Method for producing acidic water or alkaline water by using electric energy
Technical Field
The invention belongs to the field of acid water or alkaline water generated by electrolysis, and particularly relates to a production method for producing acid water or alkaline water by using electric energy.
Background
The acidic water or strong oxidized water is water with pH value of 2-7, and has acidity and strong oxidizing property; the alkaline water is water with pH value of 7-12, and has alkalinity. The acidic water is often widely applied to the traditional industries such as sterilization, disinfection, sanitation and medical treatment, and the requirements of some emerging industries such as agricultural growth promotion of agricultural products, soil modification, restoration and the like, cleaning of the electronic industry, and hydrometallurgy of mineral metallurgy such as extraction and concentration of nonferrous metals, rare earth and rare elements. The alkaline water is widely applied to processes of hydroxide formation, deposition, sedimentation and the like, such as processes of deionized water, softened water and chemical product acquisition, separation and purification. The common acidic water or alkaline water is realized by adding inorganic acid, organic acid, inorganic base and the like, and the water inevitably contains other considerable negative ions or positive ions, so that a plurality of adverse effects are caused, such as side effects caused by redundant positive and negative ions in use, and problems of treatment procedures after the requirement of acidity or alkalinity is finished.
Some prior patents report that acidic or alkaline water can be generated, and the addition of inorganic acid and organic acid is basically adopted for assistance, so that the acidic or alkaline water is not really pure acidic or alkaline water without negative ions, and inconvenience or negative influence is brought to subsequent use. Conventional electrochemical methods can generate excessive hydrogen ions or hydroxide ions in water, if the hydrogen ions or the hydroxide ions are not equal in quantity, the water is acidic or alkaline, the methods further extend to generate hydrogen or oxygen, namely, so-called electrolyzed water, only acidic or alkaline water is generated, or the electrolyzed water directly generates hydrogen and oxygen depending on specific electrolysis implementation conditions, methods and electrode materials adopted, the process control is complicated, and the electric conversion efficiency is involved in the use.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provides a production method for directly producing acidic water or alkaline water by using electric energy or indirectly producing renewable energy. The process does not relate to the use of organic acid and inorganic acid, does not generate hydrogen and oxygen in the process, ensures that the generation of the electric conversion acidic water is efficient, has small current density, simple implementation and small voltage, and can be used together with renewable energy sources such as solar energy.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a method for producing acidic water or alkaline water by using electric energy includes applying a potential between a working electrode and a counter electrode, which is less than a potential generated by hydrogen, when acidic water is produced, and generating alkaline water in which the working electrode and the counter electrode are in a discharge state.
An electric potential of less than 1volt is applied between the working electrode and the counter electrode. If the applied potential exceeds the hydrogen-producing potential, the pH value of the acidic water will be reduced to a lower value, but a part of hydrogen gas will be generated, so that the ineffective energy consumption of the process is increased.
The working electrode mainly comprises metal oxide, metal oxysulfide, metal carbide, metal nitride or metal hydride, composite metal oxide, composite metal sulfide, composite metal carbide, composite metal nitride or composite metal hydride, graphene oxide or reduced graphene oxide, or carbon nitride, silicon molybdenum, silicon carbon and other materials.
The electrode working material is attached to the porous conductive material by means of growing, coating and the like.
The porous conductive material is foamed nickel, or foamed aluminum, or foamed copper, or foamed iron, or foamed zinc, or foamed manganese, or foamed cobalt, or a platinum electrode.
The preparation method of the active material of the working electrode adopts a liquid phase deposition method, a coprecipitation method, a hydrothermal method, an organic solvent thermal method, a chemical vapor deposition method or a physical deposition method.
The counter electrode can be an inert carbon electrode, or a graphite electrode, or a platinum electrode, or a silver electrode, or a gold electrode, and generally requires good conductivity.
The invention has the advantages and positive effects that:
the working principle of the system is that the electrodes start to work to generate acidic and strong oxidized water under the condition of energy input, and the electrodes reversely generate alkaline water under the condition of energy output, wherein the input energy can be conventional electric energy, solar energy or wind energy and the like. The working electrode and the counter electrode are directly electrified to generate acidic water and strong oxidation water. An electric discharge between the working electrode and the counter electrode generates alkaline water. The applied voltage is 0.1-1V, and the applied current depends on the effective flow area of the electrode and other factors.
Similarly, if solar energy is used, acidic water and strongly oxidized water are generated, and discharge is generated between the working electrode and the counter electrode, so that alkaline water is generated. There are two specific ways to implement solar energy, including solar panel power supply, or direct sunlight on the working electrode material. The working environment of the electrode and the electrolyte can be from lower temperature to higher temperature (-40 ℃ to 250 ℃) and from lower pressure to higher pressure (0 MPa to 10 MPa).
Drawings
Fig. 1 shows a surface morphology of a cobalt-iron composite metal oxide electrode.
Fig. 2 is a surface morphology case of manganese-iron-cobalt composite oxide electrode.
FIG. 3 is a surface topography case of a metal oxysulfide electrode.
FIG. 4 is a surface morphology case of graphene + rare earth iron perovskite material.
Fig. 5 is a photocatalytic electrode: surface topography case for graphene + TIO 2.
Fig. 6 is a surface morphology case of graphene + composite iron oxide.
Fig. 7 is a surface topography case of a three-dimensional graphene electrode material.
FIG. 8 is a graph of the electrical conversion efficiency and material durability results for metal oxysulfides.
Fig. 9 shows the results of the electrical conversion efficiency and the material durability of the ferromanganese-cobalt composite oxide electrode.
