxial packing rotor, a liquid receiving device is set between the upper and lower reaction zones, and an air outlet is set at the top of the lower reaction zone.

The liquid receiving device is a conical liquid receiving plate, the bottom of the conical liquid receiving plate is a circular flat plate, and a number of liquid distribution holes are evenly distributed on the flat plate, and the outer edge of the conical liquid receiving plate is connected with the shell of the rotary bed. The inclination angle of the conical liquid receiving plate is 5°-45°, and the opening rate of the circular flat plate at the bottom of the conical liquid receiving plate is 30%-60%.

The inside of the filler rotor in the gas-liquid reaction zone has an inclined surface, and several inclined plates with holes at an angle to the inclined surface are arranged on the inclined surface. The design angle between the inner slope and the vertical surface is 15°-45°, and the design angle between the inclined plate with holes and the slope is 60°-90°.

The impingement flow device is the feeding pipe III and the feeding pipe IV with opposite nozzles III and IV at the bottom, and the feeding pipe III and the feeding pipe IV pass through the pump IV and the pump V and the liquid storage tank V and the liquid storage tank respectively. Ⅵ connection, liquid flow meter Ⅲ and flow meter Ⅳ are installed between feed pipe Ⅲ and feed pipe Ⅳ and pump Ⅳ and pump Ⅴ respectively, and the liquid outlet is set at the bottom of impinging flow-rotating packed bed Ⅲ and leads to the storage Liquid tank VII; the air inlet is connected to the ozone generator through the gas flow meter, and the ozone generator is connected to the oxygen cylinder; the gas outlet is connected to the tail gas treatment device.

Based on the above-mentioned high-gravity enhanced nano-zero-valent iron-ozone method for advanced treatment of nitrobenzene wastewater, the high-gravity enhanced nano-zero-valent iron-ozone method for advanced treatment of nitrobenzene wastewater method: Ferrous ferrous salt nitrobenzene waste The aqueous solution and KBH ₄ or NaBH ₄ aqueous solution are respectively measured by the pump IV and pump V through the liquid flow meter III and the flow meter IV, and then injected into the impinging flow device from the feed pipe III and IV, and passed through the nozzle III of the impinging flow device. After the high-speed jetting with nozzle IV, the initial rapid collision, mixing, and reaction are carried out, and then the liquid enters the high-speed rotating packing rotor II for a second deep mixing reaction; after the liquid-liquid two-phase mixing reaction is completed, it becomes aniline-containing wastewater, and the aniline-containing wastewater is Throw it to the inner wall of the rotary bed shell, flow along the inner wall to the liquid receiving device under the action of gravity, and then distribute it to the sloping plate with holes inside the filler rotor III from the liquid distribution hole; the aniline-containing wastewater is thrown into the filler rotor III under the action of centrifugal force And thrown out from the inside to the outside, ozone enters from the air inlet, and the waste water containing aniline is in countercurrent or cross-flow contact in the packing rotor III; after the gas-liquid two-phase mass transfer and reaction are completed, the ozone tail gas is discharged from the gas outlet to degrade The final waste water is discharged from the liquid outlet to the liquid storage tank VII.

The invention combines the reduction of nanometer zero-valent iron with ozone oxidation, firstly reduces the refractory nitrobenzene to easy-degradable aniline, and then utilizes nanometer zerovalent iron and nanometer zerovalent iron to reduce the ^Fe2 produced in the process of reducing nitrobenzene ⁺ Catalyzing ozone to generate hydroxyl radicals to degrade aniline, thereby realizing advanced treatment of p-nitrobenzene wastewater. Both the reduction and oxidation processes are carried out under the strengthening of the hypergravity device. Utilizing the fast and efficient mixed mass transfer characteristics of the high-gravity rotating packed bed, the reduction and ozone oxidation process of nano-zero-valent iron was strengthened, and the rapid, efficient and continuous nano-zero-valent iron-ozone oxidation method was used for advanced treatment of nitrobenzene waste water. Using this method to treat nitrobenzene wastewater has simple process, low cost, high speed and high efficiency.

The beneficial effects of the present invention are:

1. Using high-gravity technology to prepare nano-zero-valent iron online and simultaneously treat nitrobenzene wastewater, avoiding the traditional agitator feeding in the way of "dropping", the mixing is rapid and uniform, the reaction is fast and sufficient, the method is easy to operate, and can be continuous run.

