Method for removing organic impurities from cadmium plating bath solution

Abstract

The invention relates to a method for removing organic impurities from a cadmium plating bath solution. By utilizing the characteristics of a filter paper semi-permeable membrane and the characteristics of small molecular weight and short chain of organic impurities, the filter paper is used for coating activated carbon and placed in a cadmium plating bath solution, the organic impurities penetrate through the filter paper and are adsorbed by the activated carbon, and sulfonated castor oil cannot penetrate through the filter paper in chain length, so that the organic impurities are prevented from being adsorbed by the activated carbon; by utilizing the property that the organic impurities are polar molecules, small-current electrifying is carried out on the bath solution while adsorption is carried out, so that the organic impurities are migrated along a power line and are convenient to gather and adsorb. In addition, the filter paper bag is easy to clean, and the analysis phenomenon in the activated carbon cleaning process is avoided. By adopting the method disclosed by the invention, the removal efficiency of the activated carbon on the organic impurities in the cadmium plating bath solution can be improved, the damage of the active ingredient sulfonated castor oil in the bath solution is avoided, and the method is simple and convenient to operate, short in time and high in efficiency.

Description

Technical Field

[0001] The invention relates to a surface treatment cadmium plating bath solution and provides a method for removing organic impurities from the cadmium plating bath solution. Background Art

[0002] According to HB / Z5068-1992 "Electro-zinc and Electro-cadmium Processes", the most widely used electro-cadmium plating method is to use a cadmium plating bath containing sulfonated castor oil as a brightener. During the use of this bath, sulfonated castor oil will produce organic impurities due to partial electrolysis during the electroplating process. If the organic impurities are too high, the coating will have defects such as agglomeration and mottle, affecting the quality of the electroplated cadmium.

[0003] In the past, the method of removing organic impurities from cadmium electroplating bath was to use activated carbon adsorption, that is, pouring activated carbon into the bath, stirring the bath for 1 hour, and then letting it stand for 24 hours. Because the activated carbon is granular, filtering it with a filter will clog the filter element, so the bath can only be filtered manually to remove the activated carbon. This method has the characteristics of high labor intensity, low efficiency in adsorbing organic impurities, and long operation cycle. Summary of the invention

[0004] Purpose of the invention: The present invention provides a method for quickly and efficiently removing organic impurities from a cadmium plating bath solution. The method of the present invention can not only quickly remove small molecular organic impurities from the bath solution, but also achieve the effect of quickly adjusting the composition of the cadmium plating bath solution.

[0005] A method for removing organic impurities from a cadmium plating bath solution is provided, comprising the following steps:

[0006] Step 1: Determine the total mass of activated carbon

[0007] The total mass of activated carbon was obtained by the following formula: V×(0.05-0.08) g / L, where V is the volume of the cadmium plating bath;

[0008] Step 2: Clean the activated carbon

[0009] The surface of the activated carbon is cleaned with a cleaning liquid to remove floating dust on the activated carbon;

[0010] Step 3: Coating activated carbon

[0011] The activated carbon is divided into a plurality of portions, and each portion of the activated carbon is coated into an activated carbon bag;

[0012] Step 4: Hang activated carbon

[0013] Immersing a plurality of activated carbon packages in the cadmium plating bath in a suspended manner, wherein the plurality of activated carbon packages are evenly distributed relative to the electrolytic cell;

[0014] Step 5: Stirring the tank liquid

[0015] The cadmium plating bath solution is mechanically stirred so that the liquid is filtered through the activated carbon bag;

[0016] Step 6: Power on

[0017] Connect the cathode to the iron plate and the anode to the cadmium plate, and apply power.

[0018] Step 7: Take out the activated carbon bag

[0019] After the power is turned on, take out the activated carbon bag.

[0020] Furthermore, during step 7, the cadmium plating bath solution is in a static state.

[0021] Furthermore, in step 6, the current is low and the current density is 0.2-0.4A / dm 2 .

[0022] Furthermore, in step 6, the power-on time is 12 hours to 14 hours.

[0023] Furthermore, the iron plate and the cadmium plate have the same area.

[0024] Furthermore, the stirring time of the tank liquid in step 5 is 20 minutes to 30 minutes.

[0025] Furthermore, each activated carbon bag has a weight of 400 g to 500 g. Furthermore, each activated carbon bag has 2 to 4 layers of filter paper as the inner layer and 1 to 2 layers of cloth as the outer layer.

[0026] Furthermore, a supporting guide rod is provided above the cadmium plating tank, and the multiple activated carbon packages are mounted on the supporting guide rod.

[0027] Beneficial effects of the present invention

[0028] (1) Utilize the semi-permeable membrane properties of filter paper to increase the removal of organic impurities.

[0029] Filter paper has the properties of a semi-permeable membrane, small molecules can easily pass through, but large molecules cannot. The organic impurities in the cadmium plating bath are the products of the decomposition of sulfonated castor oil during the electroplating process. They have a small molecular weight and can pass through the filter paper; while sulfonated castor oil is a large molecule and cannot pass through the filter paper. Therefore, the method of wrapping activated carbon with filter paper can be used to improve the specificity of activated carbon to organic impurities, while also preventing the activated carbon from adsorbing sulfonated castor oil. In order to prevent the filter paper from being damaged during the immersion in the bath and causing the activated carbon to scatter in the bath, one or two layers of cloth can be wrapped around the filter paper.

[0030] (2) Utilize the electrosorption effect of organic matter to facilitate the aggregation of organic impurities.

