Application of bipolar membrane electrodialysis for acidification of skim milk. A comprehensive study on process performance and effects on ion-exchange membranes

Bipolar membrane electrodialysis (EDBM) can be applied for the electro-acidification of skim milk (SM) using a water-splitting effect. A new method of acidification of SM gives opportunities and perspectives to the development of alternative and novel products in the dairy industry. The present study assessed the effect of temperatures from 5 °C, 10 °C, 15 °C, 20 °C, 25 °C and 30 °C of EDBM on the electro-acidification of SM in terms of the mineral composition of the side streams. The mechanisms of ion transport during electro-acidification by bipolar membranes (BMs) coupled with cation-exchange membranes (CMs) were investigated. The results showed that the pH of the SM was decreased by ∼14.3% through the proton ions generated due to a water-splitting reaction in the bipolar interface region. Since the BMs and CMs are suspected to change their properties at different temperatures in the high protein solution, their properties and characteristics were investigated. The EDBM performance parameters were calculated. Furthermore, performance efficiency coefficients of the EDBM process as mass flux (J), capacity (CF), specific energy consumption (E) and the current efficiency (η) were calculated.