2. Using high-gravity technology to prepare nano-zero-valent iron online and simultaneously treat nitrobenzene wastewater, realize the reduction of p-nitrobenzene wastewater during the preparation of nano-zero-valent iron, shorten the reaction time, and avoid nano-zero waste in traditional methods. The complex operations such as washing, separation, drying, and storage in the preparation process of valent iron have changed from multiple steps to one step, which greatly simplifies the preparation and use steps; changed the grain state of nano-zero-valent iron when it reacts with nitrobenzene wastewater ( As shown in Figure 5), the nano-zero-valent iron grains undergo a reduction reaction with nitrobenzene at the initial stage of nucleation and during the growth process, which avoids the reaction of nano-zero-valent iron with nitrobenzene in the state of large particles in conventional methods. The utilization rate of zero-valent iron is more sufficient. When conventional nano-zero-valent iron reduces nitrobenzene, the dosage concentration of nano-zero-valent iron is 100 to 200 times that of nitrobenzene in nitrobenzene wastewater. In this method, it is converted into nanometer The dose concentration of zero-valent iron is 20 to 30 times that of nitrobenzene in nitrobenzene wastewater.

3. The mass transfer of ozone in water is enhanced by the use of supergravity technology, and the nano-zero-valent iron and Fe ²⁺ produced during the reduction of nitrobenzene by nano-zero-valent iron are used to catalyze the oxidation of ozone, without adding additional chemicals. , Improve the ozone utilization rate and oxidation efficiency, and effectively reduce the treatment cost.

4. The supergravity device is adopted, the equipment is small in size, easy to install, convenient to start and stop, and can be operated continuously. It is suitable for the treatment of nitrobenzene wastewater with large batches and heavy processing tasks.

5. The liquid-liquid two-phase reaction is fully mixed and then the gas-liquid two-phase reaction is integrated into the same device to realize the integrated design and effectively reduce the equipment footprint. The inclined surface design on the inner side of the lower filling rotor is beneficial to accept the liquid distributed from the liquid receiving device as a liquid redistributor. The device of the invention can realize the mixing and dosing of two strands of raw materials, followed by process intensification of absorption reaction. It can also realize the process intensification of the mixed reaction of the raw materials first, and then the mass transfer reaction between the gas-liquid two phases.

Description of drawings

Fig. 1 is a process flow diagram of the advanced treatment of nitrobenzene wastewater by a supergravity-enhanced nano-zero-valent iron-ozone method according to the present invention.

In the figure: 1-liquid storage tank Ⅰ; 2-pump Ⅰ; 3-liquid flow meter Ⅰ; 4-impingement flow-rotating packed bed Ⅰ; 5-liquid storage tank Ⅱ; 6-pump Ⅱ; 7-liquid flow meter Ⅱ ;8-motor Ⅰ; 9-reservoir Ⅲ; 10-pump Ⅲ; 11-liquid flow meter Ⅲ; 12-rotary packed bed Ⅱ; 13-reservoir Ⅳ; -ozone generator; 17-gas flow meter; 18-tail gas treatment device.

Fig. 2 is a main body diagram of an impinging flow-rotating packed bed device for advanced treatment of nitrobenzene wastewater by supergravity-enhanced nano-zero-valent iron-ozone method according to the present invention.

In the figure: 19-impact area; 20-nozzle Ⅰ; 21-nozzle Ⅱ; 22-filling rotor Ⅰ; 23-feed pipe Ⅰ; 24-feed pipe Ⅱ; Liquid outlet; 28-rotary shaft.

Fig. 3 is a process flow diagram of another high-gravity enhanced nano-zero-valent iron-ozone method for advanced treatment of nitrobenzene wastewater according to the present invention.

In the figure: 29-liquid storage tank Ⅴ; 30-pump Ⅳ; 31-liquid flow meter Ⅲ; 32-impingement flow-rotating packed bed Ⅲ; 33-liquid storage tank Ⅵ; 34-pump Ⅴ; 35-liquid flow meter Ⅳ ; 36-motor III; 37-liquid storage tank VII; 38-oxygen cylinder; 39-ozone generator; 40-gas flow meter; 41-tail gas treatment device.

Fig. 4 is the main body diagram of another impingement flow-rotating packed bed device for advanced treatment of nitrobenzene wastewater by the supergravity-enhanced nano-zero-valent iron-ozone method.

In the figure: 42-liquid inlet; 43-feed pipe III; 44-feed pipe IV; 45-nozzle III; 46-nozzle IV; 47-shell; 48-air outlet; 49-air inlet; 50- Liquid outlet; 51-rotating shaft; 52-sloping plate with holes; 53-filling rotor III; 54-liquid receiving device; 55-impact area; 56-filling rotor II.

Figure 5 is a transmission electron microscope morphology comparison of nano-zero-valent iron in the reaction process of a kind of supergravity-enhanced nano-zero-valent iron-ozone method in the advanced treatment of nitrobenzene wastewater according to the present invention and the nano-zero-valent iron in the reaction process of conventional methods picture.

In the figure: a-high gravity method; b-conventional method.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments, but the content of the present invention is not limited by the following embodiments.

