U.S. patent application number 16/846709 was filed with the patent office on 2021-10-14 for method and device for removing chloride ion in desulfurized wastewater by electrochemical coupling.
The applicant listed for this patent is Taiyuan University of Technology. Invention is credited to Xiao DU, Xiaogang HAO, Xiaoqiong HAO, Zhonglin ZHANG.
Application Number | 20210317013 16/846709 |
Document ID | / |
Family ID | 1000005866173 |
Filed Date | 2021-10-14 |
United States Patent
Application |
20210317013 |
Kind Code |
A9 |
HAO; Xiaogang ; et
al. |
October 14, 2021 |
METHOD AND DEVICE FOR REMOVING CHLORIDE ION IN DESULFURIZED
WASTEWATER BY ELECTROCHEMICAL COUPLING
Abstract
A method and device for removing chloride ions in desulfurized
wastewater by electrochemical coupling in which the device
comprises: an electrolyte tank having a top and a bottom wherein
the tank is used as a separator in a separation process and as an
electrode regenerator in an electrode regeneration process; two
electrodes comprising a hydrogen evolution electrocatalysis
function electrode and an electrochemically switched ion exchange
(ESIX) function electrode respectively, wherein the electrodes are
connected with each other by a wire; two DC circuits having
opposite electric field directions and used alternately in the
separation process and the electrode regeneration process
respectively; the bottom of the electrolyte tank is provided with a
purified high-concentration chloride ion wastewater inlet and a
flocculation product outlet; the top of the tank is provided with a
dechlorination treatment water outlet and a hydrogen collecting
port; and, in the electrode regeneration process, the electrolyte
tank is connected to an electrode regeneration liquid storage tank
through a pump and a pipeline.
Inventors: |
HAO; Xiaogang; (Taiyuan,
CN) ; HAO; Xiaoqiong; (Taiyuan, CN) ; DU;
Xiao; (Taiyuan, CN) ; ZHANG; Zhonglin;
(Taiyuan, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Taiyuan University of Technology |
Taiyuan |
|
CN |
|
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20210002151 A1 |
January 7, 2021 |
|
|
Family ID: |
1000005866173 |
Appl. No.: |
16/846709 |
Filed: |
April 13, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C02F 1/46109 20130101;
C02F 2101/12 20130101; C02F 1/463 20130101 |
International
Class: |
C02F 1/461 20060101
C02F001/461; C02F 1/463 20060101 C02F001/463 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 1, 2019 |
CN |
201910583372.4 |
Claims
1. A device for removing chloride ions in desulfurized wastewater
by electrochemical coupling, comprising an electrolyte tank having
a top and a bottom, two electrodes and two direct current (DC)
circuits; wherein the electrolyte tank can be used as a separator
in a separation process and used as an electrode regenerator in an
electrode regeneration process; the two electrodes are a hydrogen
evolution electrocatalysis function electrode and an
electrochemically switched ion exchange (ESIX) function electrode
respectively, and the electrodes are connected with each other by a
wire; the two DC circuits have opposite electric field directions
and can alternately be used in the separation process and the
electrode regeneration process respectively; the bottom of the
electrolyte tank is provided with a purified high-concentration
chloride ion wastewater inlet and a flocculation product outlet;
and the top is provided with a dechlorination treatment water
outlet and a hydrogen collecting port; and further wherein, in the
electrode regeneration process, the electrolyte tank is connected
to an electrode regeneration liquid storage tank through a pump and
a pipeline.
2. The device for removing chloride ions in desulfurized wastewater
by electrochemical coupling according to claim 1, wherein the ESIX
function electrode comprises an ESIX functional material with high
selectivity and high flux for chloride ions coated or deposited on
a carbon-based conductive matrix or a metal conductive matrix.
3. The device for removing chloride ions in desulfurized wastewater
by electrochemical coupling according to claim 2, wherein the ESIX
functional material comprises chlorine doped polypyrrole.
4. The device for removing chloride ions in desulfurized wastewater
by electrochemical coupling according to claim 1, wherein the
hydrogen evolution electrocatalysis function electrode comprises a
blank electrode plate or an electrode coated with a hydrogen
evolution catalyst material.
5. The device for removing chloride ions in desulfurized wastewater
by electrochemical coupling according to claim 4, wherein the blank
electrode plate comprises a member selected from the group
consisting of carbon paper, a platinum mesh and graphite paper; and
the hydrogen evolution catalyst material comprises a member
selected from the group consisting of a metal oxide, a metal
phosphide, a metal sulfide, an alloy and a carbon nitride
catalyst.
