Enhanced fenton process for treating dimethyl sulfoxide-containing wastewater

Abstract

The application discloses an enhanced Fenton process for treating dimethyl sulfoxide-containing wastewater. The method comprises the following steps: pretreating dimethyl sulfoxide-containing wastewater by a high-frequency electromagnetic water treatment device, and then feeding the magnetized wastewater into a Fenton reactor, and adding FeSO4 solution and H2O2 solution in batches to perform Fenton oxidation treatment. The application utilizes a magnetic field to increase the activity of water, so that water molecules are no longer tightly wrapped around dimethyl sulfoxide, and the action between hydroxyl radicals and dimethyl sulfoxide in the subsequent Fenton reaction is promoted. Meanwhile, FeSO4 and H2O2 are used as Fenton reagents, and the reaction process does not need to be adjusted for acid, the use amount of reagents can be reduced, and the treatment effect is stable and efficient.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of dimethyl sulfoxide wastewater oxidation treatment, and relates to an enhanced Fenton process for treating dimethyl sulfoxide-containing wastewater. BACKGROUND

[0002] Polyacrylonitrile-based carbon fiber takes acrylonitrile monomer as a main raw material, dimethyl sulfoxide as a main solvent, and is obtained through polymerization, spinning, carbonization and other sections to be finished carbon fiber. After the coagulation bath in the spinning process is recovered through rectification column, most of the dimethyl sulfoxide can be recycled, but a small amount of dimethyl sulfoxide will still be discharged with wastewater. Dimethyl sulfoxide is a toxic substance, which has inhibitory or toxic effects on microorganisms, so when the wastewater is discharged into the environment, it is difficult to be biodegraded in the natural environment, and in addition, it has persistence and will accumulate in the environment, causing long-term harm to humans and other organisms, so it must be treated and discharged up to standard.

[0003] At present, the main methods for treating dimethyl sulfoxide wastewater include chemical oxidation method, solvent extraction method, adsorption method, incineration method, photocatalytic method and biochemical treatment method. Advanced oxidation technology is an improvement on the basis of classical chemical oxidation method, which produces highly active hydroxyl radicals in the treatment process, and directly mineralizes pollutants into carbon dioxide and other inorganic substances, without producing secondary pollution. Hydroxyl radical is a strong oxidant, which can react with almost all biological macromolecules and organic pollutants, and is the most effective method for pretreatment of refractory organic wastewater. Fenton reagent oxidation method is one of the commonly used advanced oxidation technologies, and Fenton reagent is a combination of soluble ferrous salt and H2O2. In dimethyl sulfoxide-containing wastewater, Fe 2 + is a reaction catalyst, and H2O2 can produce hydroxyl radicals under the catalysis of Fe 2+ , and the optimal pH range is generally 2.5-3.5, so the wastewater to be treated generally needs to be acidified; due to the extremely short existence time of hydroxyl radicals and the slow reaction rate of dimethyl sulfoxide, a large amount of Fenton reagent is added, which causes reagent waste. SUMMARY

[0004] The present application provides an enhanced Fenton process for treating dimethyl sulfoxide-containing wastewater, which can effectively reduce the amount of reagent used, improve the utilization rate of Fe 2+ , and reduce the reaction time.

[0005] The enhanced Fenton process for treating dimethyl sulfoxide-containing wastewater of the present application comprises the following steps:

[0006] Step 1: dimethyl sulfoxide-containing wastewater is pretreated by a high-frequency electromagnetic water treatment device, the frequency of the controller of the high-frequency electromagnetic water treatment device is uniformly reduced from 500Hz to 100Hz, and then is increased to 500Hz, so that the magnetic field strength is reciprocally cycled between 30mT and 500mT, the cycle is 5-10min, and the total pretreatment time is 30-60min;

[0007] Step 2: the magnetized wastewater is introduced into a Fenton reactor, FeSO4 solution and H2O2 solution are added in batches, after the reaction is completed, the wastewater is adjusted with alkali, flocculated, precipitated, and the residual dimethyl sulfoxide concentration of the effluent is detected, and after the requirement is reached, the wastewater is introduced into subsequent biochemical treatment.

[0008] Further, in step 1, the concentration of dimethyl sulfoxide in the dimethyl sulfoxide-containing wastewater is 100-1000mg / L.

[0009] Further, in step 1, the dimethyl sulfoxide-containing wastewater is carbon fiber production wastewater containing dimethyl sulfoxide.