The method for the advanced treatment of nitrobenzene wastewater by high-gravity enhanced nano-zero-valent iron-ozone method is characterized in that it includes the following steps:

1) First dissolve the soluble ferrous salt in the nitrobenzene wastewater to prepare a ferrous ferrous salt-containing nitrobenzene wastewater solution;

2) Take KBH ₄ or NaBH ₄ aqueous solution;

3) Two liquids, nitrobenzene wastewater solution containing ferrous iron salt and KBH ₄ or NaBH ₄ aqueous solution, collide, mix and react in the impinging flow-rotating packed bed, and reduce nitrobenzene while preparing nanometer zero-valent iron into aniline to form aniline-containing wastewater;

4) The aniline-containing wastewater is in countercurrent or cross-current contact with ozone in the rotating packed bed to undergo oxidative degradation reaction. After degradation, the wastewater is discharged and the ozone tail gas is discharged.

The concentration of the nitrobenzene wastewater is 50-500 mg·L ^-1 ; the concentration of ferrous iron in the soluble ferrous salt nitrobenzene wastewater solution is 20-30 times the concentration of nitrobenzene in the nitrobenzene wastewater The concentration of the KBH ₄ or NaBH ₄ aqueous solution is 2 to 4 times the concentration of ferrous iron in the selected soluble ferrous salt nitrobenzene wastewater solution, and the gas phase ozone concentration is 10 to 100 mg·L ^-1 , the The volume flow ratio of aniline-containing wastewater to ozone is 500-2000 L·m ^-3 ; the soluble ferrous salt is ferrous chloride, ferrous nitrate or ferrous sulfate, and the ferrous salt-containing nitrobenzene wastewater solution The initial pH value is 2.0-9.0. The two liquids of the ferrous salt-containing nitrobenzene wastewater solution and the KBH ₄ or NaBH ₄ aqueous solution are equal-volume fluids, and the initial impact velocity of the two equal-volume fluids is 1-25 m·s ^-1 . The rotating speed of the supergravity device is 100-3000 rpm. The reaction temperature is 10-30°C.

Examples 1-6, using the process flow shown in Figure 1 to treat nitrobenzene wastewater. The device includes impingement flow-rotating packed bed I and rotating packed bed II, impinging flow-rotating packed bed I includes impinging flow device and rotating packed bed I, and impinging flow device includes feed pipe I with opposite nozzles at the bottom and Feed pipe II, feed pipe I and feed pipe II are respectively connected to storage tank I and liquid storage tank II through pump I and pump II, between feed pipe I and feed pipe II and pump I and pump II Both are equipped with liquid flowmeters, and the bottom of the impinging flow-rotary packed bed is provided with a liquid outlet, which leads to the liquid storage tank III; the rotary packed bed II and the liquid storage tank III are connected by the pump III and the liquid flow meter III; the rotary packed bed The air inlet of II is connected to the ozone generator through the gas flow meter, and the ozone generator is connected to the oxygen cylinder; the gas outlet of the rotary packed bed II is connected to the tail gas treatment device, and the liquid outlet is connected to the liquid storage tank IV. In the following examples, the rotating packed bed is a countercurrent rotating packed bed.

Dissolve the soluble ferrous salt in the nitrobenzene wastewater in the storage tank Ⅰ 1 to prepare a certain concentration of ferrous salt-containing nitrobenzene wastewater, and adjust the initial pH to 2.0-9.0; use tap water to dissolve KBH ₄ or NaBH ₄ In the liquid storage tank II5, make a certain concentration of NaBH ₄ aqueous solution. The two streams of liquid are respectively measured by the pump I2 and the pump II6 through the liquid flowmeter I3 and the flowmeter II7, and then sprayed out from the nozzle I20 and the nozzle II21 of the feed pipe I23 and the feed pipe II 24, and perform the initial rapid collision in the impact area 19 , mix, react. Subsequently, the liquid enters the high-speed rotating filling rotor I22 from the inside to the outside along the radial direction, and performs secondary deep and uniform mixing and reaction. Then the liquid is thrown out, flows along the inner wall of the rotating packed bed shell 26 to the liquid outlet 27, and is discharged into the liquid storage tank III9. The waste water in the liquid storage tank III9 is pumped into the rotating packed bed II12 by the pump III10 through the liquid flowmeter III11, and is catalyzed by nanometer zero-valent iron and Fe ²⁺ , in the packing rotor I22 rotating at a high speed and generated from ozone. The ozone contact reaction measured by the gas flow meter 17 in the device 16, the waste water after the reaction is discharged into the liquid storage tank IV13, and the tail gas is discharged from the gas outlet into the tail gas treatment device 18. The waste water in the liquid storage tank IV13 can be pumped into the rotary packed bed 12 by the pump III10 for circulation treatment.

