KR101872125B1 - Water treatment system which is possible to make desalinization and oxidant - Google Patents

Abstract

The present invention relates to a water treatment system capable of producing desalting and oxidizing agents. More particularly, the present invention relates to a water treatment system comprising a desalting electrode and an oxidizing electrode, an anion exchange membrane capable of securing a passage for an anion between the desalting electrode and the oxidizing electrode, And a desalination reaction is performed in a space between the desalting electrode and the anion exchange membrane and an oxidant is formed in a space between the oxidation electrode and the anion exchange membrane.

Description

[0001] The present invention relates to a water treatment system capable of producing desalting and oxidizing agents,

The present invention relates to a water treatment system capable of producing desalting and oxidizing agents, and more particularly, to a water treatment system capable of forming a desalting reactor and an oxidant generating reactor around an anion exchange membrane.

In the world, the value of water resources is increasing due to the deepening of drought phenomenon caused by global warming, depletion of groundwater, progress of desertification, population increase, industrialization, and increase of industrial water use. Therefore, recycling of living and industrial wastewater and desalination of seawater This is emerging as a new issue.

In general, seawater desalination is performed by reverse osmosis membrane, electrodialysis by ion exchange membrane, evaporation method by converting seawater into steam, desalination, and solar heat. Currently, commercialization of desalination technology includes a vaporization process for separating the salt by heat and a reverse osmosis membrane process for passing only water.

However, the above-mentioned technology has the following problems. The evaporation process is a method of separating salinity and water vapor by evaporating seawater and condensing water vapor to obtain fresh water. Because energy consumption is very large, the crude oil price is stable, It is mainly used in the Middle East. Reverse osmosis membrane process is a method to obtain fresh water by pressurizing seawater into a reverse osmosis membrane that does not permeate water that passes through water but is dissolved in water. Because it requires high pressure process, small scale process is difficult and operation cost is high due to clogging Have. In order to overcome the disadvantages of these conventional processes, desalination technologies using electrochemical methods such as a storage desalination process and a battery desalination process have been recently developed, and these technologies are widely used in the future desalination market It is expected to be used.

In addition, the treatment of the remaining materials after the water treatment is also important, and a need for measures to recycle them is emerging.

Patent Document 1: Korean Patent No. 0899290 (Published on May 28, 2009) Patent Document 2: Korean Patent No. 1637539 (issued on July 27, 2016)

In order to solve the above problems, an object of the present invention is to provide a system capable of recycling waste remaining in the desalination process.

Another object of the present invention is to provide a system capable of producing an oxidizing agent by combining other processes besides the desalination treatment.

In order to accomplish the above object, the present invention provides an anion exchange membrane comprising a desalting electrode and an oxidizing electrode, the anion exchange membrane capable of securing a path for moving anion between the desalting electrode and the oxidizing electrode, Wherein the desalination reaction is performed in a space between the oxidation electrode and the anion exchange membrane, and an oxidizing agent is formed in a space between the oxidation electrode and the anion exchange membrane.

According to another aspect of the present invention, there is provided a water treatment system capable of producing desalination and oxidizing agents, wherein the desalting electrode and the oxidation electrode are electrodes capable of electrochemically reacting various positive ions and anions.

According to the present invention, in the space between the desalting electrode and the anion exchange membrane, the cation is removed by the electrochemical reaction with the desalting electrode, and the anion is diffused into the space between the oxidation electrode and the anion exchange membrane through the anion exchange membrane. And a water treatment system capable of producing desalting and oxidizing agents.

According to the present invention, in the space between the oxidation electrode and the anion exchange membrane, the anion or the anion diffused through the anion exchange membrane is converted into the oxidizing agent due to the electrochemical reaction with the oxidation electrode. Provides a possible water treatment system.

According to the present invention, the oxidizing agent formed in the space between the oxidation electrode and the anion exchange membrane is at least one of chlorine, chlorine dioxide, chloramine, hydroxyl radical, and ozone. .

According to the present invention, the desalting electrode is made of Na _{0 . 44} MnO ₂ , λ-MnO ₂ , NaFePO ₄ , NaFeP ₂ O ₇ , NaMn _x Co _y Fe _z PO ₄ , activated carbon, graphene carbon material, and carbon nanotube. To provide a water treatment system.

According to the present invention, the oxidation electrode may be formed of RuO ₂ , IrO ₂ , SnO ₂ , PbO ₂ , TiO ₂ The present invention provides a water treatment system capable of producing desalination and oxidizing agent.

A water treatment system capable of producing desalination and oxidizing agents according to embodiments of the present invention can purify water and produce an oxidizing agent.