6. The device for removing chloride ions in desulfurized wastewater
by electrochemical coupling according to claim 1, wherein in the
electrode regeneration process, an electrode regeneration liquid
outlet I at the bottom of the electrolyte tank is connected to an
electrode regeneration liquid inlet II at the top of the electrode
regeneration liquid storage tank through an electrode regeneration
liquid pump I; and an electrode regeneration liquid outlet II at
the bottom of the electrode regeneration liquid storage tank is
connected to an electrode regeneration liquid inlet I at the top of
the electrolyte tank through an electrode regeneration liquid pump
II.
7. A method for removing chloride ions in desulfurized wastewater
by electrochemical coupling using the device according to claim 1
wherein the method comprises a separation process and an electrode
regeneration process such that when an ESIX function electrode in
the separation process is saturated by adsorption, the electrode is
subjected to the electrode regeneration process in situ, and the
two processes are performed intermittently and repeatedly; the
method comprising the following steps: (a) Separation process:
installing a chloride ion exchange function electrode on an anode;
installing a hydrogen evolution electrocatalysis function electrode
on a cathode; pouring purified high-concentration chloride ion
wastewater into an electrolyte tank; applying a direct voltage;
performing adsorption by the anode and hydrogen evolution
flocculation by the cathode to subject chloride ions to adsorption
and flocculation separation; collecting hydrogen byproducts and
flocculation products generated by the cathode; and discharging a
treated liquid which can be reused after dechlorination; and (b)
Electrode regeneration: using the separation process devices,
adding an electrode regeneration liquid into an electrolyte tank
through a pump, and switching to a reverse circuit, so that the
electrode saturated by adsorption realizes in-situ desorption
regeneration.
8. A method for removing chloride ions in desulfurized wastewater
by electrochemical coupling using the device according to claim 2
wherein the method comprises a separation process and an electrode
regeneration process such that when an ESIX function electrode in
the separation process is saturated by adsorption, the electrode is
subjected to the electrode regeneration process in situ, and the
two processes are performed intermittently and repeatedly; the
method comprising the following steps: (a) Separation process:
installing a chloride ion exchange function electrode on an anode;
installing a hydrogen evolution electrocatalysis function electrode
on a cathode; pouring purified high-concentration chloride ion
wastewater into an electrolyte tank; applying a direct voltage;
performing adsorption by the anode and hydrogen evolution
flocculation by the cathode to subject chloride ions to adsorption
and flocculation separation; collecting hydrogen byproducts and
flocculation products generated by the cathode; and discharging a
treated liquid which can be reused after dechlorination; and (b)
Electrode regeneration: using the separation process devices,
adding an electrode regeneration liquid into an electrolyte tank
through a pump, and switching to a reverse circuit, so that the
electrode saturated by adsorption realizes in-situ desorption
regeneration.
9. A method for removing chloride ions in desulfurized wastewater
by electrochemical coupling using the device according to claim 3
wherein the method comprises a separation process and an electrode
regeneration process such that when an ESIX function electrode in
the separation process is saturated by adsorption, the electrode is
subjected to the electrode regeneration process in situ, and the
two processes are performed intermittently and repeatedly; the
method comprising the following steps: (a) Separation process:
installing a chloride ion exchange function electrode on an anode;
installing a hydrogen evolution electrocatalysis function electrode
on a cathode; pouring purified high-concentration chloride ion
wastewater into an electrolyte tank; applying a direct voltage;
performing adsorption by the anode and hydrogen evolution
flocculation by the cathode to subject chloride ions to adsorption
and flocculation separation; collecting hydrogen byproducts and
flocculation products generated by the cathode; and discharging a
treated liquid which can be reused after dechlorination; and (b)
Electrode regeneration: using the separation process devices,
adding an electrode regeneration liquid into an electrolyte tank
through a pump, and switching to a reverse circuit, so that the
electrode saturated by adsorption realizes in-situ desorption
regeneration.
10. A method for removing chloride ions in desulfurized wastewater
by electrochemical coupling using the device according to claim 4
wherein the method comprises a separation process and an electrode
regeneration process such that when an ESIX function electrode in
the separation process is saturated by adsorption, the electrode is
subjected to the electrode regeneration process in situ, and the
two processes are performed intermittently and repeatedly; the
method comprising the following steps: (a) Separation process:
installing a chloride ion exchange function electrode on an anode;
installing a hydrogen evolution electrocatalysis function electrode
on a cathode; pouring purified high-concentration chloride ion
wastewater into an electrolyte tank; applying a direct voltage;
performing adsorption by the anode and hydrogen evolution
flocculation by the cathode to subject chloride ions to adsorption
and flocculation separation; collecting hydrogen byproducts and
flocculation products generated by the cathode; and discharging a
treated liquid which can be reused after dechlorination; and (b)
Electrode regeneration: using the separation process devices,
adding an electrode regeneration liquid into an electrolyte tank
through a pump, and switching to a reverse circuit, so that the
electrode saturated by adsorption realizes in-situ desorption
regeneration.
