CN108164056B - Aniline alkaline wastewater treatment method - Google Patents

Aniline alkaline wastewater treatment method Download PDF

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CN108164056B
CN108164056B CN201711500541.0A CN201711500541A CN108164056B CN 108164056 B CN108164056 B CN 108164056B CN 201711500541 A CN201711500541 A CN 201711500541A CN 108164056 B CN108164056 B CN 108164056B
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ion conductor
fast ion
water
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particle electrode
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CN108164056A (en
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武静轩
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Shanxi E Turn Ecological Environmental Protection Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/46104—Devices therefor; Their operating or servicing
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/467—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/469—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/30—Organic compounds
    • C02F2101/38—Organic compounds containing nitrogen
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2201/00—Apparatus for treatment of water, waste water or sewage
    • C02F2201/46—Apparatus for electrochemical processes
    • C02F2201/461—Electrolysis apparatus

Abstract

A method for treating aniline alkaline wastewater relates to the technical field of wastewater treatment, and is characterized in that fast ion conductor membrane electrochemical equipment and a two-stage fast ion conductor particle electrode electrochemical device are utilized to treat aniline alkaline wastewater, so that the aniline alkaline wastewater has the characteristics of traditional electrochemistry, such as multiple functions, high energy utilization rate, controllable process, high environmental compatibility and economy, the purpose of removing pollutants in the wastewater is achieved through a series of electrochemical processes in a double fast ion conductor anode membrane and fast ion conductor particle electrode electrochemical reaction device, and the COD removal rate reaches over 50-95%.

Description

Aniline alkaline wastewater treatment method
Technical Field
The invention relates to the technical field of wastewater treatment, in particular to a method for treating aniline alkaline wastewater.
Background
Benzene and nitric acid are subjected to nitration reaction under the catalysis of sulfuric acid to obtain the crude aniline alkaline wastewater. Aniline alkaline waste water (NB) is an important chemical raw material and an intermediate, and can be used for dyes, pesticides, plastic auxiliaries, detergents and the like. Aniline alkaline wastewater (NB) is extremely difficult to biodegrade, and after entering a water body, the water quality can be seriously deteriorated for a long time, and is one of fifty-eight preferentially controlled toxic chemicals determined in China. Removing entrained sulfuric acid from the crude aniline alkaline wastewater by acid washing, removing a byproduct of nitration reaction, namely triphenylamine alkaline wastewater phenol by alkali washing, feeding the aniline alkaline wastewater subjected to acid washing and alkali washing into a stripping tower to remove excessive benzene in the aniline alkaline wastewater, and performing hydrogenation reaction on the qualified aniline alkaline wastewater to obtain aniline. The crude aniline alkaline wastewater enters a thermal cracking system, the effluent of the system is called aniline alkaline wastewater (namely thermal cracking wastewater), the components of the wastewater are complex and difficult to biodegrade, and the wastewater is mixed with other wastewater after being pretreated for subsequent treatment.
At present, a plurality of methods for oxidizing and degrading aniline alkaline wastewater at home and abroad are available, such as ozone oxidation degradation, UV-TiO2 catalytic oxidation, UV-Fenton oxidation degradation and the like, but the methods have different degrees of problems in the aspects of economy, technical control and the like, and the practical application is greatly influenced.
Disclosure of Invention
The invention aims to provide a method for treating aniline alkaline wastewater, which utilizes fast ion conductor membrane electrochemical equipment and a two-stage fast ion conductor particle electrode electrochemical device to treat aniline alkaline wastewater, and the COD removal rate reaches over 50-95%.
The technical scheme adopted by the invention for realizing the purpose is as follows: the aniline alkaline wastewater treatment method comprises the following steps:
(1) filtering the aniline alkaline wastewater to remove solid matters, thereby obtaining filtered solution;
(2) adding the filtered solution obtained in the step (1) into a waste water area surrounded by a fast ion conductor membrane in fast ion conductor membrane electrochemical equipment, adding sodium hydroxide into two outer sides of the fast ion conductor membrane, introducing tap water, electrifying the fast ion conductor membrane electrochemical equipment to perform electrochemical sodium removal catalytic reaction on the fast ion conductor membrane, and discharging all water treated in the waste water area after the reaction to obtain treated effluent; FeCl accounting for 10-15% of the total weight of the effluent is added into the effluent3Stirring the aqueous solution for reaction for 30min, adding a polyacrylamide aqueous solution accounting for 0.1 percent of the total weight of effluent, stirring for 5min, standing for reaction and precipitation for 2h, taking supernatant, and filtering to obtain filtrate I; filtering the sediments with filter cloth to obtain filtrate II, and combining the filtrate I and the filtrate II to obtain filtrate;
(3) adding the filtrate obtained in the step (2) into two cathode chambers of a first-stage fast ion conductor particle electrode electrochemical device, electrifying the first-stage fast ion conductor particle electrode electrochemical device to perform fast ion conductor particle electrode electrochemical degradation pollutant treatment, discharging the treated water from the lower end of the anode chamber completely when the treatment time is up, and adding FeCl accounting for 10 percent of the total weight of the treated water into the discharged treated water3Stirring the aqueous solution for reaction for 30min, adding polyacrylamide aqueous solution accounting for 0.1 percent of the total weight of the treated water, stirring for 5min, standing for reaction and precipitation for 2h, taking supernatant, and filtering to obtain filtrate; filtering the residue with filter cloth to obtain filtrate, and mixing the filtrates;
(4) adding the combined filtrate obtained in the step (3) into two cathode chambers of a secondary fast ion conductor particle electrode electrochemical device, electrifying the secondary fast ion conductor particle electrode electrochemical device to perform fast ion conductor particle electrode electrochemical degradation pollutant treatment, discharging the treated water from the lower end of the anode chamber under the condition of no power interruption after the treatment time is up, adding the discharged treated water into alkali liquor on two outer sides of a fast ion conductor membrane in fast ion conductor membrane electrochemical equipment to adjust the pH value to 6-7, stirring for 5min, standing for reaction for 25min, and re-precipitating or filtering; the supernatant after precipitation can be discharged after reaching the standard, and the sludge generated in each treatment section can be added into coal for combustion treatment.
