CN112609209B

CN112609209B - Electrolytic bath device for preparing colloid nano silver by low-current mobile phase

Info

Publication number: CN112609209B
Application number: CN202011365379.8A
Authority: CN
Inventors: 田军
Original assignee: Ouzhimeng Wuhan International Trade Co ltd
Current assignee: Ouzhimeng Wuhan International Trade Co ltd
Priority date: 2020-11-28
Filing date: 2020-11-28
Publication date: 2022-06-07
Anticipated expiration: 2040-11-28
Also published as: CN112609209A

Abstract

The invention provides an electrolytic bath device for preparing colloidal nano silver by a low-current mobile phase, which comprises a feeding pool, a mobile electrolytic pool, a direct-current power supply, a discharging pool and a recirculation pipeline, wherein the feeding pool is communicated with a feeding hole of the mobile electrolytic pool through a feeding pipe; a silver cathode and a silver anode are arranged in the flowing electrolytic cell, a plurality of labyrinth clapboards are oppositely arranged on the silver cathode and the silver anode to form labyrinth stacking channels which are mutually inserted, the labyrinth stacking channels prolong the area of microfluid electrolysis in the flowing electrolytic cell, and the silver anode and the silver cathode are respectively connected with the positive electrode and the negative electrode of a direct current power supply; the direct current direction is exchanged by the direct current power supply at intervals so as to ensure that the electrode plates of the silver cathode and the silver anode uniformly participate in the electrolysis process. The device effectively improves the mass transfer diffusion current and reduces the side reaction of the electrolytic reaction by lengthening the path length of the electrolyte channel.

Description

Electrolytic cell device for preparing colloid nano silver by low-current mobile phase

Technical Field

The invention belongs to the technical field of precious metal nano material aqueous solution electrolytic preparation devices, and particularly relates to an electrolytic cell device for preparing colloidal nano silver by a low-current mobile phase.

Background

With the development of nanotechnology, mankind has synthesized and used a large number of nanotechnology products, most of which are discharged into the natural environment without treatment, which inevitably results in direct contact of organisms and ecosystems with nanoparticles. The nano silver has attracted attention of researchers in recent years due to its high heat transfer conductivity, antibacterial ability and catalytic performance.

In recent decades, various physical and chemical methods for preparing nano silver have been reported. Common physical methods for preparing nano silver include mechanical ball milling, vapor deposition, ion sputtering and the like, but the requirements on instruments and equipment are high and the production cost is high. In contrast, chemical methods including chemical reduction, microemulsion, electrochemical methods, etc. are simple to operate and easy to control. The chemical reduction method utilizes a reducing agent to reduce silver from a salt solution thereof, the commonly used reducing agent comprises sodium borohydride, ascorbic acid, sodium citrate, hydrazine, organic amine and the like, and a certain coordination stabilizer is usually required to be added to prevent silver particles from agglomerating. The microemulsion method prepares inorganic nanoparticles through a W/O type emulsion system, and has the advantages that the size and the stability of the nano material can be accurately regulated and controlled, the operation is easy, the obtained particles are controllable and have good dispersibility, but an emulsifier residual system is additionally introduced. The electrochemical method is to realize the oxidation-reduction process directly by adding direct current, and a proper amount of coordination stabilizer is required to be additionally added to prevent the nano simple substance particles generated by electrolysis from agglomerating and settling. Compared with homogeneous reaction systems of a chemical reduction method and a microemulsion method, the electrochemical method realizes the oxidation-reduction process of reactants on the surface of an electrode only through an external circuit, and the size of the obtained particles is difficult to regulate and control due to the difference of mass transfer diffusion kinetics of substrates in each reaction micro-area. Compared with simple in-container mixing reaction, the electrochemical method for electrolyzing the nano silver also needs to specially design an electrolytic cell to complete the electrolytic process.

Disclosure of Invention

Aiming at the defects, the invention provides the electrolytic cell device for preparing the colloidal nano silver by the low-current mobile phase, which is provided with the labyrinth partition plates to form the labyrinth stacking channel with a plurality of groups of labyrinth partition plate pore passages, thereby prolonging the path length of the electrolyte channel, enabling the path design of the electrolyte channel to be compact, effectively improving the mass transfer diffusion current, reducing the occurrence of side reactions of the electrolytic reaction and simultaneously easily amplifying the reaction flux in a parallel connection mode.