Fig. 10 shows the results of the electrical conversion efficiency and the material durability of the cobalt-iron composite metal oxide electrode.
Fig. 11 shows the results of the electrical conversion efficiency and the material durability of the three-dimensional graphene electrode material.
Figure 12 is a graph of the results of tests on nickel sulfide and metal-coated Pt electrodes to produce acidic water at different voltages.
Fig. 13 is a schematic diagram of an apparatus for generating acidic water and alkaline water (a) by direct illumination and generating acidic water or alkaline water (B) by inputting electric energy.
Detailed Description
The present invention will be described in detail with reference to the following embodiments in order to make the objects, features and advantages thereof comprehensible.
As shown in fig. 13, the method for producing acidic water or alkaline water by using electric energy includes a working electrode, a counter electrode and neutral water, wherein when acidic water is produced, the electrode material is in a discharge state, the electrode material reacts with trace amount of hydroxide ions in the neutral water to produce metal hydroxide, the hydroxide ions in the neutral water are reduced, the balance between the hydrogen ions and the hydroxide ions produced by water is broken, the water moves to the direction of the product, more hydrogen ions and hydroxide ions are produced, and the hydroxide ions react with the electrode material and are fixed on the electrode, so that the concentration of the hydrogen ions in the water is gradually increased, and the acidity enhancement trend is obvious. But the other reversible reaction, namely the chemical potential of hydrogen ions combined with input electrons to generate hydrogen is also enhanced simultaneously, in order to enable the reaction of generating the hydrogen ions and hydroxide ions by water to be continuous and keep the concentration of the hydrogen ions in water to be continuously increased, the potential of an electrode needs to be controlled to be smaller than the hydrogen generation potential, the potential corresponds to the acid state of the water, the higher the potential is, the higher the acidity of the water is, namely the pH value is lower, generally the potential is controlled to be 1volt, the reaction is also related to the chemical state of the electrode, and the more remarkable the reduction state is, the more remarkable the acidity of the water can be realized; and the chemical reduction states of different materials also differ. Under the combined action of the three components, the pH value can be between 3 and 4 and even lower, and the electrode material plays a determining role. Fig. 8-12 are graphs showing the conversion efficiency and material durability results of different electrode materials tested by the inventors, as shown in fig. 8, the conversion efficiency and material durability results of the metal oxysulfide electrode material, fig. 9, fig. 10, fig. 11, the conversion efficiency of the cobalt-iron composite metal oxide electrode, and fig. 11, the Coulombic electrical conversion efficiency and the cycle experiment results of the three-dimensional graphene electrode material under the conditions of 0.1A/g,4A/g,10A/g, and 3V, respectively.
Fig. 12 shows the test results of the production of acidic water and alkaline water at different voltages of nickel sulfide and metal Pt.
When alkaline water is generated, the electrode is in a discharge state, the electrode material is recovered to the original state, hydroxide ions on the electrode are transferred to the water, the concentration of the hydroxide ions in the water is increased, and the pH value is changed from acidity to neutrality and then to alkalinity and is enhanced.
The active material of the working electrode used in the preparation method mainly comprises metal oxide, metal oxysulfide, metal carbide, metal nitride or metal hydride, composite metal oxide, composite metal oxysulfide, composite metal carbide, composite metal nitride or composite metal hydride, composite metal oxysulfide, and nano materials such as graphene, graphene oxide or reduced graphene oxide, or carbon nitride, silicon molybdenum, silicon carbon and the like. In order to increase the process conductivity and increase the working current to increase the yield of acidic water, the electrode working material can be attached to a porous conductive material such as foamed nickel, foamed aluminum, foamed copper, foamed iron, foamed zinc, foamed manganese, foamed cobalt, etc. by means of growing, coating, etc. Fig. 1 is a surface morphology case of a cobalt-iron composite metal oxide electrode, fig. 2 is a surface morphology case of a manganese-iron-cobalt composite oxide electrode, fig. 3 is a surface morphology case of a metal oxysulfide electrode, fig. 4 is a surface morphology case of a graphene + rare earth iron perovskite material, and fig. 5 is a photocatalytic electrode: graphene + TIO2Fig. 6 is a schematic diagram of graphene + composite iron oxide, and fig. 7 is a surface morphology case of a three-dimensional graphene electrode material.
The active material of the working electrode can be prepared by a liquid phase deposition method, a co-precipitation method, a hydrothermal method, an organic solvent thermal method, a chemical vapor deposition method, and a physical deposition method. The liquid phase deposition method or the co-precipitation method is to utilize liquid phase deposition of metal salts including organic salts or inorganic salts under the application of a precipitation agent, and the hydrothermal method and the organic solvothermal method are to respectively heat and pressurize under the condition of water or organic phase substances to deposit active substances of a working electrode, generally to generate metal hydroxides or organic salts and the like, and then to form corresponding oxidation state active materials by roasting. The chemical deposition method comprises organic metal decomposition deposition, methane decomposition deposition and the like, and the physical vapor deposition method comprises plasma enhanced physical vapor deposition, microwave enhanced physical deposition or a physical deposition method enhanced by combining a plurality of physical methods. After the metal active substance is deposited on the electrode conductive carrier, the metal active substance is required to be further roasted at high temperature under the air or oxygen condition, and then the metal oxide active material can be obtained.
The electrolyte is a liquid phase, and a liquid environment for accommodating the working electrode and the counter electrode, and the water used in the above-described embodiments may be saline (containing settleable), inorganic acid water, inorganic alkaline water, organic acid water, or the like, but the role of these electrolytes is different from the prior art, and the purpose is to increase the conductivity of the electrolyte in the initial stage of operation to achieve the acidic and alkaline targets more quickly.
Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art.