In the step (1), the aniline alkaline wastewater is sequentially filtered by a settling pond and a filter to remove solids.
In the invention, in the step (2), in the process of carrying out the electrochemical sodium removal catalytic reaction of the fast ion conductor membrane by electrifying the fast ion conductor membrane electrochemical equipment, the current is 15-20A, the reaction time is 30min, all water treated in the wastewater area is discharged after the reaction, treated effluent is obtained, and the pH value of the effluent is 8-13.
In the invention, in the step (3), the first-stage fast ion conductor particle electrode electrochemical device is electrified to carry out the electrochemical degradation treatment of pollutants by the fast ion conductor particle electrode, the current is 9-15A, and the retention time is 60 min; the pH value of the effluent of the treated water is 5-7.
In the invention, when the secondary fast ion conductor particle electrode electrochemical device is electrified to carry out the treatment of electrochemical degradation of pollutants by the fast ion conductor particle electrode, the current is 6-12A, the retention time is 30-60min, and the pH value of the effluent of the treated water is 2-5.
The fast ion conductor membrane electrochemical equipment comprises a reaction kettle I, wherein two porous clamping plates I which are arranged in parallel are fixed in the reaction kettle I, a fast ion conductor membrane is clamped in an interlayer in each porous clamping plate I, and an inner cavity of the reaction kettle I is sequentially divided into a sodium hydroxide area I, a waste water area and a sodium hydroxide area II which are not communicated with each other; wherein, be located and be equipped with fast ion conductor anode in the waste water district between two porous splint I, be located and be equipped with the negative pole in the sodium hydroxide district I and the sodium hydroxide district II of two outside of two porous splint I respectively.
The first-stage fast ion conductor particle electrode electrochemical device and the second-stage fast ion conductor particle electrode electrochemical device are identical in structure and respectively comprise a reaction kettle II, two porous clamping plates II which are arranged in parallel are fixed in the reaction kettle II, a diaphragm is clamped in an interlayer in each porous clamping plate II, an inner cavity of the reaction kettle II is sequentially divided into a cathode chamber I, an anode chamber and a cathode chamber II which are not communicated with each other, and particle electrodes are filled in the cathode chamber I, the anode chamber and the cathode chamber II; wherein, be located and be equipped with fast ion conductor anode in the anode chamber between two porous splint II, be located cathode chamber I and the cathode chamber II of two outsides of two porous splint II and be equipped with the negative pole respectively.
Has the advantages that: the research and test on the effect of oxidizing and reducing the aniline alkaline wastewater by the fast ion conductor double-positive film and the fast ion conductor electrochemical technology shows that the amino group in the cathode region reaches 98 percent, the anode region is basically unchanged, the nitro group on the benzene ring is a strong electron-withdrawing group and is difficult to oxidize, and the amino electrochemical oxidation index is far greater than the nitro group, so that the nitro group is oxidized and degraded by the fast ion electrode after being reduced into the amino group, and the efficiency is extremely high. The aniline alkaline wastewater is oxidized and degraded by adopting a double fast ion conductor anode film and fast ion conductor particle electrode technology, and the removal rate of COD (chemical oxygen demand) of the wastewater is higher. Under the condition of the invention, the COD removal rate of the wastewater is slightly influenced by the water temperature; the aniline alkaline wastewater is treated by adopting the conditions, and the COD removal rate reaches over 50-95 percent.
The electrochemical redox degradation method of the double fast ion conductor anode film and the fast ion conductor particle electrode not only has the characteristics of traditional electrochemistry such as multiple functions, high energy utilization rate, controllable process, high environmental compatibility and economy, but also achieves the purpose of removing pollutants in wastewater through a series of electrochemical processes in the electrochemical reaction device of the double fast ion conductor anode film and the fast ion conductor particle electrode.