Example 1:

Using the process flow shown in Figure 1, wastewater containing nitrobenzene with an initial concentration of 250 mg·L ^-1 was treated at 15 °C. Dissolve ferrous sulfate (FeSO ₄ 7H ₂ O) in the nitrobenzene wastewater in the storage tank Ⅰ1 to prepare a FeSO 4 nitrobenzene wastewater solution containing FeSO ₄ with a concentration ²⁵ times the nitrobenzene concentration, and adjust the initial The pH is 9.0; use tap water to dissolve NaBH ₄ in the liquid storage tank Ⅱ5, and make a NaBH ₄ aqueous solution whose concentration of NaBH ₄ is 3 times of the concentration of Fe ²⁺ in the FeSO ₄ nitrobenzene wastewater solution. The two liquids collided, mixed, and reacted quickly in the impact area 19 at an initial impact velocity of 15 m s ^-1 , and then entered the packing rotor I22 with a rotation speed of 100 rpm for a second deep and uniform mixing and reaction. The liquid is then drained into reservoir III9. The wastewater in the liquid storage tank III9 is measured by the pump III10 through the liquid flow meter III11, and then poured into the rotary packed bed II12, where it is oxidized by ozone in the packing at 100 rpm, the ozone flow rate is 75 L·h ^-1 , and the gas phase ozone concentration is 50 mg·L ^-1 , the liquid-gas ratio is 1500 L·m ^-3 , and the waste water after the reaction is discharged into the liquid storage tank IV13.

Sampling and analysis from liquid storage tank Ⅲ9 showed that the removal rate of nitrobenzene reached 96% and the removal rate of COD reached 5% after reduction of nano-zero-valent iron; sampling and analysis from liquid storage tank Ⅳ13 showed that the removal rate of nitrobenzene was 99% and the removal rate of COD was 99%. rate of 70%. Compared with the traditional method, the invention has high treatment efficiency, significantly shortened treatment time and significantly reduced ozone consumption.

Example 2:

Using the process flow shown in Figure 1, wastewater containing nitrobenzene with an initial concentration of 50 mg·L ^-1 was treated at 30 °C. Dissolve ferrous chloride (FeCl ₂ ) in the nitrobenzene wastewater in the liquid storage tank Ⅰ1, prepare a FeCl ₂ nitrobenzene wastewater solution containing FeCl ² with a concentration of 20 times the nitrobenzene concentration, and adjust the initial pH to 7.0 ; Prepare the KBH ₄ aqueous solution whose concentration is 2.5 times of the Fe ²⁺ concentration in the FeCl ₂ nitrobenzene wastewater solution and place it in _the liquid storage tank Ⅱ5. The two liquids reacted in the impinging flow-rotating packed bed I4 with a rotational speed of 1200 rpm at an impingement initial velocity of 25 m·s ^-1 and then discharged into the liquid storage tank III9. The wastewater in the liquid storage tank III9 is pumped into the rotary packed bed II12 by the pump III10, and is oxidized by ozone in the packing at 1200 rpm. The ozone flow rate is 40 L·h ^-1 , the gas phase ozone concentration is 10 mg·L ^-1 The gas ratio is 2000 L·m ^-3 , and the waste water after the reaction is discharged into the liquid storage tank IV13. After a single reaction, sampling and analysis from liquid storage tank Ⅲ9 showed that the removal rate of nitrobenzene was 98% and COD removal rate was 7% after reduction of nano-zero-valent iron; sampling and analysis from liquid storage tank Ⅳ13 showed that the removal rate of nitrobenzene was 100%, COD removal rate reaches 75%.

Example 3:

Using the process flow shown in Figure 1, wastewater containing nitrobenzene with an initial concentration of 500 mg·L ^-1 was treated at 20 °C. Dissolve FeCl ₂ in the nitrobenzene wastewater in the liquid storage tank Ⅰ1, prepare FeCl ₂ nitrobenzene wastewater solution containing FeCl ² , whose concentration is 30 times the nitrobenzene concentration, and adjust the initial pH to 2.0; prepare KBH ₄ with a concentration of The KBH ₄ aqueous solution containing 3 times the Fe ²⁺ concentration in the FeCl ₂ nitrobenzene wastewater solution was placed in the liquid storage tank Ⅱ5. The two streams of liquids reacted in the impinging flow-rotating packed bed I4 with a rotational speed of 1000 rpm at the initial impact velocity of 1 m·s ^-1 and then discharged into the liquid storage tank III9. The wastewater in the liquid storage tank III9 is pumped into the rotary packed bed II12 by the pump III10, and is oxidized by ozone in the packing at 1000 rpm. The ozone flow rate is 75 L·h ^-1 , the gas phase ozone concentration is 100 mg·L ^-1 The ratio is 500 L·m ^-3 , and the waste water after the reaction is discharged into the liquid storage tank IV13. Afterwards, the wastewater in the liquid storage tank IV13 is pumped into the rotary packed bed II12 by the pump III10, and the circulation reaction is 5 minutes. The removal rate of nitrobenzene is 99%, and the removal rate of COD is 94%.