11. A method for removing chloride ions in desulfurized wastewater
by electrochemical coupling using the device according to claim 5
wherein the method comprises a separation process and an electrode
regeneration process such that when an ESIX function electrode in
the separation process is saturated by adsorption, the electrode is
subjected to the electrode regeneration process in situ, and the
two processes are performed intermittently and repeatedly; the
method comprising the following steps: (a) Separation process:
installing a chloride ion exchange function electrode on an anode;
installing a hydrogen evolution electrocatalysis function electrode
on a cathode; pouring purified high-concentration chloride ion
wastewater into an electrolyte tank; applying a direct voltage;
performing adsorption by the anode and hydrogen evolution
flocculation by the cathode to subject chloride ions to adsorption
and flocculation separation; collecting hydrogen byproducts and
flocculation products generated by the cathode; and discharging a
treated liquid which can be reused after dechlorination; and (b)
Electrode regeneration: using the separation process devices,
adding an electrode regeneration liquid into an electrolyte tank
through a pump, and switching to a reverse circuit, so that the
electrode saturated by adsorption realizes in-situ desorption
regeneration.
12. A method for removing chloride ions in desulfurized wastewater
by electrochemical coupling using the device according to claim 6
wherein the method comprises a separation process and an electrode
regeneration process such that when an ESIX function electrode in
the separation process is saturated by adsorption, the electrode is
subjected to the electrode regeneration process in situ, and the
two processes are performed intermittently and repeatedly; the
method comprising the following steps: (a) Separation process:
installing a chloride ion exchange function electrode on an anode;
installing a hydrogen evolution electrocatalysis function electrode
on a cathode; pouring purified high-concentration chloride ion
wastewater into an electrolyte tank; applying a direct voltage;
performing adsorption by the anode and hydrogen evolution
flocculation by the cathode to subject chloride ions to adsorption
and flocculation separation; collecting hydrogen byproducts and
flocculation products generated by the cathode; and discharging a
treated liquid which can be reused after dechlorination; and (b)
Electrode regeneration: using the separation process devices,
adding an electrode regeneration liquid into an electrolyte tank
through a pump, and switching to a reverse circuit, so that the
electrode saturated by adsorption realizes in-situ desorption
regeneration.
13. The method for removing chloride ions in desulfurized
wastewater by electrochemical coupling according to claim 7,
wherein step (a) comprises: a DC that causes the chloride ions in
the desulfurized wastewater to migrate to the anode under the
action of an electric field where they are adsorbed into pores of
the ESIX function electrode with selectivity for the chloride ions,
thus realizing the adsorption process while a hydrogen evolution
reaction occurs at the cathode; following hydrogen separation,
allowing hydrogen ions on the cathode surface to decrease and
hydroxide radicals to increase, and metal ions in the solution to
bond with locally surplus hydroxide ions and chloride ions
generating flocculation products that settle to a lower layer of
the electrolyte tank; and, when the bottom of the electrolyte tank
is filled with the floccules, discharging the floccules out of the
system through filtration; and further wherein step (b) comprises:
allowing the chloride ions in the ESIX function electrode to be
desorbed into the regeneration liquid under the action of the
electric field so that the electrode functions to adsorb chloride
ions again.
14. The method for removing chloride ions in desulfurized
wastewater by electrochemical coupling according to claim 8,
wherein step (a) comprises a DC that causes the chloride ions in
the desulfurized wastewater to migrate to the anode under the
action of an electric field where they are adsorbed into pores of
the ESIX function electrode with selectivity for the chloride ions,
thus realizing the adsorption process while a hydrogen evolution
reaction occurs at the cathode; following hydrogen separation,
allowing hydrogen ions on the cathode surface to decrease and
hydroxide radicals to increase, and metal ions in the solution to
bond with locally surplus hydroxide ions and chloride ions
generating flocculation products that settle to a lower layer of
the electrolyte tank; and, when the bottom of the electrolyte tank
is filled with the floccules, discharging the floccules out of the
system through filtration; and further wherein step (b) comprises:
allowing the chloride ions in the ESIX function electrode to be
desorbed into the regeneration liquid under the action of the
electric field so that the electrode functions to adsorb chloride
ions again.