Drawings
FIG. 1 is a flow chart of the treatment of aniline alkaline wastewater according to the present invention;
FIG. 2 is a schematic diagram of a fast ion conductor membrane electrochemical device of the present invention;
FIG. 3 is a schematic diagram of a first-stage fast ion conductor particle electrode electrochemical device or a second-stage fast ion conductor particle electrode electrochemical device according to the present invention;
FIG. 4 is a graph showing the results of a current density test;
FIG. 5 is a graph showing the relationship between the pH value of effluent and the COD removal rate;
FIG. 6 shows the quality of pretreated influent water;
FIG. 7 shows the removal rate of degraded COD at different electrochemical reaction times;
FIGS. 8 to 13 show the results of the water treatment experiment according to the present invention;
FIG. 14 and FIG. 15 are the TDZ influent primary effluent aniline alkaline wastewater test analysis data records;
FIG. 16 is a TDZ influent secondary effluent aniline alkaline wastewater test analysis data record;
FIG. 17 is a data record of aniline alkaline wastewater test analysis;
FIG. 18 shows the results of HCF treatment.
Detailed Description
In order to facilitate understanding of the technical means, technical features and objects achieved by the present invention, the present invention is further described below with reference to specific embodiments, but the scope of the present invention as claimed is not limited to the scope described in the specific embodiments.
The aniline alkaline wastewater treatment method is applied to fast ion conductor membrane electrochemical equipment, a primary fast ion conductor particle electrode electrochemical device and a secondary fast ion conductor particle electrode electrochemical device, wherein as shown in figure 2, the fast ion conductor membrane electrochemical equipment comprises a reaction kettle I, two porous clamping plates I which are arranged in parallel are fixed in the reaction kettle I, a fast ion conductor membrane is clamped in an interlayer in each porous clamping plate I, and an inner cavity of the reaction kettle I is sequentially divided into a sodium hydroxide area I, a wastewater area and a sodium hydroxide area II which are not communicated with each other; wherein, be located and be equipped with fast ion conductor anode in the waste water district between two porous splint I, be located and be equipped with the negative pole in the sodium hydroxide district I and the sodium hydroxide district II of two outside of two porous splint I respectively. Wherein, the fast ion conductor anode is 500mm multiplied by 250 mm; the 316 stainless steel cathode is 500mm × 250mm, and is divided into 1 anode chamber and 2 cathode chambers by two fast ion conductor anode membranes.
As shown in fig. 3, the first-stage fast ion conductor particle electrode electrochemical device and the second-stage fast ion conductor particle electrode electrochemical device have the same structure, and both comprise a reaction kettle II, two porous clamping plates II arranged in parallel are fixed in the reaction kettle II, a diaphragm is clamped in an interlayer inside each porous clamping plate II, an inner cavity of the reaction kettle II is sequentially divided into a cathode chamber I, an anode chamber and a cathode chamber II which are not communicated with each other, and particle electrodes are filled in the cathode chamber I, the anode chamber and the cathode chamber II; wherein, be located and be equipped with fast ion conductor anode in the anode chamber between two porous splint II, be located cathode chamber I and the cathode chamber II of two outsides of two porous splint II and be equipped with the negative pole respectively. Wherein, the fast ion conductor anode is 500mm multiplied by 250 mm; the 316 stainless steel cathode is 500mm 250mm, and is divided into 1 anode chamber and 2 cathode chambers by two fast ion conductor reticular membranes, the fast ion particle electrodes of each chamber are separated and not communicated, and the cathode chambers are filled with the fast ion conductor particle electrodes. The fast ion conductor particle electrodes are filled in the cathode chamber I, the anode chamber and the cathode chamber II, the cathode chamber I, the anode chamber and the cathode chamber II are separated by two diaphragms, the fast ion particle electrodes in the chambers are not in contact, water can permeate, and water to be treated enters from the cathode chamber I and the cathode chamber II and is discharged from the anode chamber.
The treatment method of the aniline alkaline wastewater comprises the following steps:
(1) sequentially filtering the aniline alkaline wastewater by a settling pond and a filter to remove solid matters, thereby obtaining filtered liquid;
(2) adding the filtered solution obtained in the step (1) into a waste water area surrounded by a fast ion conductor film in fast ion conductor film electrochemical equipment, adding sodium hydroxide on two outer sides of the fast ion conductor film to form a sodium hydroxide area I and a sodium hydroxide area II, introducing tap water into the sodium hydroxide area I and the sodium hydroxide area II, electrifying the fast ion conductor film electrochemical equipment, carrying out fast ion conductor film electrochemical sodium removal catalytic reaction to change a chemical structure, wherein the current is 15-20A, the reaction time is 30min, and after the reaction, discharging all water treated in the waste water area to obtain treated effluent, wherein the pH value of the effluent is 8-13; FeCl accounting for 10-15% of the total weight of the effluent is added into the effluent3Stirring the aqueous solution for reaction for 30min, adding a polyacrylamide aqueous solution accounting for 0.1 percent of the total weight of effluent, stirring for 5min, standing for reaction and precipitation for 2h, taking supernatant, and filtering to obtain filtrate I; filtering the sediments with filter cloth to obtain filtrate II, and combining the filtrate I and the filtrate II to obtain filtrate; wherein, 15 percent of FeCl by weight is added into raw water before cracking3Aqueous solution, cracked raw water added with 8% by weight of FeCl3An aqueous solution; the volume of water solution of water-plus-polyacrylamide before cracking150mL/L of the total amount of the aqueous solution of the water-polymerized acrylamide after the cracking accounts for 100mL/L of the volume of the water after the cracking;