Example 4:

Using the process flow shown in Figure 1, wastewater containing nitrobenzene with an initial concentration of 400 mg·L ^-1 was treated at 10 °C. Dissolve FeCl ₂ in the nitrobenzene wastewater in the storage tank Ⅰ1, prepare FeCl ₂ nitrobenzene wastewater solution containing FeCl ² , whose concentration is 25 times the nitrobenzene concentration, and adjust the initial pH to 4.0; prepare NaBH ₄ with a concentration of The NaBH ₄ aqueous solution containing 4 times the Fe ²⁺ concentration in the FeCl ₂ nitrobenzene wastewater solution is placed in the liquid storage tank II5. The two streams of liquids reacted in the impinging flow-rotating packed bed I4 with a rotational speed of 3000 rpm at an impact initial velocity of 10 m·s ^-1 and then discharged into the liquid storage tank III9. The wastewater in the liquid storage tank III9 is pumped into the rotary packed bed II12 by the pump III10, and is oxidized by ozone in the packing at 3000 rpm. The ozone flow rate is 50 L·h ^-1 , the gas phase ozone concentration is 60 mg·L ^-1 The ratio is 1000 L·m ^-3 , and the waste water after the reaction is discharged into the liquid storage tank IV13. Afterwards, the wastewater in the liquid storage tank IV13 is pumped into the rotary packed bed II12 by the pump III10, and the circulation reaction is 10 minutes. The removal rate of nitrobenzene is 99%, and the removal rate of COD is 97%.

Example 5:

Using the process flow shown in Figure 1, wastewater containing nitrobenzene with an initial concentration of 300 mg·L ^-1 was treated at 25 °C. Dissolve FeSO ₄ 7H ₂ O in the nitrobenzene wastewater in the storage tank Ⅰ1 to prepare a FeSO ⁴ nitrobenzene wastewater solution containing FeSO ₄ nitrobenzene whose concentration is 25 times the nitrobenzene concentration, and adjust the initial pH to 7.0; Tap water dissolves NaBH in liquid storage tank _Ⅱ5 , and makes NaBH ₄ aqueous solution whose NaBH ₄ concentration is 2.5 times of Fe ²⁺ concentration in FeSO ₄ nitrobenzene wastewater solution. The two streams of liquid reacted in the impinging flow-rotating packed bed I4 with a rotation speed of 100 rpm at the initial impact velocity of 20 m·s ^-1 and then discharged into the liquid storage tank III9. The wastewater in the liquid storage tank III9 is pumped into the rotary packed bed II12 by the pump III10, and is oxidized by ozone in the packing at 100 rpm. The ozone flow rate is 65 L·h ^-1 , the gas phase ozone concentration is 40 mg·L ^-1 The gas ratio is 1500 L·m ^-3 , and the waste water after the reaction is discharged into the liquid storage tank IV13. After a single reaction, the removal rate of nitrobenzene is 99%, and the removal rate of COD is 79%.

Embodiment 6:

Using the process flow shown in Figure 1, wastewater containing nitrobenzene with an initial concentration of 200 mg·L ^-1 was treated at 20 °C. Dissolve FeSO ₄ ·7H ₂ O in the nitrobenzene wastewater in the liquid storage tank Ⅰ1 to prepare FeSO ⁴ nitrobenzene wastewater containing FeSO ₄ nitrobenzene wastewater solution whose concentration is 20 times of the nitrobenzene concentration, and adjust the initial pH to 5.0; Tap water dissolves NaBH in liquid storage tank _Ⅱ5 , and makes NaBH ₄ aqueous solution whose NaBH ₄ concentration is 2.5 times of Fe ²⁺ concentration in FeSO ₄ nitrobenzene wastewater solution. The two liquids reacted in the impinging flow-rotating packed bed I4 with a rotational speed of 1200 rpm at the initial impact velocity of 5 m·s ^-1 and then discharged into the liquid storage tank III9. The wastewater in the liquid storage tank III9 is pumped into the rotary packed bed II12 by the pump III10, and is oxidized by ozone in the packing at 1200 rpm. The ozone flow rate is 55L·h ^-1 , the gas phase ozone concentration is 30 mg·L ^-1 The ratio is 1000 L·m ^-3 , and the waste water after the reaction is discharged into the liquid storage tank IV13. After a single reaction, the removal rate of nitrobenzene is 99%, and the removal rate of COD is 68%.

Embodiment 7 utilizes the technological process shown in Fig. 3, and described device comprises impinging flow-rotating packed bed, and impinging flow-rotating packed bed comprises impinging flow device and rotating packed bed, and rotating packed bed shell is provided with liquid inlet, liquid outlet , air inlet and air outlet, the impinging flow device enters the rotating packed bed from the top liquid inlet, and the rotating packed bed is equipped with an upper reaction zone and a lower reaction zone, and the upper reaction zone is the ferrous ferrous salt nitrobenzene wastewater solution and KBH ₄ or the liquid-liquid reaction zone of NaBH ₄ aqueous solution, the lower reaction zone is the gas-liquid reaction zone of wastewater containing aniline and ozone, the upper and lower reaction zones are respectively equipped with coaxial packing rotors, and the upper and lower reaction zones are provided with receiving Liquid device, the uppermost part of the lower reaction zone is provided with a gas outlet.