[0010] Further, in step 2, a paddle stirring device is arranged in the Fenton reactor, and the wastewater is fully mixed with the FeSO4 solution and the H2O2 solution through stirring.

[0011] Further, in step 2, the concentration of the FeSO4 solution is 15wt%, the dosage is 3‰-9‰ of the wastewater volume, the concentration of the H2O2 solution is 26.5wt%, the dosage is 1‰-3‰ of the wastewater volume, and the pH is reduced to 2.5-3.5, without adding sulfuric acid or hydrochloric acid to adjust the pH.

[0012] Further, in step 2, the number of additions is 2-6 times, and the reaction time is 1-3h.

[0013] Further, in step 2, the residual dimethyl sulfoxide concentration of the effluent is 0-10mg / L.

[0014] Compared with the prior art, the present application has the following advantages:

[0015] (1) The present application uses a high-frequency electromagnetic water treatment device to pretreat the wastewater, magnetizes the wastewater, changes the arrangement order between dimethyl sulfoxide molecules and water molecules, the water molecules are constantly polarized to produce deformation, vibration and inversion as dipoles, and resonate with the external electromagnetic field to strengthen the molecular motion, so that the original large molecular clusters are dissociated into single water molecules, the activity of water is increased, the water molecules no longer tightly wrap the dimethyl sulfoxide, a channel is left for the reaction between hydroxyl radicals and dimethyl sulfoxide in the subsequent Fenton reaction, and the Fenton reaction efficiency is improved.

[0016] (2) The application selects FeSO4 and H2O2 as Fenton reagent, and no acid needs to be adjusted in the reaction process, thereby reducing the use amount of reagent and the acid-base storage risk. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the application more clear, the application is further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the application, and are not used to limit the application.

[0018] The high-frequency electromagnetic water treatment device used in the application is a common high-frequency electromagnetic water treatment device in the field of water treatment, which can be directly purchased and is composed of a controller and an electromagnet, has a fixed air gap, a magnetic field strength of 30mT-1.0T, a pole column diameter of 70mm, a pole surface diameter of 45mm, and a magnetic field air gap of 10mm.

[0019] The dimethyl sulfoxide-containing wastewater to be treated used in the following examples and comparative examples is dimethyl sulfoxide-containing wastewater generated in the process of producing carbon fibers, and the dimethyl sulfoxide concentration is 826mg / L detected by liquid phase.

[0020] Example 1

[0021] First, the dimethyl sulfoxide-containing wastewater is pretreated by the high-frequency electromagnetic water treatment device, the frequency of the high-frequency electromagnetic water treatment device is uniformly reduced from 500Hz to 100Hz and then increased to 500Hz, so that the magnetic field strength is reciprocally cycled between 30mT and 500mT, the cycle is 5min, and the pretreatment time is 30min. Then, 100L of the magnetized wastewater is introduced into the Fenton reactor, 15wt%FeSO4 solution and 26.5wt%H2O2 solution are added in two batches, the amount of the first added reagent is 0.4L of 15wt%FeSO4 solution and 0.15L of 26.5wt%H2O2 solution, the paddle in the reactor is stirred for 30min, the above steps are repeated to add reagent again, and the total reaction time is 1h. After the reaction is completed, the residual dimethyl sulfoxide concentration in the effluent is 7mg / L after adjusting the alkali, flocculating and precipitating.

[0022] Comparative Example 1

[0023] In this comparative example, the dimethyl sulfoxide-containing wastewater is not pretreated by the high-frequency electromagnetic water treatment device, and the reagent is not added in batches. Instead, 100L of the dimethyl sulfoxide-containing wastewater, 0.8L of 15wt%FeSO4 solution and 0.3L of 26.5wt%H2O2 solution are directly added into the Fenton reactor, the paddle in the reactor is stirred for 1h, and the residual dimethyl sulfoxide concentration in the effluent is 351mg / L after adjusting the alkali, flocculating and precipitating.

[0024] Comparative Example 2

[0025] The comparative example is pretreated by the high-frequency electromagnetic water treatment device, but without batchwise dosing. 100 L of magnetized wastewater, 0.8 L of 15 wt% FeSO4 solution and 0.3 L of 26.5 wt% H2O2 solution are directly added into the Fenton reactor, and the paddle in the reactor is stirred for 1 h. After the reaction is completed, the residual dimethyl sulfoxide concentration in the effluent is measured to be 214 mg / L after adjusting the alkali, flocculating and precipitating.