wherein, the upper end of the waste water area is provided with a valve, the valve of the waste water area is closed until the valve discharges water, tap water is added into the sodium hydroxide area I and the sodium hydroxide area II, the valve at the upper end of the sodium hydroxide area I and the valve at the upper end of the sodium hydroxide area II discharge water, the valve of the sodium hydroxide area I and the valve of the sodium hydroxide area II are closed, the tap water can be circulated to 30 times of the water quantity of the waste water and then discharged, and the tap water is used as the final discharged water of the secondary fast ion conductor particle electrode for adjusting the pH value;
(3) adding the filtrate obtained in the step (2) into two cathode chambers of a first-stage fast ion conductor particle electrode electrochemical device, electrifying the first-stage fast ion conductor particle electrode electrochemical device to perform fast ion conductor particle electrode electrochemical degradation pollutant treatment, wherein the current is 9-15A, and the retention time is 60 min; after the treatment time is up, the treated water is discharged from the lower end of the anode chamber under the condition of no power failure, and the pH value of the effluent of the treated water is 5-7; FeCl accounting for 10 percent of the total weight of the treated water is added into the discharged treated water3Stirring the aqueous solution for reaction for 30min, adding polyacrylamide aqueous solution accounting for 0.1 percent of the total weight of the treated water, stirring for 5min, standing for reaction and precipitation for 2h, taking supernatant, and filtering to obtain filtrate; filtering the residue with filter cloth to obtain filtrate, and mixing the filtrates; wherein 6% by weight of FeCl is added to the raw water before cracking3Aqueous solution, cracked raw water added with 6% by weight of FeCl3An aqueous solution; the water-plus-polyacrylamide aqueous solution before cracking accounts for 110mL/L of the water volume before cracking, and the water-plus-polyacrylamide aqueous solution after cracking accounts for 90mL/L of the water volume before cracking; the water current before cracking is 15A, and the water current after cracking is 13A;
(4) adding the combined filtrate obtained in the step (3) into two cathode chambers of a secondary fast ion conductor particle electrode electrochemical device, electrifying the secondary fast ion conductor particle electrode electrochemical device to carry out fast ion conductor particle electrode electrochemical degradation on pollutants, wherein the treatment current is 6-12A, the retention time is 30-60min, and after the treatment time is up, discharging all the treated water from the lower end of an anode chamber under the condition of no power interruption, and the pH value of the effluent of the treated water is 2-5; adding the discharged treated water into alkali liquor on two outer sides of a fast ion conductor membrane in fast ion conductor membrane electrochemical equipment to adjust the pH value to 6-7, stirring for 5min, standing for reaction for 25min, and precipitating or filtering; the supernatant after precipitation can be discharged after reaching the standard, and the sludge generated in each treatment section can be added into coal for combustion treatment; wherein the water current before cracking is 12A, and the water current after cracking is 10A; clear liquid after sedimentation or filtration is treated by the section 2 of the secondary fast ion conductor particle electrode device, and the pH value is adjusted to 6-7 by alkaline catholyte produced by the cathode area of the fast ion conductor membrane electrochemical device.
In the above process flow, the specific parameters in the aniline alkaline wastewater treatment process can refer to the following test analysis report.
In the above process flow, FeCl at each stage can be used3The aqueous solution was replaced with technical grade sodium chloride at a mass concentration of 5 g/L.
In the invention, aniline alkaline wastewater and raw water are diluted to 1: 50 (volume ratio); the test instrument is a COD tester, and comprises a HE99125 type COD special heating digester and an ET99109 type COD special spectrophotometer.
Respectively utilizing industrial-grade sodium chloride and FeCl with the mass concentration of 5g/L3The aqueous solution treats the aniline alkaline wastewater, and the experimental process and the result are compared as follows:
water treatment amount: 120t/d, the quality of the pretreated inlet water is shown in the following figure 6.
Firstly, sodium chloride addition test: taking 13L of cracked wastewater, and carrying out PH value determination and COD (chemical oxygen demand) determination on the wastewater before testcrAnd (4) measuring. Adding 38 g/L sodium chloride into 13L of wastewater to dissolve, then adding the anode chamber of the first-stage fast ion conductor particle electrode electrochemical decomposition device, and adding the rest part into a water tank to be used as circulating water; adjusting the current to a certain value to perform electrochemical decomposition test. Investigating COD under different current, treatment time and pH value conditionscrThe removal rate of (3).
II, iron trichloride addition test: taking 13L of cracked wastewater, and carrying out PH value determination and COD (chemical oxygen demand) determination on the wastewater before testcrAnd (4) measuring. Adding 515 g/L of wastewater 13L into the reactor, dissolving, adding into the anode chamber of the first-stage fast ion conductor particle electrode electrochemical decomposition device, and collecting the restPart of the mixture is added into a water tank to be used as circulating water; adjusting the current to a certain value to perform electrochemical decomposition test. Investigating COD under different current, treatment time and pH value conditionscrThe removal rate of (3).
Influence of time and current: in the electrochemical degradation process of the fast ion conductor, the removal rate of COD is increased along with the increase of time, and the electrochemical primary degradation of the fast ion conductor reaches 60minCOD, and the removal rate reaches 70%; the second-level 60minCOD removal rate is about 95 percent. In the electrochemical degradation process of the fast ion conductor, R + cations in the anode region continuously migrate to enter the cathode region, R anions in the anode region are continuously oxidized, oxidized species generated by the oxidation of the fast ion conductor in the anode region are continuously increased, the degradation amount of wastewater is increased, and the removal rate of COD is increased; and the electrochemical degradation reaction of the fast ion conductor reaches a certain time, and the electrode is polarized due to the reduction of the concentration of the wastewater, so that the degradation efficiency is reduced.