The invention provides the following technical scheme: an electrolytic cell device for preparing colloidal nano silver by a low-current mobile phase comprises a feeding pool, a mobile electrolytic pool, a direct-current power supply, a discharging pool and a recirculation pipeline, wherein the feeding pool is communicated with a feeding hole of the mobile electrolytic pool through a feeding pipe;

a silver cathode and a silver anode are arranged in the flowing electrolytic cell, a plurality of labyrinth partition plates are oppositely arranged on the silver cathode and the silver anode to form labyrinth stacking channels which are mutually inserted, the labyrinth stacking channels prolong the area of microfluid electrolysis in the flowing electrolytic cell, and the silver anode and the silver cathode are respectively connected with the positive electrode and the negative electrode of a direct current power supply; the direct current power supply exchanges direct current directions at intervals so as to ensure that the electrode plates of the silver cathode and the silver anode uniformly participate in the electrolysis process.

Furthermore, an ammeter used for monitoring the current capacity of the electrolytic cell is arranged on the discharge pipe.

Furthermore, the silver cathode and the silver anode are high-purity flaky silver electrodes and are prepared from silver sheets with the purity of 99.99-99.999%.

Further, the silver cathode and the silver anode are both 50mm in length, 50.0mm in width and 1.0mm in thickness.

Furthermore, each labyrinth partition plate is a semi-cylindrical body with a semicircular section and is prepared by processing polytetrafluoroethylene, and then a circular groove is formed for fixing.

Furthermore, the labyrinth partition plate is 50mm long, 50mm wide, and 1.0mm thick, and the semicircular cross-section diameter of each labyrinth partition plate is 4.0 mm.

Furthermore, a group of labyrinth separator pore channels are formed between one labyrinth separator on the silver cathode and one labyrinth separator on the silver anode, and a snake-shaped distribution labyrinth stacking channel is formed by a plurality of groups of labyrinth separator pore channels; the length of the labyrinth partition plate pore passage is 200mm, and the width of the labyrinth partition plate pore passage is 4.0 mm.

Further, the feeding pool, the feeding pipe, the discharging pipe and the discharging pool are all made of borosilicate glass materials.

Furthermore, the time interval of the direct current power supply for exchanging the direct current direction at intervals is 10 s-60 s, the working voltage of the direct current power supply is 2V-10V, and the working current of the direct current power supply is 0.001A-0.01A.

Further, the recirculation conduit is opened to flow when needed, so that the electrolyte in the device passes through the flow cell multiple times.

The beneficial effects of the invention are as follows:

1. compared with the traditional one-dimensional flow channel design, the device provided by the invention introduces the low-current mobile phase with the extended channel length to prepare the colloidal nano silver electrolytic cell device, and the flow channels among the cathode and the anode are distributed in a snake shape on a two-dimensional plane by changing the appearance of the cathode and the anode.

2. On one hand, the geometrical morphology of the positive and negative electrodes is changed to make the positive and negative electrodes compactly arranged, so that i in the electrolyte can be effectively reduced_solR resistance, which enables the electrolytic cell body to operate at a lower voltage.

3. On the other hand, on the basis of keeping the space compact design, under the condition of the same electrolyte flow rate and the same impressed current, the electrode surface area/retention volume is larger, the current density on the unit electrode area is smaller, the polarization degree is lower, and higher electrolytic conversion selectivity and conversion rate are easier to realize on an electrolyte flow channel. Different channel lengths of the flow electrolysis equipment are related to the conversion rate of primary electrolytic conversion, and the longer the channel length is, the higher the conversion rate of the primary electrolytic conversion is under the same electrolyte flow rate and voltage.

4. The flowing electrolysis equipment with the extended channel length formed by a plurality of groups of labyrinth separator pore passages formed by the labyrinth separators can accurately regulate and control the contact residence time (momentum transfer) and the reaction heat effect control (heat transfer) between the substrate and the electrode surface by controlling the flow rate (mass transfer) of the electrolyte, and can better regulate a plurality of sets of condition parameters of external voltage, the formula of the electrolyte raw material (reaction control) and the flow rate of the electrolyte. Compared with a tank type electrolytic reaction device, the running output of the electrolytic product of the flowing electrolytic device in unit time is more uniform, the electrolytic product flowing out in each time period can be intuitively collected and represented, and the parameters of the electrolytic reaction condition are easier to accurately control and easier to linearly amplify.