[0026] Comparative Example 3

[0027] The comparative example is not pretreated by the high-frequency electromagnetic water treatment device, but is batchwise dosed. 100 L of dimethyl sulfoxide-containing wastewater is directly introduced into the Fenton reactor, and 15 wt% FeSO4 solution and 26.5 wt% H2O2 solution are added twice. The first time, 0.4 L of 15 wt% FeSO4 solution and 0.15 L of 26.5 wt% H2O2 solution are added, and the paddle in the reactor is stirred for 30 min. The above steps are repeated for the second time, and the total reaction time is 1 h. After the reaction is completed, the residual dimethyl sulfoxide concentration in the effluent is measured to be 169 mg / L after adjusting the alkali, flocculating and precipitating.

[0028] Comparative Example 4

[0029] The comparative example is substantially the same as Example 1, except that the frequency of the high-frequency electromagnetic water treatment device is kept at 500 Hz and the magnetic field is controlled at 30 mT for 30 min during pretreatment. The rest of the operations are the same as those in Example 1. The residual dimethyl sulfoxide concentration in the effluent is measured to be 144 mg / L.

[0030] Comparative Example 5

[0031] The comparative example is substantially the same as Example 1, except that the frequency of the high-frequency electromagnetic water treatment device is kept at 100 Hz and the magnetic field is controlled at 500 mT for 30 min during pretreatment. The rest of the operations are the same as those in Example 1. The residual dimethyl sulfoxide concentration in the effluent is measured to be 102 mg / L.

[0032] Example 2

[0033] Firstly, the dimethyl sulfoxide wastewater was pretreated by high frequency electromagnetic water treatment device, the frequency of the device was decreased from 500 Hz to 100 Hz and then increased to 500 Hz, the magnetic field intensity was 30 mT-500 mT, the cycle was 10 min, and the pretreatment time was 60 min. Then, 100 L of the magnetized wastewater was introduced into the Fenton reactor, 15 wt% FeSO4 solution and 26.5 wt% H2O2 solution were added twice, the amount of the first addition was 0.4 L of 15 wt% FeSO4 solution and 0.15 L of 26.5 wt% H2O2 solution, the reactor was stirred by the paddle for 60 min, the above steps were repeated for the second addition, the total reaction time was 2 h, after the reaction was completed, the residual dimethyl sulfoxide concentration in the effluent was 4.8 mg / L after adjusting the pH, flocculating and precipitating.

Claims

1. An enhanced Fenton process for treating wastewater containing dimethyl sulfoxide, characterized in that, Includes the following steps: Step 1: Wastewater containing dimethyl sulfoxide is pretreated by a high-frequency electromagnetic water treatment device. The controller frequency of the high-frequency electromagnetic water treatment device is adjusted to decrease from 500Hz to 100Hz at a constant speed, and then increase to 500Hz, so that the magnetic field strength is 30mT~500mT in a cycle of 5~10min. The total pretreatment time is 30~60min. Step 2: The magnetized wastewater is fed into the Fenton reactor, and FeSO4 solution and H2O2 solution are added in batches. After the reaction is completed, the alkali is adjusted, flocculation and precipitation are carried out, and the residual concentration of dimethyl sulfoxide in the effluent is detected. After the requirements are met, it enters the subsequent biological treatment.

2. The enhanced Fenton process according to claim 1, characterized in that, In step 1, the concentration of dimethyl sulfoxide in the wastewater containing dimethyl sulfoxide is 100~1000 mg / L.

3. The enhanced Fenton process according to claim 1, characterized in that, In step 1, the wastewater containing dimethyl sulfoxide is the wastewater from the production of carbon fiber containing dimethyl sulfoxide.

4. The enhanced Fenton process according to claim 1, characterized in that, In step 2, the Fenton reactor is equipped with a paddle agitator.

5. The enhanced Fenton process according to claim 1, characterized in that, In step 2, the concentration of the FeSO4 solution is 15 wt%, and the concentration of the H2O2 solution is 26.5 wt%.

6. The enhanced Fenton process according to claim 1, characterized in that, In step 2, the amount of FeSO4 solution used is 3‰ to 9‰ of the wastewater volume, and the amount of H2O2 solution used is 1‰ to 3‰ of the wastewater volume.

7. The enhanced Fenton process according to claim 1, characterized in that, In step 2, the addition is performed 2 to 6 times, and the reaction time is 1 to 3 hours.

8. The enhanced Fenton process according to claim 1, characterized in that, In step 2, the residual concentration of dimethyl sulfoxide in the effluent is 0~10 mg / L.