15. The method for removing chloride ions in desulfurized
wastewater by electrochemical coupling according to claim 9,
wherein step (a) comprises: a DC that causes the chloride ions in
the desulfurized wastewater to migrate to the anode under the
action of an electric field where they are adsorbed into pores of
the ESIX function electrode with selectivity for the chloride ions,
thus realizing the adsorption process while a hydrogen evolution
reaction occurs at the cathode; following hydrogen separation,
allowing hydrogen ions on the cathode surface to decrease and
hydroxide radicals to increase, and metal ions in the solution to
bond with locally surplus hydroxide ions and chloride ions
generating flocculation products that settle to a lower layer of
the electrolyte tank; and, when the bottom of the electrolyte tank
is filled with the floccules, discharging the floccules out of the
system through filtration; and further wherein step (b) comprises:
allowing the chloride ions in the ESIX function electrode to be
desorbed into the regeneration liquid under the action of the
electric field so that the electrode functions to adsorb chloride
ions again.
16. The method for removing chloride ions in desulfurized
wastewater by electrochemical coupling according to claim 10,
wherein step (a) comprises: a DC that causes the chloride ions in
the desulfurized wastewater to migrate to the anode under the
action of an electric field where they are adsorbed into pores of
the ESIX function electrode with selectivity for the chloride ions,
thus realizing the adsorption process while a hydrogen evolution
reaction occurs at the cathode; following hydrogen separation,
allowing hydrogen ions on the cathode surface to decrease and
hydroxide radicals to increase, and metal ions in the solution to
bond with locally surplus hydroxide ions and chloride ions
generating flocculation products that settle to a lower layer of
the electrolyte tank; and, when the bottom of the electrolyte tank
is filled with the floccules, discharging the floccules out of the
system through filtration; and further wherein step (b) comprises:
allowing the chloride ions in the ESIX function electrode to be
desorbed into the regeneration liquid under the action of the
electric field so that the electrode functions to adsorb chloride
ions again.
17. The method for removing chloride ions in desulfurized
wastewater by electrochemical coupling according to claim 11,
wherein step (a) comprises: a DC that causes the chloride ions in
the desulfurized wastewater to migrate to the anode under the
action of an electric field where they are adsorbed into pores of
the ESIX function electrode with selectivity for the chloride ions,
thus realizing the adsorption process while a hydrogen evolution
reaction occurs at the cathode; following hydrogen separation,
allowing hydrogen ions on the cathode surface to decrease and
hydroxide radicals to increase, and metal ions in the solution to
bond with locally surplus hydroxide ions and chloride ions
generating flocculation products that settle to a lower layer of
the electrolyte tank; and, when the bottom of the electrolyte tank
is filled with the floccules, discharging the floccules out of the
system through filtration; and further wherein step (b) comprises:
allowing the chloride ions in the ESIX function electrode to be
desorbed into the regeneration liquid under the action of the
electric field, so that the electrode functions to adsorb chloride
ions again.
18. The method for removing chloride ions in desulfurized
wastewater by electrochemical coupling according to claim 12,
wherein step (a) comprises: a DC that causes the chloride ions in
the desulfurized wastewater to migrate to the anode under the
action of an electric field where they are adsorbed into pores of
the ESIX function electrode with selectivity for the chloride ions,
thus realizing the adsorption process while a hydrogen evolution
reaction occurs at the cathode; following hydrogen separation,
allowing hydrogen ions on the cathode surface to decrease and
hydroxide radicals to increase, and metal ions in the solution to
bond with locally surplus hydroxide ions and chloride ions
generating flocculation products that settle to a lower layer of
the electrolyte tank; and, when the bottom of the electrolyte tank
is filled with the floccules, discharging the floccules out of the
system through filtration; and further wherein step (b) comprises:
allowing the chloride ions in the ESIX function electrode to be
desorbed into the regeneration liquid under the action of the
electric field so that the electrode functions to adsorb chloride
ions again.
19. The method for removing chloride ions in desulfurized
wastewater by electrochemical coupling according to claim 7,
wherein after the ESIX function electrode is regenerated; (a) if
the electrode regeneration liquid is not saturated, the electrode
regeneration liquid is poured into an electrode regeneration liquid
storage tank again by a pump for recycling; or (b) if the electrode
regeneration liquid is saturated, the processes of adsorption by
the anode and hydrogen evolution flocculation separation by the
cathode are realized by reversing the circuit, and the chloride
ions in the saturated electrode regeneration liquid are separated,
so that the chloride ions in the saturated electrode regeneration
liquid form solid phase flocculation products that are discharged
out of the system.