The liquid receiving device is a conical liquid receiving plate, the bottom of the conical liquid receiving plate is a circular flat plate, and a number of liquid distribution holes are evenly distributed on the flat plate, and the outer edge of the conical liquid receiving plate is connected with the shell of the rotary bed. The inclination angle of the conical liquid receiving plate is 5°-45°, and the opening rate of the circular flat plate at the bottom of the conical liquid receiving plate is 30%-60%.

The inside of the filler rotor in the gas-liquid reaction zone has an inclined surface, and several inclined plates with holes at an angle to the inclined surface are arranged on the inclined surface. The design angle between the inner slope and the vertical surface is 15°-45°, and the design angle between the inclined plate with holes and the slope is 60°-90°.

The impingement flow device is the feeding pipe III and the feeding pipe IV with opposite nozzles III and IV at the bottom, and the feeding pipe III and the feeding pipe IV pass through the pump IV and the pump V and the liquid storage tank V and the liquid storage tank respectively. Ⅵ connection, liquid flow meter Ⅲ and flow meter Ⅳ are installed between feed pipe Ⅲ and feed pipe Ⅳ and pump Ⅳ and pump Ⅴ respectively, and the liquid outlet is set at the bottom of impinging flow-rotating packed bed Ⅲ and leads to the storage Liquid tank VII; the air inlet is connected to the ozone generator through the gas flow meter, and the ozone generator is connected to the oxygen cylinder; the gas outlet is connected to the tail gas treatment device.

Nitrobenzene wastewater solution containing ferrous salt and KBH ₄ or NaBH ₄ aqueous solution are respectively measured by pump IV and pump V through liquid flow meter III and flow meter IV, and then injected into the impact flow from feed pipe III and feed pipe IV After the nozzle III and nozzle IV of the impinging flow device are ejected at high speed, the first rapid collision, mixing and reaction are carried out, and then the liquid enters the high-speed rotating packing rotor II for the second deep mixing reaction; after the liquid-liquid two-phase mixing reaction is completed It becomes aniline-containing wastewater, which is thrown to the inner wall of the rotating bed shell, flows along the inner wall to the liquid receiving device under the action of gravity, and is distributed from the liquid distribution hole to the sloping plate with holes inside the packing rotor III; Under the action, it is thrown into the filler rotor III and thrown out from the inside to the outside, ozone enters through the air inlet, and is in countercurrent or cross-flow contact with the aniline-containing wastewater in the filler rotor III; after completing the gas-liquid two-phase mass transfer and reaction , the ozone tail gas is discharged from the gas outlet, and the degraded waste water is discharged to the liquid storage tank VII through the liquid outlet.

Embodiment 7:

Using the process flow shown in Figure 3, wastewater containing nitrobenzene with an initial concentration of 250 mg·L ^-1 was treated at 20 °C. Dissolve FeSO ₄ 7H ₂ O in the nitrobenzene wastewater in the liquid storage tank Ⅴ29, prepare FeSO ⁴ nitrobenzene wastewater containing FeSO ₄ nitrobenzene wastewater solution whose concentration is 25 times of the nitrobenzene concentration, and adjust the initial pH to 4.0; Tap water dissolves NaBH in liquid storage tank Ⅵ33, and makes NaBH ₄ aqueous solution whose NaBH ₄ concentration is 3 times of Fe ²⁺ concentration in FeSO ₄ nitrobenzene _wastewater solution. _FeSO4- containing nitrobenzene wastewater solution and NaBH4 aqueous solution are measured by pump IV30 and pump _V34 respectively through liquid flowmeter III31 and liquid flowmeter IV35, and then injected into the impingement flow device from feed pipe III43 and feed pipe IV44. After the nozzles III45 and IV46 of the flow device are sprayed out, the two streams of liquid collide, mix, and react quickly at the initial impact velocity of 20 m·s ^-1 , and then the liquid enters the packing rotor II56 at 1000 rpm for the second deep mixing reaction; -After the liquid two-phase mixing reaction is completed, it becomes aniline-containing wastewater, and the aniline-containing wastewater is thrown to the inner wall of the rotating bed shell 47, and flows along the inner wall to the liquid receiving device 54 under the action of gravity, and is distributed to the inner side of the packing rotor III 53 by the liquid distribution hole with holes On the inclined plate 52; the aniline-containing wastewater is thrown into the packing rotor III53 under the action of centrifugal force and thrown out from the inside to the outside, and is oxidized by the ozone entering from the air inlet 49 in the packing rotor III53 at 1000 rpm, and the ozone flow rate is 50 L·h ^-1 , the gas phase ozone concentration is 40 mg·L ^-1 , the liquid-gas ratio is 1000 L·m ^-3 , after the reaction, the ozone tail gas is discharged from the gas outlet 48, and the degraded waste water is discharged from the liquid outlet 50 To reservoir VII37. After a single reaction, samples were taken from the liquid outlet 50 for detection, and the removal rate of nitrobenzene was 99%, and the removal rate of COD was 71%.

