When the concentration of solute on the surface of the membrane reaches its saturation point, a deposited or gel-like layer may form, increasing the resistance to fluid flow and reducing membrane efficiency. This phenomenon is known as concentration polarization, and it can significantly impact the performance of membrane separation processes.
The hazards associated with concentration polarization include:
1. An increase in solute concentration on the membrane surface leads to higher osmotic pressure, which reduces the driving force for mass transfer.
2. Once the solute concentration reaches saturation, a layer of deposits or gel forms on the membrane surface, further increasing the resistance to permeation.
3. The formation of this layer alters the membrane’s separation characteristics, potentially decreasing its selectivity and efficiency.
4. If organic solutes accumulate on the membrane surface, they may cause swelling or degradation of the membrane material, leading to reduced lifespan and performance.
5. In severe cases, concentration polarization can result in the precipitation of salts or other substances, blocking the flow channels and causing operational issues.
In summary, concentration polarization negatively affects the rejection rate of the membrane, reduces the permeate flux, and ultimately lowers the overall separation efficiency. To mitigate these effects, proper operating conditions such as flow velocity, temperature, and feed concentration must be carefully controlled.
Source: http://news.chinawj.com.cn
Editor: Hardware Business Network Information Center
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Globe Valve
The globe valve is used to cut off the flow of the medium. The globe valve is suitable for frequently opened occasions. The sealing parts of the globe valve are the disc and the valve seat. In order to make the globe valve close tightly, the mating surface of the disc and the valve seat should be grinding or using gaskets. The sealing surface can also be inset with bronze, stainless steel and other corrosion-resistant and wear-resistant materials. The disc and stem of the globe valve are connected with each other, so that the disc and stem are closely fitted. The lifting of the disc of the globe valve is generally controlled by the stem. The upper part of the stem of the globe valve is the handwheel, and the middle part is the thread and packing sealing section. The role of the packing is to prevent the internal medium of the valve body from leaking along the stem.
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