[0031] Organic impurities are polar molecules, and they migrate along the lines of force under the action of an external electric field. While the activated carbon is adsorbing, the cadmium plating bath is electrified to facilitate the accumulation of organic impurities. If the current is too large, the cathode will produce too much H2 and the anode will produce too much O2, causing the liquid surface to flow and the activated carbon to decompose. Therefore, a small current is used for electrification.

[0032] (3) Direct cleaning after activated carbon adsorption to avoid decomposition of activated carbon.

[0033] The adsorption of organic impurities by activated carbon involves a process of adsorption and desorption. After the activated carbon adsorption treatment, the tank liquid needs to be filtered in order to remove the activated carbon in the tank liquid. During the filtration process, the activated carbon that has adsorbed organic impurities will undergo desorption, causing the adsorbed organic impurities to separate from the surface of the activated carbon and enter the tank liquid. If the activated carbon is cleaned directly after adsorption, the desorption phenomenon can be avoided. DETAILED DESCRIPTION

[0034] The technical scheme of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0035] A method for removing organic impurities from a cadmium plating bath solution is provided, comprising the following steps:

[0036] Step 1: Determine the total mass of activated carbon

[0037] The total mass of activated carbon was obtained by the following formula: V×(0.05-0.08) g / L, where V is the volume of the cadmium plating bath;

[0038] Step 2: Clean the activated carbon

[0039] The surface of the activated carbon is cleaned with a cleaning liquid to remove floating dust on the activated carbon;

[0040] Step 3: Coating activated carbon

[0041] The activated carbon is divided into a plurality of portions, and each portion of the activated carbon is coated into an activated carbon bag;

[0042] Step 4: Hang activated carbon

[0043] Immersing a plurality of activated carbon packages in the cadmium plating bath in a suspended manner, wherein the plurality of activated carbon packages are evenly distributed relative to the electrolytic cell;

[0044] Step 5: Stirring the tank liquid

[0045] The cadmium plating bath solution is mechanically stirred so that the liquid is filtered through the activated carbon bag;

[0046] Step 6: Power on

[0047] Connect the cathode to the iron plate and the anode to the cadmium plate, and apply power.

[0048] Step 7: Take out the activated carbon bag

[0049] After the power is turned on, take out the activated carbon bag.

[0050] During step 7, the cadmium plating bath solution is in a static state.

[0051] In step 6, a small current is applied, and the current density is 0.2 to 0.4 A / dm 2 The power-on time is 12h~14h.

[0052] The iron plate and the cadmium plate have the same area.

[0053] The stirring time of the tank liquid in step 5 is 20min to 30min.

[0054] The weight of each activated carbon bag is 400g to 500g. Each activated carbon bag has 2 to 4 layers of filter paper as the inner layer and 1 layer of cloth as the outer layer.

[0055] A supporting guide rod is arranged above the cadmium plating tank, and the multiple activated carbon bags are all mounted on the supporting guide rod.

[0056] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined in this specification may be implemented in other embodiments without departing from the scope of the present invention. Therefore, the present invention will not be limited to the embodiments described in this specification, but should conform to the broadest scope consistent with the principles and novel features disclosed in this specification.

Claims

1. A method for removing organic impurities from a cadmium plating bath, characterized in that: The process comprises the following steps: cadmium plating bath solution, Step 1: Determine the total mass of activated carbon The total mass of activated carbon was obtained by the following formula: V×(0.05-0.08) g / L, where V is the volume of the cadmium plating bath; Step 2: Clean the activated carbon The surface of the activated carbon is cleaned with a cleaning liquid to remove floating dust on the activated carbon; Step 3: Coating activated carbon The activated carbon is divided into a plurality of portions, and each portion of the activated carbon is coated into an activated carbon bag; Step 4: Hang activated carbon Immersing a plurality of activated carbon packages in the cadmium plating bath in a suspended manner, wherein the plurality of activated carbon packages are evenly distributed relative to the electrolytic cell; Step 5: Tank liquid stirring The cadmium plating bath solution is mechanically stirred so that the liquid is filtered through the activated carbon bag; Step 6: Power on Connect the cathode to the iron plate and the anode to the cadmium plate, and apply power. Step 7: Take out the activated carbon bag After the power is turned on, take out the activated carbon bag.

2. The method for removing organic impurities from a cadmium plating bath according to claim 1, wherein: During step 7, the cadmium plating bath solution is in a static state.

3. The method for removing organic impurities from a cadmium plating bath according to claim 1, wherein: In step 6, the power supply is a small current power supply, and the current density of the power supply is 0.2-0.4A / dm 2 .

4. The method for removing organic impurities from a cadmium plating bath according to claim 1, wherein: In step 6, the power-on time is 12h to 14h.

5. The method for removing organic impurities from a cadmium plating bath according to claim 1, characterized in that: The iron plate and the cadmium plate have the same area.

6. The method for removing organic impurities from a cadmium plating bath according to claim 1, characterized in that: The stirring time of the tank liquid in step 5 is 20min to 30min.

7. The method for removing organic impurities from a cadmium plating bath according to claim 1, characterized in that: The weight of each activated carbon bag is 400g to 500g.

8. The method for removing organic impurities from a cadmium plating bath according to claim 1, characterized in that: Each activated carbon package has 2 to 4 layers of filter paper as the inner layer and 1 to 2 layers of cloth as the outer layer.

9. The method for removing organic impurities from a cadmium plating bath according to claim 1, characterized in that: A supporting guide rod is arranged above the cadmium plating tank, and the multiple activated carbon bags are all mounted on the supporting guide rod.