Aplication Of Nanofiltration Membrane On Whey Demineralization

Whey is the main byproduct obtained from cheese production, and it has high biological value and various functional characristics. However, the mineral salt contents within whey, especially NaCl, cause a great drop in the quality of whey. In recent years, the development and application of whey become a research hotspot from abroad, but in China, the research of whey is just beginning. Therefore, the development and use of whey is a new point in recent-year research. Nanofiltration (NF) is a membrane separation technology which can intercept substances with molecular weights between 200-1000. NF can remove salt contents while keep the organic contents effectively. Most NF membranes are compound membranes, and the surface layer is composed of polyelectrolytes, so the separation properties are strongly related to the pH value of the feed solution.In this research, the desalination effect under different pH through a TFC-SR2 spiral NF membrane was studied by adjusting the pH value of whey, the desalination rate was improved by introducing the Diafiltration method, and the effect of temperature on the flux and the desalination rate was investigated. The effect of pH value on the desalination rate of whey was studied by adjusting the pH value of whey in a small range around the isoelectric point of whey protein (WP). Based on this, the Diafiltration method was introduced in order to improve the desalination rate. Then the effect of temperature on the desalination rate was investigated using flat membranes under certain pressure and pH value.The results showed that, when the pH value of whey was adjusted to 4.60, which is the isoelectric point of WP, the concentrated solution had the least ash content, and the ash removal rate was 50%; on the other hand, when the pH value of whey was 5.18, which is the isoelectric point ofβ-laoctoglobulin, the desalination effect was also good. After the Diafiltration method was introduced, the ash removal rate under pH=4.60 reached 74%. With the increase of operating temperature, the membrane flux increased, but the temperature had little effect on the desalination rate.