5. Compared with the traditional electrolytic cell device for single batch electrolysis in a beaker or a reaction kettle, the device provided by the invention can constantly produce the nano-silver aqueous solution with stable quality based on the mobile phase.

6. The device provided by the invention effectively improves the mass transfer diffusion current and reduces the side reaction of the electrolytic reaction by lengthening the path length of the electrolyte channel.

7. The device provided by the invention has a compact design of a lengthened electrolyte channel path, and is easy to amplify reaction flux in a parallel connection mode.

Drawings

The invention will be described in more detail hereinafter on the basis of embodiments and with reference to the accompanying drawings. Wherein:

FIG. 1 is a schematic view of the whole electrolytic cell apparatus for preparing colloidal nano silver by using low current mobile phase according to the present invention;

FIG. 2 is a schematic structural diagram of an electrolytic cell for preparing colloidal nano silver by a low-current mobile phase with a side view of a flowing electrolytic cell, provided by the invention;

FIG. 3 is a schematic diagram of the production of nano-silver by a flow cell in an electrolytic cell apparatus according to the present invention.

Detailed description of the preferred embodiments

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1-2, the electrolytic cell apparatus for preparing colloidal nano silver by using a low-current mobile phase provided by the invention comprises a feeding pool 1, a mobile electrolytic cell 3, a direct-current power supply 4, a discharging pool 6 and a recirculation pipeline 7, wherein the feeding pool 1 is communicated with a feeding port 3-1 of the mobile electrolytic cell 3 through a feeding pipe 1-1, a discharging port 3-2 of the mobile electrolytic cell is communicated with the discharging pool through a discharging pipe 6-1, the feeding pipe 1-1 is provided with a mobile pump 2, the discharging pipe 6-1 is provided with an ammeter 5 for monitoring the current capacity of the electrolytic cell, the recirculation pipeline 7 is communicated with the discharging pool 6 and the mobile pump 2, and the recirculation pipeline 7 is opened to flow when needed, so that an electrolyte in the apparatus passes through the mobile electrolytic cell 3 for multiple times;

a silver cathode 3-3 and a silver anode 3-4 are arranged in the flow electrolytic cell 3, a plurality of labyrinth partition plates 3-5 are oppositely arranged on the silver cathode 3-3 and the silver anode 3-4 to form labyrinth stacking channels 3-6 which are mutually inserted, the labyrinth stacking channels 3-6 prolong the micro-fluid electrolysis area in the flow electrolytic cell 3, and the silver anode 3-4 and the silver cathode 3-3 are respectively connected with the positive electrode and the negative electrode of the direct-current power supply 4; the direct current direction is exchanged by the direct current power supply 4 at intervals so as to ensure that the electrode plates of the silver cathode 3-3 and the silver anode 3-4 uniformly participate in the electrolysis process.

The time interval of the direct current power supply 4 for exchanging the direct current direction at intervals is 10 s-60 s, the working voltage of the direct current power supply 4 is 2V-10V, and the working current is 0.001A-0.01A.

The silver cathode 3-3 and the silver anode 3-4 are high-purity flaky silver electrodes and are prepared from silver sheets with the purity of 99.99% -99.999%, and the silver cathode 3-3 and the silver anode 3-4 are both 50mm in length, 50.0mm in width and 1.0mm in thickness.

Each labyrinth partition plate 3-5 is a semi-cylindrical body with a semicircular section and is prepared by processing polytetrafluoroethylene, and a circular groove is formed for fixing; the labyrinth partition plate is 50mm long, 50mm wide and 1.0mm thick, and the diameter of the semicircular section of each labyrinth partition plate 3-5 is 4.0 mm. A group of labyrinth separator pore passages 3-61 are formed between one labyrinth separator on the silver cathode 3-3 and one labyrinth separator on the silver anode 3-4, and a plurality of groups of labyrinth separator pore passages 3-61 form a snake-shaped distribution labyrinth stacking channel 3-6; the length of the labyrinth partition plate pore canal 3-61 is 200mm, and the width is 4.0 mm.

The feeding tank 1, the feeding pipe 1-1, the discharging pipe 6-1 and the discharging tank 6 are all made of borosilicate glass materials.