Further, there is an advantage that the oxidizing agent such as Cl ₂ used in the desalination process can be directly supplied through the oxidizing agent manufacturing process.

1 is a conceptual diagram of a water treatment system capable of producing desalting and oxidizing agents according to an embodiment of the present invention.
FIG. 2 is a flow chart for explaining a desalting and oxidizing agent generating method according to an embodiment.
3 is a graph showing the concentration and Coulomb efficiency of chlorine generated according to the charge amount in the embodiment of the present invention.
4 is a graph showing a potential difference according to the amount of charge in the embodiment of the present invention.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

First, in the drawings, it is noted that the same components or parts are denoted by the same reference numerals as possible. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted so as to avoid obscuring the subject matter of the present invention.

The terms " about ", " substantially ", etc. used to the extent that they are used herein are intended to be taken to mean an approximation of, or approximation to, the numerical values of manufacturing and material tolerances inherent in the meanings mentioned, It is used to prevent unauthorized exploitation by an unscrupulous infringer from disclosing the exact or absolute numerical value to help.

The present invention relates to a water treatment system capable of producing desalting and oxidizing agents, wherein an anion exchange membrane (AEM) capable of moving anions between a desalting electrode and an oxidizing electrode is present, and in the electrochemical reaction, And an oxidizing agent is formed in a space between the anion exchange membrane and the oxidation electrode.

Referring to FIG. 1, the anion exchange membrane is disposed to maintain a certain distance from the desalting electrode and the oxidation electrode, and a space between the desalting electrode and the anion exchange membrane and a space between the oxidation electrode and the anion exchange membrane are separated .

In addition, the space between the desalting electrode and the anion exchange membrane and the space between the oxidation electrode and the anion exchange membrane may flow seawater, brine or wastewater, and the seawater, brine or wastewater may contain desalting cations and anions have.

First, the operation principle of a water treatment system capable of producing desalting and oxidizing agents will be described.

FIG. 2 is a flow chart for explaining a desalting and oxidizing agent generating method according to an embodiment.

Referring to FIG. 2, when the desalting electrode and the oxidizing electrode are connected to each other by a single circuit to apply electric energy (S10), the positive ions existing in the space between the desalting electrode and the anion- And is inserted into the desalting electrode due to a chemical reaction (S20).

In addition, the anions present in the space between the oxidation electrode and the anion exchange membrane are converted into oxidants from the surface of the oxidation electrode due to the electrochemical reaction with the oxidation electrode (S30).

At this time, the electrical neutrality of the space between the desalting electrode and the anion exchange membrane and the space between the oxidation electrode and the anion exchange membrane is temporarily broken, and the anion existing in the space between the desalination electrode and the anion exchange membrane is anion exchange (S40) through the membrane to the space between the oxidation electrode and the anion exchange membrane.

Therefore, the cation existing in the space between the desalting electrode and the anion exchange membrane is removed through the electrochemical reaction with the desalting electrode, and in the case of the anion, the desalting can be performed through diffusion (S50).

In other words, the anion exchange membrane can be disposed between the desalting electrode and the oxidation electrode to allow the anion to migrate, so that desalination and oxidant preparation can be performed at the same time.

The desalting electrode and the oxidizing electrode are electrodes capable of reversibly reacting with a cation and an anion.

When the voltage is applied, a reduction reaction occurs at the desalting electrode and an oxidation reaction occurs at the oxidation electrode.

According to the embodiment of the present invention, the material constituting the desalting electrode and the oxidation electrode may have a large internal grating structure, and various positive ions may be inserted or removed.

The cation can be separated and inserted, and may include sodium, potassium, magnesium, calcium ions, and the like.

Therefore, the desalting electrode and the oxidizing electrode can perform desalination for a fluid having a high ion concentration and various ions dissolved therein, such as seawater, brine or wastewater.

The desalting electrode has a high reaction potential and the oxidation electrode has a low reaction potential.

The desalting electrode is characterized in that it has a relatively low reactivity due to its high reaction potential and is difficult to oxidize. The oxidation electrode has a low reaction potential and is relatively reactive and easily oxidized.

The desalting electrode is made of Na _{0 . 44 MnO 2, λ-Mn0 2} , NaFePO 4, NaFeP 2 O 7, NaMn x Co y Fe z PO 4, activated carbon, graphene-based carbon material, preferably at least one of a carbon nanotube and said anode is _{RuO 2, IrO 2, SnO 2} , PbO 2, TiO 2 Or the like.

In addition, the desalination electrode may be a battery electrode material series in which cations can be inserted and removed, a metal phosphide series, a metal mixed phosphide, or a carbon material capable of ion adsorption.