20. The method for removing chloride ions in desulfurized
wastewater by electrochemical coupling according to claim 7,
wherein, in the separation process, the voltage is 1-3 V and the
liquid inlet rate of a high-concentration chloride ion wastewater
inlet is 1-10 L/h; and also in the electrode regeneration process,
the voltage is 0.8-2V, the liquid inlet rate of an electrode
regeneration liquid pump I is 10-30 L/h, and the liquid inlet rate
of an electrode regeneration liquid pump II is 20-40 L/h.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit of priority under
35 USC 119 to Chinese patent application 201910583372.4, filed Jul.
1, 2019, the contents of which are incorporated herein by
reference.
TECHNICAL FIELD
[0002] The present invention relates to a method and device for
removing chloride ions in desulfurized wastewater, and belongs to
the technical field of wastewater treatment The present invention
pertains to a technology for treating high-concentration chloride
ion wastewater and, in particular, to a coupling system of an
electrochemically switched ion exchange (ESIX) method and an
electrocatalytic flocculation method.
BACKGROUND
[0003] A limestone-gypsum wet flue gas desulfurization technology
is widely used in tail gas treatment of an industrial production
process due to its advantages of low cost, simple operation and
good desulfurization effect, etc. However, the wastewater produced
in the desulfurization process contains a large amount of
chlorides, sulfate, a variety of heavy metals and suspended solids
and other pollutants. Direct discharge of this wastewater can cause
environmental pollution and endangers human health. When the
desulfurized wastewater is recycled, the concentration of salt
(especially chlorides) in the wastewater is high, which leads to
serious corrosion of the processing equipment. At present, a
chemical precipitation method, which is a commonly used
desulfurized wastewater treatment method, requires high maintenance
cost and a large amount of chemical agents resulting in a high
content of heavy metal elements, which in turn leads to a large
number of hazardous wastes. Additionally, the chloride ions cannot
be effectively removed. As a result, it is difficult for current
desulfurization technology to meet the market application
requirements Therefore, the development of new technologies for the
treatment of desulfurized wastewater, especially including more
efficient removal of chloride ions and heavy metal ions, is highly
desirable and has important application value.
[0004] In recent years, there have been some novel desulfurized
wastewater treatment methods Chinese patent No. CN201510750966.1
discloses a method and system for treating ions in a wet
desulfurization system by electrolytic electrodialysis. This method
can effectively separate chloride ions in the desulfurization
system and convert, by electrolysis, the chloride ions into
chlorine for recycling. Valuable byproducts such as calcium
hydroxide and hydrogen can be obtained at the same time However,
the process is complex, the cation exchange membranes and anion
exchange membranes used in the process are costly, and a foreign
reagent (i.e., hydrochloric acid) needs to be added, which further
increases the process cost. Chinese patent No. CN107628687A
discloses a treatment method for synchronously removing fluoride
ions and chloride ions from industrial wastewater. This method
includes two stages: precipitation pretreatment by using
Ca(OH).sub.2 and NaAlO.sub.2 followed by advanced treatment using a
biological coagulant. This approach has the advantages of
non-toxicity, high efficiency, natural degradation and the like.
However, chemical reagents need to be added in the treatment
process, and other salt substances are introduced, which is not
conducive to re-pumping the treated wastewater into a
desulfurization tower for recycling. In addition, biological
bacteria are easily inactivated due to the influence of
environmental factors. Chinese patent No. CN107082516A discloses a
system and treatment method for removing chloride ions in
circulating water. The method connects electric adsorption to an
electrolytic dechlorination device. After soluble salts in the
water are removed by an electric adsorption device, the
concentration of chloride ions in the water is continuously
increased. A diaphragm electrolysis principle is adopted to
electrolyze high-concentration chloride ions in the circulating
water. But, in the adsorption process, desalting adsorption is
performed only by the action of an electric field, so that there is
no selectivity for target ions. In addition, an ion diaphragm used
in the electrolysis process is high in cost and the energy
consumption of the whole process operation is high. However, an
electrochemical coupling technology for removing chlorine and metal
ions by using the principle of combining adsorption and
flocculation and a related device thereof have never been reported
in the literature in this field at present. Under this system, the
double action of a cathode and an anode can greatly enhance the
treatment effect of chloride ions and metal ions, and this approach
is also conducive to reducing the energy consumption of the system
at the same time. In addition, high value-added byproducts can also
be produced to further enhance the advantages of this approach to
the problem.
SUMMARY
[0005] The present invention provides a method and device for
removing chloride ions in desulfurized wastewater by
electrochemical coupling, which achieve efficient recycling and
removal of chloride ions.