The working principle is as follows:

in flow electrolyzers with elongated channels, the electrolyte feed is brought into contact with and counter-current to the electrodes during flow from the electrolyzerIn the process, the concentration of the raw material is gradually reduced along the channel, the local current density is gradually reduced in an exponential form from the highest value at the inlet to the lowest value at the outlet along the channel, and the mass transfer coefficient k_m,xAt a distance c from the entrance_xThe function of interest. If the electrolysis reaction is mass transfer diffusion control, the total current I of the electrolytic cell_cellIs the integral of the local current density along the channel, i.e.:

the definitions and units of the parameters in the formula are shown in the following table 1:

TABLE 1

I_cell,mt	Total current of electrolytic cell	Unit A
			x	Distance along the channel from the inlet	Unit of cm
I_x,mt	Mass transfer diffusion control current x distance from inlet	Unit A
			L	Total length of the channel	Unit of cm
w	Width of the channel	Unit of cm
			k_m,x	Mass transfer coefficient x distance from inlet	Unit: cm/s
c_x	Substrate concentration x distance from entrance	Unit: mol/cm³

In order to achieve 100% faradaic current efficiency for a given electrolytic reaction, and avoid competing side reactions during the electrolytic reaction, the mass transfer diffusion current must be large enough to allow mass transfer diffusion-controlled limiting current I of the electrolytic reaction_cell,minimumCan consume all the passing charges per unit time, i.e. I_cell,mt＞I_cell,minimumOn the contrary, if the mass transfer diffusion is not enough to maintain I_cell,minimum(I_cell,mt＜I_cell,minimum) Competing electrolytic side reactions will occur at the electrodes.

When the current efficiency of mass transfer diffusion is large enough, the current I of the electrolytic cell can be estimated according to Faraday's law_cell,mtAnd conversion X:

I_cell，mt＝nFQ_vc_inX(eq.2)；

the definitions and units of the parameters in the formula are shown in the following table 2:

TABLE 2

I_cell,mt	Total current of electrolytic cell	Unit A
			n	Total amount of electron transfer required to complete the electrolytic process	Unit of mol
F	Faraday constant	F＝96485C/mol
			Q_v	Volume flow of electrolyte	Unit of cm³/s
c_in	Substrate concentration at inlet	Unit: mol/cm³

Given such ideal mass transfer controlled diffusion electrolysis, the volumetric flow rate Q of the electrolyte is given_vThe total length L of the effective electrode channel through which the flowing electrolyte is required to achieve the conversion ratio X can be estimated by the following equation:

TABLE 1

X	Conversion ratio of cell substrate	Unit (a)
			c_in	Substrate concentration at inlet	Unit: mol/cm³
c_out	Concentration of substrate at the outlet	Unit: mol/cm³
			k_m	Comprehensive mass transfer coefficient of electrolytic cell	Unit: cm/s
w	Width of the channel	Unit of cm
			L	Length of the channel	Unit of cm
Q_v	Volume flow of electrolyte	Unit of cm³/s

From the equation (eq.3), the cell with the elongated channels is effective in increasing the single pass conversion of the electrolysis reaction, while the rate of substrate production is determined by the electrolyte feed concentration and flow rate. The final product selectivity, rate of formation and overall conversion depend on feed concentration, flow rate and applied current, among other things, and the corners of the electrolysis apparatus, temperature gradients within the channels and gases that may be generated have an effect on the electrolysis reaction.

As shown in FIG. 3, the principle of preparing the nano-silver aqueous solution by the electrolysis method is that the silver electrode is used as a sacrificial anode, and the oxidation reaction Ag (bulk) → Ag occurs at the anode⁺+e^-Thereby releasing silver ions Ag into the solution⁺Silver ion Ag⁺Then the silver ions are diffused to the surface of a cathode to be reduced to generate nano silver stabilized by ligand into solution nAg⁺+ne^-→Ag_n. It is noted that a possible side reaction of the anode is 2Ag⁺+H₂O→Ag₂O↓+2H⁺The cathode may have a side reaction in which silver ions are largely reduced on the cathode to form bulk silver deposited on the surface thereof, thereby reducing the yield of nano silver. In all electrolytic cells, the oxidation-reduction reaction with the same quantity of electrons on the working electrode and the counter electrode occurs, and ideally, the silver ions Ag after anodic oxidation⁺Reducing the silver into nano silver in a cathode in a sufficient equal amount, and dissolving the silver in an aqueous solution under the protection of a ligand. The two side reactions are related to substrate mass transfer diffusion between the cathode and the anode in the solution, for example, the S-shaped bent flow electrolytic pipeline design is beneficial to the electrolyte to be in full contact with the cathode and the anode successively in the process of fluid mass transfer turning. And the direct current direction is exchanged within a certain time in the electrolytic process, so that the silver electrodes at two ends are uniformly oxidized, the silver electrodes at two ends are prevented from being unbalanced, and the silver electrodes are uniformly reduced into soluble nano silver to enter the aqueous solution.

