Application Of Bipolar Membrane Technology In Organic Electro-syntheses

The carboxy methyl cellulose sodium (CMC) cation layer was modified by Cr3+ and Sodium polyacrylate (PAAS) while the chitosan (CS) anion layer was modified by glutaraldehyde and melamine to prepare the PAAS-CMC/Mel-CS bipolar membrane (BPM). Besides, the mCMC/mCS BPM, mCMC/Mel-CS BPM and PAAS-CMC/mCS BPM were prepared by the same way. Series of experiments, including ion exchange capacities, hydrogen ion (hydroxide ion) transmigration rates and impedances were carried out. The experimental results showed that the PAAS-CMC/Mel-CS BPM exhibited well ion exchange capacities, high hydrogen ion (hydroxide ion) transmigration rates, lower impedance and working voltage.The mCMC/mCS bipolar membrane with a proportion of 0.7×1.7 m2 was prepared by carboxymethyl cellulose as an anodic layer and chitosan as a cathodic layer modified by Cr3+ and glutaraldehyde as linking reagents, respectively. The mCMC/mCS bipolar membrane was used as a diaphragm between the anode chamber and cathode chamber to electro-generate glyoxylic acid with pilot-plant-scale study. Under the function of electric field for 10 h during the working voltage was about 5 V and the current was about 300 A, the yield of glyoxylic acid was 85%. Based on the cost accounting for the synthesis of glyoxalic acid, it was known that used the mCMC/mCS bipolar membrane as the diaphragm of electrolyzer and cathode room to electro-generate glyoxalic acid had certain economic benefits and certain space for development.The mCMC/TiO2-Oxine/mCS bipolar membrane was prepared by carboxymethyl cellulose as an anodic layer and chitosan as a cathodic layer modified by Cr3+ and glutaraldehyde as linking reagents, respectively. SEM images indicated that the mCMC/TiO2-Oxine/mCS BPM showed a sandwich composition, including anion exchange membranes, interlayer and cation exchange membranes. The Nano-TiO2 modified with the photosensitizer oxine was taken as a photocatalytic interlayer to enhance the water splitting in the interlayer of the bipolar membrane. The mCMC/TiO2-Oxine/mCS BPM showed a sandwich composition, and exhibited an excellent hydrophilic performance, lower impedance and working voltage. When the working current density was as high as 120 mA-cm-2, the working voltage was as low as 5.0 V with UV irradiation.