In the filtration process of hollow fiber ultrafiltration membrane water purifiers, the variation law of membrane flux is one of the important contents for studying membrane technology and its application fields. Membrane flux refers to the mass or volume of fluid passing through the membrane per unit area of membrane surface per unit time under certain conditions, which is one of the key indicators for evaluating membrane performance. In the filtration process, the variation of membrane flux in hollow fiber ultrafiltration membrane water purifiers is affected by various factors, including the pore size of the membrane, the surface characteristics of the membrane, the nature of pollutants, the properties of the fluid, and the operating conditions, etc.

The pore size of the hollow fiber ultrafiltration membrane determines its filtration accuracy and directly affects the flux change. Generally, the smaller the membrane pore size, the lower the flux will gradually decrease. This is because as the membrane pore size decreases, the path of pollutants through the membrane becomes shorter, thereby increasing the resistance of pollutants passing through the membrane, leading to a decrease in flux. In addition, the hydrophilicity or hydrophobicity of the membrane surface also affects the flux; generally, hydrophilic membrane surfaces are conducive to the penetration of water molecules, while hydrophobic membrane surfaces are conducive to the interception of pollutants.

The flux change during the filtration process is also affected by the nature of pollutants. Different types of pollutants (such as particulates, organics, microorganisms, etc.) have different physical and chemical properties, and they have different ways and resistance through the membrane. For particulates, the decrease in flux is mainly caused by the interception of particulates; for organics and microorganisms, the decrease in flux is affected by adsorption, chemical reactions, and other processes in addition to interception.

Fluid properties, such as flow rate, pressure, and temperature, are also important factors affecting the flux of the membrane. An increase in flow rate can improve the flux, but an excessively high flow rate may cause wear on the membrane surface, thereby affecting the service life of the membrane. An increase in pressure can help improve the flux, but excessive pressure will also increase the energy consumption of the membrane. Temperature change also affects the flux; generally, an increase in temperature will increase the flux, but a low temperature may cause an increase in the thickness of the water film on the membrane surface, thus reducing the flux.

Operating conditions, such as running time, cleaning frequency, and cleaning methods, also affect the flux of the membrane. With the increase of running time, pollutants may accumulate on the membrane surface, leading to a decrease in flux. Regular cleaning can restore the flux of the membrane, but the cleaning method and frequency need to be adjusted according to the actual situation. For example, frequent cleaning may cause damage to the membrane surface, while incomplete cleaning may not effectively remove pollutants.

To study the law of flux change of the hollow fiber ultrafiltration membrane water purifier during the filtration process, it is usually necessary to use experimental methods. In the experiment, parameters such as the pore size of the membrane, the concentration of pollutants, fluid properties, and operating conditions can be changed to observe the trend of flux change and thus reveal the law of flux change. In addition, numerical simulation can also predict the flux change, providing theoretical guidance for practical applications.

In summary, during the filtration process, the flux of the hollow fiber ultrafiltration membrane is affected by various factors, including the pore size of the membrane, the nature of pollutants, fluid properties, and operating conditions. Through experiments and numerical simulation, the law of flux change can be revealed, thereby optimizing the design and operating conditions of the membrane and improving the performance and service life of the water purifier.