Effect of Lactose on the Transport Properties of Ion-Exchange Membranes

The influence of lactose on the main transport characteristics of ion-exchange membranes including surface-modified with polyaniline cation-exchange membranes is studied. A pronounced to different extents positive effect of modification of MK-40 and Ralex CMHPES membranes with polyaniline on their biofouling by Bacillus sp. or Shewanella oneidensis MR-1 cell cultures is found which is due to the different conductive surface areas of these membranes. It is revealed that the presence of lactose in a solution leads to a decrease in the electrical conductivity of all the studied membranes; however, the effect the most substantially manifests itself for a modified with polyaniline MK-40 membrane: its electrical conductivity decreases by 15–25%. The diffusion permeability of the anion-exchange and initial cation-exchange membranes weakly depends on the presence of lactose in a solution; however, its 2–2.5-fold decrease is observed in the case of modified with polyaniline cation-exchange membranes. A significant effect of lactose on the current–voltage characteristics of the anion-exchange membranes has been found, which indicates significant adsorption of lactose on their surface under the conditions of an external constant electric field. It is shown that ion-exchange membranes remain quite effective for electrodialysis of solutions of lactoserum but their use in underlimiting current modes will be more effective.