While the invention has been described with reference to a preferred embodiment, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In particular, the technical features mentioned in the embodiments can be combined in any way as long as there is no structural conflict. It is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. The electrolytic cell device for preparing the colloidal nano silver by using the low-current mobile phase is characterized by comprising a feeding pool (1), a flowing electrolytic cell (3), a direct-current power supply (4), a discharging pool (6) and a recycling pipeline (7), wherein the feeding pool (1) is communicated with a feeding hole (3-1) of the flowing electrolytic cell (3) through a feeding pipe (1-1), a discharging hole (3-2) of the flowing electrolytic cell is communicated with the discharging pool through a discharging pipe (6-1), the feeding pipe (1-1) is provided with a flowing pump (2), and the discharging pool (6) is communicated with the flowing pump (2) through the recycling pipeline (7);

a silver cathode (3-3) and a silver anode (3-4) are arranged in the flowing electrolytic cell (3), a plurality of labyrinth partition plates (3-5) are oppositely arranged on the silver cathode (3-3) and the silver anode (3-4) to form labyrinth stacking channels (3-6) which are mutually inserted, the labyrinth stacking channels (3-6) prolong the area of microfluid electrolysis in the flowing electrolytic cell (3), and the silver anode (3-4) and the silver cathode (3-3) are respectively connected with the positive electrode and the negative electrode of the direct current power supply (4); the direct current power supply (4) exchanges direct current directions at intervals so as to ensure that electrode plates of the silver cathode (3-3) and the silver anode (3-4) uniformly participate in the electrolysis process.

2. The electrolyzer apparatus for preparing colloidal nano-silver with low-current mobile phase according to claim 1 characterized in that the tapping pipe (6-1) is provided with an ammeter (5) for monitoring the amount of electrolyzer current.

3. The electrolyzer apparatus for preparing colloidal nanosilver with low current mobile phase according to claim 1 characterized in that the silver cathode (3-3) and the silver anode (3-4) are high purity flaky silver electrodes prepared from silver flakes with a purity of 99.99% to 99.999%.

4. The electrolyzer apparatus for the preparation of colloidal nanosilver with low current mobile phase according to claim 1 characterized in that the silver cathodes (3-3) and the silver anodes (3-4) are both 50mm in length, 50.0mm in width and 1.0mm in thickness.

5. The electrolyzer apparatus for the preparation of colloidal nanosilver from mobile phase at low current according to claim 1, characterized in that each of said labyrinth plates (3-5) is made of teflon to form a semi-cylindrical body with a semi-circular cross-section, and then forms a circular groove for fixation.

6. The electrolyzer apparatus for the preparation of colloidal nanosilver from low current mobile phase according to claim 5 characterized in that said labyrinth separators have a length of 50mm, a width of 50mm and a thickness of 1.0mm, and each of said labyrinth separators (3-5) has a semicircular cross-sectional diameter of 4.0 mm.

7. The electrolyzer apparatus for preparing colloidal nanosilver with low current mobile phase according to claim 1, characterized in that a group of labyrinth separator channels (3-61) is formed between one labyrinth separator on the silver cathode (3-3) and one labyrinth separator on the silver anode (3-4), and a plurality of groups of labyrinth separator channels (3-61) form a serpentine-distribution labyrinth stacked channel (3-6); the length of the labyrinth partition plate pore canal (3-61) is 200mm, and the width is 4.0 mm.

8. The electrolyzer apparatus for preparing colloidal nanosilver with low current mobile phase according to claim 1 characterized in that the feed tank (1), the feed pipe (1-1), the discharge pipe (6-1) and the discharge tank (6) are all made of borosilicate glass material.

9. The electrolyzer apparatus for preparing colloidal nano-silver by using low-current mobile phase according to claim 1, characterized in that the time interval for the direct-current power supply (4) to alternate the direct-current direction is 10 s-60 s, the working voltage of the direct-current power supply (4) is 2V-10V, and the working current is 0.001A-0.01A.

10. The electrolyzer unit for the preparation of colloidal nanosilver from a low current mobile phase according to claim 1 characterized in that the recirculation conduit (7) is opened to flow when needed, so that the electrolyte in the unit passes through the flow cell (3) several times.