[0006] The present invention is implemented by coupling highly
selective adsorption of target chloride ions by an ESIX technology
with electrocatalytic hydrogen evolution reaction. After the
hydrogen evolution reaction, locally surplus hydroxide ions bond
with metal ions and chloride ions in a solution to generate solid
flocculation products. The coupling enhancement of reactions of an
anode and a cathode reduces the concentration of the chloride ions
in wastewater in different ways. The process also generates
high-purity hydrogen byproducts, and the concentration of metal
ions in the wastewater is also reduced while floccules are
generated. This is beneficial to the recycling of the wastewater,
is simple to operate, and improves economic and environmental
benefits. The ESIX technology makes an electroactive ion exchange
function material and a conductive matrix into an electrode, and
switches a redox state of the electrode by regulating an electrode
potential. As a result, target ions in the solution can be
reversibly placed and released, thus realizing the enrichment and
recycling of ions in the solution The ESIX technology has the
advantages of simple operation, high selectivity, reversible
process and no secondary pollution. It is a novel
environment-friendly and efficient separation technology, and its
main driving force is the electrode potential. Moreover, a chloride
ion type ESIX function electrode adopted for use in the present
invention can be recycled many times.
[0007] The present invention provides a device for removing
chloride ions in desulfurized wastewater by electrochemical
coupling, including an electrolyte tank, two electrodes and two
direct current (DC) circuits;
[0008] whereby: the electrolyte tank can be used as a separator in
a separation process and as an electrode regenerator in an
electrode regeneration process, the two electrodes are a hydrogen
evolution electrocatalysis function electrode and an ESIX function
electrode respectively, and the electrodes are connected with each
other by a conductor, e.g., a wire; the two DC circuits have
opposite electric field directions and are alternately used in the
separation process and the electrode regeneration process
respectively; the bottom of the electrolyte tank is provided with a
purified high-concentration chloride ion wastewater inlet and a
flocculation product outlet, and the top is provided with a
dechlorination treatment water outlet and a hydrogen collecting
port; and the electrolyte tank is connected to an electrode
regeneration liquid storage tank through a pump and a pipeline.
[0009] In the foregoing device according to this invention, the
ESIX function electrode may be obtained by depositing or coating an
ESIX functional material with high selectivity and high flux for
chloride ions, such as chlorine doped polypyrrole, on a
carbon-based conductive matrix or a metal conductive matrix.
[0010] In the foregoing device according to this invention, the
hydrogen evolution electrocatalysis function electrode may include
a blank electrode plate, such as any of carbon paper, a platinum
mesh and graphite paper, and may also include an electrode coated
with a hydrogen evolution catalyst material, such as any one or
more of a metal oxide, a metal phosphide, a metal sulfide, an alloy
and a carbon nitride catalyst.
[0011] The present invention also provides a method for removing
chloride ions in desulfurized wastewater by electrochemical
coupling. The method includes a separation process and an electrode
regeneration process; when an ESIX function electrode in the
separation process is saturated by adsorption, the electrode needs
to be subjected to the electrode regeneration process in situ, and
the two processes need to be performed intermittently and
repeatedly. The method specifically includes the following
steps:
[0012] (1) Separation: Install a chloride ion exchange function
electrode on an anode; install a hydrogen evolution
electrocatalysis function electrode on a cathode; pour purified
high-concentration chloride ion wastewater into an electrolyte
tank; apply a direct voltage, and perform adsorption by the anode
and hydrogen evolution flocculation by the cathode to subject
chloride ions to adsorption and flocculation separation; collect
hydrogen products and flocculation products generated by the
cathode; and discharge a treatment liquid which can be reused after
dechlorination.
[0013] (2) Electrode regeneration: On the basis of the separation
process described above, add an electrode regeneration liquid into
an electrolyte tank through a pump, and switch a reverse circuit,
so that the electrode saturated by adsorption realizes in-situ
desorption regeneration.
[0014] In step (1), applying a DC causes the chloride ions in the
desulfurized wastewater to migrate to the anode under the action of
an electric field, and they are adsorbed into pores of the ESIX
function electrode with selectivity for the chloride ions, thus
realizing the adsorption process. However, the following hydrogen
evolution reaction occurs at the cathode:
2H.sub.2O+2e.sup.-.fwdarw.H.sub.2.uparw.+2OH.sup.-
[0015] After hydrogen is separated out, hydrogen ions on the
cathode surface decrease and hydroxide radicals increase, and a
large amount of metal ions in the solution bond with locally
surplus hydroxide ions and chloride ions according to the following
reaction:
kM.sup.j++xCl.sup.-+yOH.sup.-.fwdarw.M.sub.jkCl.sub.x(OH).sub.y.dwnarw.
