Working principle of membrane separation technology in electrophoretic coating industry

October 13, 2020

Membrane is a kind of medium with molecular separation and filtration function. When the solution or mixed gas contacts with the membrane, some substances can pass through the membrane under the action of pressure, electric field or temperature difference, while others are selectively intercepted, so that different components in the solution or mixed gas are separated. It is different from the traditional filtration in that the membrane can pass through the membrane under the action of pressure, electric field or temperature difference The separation is carried out in the molecular range, and this process is a physical process without phase change and additives. The pore size of the membrane is generally micron. According to its pore size (or the molecular weight of interception), the membrane can be divided into microfiltration membrane, ultrafiltration membrane, nanofiltration membrane and reverse osmosis membrane. According to the different materials, it can be divided into inorganic membrane and organic membrane. Inorganic membrane is mainly ceramic membrane and metal membrane, which has low filtration accuracy and low selectivity. Organic membrane is made of polymer materials, such as cellulose acetate, aromatic polyamide, polyethersulfone, polyfluoropolymer and so on.

1、 Application of film in electrophoretic coating

Application of optional membrane module functions

Application of microfiltration membrane group in pretreatment before coating

In the ultrafiltration membrane group, micro filtration or ultrafiltration technology is used to achieve the purpose of oil-water separation in the degreasing process

Reverse osmosis membrane group uses reverse osmosis technology to obtain pure water for washing

The anodic (cathodic) film is used as a reverse electrode to remove solubilizer or neutralizer (usually organic acid) in the electrophoretic coating to maintain the chemical balance of the system.

Application of cleaning after electrophoresis

Ultrafiltration membrane group

1. To improve the economic benefit, realize the "closed loop" cleaning method after electrophoresis, and improve the utilization rate of coating;

2. It is beneficial to environmental protection to reduce the amount and cost of sewage treatment;

3. Remove the impurity ions, purify the bath solution and improve the quality of the film

Reverse osmosis membrane group

1. Improve the recovery rate of electrophoretic paint

2. Reduce the burden of wastewater treatment

3. Realize closed loop leaching

4. Reduce the use of pure water

2、 Application of ultrafiltration membrane in recovering electrophoretic coating

Ultrafiltration (UF) is a kind of membrane filtration technology which can purify, separate or concentrate the solution. The ultrafiltration process can be understood as a screening process related to the pore size of the membrane. Under a certain pressure, when the solution flows through the membrane surface, only water, inorganic salts and small molecules are allowed to pass through the membrane, and macromolecules such as suspended solids, colloids, proteins and microorganisms are prevented from passing through the membrane under a certain pressure, so as to achieve the purpose of purification, separation and concentration of the solution. In ultrafiltration, macromolecular solutes can not pass through the membrane as easily as solvents

① It is adsorbed on the surface and pore of filtration membrane (basic adsorption);

② To be retained in or discharged from the hole (clogging);

③ Mechanically trapped on the surface of the membrane (sieving).

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Author:

Mr. Zheng

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zheng@rmiplast.com

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+86 15888074637