The oxidation electrode may be a DSA (Dimensionally Stable Anode) electrode having a low oxygen overvoltage and a BDD (Boron doped diamond) electrode having a high oxygen generation overvoltage.

Hereinafter, a water treatment system capable of producing the desalination and oxidizing agent of the present invention will be described with reference to specific examples and experimental examples.

Example  One

Electrode Manufacturing

Na _{0 for the} cathode _{. 44} MnO ₂ , and TiO ₂ nanotube electrode was prepared as an anode. The cathode was prepared by the solid phase method using Na ₂ CO ₃ and Mn ₂ O ₃ powder, and the anode was an organic solvent based on ethyleneglycol (2.5 wt%) / ammonium fluoride (0.2 wt%) was prepared by electrochemical anodization in an electrolyte.

Na _{0 . 44} MnO ₂ was prepared by mixing a mixture of Na ₂ CO ₃ and Mn ₂ O ₃ in a molar ratio of 1: 1 for 1 hour using a ball mill, and then annealing at 500 ° C. for 5 hours. After the annealing, the obtained powders were mixed again and then subjected to secondary annealing at 900 ° C. for 12 hours. The annealing conditions were carried out at atmospheric conditions in the presence of oxygen. The powder obtained by the second annealing was rinsed several times with distilled water and then filtered with a 450 nm pore filter. The Na _{0 . 44} MnO ₂ (86 wt%) powders were mixed with carbon black (7 wt%) and PTFE (7 wt%) as conductors to form mixed slurries and kneaded and rolled to form sheet type electrodes. The thickness of the electrode thus formed was about 250 micrometers.

TiO ₂ was prepared by applying about 40 V for 16 hours to a platinum electrode as a negative electrode in an ethylene glycol (97.3 wt%) electrolyte mixed with water (2.5 wt%) / ammonium fluoride (0.2 wt% To prepare a nanotube electrode. The TiO2 nanotube electrode thus fabricated had a tube diameter of 100 nanometers in inner diameter of 60 nanometers and a tube height of about 30 nanometers.

Desalting and Oxidizing Agents Water treatment  System configuration

Na _{0 . 44} MnO ₂ electrode as a cathode and a TiO ₂ nanotube electrode as an anode. The system consists of a desulfurization reactor containing a cathode and a reactor capable of producing an oxidant containing an anode. The electrolytes of the two reactors are completely separated by an anion exchange membrane have.

Experimental Example  One - Desalination performance  And oxidative agent production performance evaluation

Na _{0 . 44} MnO ₂ electrode is KH ₂ PO ₄ 0.1 M solution of the 3-electrode cell (active electrode: Na _{0 44} MnO _2, the opposite _electrode:. Pt, Reference electrode: Ag / AgCl KCl) to the 0.8V configuration compared to the reference electrode 30 to And precharging was performed. After precharging, the electrode was filled with Na _0.22 MnO ₂ .

Desalting performance and oxidant production performance test is run at a constant current condition Na _{0. 44} MnO ₂ electrode and a current of 9 mA / cm ₂ based on the TiO ₂ nanotube electrode were applied while a total charge amount of 64 C was applied.

The capacity of the desalting reactor containing the anode was about 85 mL and the solution volume of the oxidant generating reactor containing the anode was about 85 mL. The ion concentration of the desalting reactor was measured using an Ion chromatograph, Of chlorine was measured by the change of absorbance through DPD reagent.

Desalination Cell Oxidation Cell Na ⁺ Ca ^{2 +} Mg ^{2 +} Cl ^- SO ₄ ^2- Cl ₂ C _i / mgL ^-1 874 63 86 1547 220 0 C _f / mgL ^-1 617 39 43 1119 157 173 ? C /% 29 38 49 28 28 - Coulombic Efficiency /% 69 7 22
-
66 98 (combined)

After the evaluation process, the concentration of each cation and the concentration of each anion were decreased and chlorine was generated. As a result, it was confirmed that the water treatment system capable of producing the desalting and oxidizing agent of the present invention proceeded with desalting and oxidizing agent production simultaneously.

Table 1 shows representative experimental results when the system is operated with synthetic water made assuming general ion concentration at the river level (total ion concentration: 50Mm).

Three kinds of cations contained were removed with a Coulomb efficiency of 98%, and two kinds of anions were transferred by diffusion.

It was also found that 66% of chlorine, a representative oxidizing agent, was generated in the space between the oxidized electrode and the anion exchange membrane, and hydroxyl radical and oxygen were partially present.

3 is a graph showing the concentration and Coulomb efficiency of chlorine generated according to the charge amount in the embodiment of the present invention.