[0016] Generated flocculation products settle to a lower layer of
the electrolyte tank; and, when the bottom of the electrolyte tank
is filled with the floccules, the floccules can be discharged out
of the system through filtration.
[0017] In step (2), applying the direct current causes the chloride
ions in the ESIX function electrode to be desorbed into the
regeneration liquid under the action of the electric field, so that
the electrode has a function of adsorbing the chloride ions
again.
[0018] In the foregoing method, after the ESIX function electrode
is regenerated, if the electrode regeneration liquid is not
saturated, the electrode regeneration liquid can be poured into an
electrode regeneration liquid storage tank again by a pump for
recycling. If the electrode regeneration liquid is saturated, the
processes of adsorption by the anode and hydrogen evolution
flocculation separation by the cathode are realized by reversing
the circuit, and the chloride ions in the saturated electrode
regeneration liquid are separated, so that the chloride ions in the
saturated electrode regeneration liquid form to the greatest extent
solid phase flocculation products that are discharged out of the
system.
[0019] Preferably, in the separation process, the voltage is 1-3 V,
and the liquid inlet rate of a high-concentration chloride ion
wastewater inlet (reference numeral 7 in FIG. 1) is 1-10 L/h.
[0020] Preferably, in the electrode regeneration process, the
voltage is 0.8-2V; the liquid inlet rate of an electrode
regeneration liquid pump I (reference numeral 14 in FIG. 2) is
10-30 L/h; and the liquid inlet rate of an electrode regeneration
liquid pump II (reference numeral 15 in FIG. 2) is 20-40 L/h.
[0021] Compared with the prior art, the present invention is
innovative in that:
[0022] (1) The ESIX function electrode can be recycled.
[0023] (2) The device is a simple dual-function reactor, which can
be used alternately as a separator and an electrode regenerator In
the regeneration process of the ESIX function electrode, the
electrode docs not need to be taken out, and only an external
circuit switch needs to be switched to perform in-situ regeneration
and reuse.
[0024] (3) When chloride ions in desulfurized wastewater are
removed by an electrochemical coupling method, by utilizing the
synergistic reinforcement of reactions of an anode and a cathode,
the chloride ion removal efficiency and energy utilization
efficiency can be improved. Also, most of the chloride ions in the
wastewater exist in flocculation products in a solid form, which
facilitates recycling. Besides, hydrogen byproducts with high added
value can be obtained at the same time, and the operation cost is
reduced, thereby effectively improving economic benefits.
[0025] (4) No additional chemical reagent needs to be added when
high-concentration chloride ion wastewater is treated.
[0026] (5) When the high-concentration chloride ion wastewater is
treated, metal ions in the wastewater can simultaneously form into
flocculation products for treatment.
[0027] (6) Expensive consumables such as ion diaphragms are not
needed in the treatment process, thus the cost of the approach of
the present invention is comparatively low.
[0028] (7) The operation is simple and efficient, which is
beneficial to industrial production.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 is a schematic diagram of an apparatus for a
separation process according to this invention; and
[0030] FIG. 2 is a schematic diagram of an apparatus for an
electrode regeneration process according to this invention.
[0031] The figures show: hydrogen evolution electrocatalysis
function electrode (A), ESIX function electrode (B), electrolyte
tank (1), DC power supply I (2), power switch I (3), dechlorination
treatment water outlet (4), hydrogen collecting port (5),
flocculation product outlet (6), purified high-concentration
chloride ion wastewater inlet (7), power switch II (8), power
switch II (9), electrode regeneration liquid inlet I (10),
electrode regeneration liquid inlet II (11), electrode regeneration
liquid outlet I (12), electrode regeneration liquid outlet II (13),
electrode regeneration liquid pump I (14); electrode regeneration
liquid pump II (15); and electrode regeneration liquid storage tank
(16).
DETAILED DESCRIPTION
[0032] The present invention is further illustrated by the
following examples, but is not limited thereto.
[0033] In the examples, an experimental device shown in FIGS. 1 and
2 is adopted, and the device includes an electrolyte tank (1), two
electrodes and two DC circuits.