Claims (10)

1. A method for supergravity-enhanced nano-zero-valent iron-ozone method for advanced treatment of nitrobenzene wastewater, characterized in that: comprise the steps: 1) First dissolve the soluble ferrous salt in the nitrobenzene wastewater to prepare a ferrous ferrous salt-containing nitrobenzene wastewater solution; 2) Take KBH4 or NaBH4 aqueous solution; 3) Nitrobenzene wastewater containing ferrous iron salt and KBH4 or NaBH4 aqueous solution collide, mix and react in the impinging flow-rotating packed bed, and reduce nitrobenzene to aniline while preparing nano-zero-valent iron , forming aniline-containing wastewater; 4) The aniline-containing wastewater is in countercurrent or cross-current contact with ozone in the rotating packed bed of the supergravity device, and undergoes oxidation and degradation reactions. After degradation, the wastewater is discharged and the ozone tail gas is discharged; The concentration of the nitrobenzene wastewater is 50 to 500 mg L -1; the concentration of ferrous iron in the ferrous salt nitrobenzene wastewater solution is 20 to 30 times the concentration of nitrobenzene in the nitrobenzene wastewater; The concentration of the KBH4 or NaBH4 aqueous solution is 2 to 4 times the concentration of ferrous iron in the ferrous salt nitrobenzene wastewater solution, the ozone concentration is 10 to 100 mg·L ^-1 , the aniline-containing wastewater and ozone The ratio of volume flow is 500～2000L·m ^-3 ; The ferrous salt is ferrous chloride, ferrous nitrate or ferrous sulfate, and the initial pH value of the ferrous salt nitrobenzene wastewater solution is 2.0 to 9.0; The two liquids of the ferrous salt nitrobenzene wastewater solution and the KBH4 or NaBH4 aqueous solution are equal-volume fluids, and the impact initial velocity of the two equal-volume fluids is 1 to 25 m·s ⁻¹ ; The rotating speed of the supergravity device is 100-3000 rpm; the reaction temperature is 10-30°C. 2. A device for completing the method for advanced treatment of nitrobenzene wastewater by supergravity-enhanced nano-zero-valent iron-ozone method as claimed in claim 1, characterized in that: it includes impinging flow-rotating packed bed I and rotating packed bed II , impinging flow-rotating packed bed Ⅰ includes impinging flow device and rotating packed bed Ⅰ, impinging flow device includes feeding pipe Ⅰ and feeding pipe Ⅱ with opposite nozzles at the bottom, feeding pipe Ⅰ and feeding pipe Ⅱ respectively pass through Pump Ⅰ and pump Ⅱ are connected to liquid storage tank Ⅰ and liquid storage tank Ⅱ, and liquid flow meters are installed between feed pipe Ⅰ and feed pipe Ⅱ and pump Ⅰ and pump Ⅱ. The liquid port leads to the liquid storage tank III; the rotating packed bed II and the liquid storage tank III are connected by the pump III and the liquid flow meter III; the air inlet of the rotating packed bed II is connected to the ozone generator through the gas flow meter, and the ozone The generator is connected to the oxygen cylinder; the gas outlet of the rotary packed bed II is connected to the tail gas treatment device, and the liquid outlet is connected to the liquid storage tank IV. 3. a supergravity strengthened nano zero valent iron-ozone method advanced treatment method for nitrobenzene wastewater based on the device of the supergravity strengthened nano zero valent iron-ozone method for advanced treatment of nitrobenzene wastewater according to claim 2, wherein It is characterized in that: ferrous salt-containing nitrobenzene wastewater solution and KBH4 or NaBH4 aqueous solution are respectively measured by pump Ⅰ and pump Ⅱ through liquid flowmeter Ⅰ and flowmeter Ⅱ, and then injected into the impact flow from feed pipe Ⅰ and feed pipe Ⅱ- In the rotating packed bed Ⅰ, two liquids collide, mix and react in the impinging flow-rotating packed bed Ⅰ, and reduce nitrobenzene to aniline while preparing nano-zero-valent iron, and then the aniline-containing wastewater is thrown out and discharged into the storage Liquid tank Ⅲ; aniline-containing wastewater is pumped into the rotating packed bed Ⅱ by the pump Ⅲ, and contacts with the ozone generated by the ozone generator in countercurrent or cross-current, and undergoes oxidation and degradation reaction. After degradation, the waste water is discharged into the liquid storage tank Ⅳ, and the ozone tail gas is discharged to the exhaust gas treatment unit. 4. A device for completing the method for supergravity-strengthened nano-zero-valent iron-ozone method for advanced treatment of nitrobenzene wastewater as claimed in claim 3, characterized in that: comprising impingement flow-rotating packed bed, impinging flow-rotating packing The bed includes an impingement flow device and a rotating packed bed. The shell of the rotating packed bed is provided with a liquid inlet, a liquid outlet, an air inlet and an air outlet. The impinging flow device enters the