FIG. 3 shows the amount and efficiency of the chlorine species generated during the operation time. In the early stage of the reaction, the efficiency of the chlorine generating charge was measured to be 90% or more. However, as the system progressed, It is possible to confirm that it is. Finally, it was confirmed that the efficiency of chlorine generation was maintained over 80% while the charge of 14 C was flowing.

Example  2 - Water treatment  System operating voltage evaluation

While the system is operating, Na _{0 . 44} MnO ₂ electrode and the TiO ₂ nanotube electrode are connected to the reference electrode (Ag / AgCl KCl), respectively. The difference in voltage applied to each electrode is the cell voltage used in the actual system.

4 is a graph showing a potential difference according to the amount of charge in the embodiment of the present invention.

In the system operating voltage, the difference between the voltage of the cathode in the desalination reactor and the voltage of the anode in the oxidizer generating reactor is the operating voltage of the system. The operating voltage of the system is the difference between the blue line and the black line in FIG. .

Referring to FIG. 4, it can be seen that the voltage of the cathode is lowered and the voltage of the anode is higher according to the time. The positive electrode is inserted into the cathode and the voltage is lowered. This is because the overvoltage increases and the voltage increases.

In synthetic water with a total ion concentration of 50 Mm, TiO2 electrode and Na _{0 . When} the system was operated using ₄₄ MnO ₂ electrodes, an operating voltage of about 2.5 ~ 3.0 V was observed.

Na _{0 . 44} MnO ₂ electrode shows reversible reaction with ions at potential between 0.1 V and 0.5 V (vs Ag / AgCl) and between 2.9 V and 3.3 V (vs. Ag / AgCl) at TiO ₂ electrode. Through the potential difference of these two materials, Na _{0 . 44} MnO ₂ electrode as a desalting electrode and a TiO ₂ electrode as an oxidation electrode to form a battery cell, desalination and oxidant preparation can proceed well.

In the case of using the DSA electrode, the operating voltage of the oxidizing electrode was lowered to 1.6 V, and the operating voltage was measured to 0.8 to 1.5 V level.

Since the operating voltage is theoretically 0 to -0.6 V because the opposite electrode of the oxidizing electrode is made of a hydrogen generating electrode (Pt, stainless) when compared with a general oxidizing agent generating system, It can be seen that more than 1V is needed.

The cell voltage of the system is determined by the voltage difference between the oxidizing electrode and the desalting electrode, and the operating voltage may be affected by various operating factors including the magnitude of the applied current.

The reaction voltage of the oxidizing electrode is influenced by the type of the electrode, the current density, the type of the oxidizing agent and the concentration of the electrolyte, and the desalting electrode may be greatly influenced by the current density and the electrolyte concentration.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. It will be clear to those who have knowledge of.

100: water treatment system 113: diffused negative ion
101: desalting electrode 114: oxidizing agent
102:
103: ion exchange membrane
111: cation
112: negative ion

Claims (7)

And an anion exchange membrane including a desalting electrode and an oxidation electrode and capable of securing a path for passage of an anion between the desalting electrode and the oxidation electrode,
A desalting reaction is performed in a space between the desalting electrode and the anion exchange membrane,
An oxidant is formed in a space between the oxidation electrode and the anion exchange membrane,
Wherein in the space between the desalting electrode and the anion exchange membrane, the cation is removed by the electrochemical reaction with the desalting electrode, and the anion is diffused into the space between the oxidation electrode and the anion exchange membrane through the anion exchange membrane. And a water treatment system capable of producing an oxidizing agent.
The method according to claim 1,
Wherein the desalting electrode and the oxidation electrode are electrodes capable of electrochemically reacting with various positive ions and negative ions.
delete The method according to claim 1,
Wherein an anion dispersed in the space between the oxidation electrode and the anion exchange membrane is converted into an oxidizing agent due to an electrochemical reaction with the oxidation electrode through the anion or the anion exchange membrane.
The method according to claim 1,
Wherein the oxidizing agent formed in the space between the oxidation electrode and the anion exchange membrane is at least one of chlorine, chlorine dioxide, chloramine, hydroxyl radical, and ozone.
The method according to claim 1,
The desalting electrode is made of Na _{0 . 44} MnO ₂ , λ-MnO ₂ , NaFePO ₄ , NaFeP ₂ O ₇ , NaMn _x Co _y Fe _z PO ₄ , activated carbon, graphene carbon material, and carbon nanotube. Water treatment system.
The method according to claim 1,
The oxidation electrode may be formed of RuO ₂ , IrO ₂ , SnO ₂ , PbO ₂ , TiO ₂ Wherein the desalting and oxidizing agent is at least one of the desalting and oxidizing agents.

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