Preparation Of Polyelectrolyte By Metal Ion Bipolar Membrane

The main structure of the bipolar membrane includes an anion exchange layer,a cation exchange layer,and intermediate interface layer.It has been widely used for the preparation of organic acids and the recovery of heavy metal ions during its industrial application because of its low energy consumption and no pollution.The purpose of this study is to improve the performance of the bipolar membrane by improving the membrane manufacturing process and to prepare new bipolar membranes with low energy consumption.In this paper,polyelectrolyte sodium alginate(SA)and polystyrene sulfonate(PSS)were used to form the composed of cation exchange layer through FeCl3 chelation reaction.Polyethyleneimine(PEI)was used as the intermediate adhesive,and the heterogeneous and homogeneous membranes were as basement membrane.Finaly,the bipolar membranes were prepared.The results show that the bipolar membrane has lower operating voltage and higher thermal stability after chelation with iron ions.The optimized values of the heterogeneous homogeneous bipolar membranes were SA 0.5 wt.%?FeCl3 9 wt.%?PSS 2 wt.%,spray ratio 1:2:1.5,14 layers sprayed,1 low voltage is 2.39V under the current density of 100mA/cm2;the optimal parameters for homogenous bipolar membranes are SA 0.5 wt.%?FeCl3 9 wt.%?PSS 2 wt.%,spray ratio 1:2:2,spraying 3-10 layers,lowest voltage is 0.69V under the current density of 100mA/cm2,11-20 layers were sprayed,and the voltage value was 1.0-1.3V under the current density of 100mA/cm2.SEM showed that the homogeneous bipolar membrane was more tightly bound than the heterogeneous membrane,and there were no bubbles between the two layers.FTIR showed that the sulfonic acid groups of the PSS were introduced into the bipolar membrane cation membrane.The XPS showed t the binding energy of Fe2p in homogeneous membrane was 712eV,which was 0.8eV higher than that of Fe2p(711.2eV)in FeCl3.but there was no change in the heterogeneous membrane,indicating that Fe3+ in the homogeneous membrane participated in the chelation reaction.The surface contact angle value of the minimum homogeneous membrane about 47.5° is smaller than that of the heterophase membrane about 76.7° and the membrane surface is more hydrophilic Thermal stability characterization indicates that the macromolecules have better high temperature resistance in the homogeneous intramembrane network structure.