rotating packed bed from the top liquid inlet, and the rotating packed bed is provided with an upper The reaction zone and the lower reaction zone, the upper reaction zone is a liquid-liquid reaction zone containing ferrous salt nitrobenzene wastewater solution and KBH4 or NaBH4 aqueous solution, the lower reaction zone is a gas-liquid reaction zone containing aniline wastewater and ozone, the upper 1. Coaxial filler rotors are respectively arranged in the lower reaction zone, a liquid receiving device is arranged between the upper and lower reaction zones, and an air outlet is arranged at the top of the lower reaction zone. 5. The device for advanced treatment of nitrobenzene wastewater by supergravity-enhanced nano-zero-valent iron-ozone method according to claim 4, characterized in that: the liquid receiving device is a conical liquid receiving plate, and the conical liquid receiving plate The bottom is a circular flat plate with a number of liquid distribution holes evenly distributed on the flat plate, and the outer edge of the conical liquid receiving plate is connected with the shell of the rotary bed. 6. The device for advanced treatment of nitrobenzene wastewater by supergravity-enhanced nano-zero-valent iron-ozone method according to claim 5, characterized in that: the inclination angle of the conical liquid-receiving plate is 5°-45°, and the conical The opening rate of the circular flat plate at the bottom of the shaped liquid receiving plate is 30% to 60%. 7. according to claim 4 or 5 or 6 described supergravity strengthened nanometer zero valent iron-ozone method advanced treatment device of nitrobenzene wastewater, it is characterized in that: the inner side of the filler rotor in the gas-liquid reaction zone has a slope, the slope There are several inclined plates with holes at an angle with the inclined plane. 8. The device for advanced treatment of nitrobenzene wastewater by supergravity-enhanced nano-zero-valent iron-ozone method according to claim 7, characterized in that: the angle between the inside slope of the filling rotor in the gas-liquid reaction zone and the vertical plane is designed to be 15° ～45 °, the inclined plate with holes (52) and the inclined plane design angle 60 °～90 °. 9. The device for advanced treatment of nitrobenzene wastewater by supergravity-enhanced nano-zero-valent iron-ozone method according to claim 8, characterized in that: the impinging flow device is a feed pipe with opposing nozzles III and IV at the bottom Ⅲ and feeding pipe IV, feeding pipe Ⅲ and feeding pipe Ⅳ are respectively connected with liquid storage tank Ⅴ and liquid storage tank Ⅵ through pump Ⅳ and pump Ⅴ, and feeding pipe Ⅲ and feeding pipe Ⅳ are connected with pump Ⅳ and pump Ⅴ There are liquid flowmeter III and flowmeter IV between them, and the liquid outlet is set at the bottom of the impingement flow-rotating packed bed III, and leads to the liquid storage tank VII; the air inlet is connected to the ozone generator through the gas flowmeter, and the ozone The generator is connected to the oxygen cylinder; the gas outlet is connected to the exhaust gas treatment device. 10. A method for advanced treatment of nitrobenzene wastewater based on the supergravity enhanced nano zero-valent iron-ozone method for advanced treatment of nitrobenzene wastewater based on the device of claim 9, wherein It is characterized in that: ferrous salt-containing nitrobenzene wastewater solution and KBH4 or NaBH4 aqueous solution are measured by pump IV and pump V respectively through liquid flow meter III and flow meter IV, and then injected into the impinging flow device from feed pipe III and feed pipe IV , after the nozzle III and nozzle IV of the impinging flow device are ejected at high speed, the initial rapid collision, mixing, and reaction are carried out, and then the liquid enters the high-speed rotating packing rotor II for the second deep mixing reaction; after the liquid-liquid two-phase mixing reaction is completed, it becomes Aniline-containing wastewater, the aniline-containing wastewater is thrown to the inner wall of the rotating bed shell, flows along the inner wall to the liquid receiving device under the action of gravity, and is distributed from the liquid distribution hole to the sloping plate with holes inside the filler rotor III; the aniline-containing wastewater is affected by the centrifugal force The bottom is thrown into the filler rotor III and thrown out from the inside to the outside, ozone enters through the air inlet, and is in countercurrent or cross-flow contact with the aniline-containing wastewater in the filler rotor III; after completing the gas-liquid two-phase mass transfer and reaction, The ozone tail gas is discharged from the gas outlet, and the degraded waste water is discharged to the liquid storage tank VII through the liquid outlet.

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