At a current density of 8mA/cm2After the first-stage treatment for 60min, the COD is 8000 mg/L. According to the experiment, the COD degradation rate is small along with the change of the PH value, and has a large relation with the oxidation-reduction current and the retention time, but when the retention time of each stage is more than 90min, the degradation rate is very slow, the optimal retention time is 60min for each stage, and the pH value is between 2 and 3.
The electrochemical water treatment process of the fast ionic conductor has good removal effect on soluble COD and insoluble COD in various water, the process can be adjusted according to different water qualities and pH values, the optimal working current is determined, the current is relatively larger when the COD concentration is high in general conditions, but the COD removal rate is also higher, and the one-time removal rate can reach more than 70%. When the COD concentration is lower, the current is relatively smaller, but the water quality is relatively water quality with extremely difficult decomposition of COD, and the removal rate of the COD is usually lower and is generally about 60 percent.
The experimental design of the influence of the current density is as follows: NaCl with a mass concentration of 5g/L, a gap of 10cm, COD concentration of 14000mg/L in the anode region and initial pH of 13 were added to the wastewater without stirring. Carrying out fast ion electrochemical degradation reaction under the condition of changing current density, and carrying out timing sampling analysis and determination under the conditions of: electrifying for 60 min; the results are shown in FIG. 4.As can be seen from FIG. 4, the COD in the wastewater was degraded faster and the treatment efficiency was increased with the increase of the current within a certain time range. Increasing the current can accelerate the electrolysis process, accelerate the release of electrons and promote the conversion of H + into H-; the proton concentration gradient between the electrode surface and the main solution is increased, and the mass transfer rate of the fast ion conductor material electrode surface can be increased. When the current is more than 25A, the electrochemical degradation process of the pollutants (such as COD) in the aniline alkaline wastewater is less influenced by the magnitude of the current, which is mainly because the side reaction 2H + +2e → H generated by the electrochemical process2The reaction rate is obviously accelerated along with the increase of the current density, so that the aniline alkaline wastewater is difficult to rapidly contact with the surface of an electrode to be reduced, and at the moment, the pH value of the effluent of the fast ion device is still alkaline.
Wherein, the experimental design of the influence of the additive content is as follows: the test voltage is 9V, the current is 13A, the timing sampling analysis and determination are carried out, and the test result shows that when the addition amount of the reagent exceeds a certain amount or is less than a certain amount, the removal rate of COD has certain influence.
In the figure 7, the effect of the electrochemical reaction time is shown when sodium chloride is used as an additive.
As can be seen from fig. 6 and 7, when the mass concentration of sodium chloride is 5g/L, the amount of the COD reaction rate of the wastewater is large, which is mainly because the conductivity of the solution increases with the increase of the electrolyte content, the conductivity is enhanced, the rate of proton transfer from the solution body to the cathode surface increases, and hydrogen radicals H with more strong reducing ability and electron groups can be generated, thereby accelerating the degradation rate of the pollutants in the solution. When the electrolyte content reaches a certain value, the ion movement is influenced and the conductivity is reduced due to the enhancement of the interaction between ions. Meanwhile, the Cl content in the biological sewage structure is too high, so that microorganisms can be inhibited and poisoned, and the biochemical treatment of the wastewater is not facilitated. Thus, under the present test conditions, the sodium chloride electrolyte addition mass concentration was determined to be 5 g/L.
Wherein, the experimental design of the influence of the pH value is as follows: under the test conditions with sodium chloride as additive: sodium chloride with mass concentration of 5g/L, plate spacing of 10cm, voltage of 10V, and flow density of 15A, and the result is shown in FIG. 5, wherein the electrification time is 60min, and the timing sampling analysis and determination are performed. The result shows that the degradation efficiency of COD is gradually increased along with the reduction of pH, the apparent reaction speed is gradually accelerated, the removal rate of COD reaches 85% when the pH value is 2, but more catholyte is consumed when the pH value of effluent is increased, and the optimal pH value is selected to be 3-4.
The basic principle of the electrochemical reduction treatment of organic pollutants in aniline alkaline wastewater by the fast ion conductor particle electrode is that the direct reduction and indirect reduction of the cathode of the particle electrode and the direct oxidation and indirect oxidation of the anode of the particle electrode are carried out, namely, electrons obtained by the organic pollutants on the cathode are subjected to direct reduction reaction, and the organic matters are subjected to reduction conversion by using strong reduction active substances generated on the surface of the cathode of the fast ion conductor particle electrode. When the content of the aniline alkaline wastewater (NB) is high, the aniline alkaline wastewater can be adsorbed on the surface of the cathode of the fast ion conductor particle electrode through mass transfer, and electrons are obtained on the surface of the cathode of the fast ion conductor particle electrode and are directly reduced. As the content of NB is reduced, the probability of direct reduction reaction on the cathode is reduced, and the treatment process is mostly indirect reduction reaction of the cathode. Meanwhile, bubbles are generated on the surface of the cathode, and according to previous researches, the final product of the hydrogen evolution reaction is molecular hydrogen, but 2 hydrated protons have very few opportunities to discharge at the same position on the surface of the cathode of the fast ion conductor particle electrode, and the initial product of the proton reduction reaction is H & lt- & gt, which has extremely high chemical activity and can reduce the structure of organic pollutants in a solution, so that the degradation rate of the fast ion conductor particle electrode on the pollutants in water is improved.