[0034] The electrolyte tank (1) can be used as a separator in a
separation process and can be used as an electrode regenerator in
an electrode regeneration process The two electrodes are a hydrogen
evolution electrocatalysis function electrode (A) and an
electrochemically switched chloride ion exchange function electrode
(B) respectively. The two DC circuits have opposite electric field
directions and are used in a switched manner in the separation
process and the electrode regeneration process respectively. The
bottom of the electrolyte tank (1) is provided with a purified
high-concentration chloride ion wastewater inlet (7) and a
flocculation product outlet (6). The top is provided with a
dechlorination treatment water outlet (4) and a hydrogen collecting
port (5). The two electrodes are connected by a conductor, e.g., a
wire; and the electrolyte tank (1) is connected to an electrode
regeneration liquid storage tank (16) through a pump and a
pipeline.
[0035] In the electrode regeneration process, an electrode
regeneration liquid outlet I (12) at the bottom of the electrolyte
tank (1) is connected to an electrode regeneration liquid inlet II
(11) at the top of the electrode regeneration liquid storage tank
(16) through an electrode regeneration liquid pump I (14). An
electrode regeneration liquid outlet II (13) at the bottom of the
electrode regeneration liquid storage tank (16) is connected to an
electrode regeneration liquid inlet I (10) at the top of the
electrolyte tank (1) through an electrode regeneration liquid pump
II (15).
[0036] The removal of chloride ions in desulfurized wastewater
using the foregoing device is further described below by specific
examples.
EXAMPLE 1
[0037] As shown in FIG. 1, a device for removing chloride ions in
desulfurized wastewater by electrochemical coupling is provided The
hydrogen evolution electrocatalysis function electrode (A) is a
CO.sub.3O.sub.4/Ti electrode, and the electrochemically switched
chloride ion exchange function electrode (B) is a PPy ion exchange
function electrode containing chloride ion imprinted vacancies. 1.0
L of purified desulfurized wastewater from a real power plant was
added to an electrochemical coupling separator (1), and 0.5 M
Na.sub.2SO.sub.4 regeneration solution was added to an electrode
regeneration liquid storage tank (16) The tank voltage used in the
separation process was 1.5 V, and the separation removal time was 3
hours. The tank voltage used in the electrode regeneration process
was 1 V and the regeneration time was 2 hours.
[0038] The initial concentration of chloride ions in the industrial
wastewater was 9000 ppm, and the concentration of chloride ions in
the treated liquid following treatment was 3000 ppm. The flocculent
precipitate was about 1.2 g, and the removal rate of chloride ions
in the electrode regeneration liquid reached 98%.
EXAMPLE 2
[0039] As shown in FIG. 1, a device for removing chloride ions in
desulfurized wastewater by electrochemical coupling is provided The
hydrogen evolution electrocatalysis function electrode (A) is a
blank carbon paper electrode, and the electrochemically switched
chloride ion exchange function electrode (B) is a PPy ion exchange
function electrode containing chloride ion imprinted vacancies. 1.0
L of purified desulfurized wastewater from a real power plant was
added to an electrochemical coupling separator (1), and 0.5 M
Na.sub.2SO.sub.4 regeneration solution w-as added to an electrode
regeneration liquid storage tank (16). The tank voltage used in the
separation process was 1.5 V, and the separation removal time was 3
hours. The tank voltage used in the electrode regeneration process
was 1 V and the regeneration time was 2 hours
[0040] The initial concentration of chloride ions in the industrial
wastewater was 9000 ppm, and the concentration of chloride ions in
the treated liquid following treatment was 4500 ppm The flocculent
precipitate was about 0 78 g, and the removal rate of chloride ions
in the electrode regeneration liquid reached 95%.
EXAMPLE 3
[0041] As shown in FIG. 1, a device for removing chloride ions in
desulfurized wastewater by electrochemical coupling is provided.
The hydrogen evolution electrocatalysis function electrode (A) is a
molybdenum disulfide electrode, and the electrochemically switched
chloride ion exchange function electrode (B) is a PPy ion exchange
function electrode containing chloride ion imprinted vacancies. 1.0
L of simulated wastewater (with a Ca concentration of 2000 ppm and
an Mg concentration of 4000 ppm) was added ta an electrochemical
coupling separator (1), and 0.5 M Na.sub.2SO.sub.4 regeneration
solution was added to an electrode regeneration liquid storage tank
(16). The tank voltage used in the separation process was 1.5 V,
and the separation removal time was 3 hours. The tank voltage used
in the electrode regeneration process was 1 V and the regeneration
time was 2 hours.
[0042] The initial concentration of chloride ions in the industrial
wastewater was 10000 ppm, and the concentration of chloride ions in
the treated liquid following treatment was 2500 ppm The flocculent
precipitate was about 1.47 g, and the removal rate of chloride ions
in the electrode regeneration liquid reached 99%.
* * * * *