After the fast ion conductor membrane is added into the fast ion conductor particle electrode electrochemical device, the COD mass concentration is 14000mg/L, 13L aniline alkaline wastewater before cracking or 13L aniline alkaline wastewater with the mass concentration of 5000mg/L is cracked. The voltage is 10V, the current is 15A, the inter-polar distance is 10cm, the initial pH of the wastewater is 14, the additive is sodium chloride 5g/L, the static test is carried out, a water sample is taken at regular time to analyze COD, and the degradation condition of the COD under different reaction time is observed. From the experiment, it was found that there was accumulation of Aniline (AN), and it was therefore inferred that AN formed in the cathode region was subsequently oxidized into other substances in the anode region, thereby improving the biodegradability of wastewater. In the first 1h, the theoretical reasoning is that the amount of aniline alkaline wastewater (NB) is gradually reduced and the amount of Aniline (AN) is gradually increased in the cathode region. After the exchange of the cathode and the anode, the content of NB is basically unchanged, and the content of AN is rapidly reduced. In conclusion, the nitro group on the benzene ring is a strong electron-withdrawing group and is difficult to be oxidized; the nitro is easier to be oxidized after the nitro is reduced to the amido at the cathode; this is due to the fact that the electrochemical oxidation index of amine groups is much greater than that of nitro groups.
In the test process of COD removal efficiency of aniline alkaline wastewater, the NaCl is added to improve the conductivity of the aqueous solution, and Cl and ClO are generated at the same time2Strong oxidizing substances such as HClO and the like have indirect degradation effect on COD in water, but the electrochemical catalysis effect is far less than that of FeCl3. Because NaCl still exists in the form of NaCl in the wastewater, and sodium ions in the wastewater are increased, the wastewater is strongly alkaline due to the fact that the sodium ions in the aniline alkaline wastewater are high, and the pH value is about 13-14, most of electricity is used for electrolysis and migration of the sodium ions, and the reduction oxidation capability of the fast ion conductor particle electrode device is reduced under the specific electricity condition. When the aniline alkaline wastewater is added with FeCl3 aqueous solution, FeCl3Ionization being Fe (OH)2、Fe2+While generating ClO2Strong oxidizing substances such as HClO and the like have good degradation effect on COD in water. Fe (OH)2The method has strong flocculation effect on suspended matters and colloidal substances in water, reduces the turbidity of the aniline alkaline wastewater after the pretreatment, has better protection effect on the fast ion conductor particle electrode, reduces the resistance of the water body and reduces the energy consumption. Fe2+Has strong catalytic function under the electrochemical action of the fast ion conductor particle electrode, and can improve the electrochemical degradation performance of the fast ion conductor particle electrode. Because the fast ion conductor particle electrode has extremely low oxygen evolution performance, Fe2+The cathode area of the fast ion conductor particle electrode is catalyzed to generate more H, HO and H2O2The substances with equal strong oxidizability and strong reducibility have good removing effect on pollutants such as COD (chemical oxygen demand) in water, and form electrochemical catalysis and Fe2+The catalytic dual degradation function greatly improves the removal rate of pollutants in water by the electrochemical device. Thus, Fe2+Is provided withThe electrochemical catalysis function of the fast ion conductor particle electrode is improved, the good flocculation and turbidity removal effects are achieved, the effect is obvious, and the effect is superior to that of adding NaCl in aniline alkaline wastewater. The addition of ferric trichloride accelerates the degradation rate of pollutants in water, improves the electrochemical utilization rate, and reduces energy consumption and operation cost.
The electrochemical degradation method of the fast ion conductor particle electrode by direct action of external current is an effective method for treating NB (aniline alkaline wastewater), the water quality structure of the aniline alkaline wastewater is changed by removing sodium by fast ion conductor membrane electrochemical equipment, the effluent is treated by adding 10% ferric trichloride aqueous solution, the COD removal rate of the effluent treated by the first-stage fast ion conductor particle electrode electrochemical device can reach 50-80%, and the COD removal rate of the effluent treated by the first-stage fast ion conductor particle electrode electrochemical device is treated by the second-stage fast ion conductor particle electrode electrochemical device can reach more than 70-95%; the optimum reaction conditions were determined experimentally to be: the initial pH value of the wastewater is 8-13, the current passing through the fast ion conductor membrane electrochemical equipment is 1520A, the pH value of the effluent is 6-9, and the retention time is 30 min; the current density of the first-stage fast ion conductor particle electrode electrochemical device is 9-10A, the initial pH value of inlet water is 6-9, the pH value of outlet water is 5-7, and the retention time is 60 min; the current density of the secondary fast ion conductor particle electrode electrochemical device is 68A, the initial pH value of inlet water is 6-9, the pH value of outlet water is 3-5, and the retention time is 30-60 min. Then the pH value is adjusted to 6-7 by cathode water of a fast ion conductor membrane device, and the COD removal rate of the final effluent is 80-99%.
In the invention, preferably, the voltage is controlled to be 8-15V and the current is controlled to be 6-9mA/cm in the electrochemical reaction process2(ii) a The time of the electrochemical reaction process is controlled in the fast ion conductor membrane electrochemical device for 30min, the first-stage fast ion conductor particle electrode electrochemical device for 60min and the second-stage fast ion conductor particle electrode electrochemical device for 30 min.
The invention uses fast ion conductor coating electrode as anode, 316 stainless steel as cathode, special fast ion conductor anode film and fast ion conductor particle electrode to form electrochemical decomposition system. The provided nitrate in benzene wastewater without cracking and aniline alkaline wastewater after cracking are subjected to electrochemical electrolysis by using a fast ion conductor membrane and a fast ion conductor particle electrode to degrade pollutants in water.
The water quality treatment experiment is carried out by utilizing the treatment method of the invention: wherein, the water quality treatment experiment is carried out in 3 days after 8 months, the treatment result is shown in figure 8, the aniline alkaline wastewater fast ion anode membrane separation experiment is carried out, tap water is put into cathodes at two sides, and wastewater is put into an anode at the middle part; the aniline alkaline wastewater fast ion conductor positive membrane separation test is carried out in 8 months and 5 days, and the treatment result is shown in figure 9; performing an aniline alkaline wastewater fast ion conductor anode membrane separation test in 8 months and 13 days, putting tap water into cathodes at two sides, putting 13L wastewater into an anode at the middle part, and processing results are shown in FIG. 10; the aniline alkaline wastewater fast ion conductor anode membrane separation test is carried out in 8 months and 14 days, tap water is put into cathodes at two sides, and 13L of wastewater is put into an anode at the middle part, and the treatment result is shown in figure 11; 8, 15-month aniline alkaline wastewater fast ion conductor anode membrane device separation test, wherein tap water is put into cathodes at two sides, wastewater is put into an anode at the middle, water separated by the fast ion conductor anode membrane device is added into a first-stage fast ion conductor particle electrode and a second-stage fast ion conductor particle electrode device, and the treatment result is shown in figure 12; 8-month-30-day aniline alkaline wastewater fast ion conductor anode membrane device separation test, tap water was put into the cathodes at both sides, wastewater was put into the anode at the middle, water separated by the fast ion conductor anode membrane device was added to the first-stage fast ion conductor particle electrode and the second-stage fast ion conductor particle electrode device, and the treatment results are shown in fig. 13. Other details not described in the present invention are prior art.
The water quality treatment is carried out by utilizing the process flow chart shown in figure 1 of the invention:
one, TDZ water accuse machine goes out water
1. Adding 100L of water discharged by a water controller into a bucket, filling tap water into a cathode chamber of the diaphragm device, adjusting the current to 18A, starting a water pump, and feeding water from an anode chamber of the diaphragm device;
2. adding 10 percent of ferric trichloride solution with the concentration of 10 percent into the effluent of the diaphragm, adjusting the pH value to 7, and adding 2 percent of polyacrylamide to precipitate;
3. taking supernatant to a second water barrel, regulating the current to 13A, and turning on a water pump to respectively feed water from a cathode chamber of the first-stage fast ion conductor;
4. adding 10% concentration 10% ferric trichloride solution into the first-stage effluent, and adjusting the pH value to be less than or equal to 5 to enable the first-stage effluent to be naturally precipitated;
5. taking supernatant to a third water tank, regulating current to 10A, and starting a water pump to feed water from the cathode chamber of the first-stage fast ion conductor respectively.
Experimental reagent: ferric trichloride with the mass concentration of 10 percent and polyacrylamide with the cation of five parts per million;
treatment capacity: the diaphragm device is 24L/h, the first-level fast ion device is 13L/h, and the second-level fast ion device is 13L/h.
Experimental phenomena: after ferric trichloride is added into the diaphragm effluent, gas is generated, the reaction is violent, the foam is large, and when the pH value is less than or equal to 5, polyacrylamide is added to prevent flocculation. When the pH value is adjusted to 6-7, flocculate is generated and rapidly precipitated, and air bubbles are generated along with the flocculate, so that the flocculate can float upwards and flocculate to form large groups again at the top and can be precipitated again. According to experimental data, the effluent is acidic and is neutralized by adding 3% alkaline solution.
Water inlet of TDZ water control machine
The experimental steps are the same as the TDZ effluent, the addition amount is 15 percent, the polyacrylamide solution is 2 percent, and the current and the voltage are not changed.
Experimental phenomena: after the ferric trichloride solution is added, trace gas is generated, which is not very violent, and a small amount of bubbles exist. After adding polyacrylamide, there was floc formation and after standing, the supernatant was free of suspended matter.
Wherein, fig. 14 and fig. 15 are TDZ inlet primary outlet aniline alkaline wastewater test analysis data records; FIG. 16 is a TDZ influent secondary effluent aniline alkaline wastewater test analysis data record; FIG. 17 shows the data records of the aniline alkaline wastewater test analysis (TDZ influent, effluent, HCF effluent); FIG. 18 shows the results of HCF treatment.
The above examples are intended to illustrate the technical aspects of the present invention, and are intended to enable those skilled in the art to understand the contents of the present invention and implement the present invention, but not to limit the scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims (3)

1. The treatment method of the aniline alkaline wastewater is characterized by comprising the following steps:
(1) filtering the aniline alkaline wastewater to remove solid matters, thereby obtaining filtered solution;
(2) adding the filtered solution obtained in the step (1) into a waste water area surrounded by a fast ion conductor membrane in fast ion conductor membrane electrochemical equipment, adding sodium hydroxide into two outer sides of the fast ion conductor membrane, introducing tap water, electrifying the fast ion conductor membrane electrochemical equipment to perform electrochemical sodium removal catalytic reaction on the fast ion conductor membrane, and discharging all water treated in the waste water area after the reaction to obtain treated effluent; FeCl accounting for 10-15% of the total weight of the effluent is added into the effluent3Stirring the aqueous solution for reaction for 30min, adding a polyacrylamide aqueous solution accounting for 0.1 percent of the total weight of effluent, stirring for 5min, standing for reaction and precipitation for 2h, taking supernatant, and filtering to obtain filtrate I; filtering the sediments with filter cloth to obtain filtrate II, and combining the filtrate I and the filtrate II to obtain filtrate;
(3) adding the filtrate obtained in the step (2) into two cathode chambers of a first-stage fast ion conductor particle electrode electrochemical device, electrifying the first-stage fast ion conductor particle electrode electrochemical device to perform fast ion conductor particle electrode electrochemical degradation pollutant treatment, discharging the treated water from the lower end of the anode chamber completely when the treatment time is up, and adding FeCl accounting for 10 percent of the total weight of the treated water into the discharged treated water3Stirring the aqueous solution for reaction for 30min, adding polyacrylamide aqueous solution accounting for 0.1 percent of the total weight of the treated water, stirring for 5min, standing for reaction and precipitation for 2h, taking supernatant, and filtering to obtain filtrate; filtering the sediments with filter cloth to obtain filtrate, and combining the filtrates;
(4) adding the combined filtrate obtained in the step (3) into two cathode chambers of a secondary fast ion conductor particle electrode electrochemical device, electrifying the secondary fast ion conductor particle electrode electrochemical device to perform fast ion conductor particle electrode electrochemical degradation pollutant treatment, discharging the treated water from the lower end of the anode chamber under the condition of no power interruption after the treatment time is up, adding the discharged treated water into alkali liquor on two outer sides of a fast ion conductor membrane in fast ion conductor membrane electrochemical equipment to adjust the pH value to 6-7, stirring for 5min, standing for reaction for 25min, and re-precipitating or filtering; the supernatant after precipitation can be discharged after reaching the standard, and the sludge generated in each treatment section is added into coal for combustion treatment;
in the step (3), the first-stage fast ion conductor particle electrode electrochemical device is electrified to carry out fast ion conductor particle electrode electrochemical degradation pollutant treatment, the current is 9-15A, and the retention time is 60 min; the pH value of effluent of the treated water is 5-7;
in the step (4), the secondary fast ion conductor particle electrode electrochemical device is electrified to carry out fast ion conductor particle electrode electrochemical degradation pollutant treatment, the current is 6-12A, the retention time is 30-60min, and the pH value of the effluent of the treated water is 2-5;
the fast ion conductor membrane electrochemical equipment comprises a reaction kettle I, wherein two porous clamping plates I which are arranged in parallel are fixed in the reaction kettle I, a fast ion conductor membrane is clamped in an interlayer in each porous clamping plate I, and an inner cavity of the reaction kettle I is sequentially divided into a sodium hydroxide area I, a waste water area and a sodium hydroxide area II which are not communicated with each other; wherein, a fast ion conductor anode is arranged in the wastewater area between the two porous splints I, and cathodes are respectively arranged in the sodium hydroxide area I and the sodium hydroxide area II which are positioned at the two outer sides of the two porous splints I;
the first-stage fast ion conductor particle electrode electrochemical device and the second-stage fast ion conductor particle electrode electrochemical device are identical in structure and respectively comprise a reaction kettle II, two porous clamping plates II which are arranged in parallel are fixed in the reaction kettle II, a diaphragm is clamped in an interlayer in each porous clamping plate II, an inner cavity of the reaction kettle II is sequentially divided into a cathode chamber I, an anode chamber and a cathode chamber II which are not communicated with each other, and particle electrodes are filled in the cathode chamber I, the anode chamber and the cathode chamber II; wherein, be located and be equipped with fast ion conductor anode in the anode chamber between two porous splint II, be located cathode chamber I and the cathode chamber II of two outsides of two porous splint II and be equipped with the negative pole respectively.
2. The method for treating aniline alkaline wastewater according to claim 1, characterized in that: in the step (1), aniline alkaline wastewater is sequentially filtered by a settling pond and a filter to remove solid matters.
3. The method for treating aniline alkaline wastewater according to claim 1, characterized in that: in the step (2), in the process of carrying out the electrochemical sodium removal catalytic reaction of the fast ion conductor membrane by electrifying the fast ion conductor membrane electrochemical equipment, the current is 15-20A, the reaction time is 30min, all the water treated in the wastewater area is discharged after the reaction, the treated effluent is obtained, and the pH value of the effluent is 8-13.
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