Application Of Bipolar Membrane On Green Environmental Protection Process

Sodium alginate (SA) and chitosan (CS) are organic polymer materials. Phosphorylation sodium alginate (P-SA) membrane was synthesized by phosphorus pentaoxide, triethyl phosphate and phosphoric acid, then modified by ferrocene; Chitosan (CS) was modified by acetylferrocene. P-ferrocene-SA/acetylferrocene-CS bipolar membrane (BPM) was prepared by a paste method, named as P-mSA/mCS BPM. The bipolar membrane was characterized by Fourier Transform Infrared Spectroscopy (FTIR), contact angle, charge density, I-Vworking curve, ion exchange capacity and alternating current impedance. The morphology of the BPM was investigated by SEM.Ferrocene is composed of two isoprene anions and bivalent iron ions form a sandwich-type compounds, which is a good electron transfer media, may activate the reactants or promote of electron transfer rate. In order to reduce the impedance of bipolar membranes and improve the efficiency of water decomposition, ferrocene was used as a cross-linker and the catalytic center cation layer modified Sodium alginate; phosphate shows a good hydrophilic property. The phosphate agent was reacted with sodium alginate in the carboxyl group. The hydrophilic property of the modified sodium alginate was improvement, and the resistance of bilpolar membrane and the working voltage were decreased.China's salt lake brine lithium reserves abundant resources, mainly distributed in Tibet and Qinghai provinces. There are several methods to extracte lithium from salt lake brine:precipitation, ion exchange adsorption, solvent extraction, calcined extraction method, salting-out method, carbonization method and selective semi-permeable membrane. In the thesis, the modified P-mSA/mCS bipolar membrane was used extracte lithium from the salt lake brine. When the pressure difference was 0.3 Mpa, the retention rate of monovalent cations less than 22%, the retention rate of divalent cations is higher than 95%. The experiment results showed that the pressure difference on retention rates for the divalent ions was invalid.2,3,5,6-tetrachloro-pyridine is an important medicine and pesticide intermediates, and a good fungicide. It also is a better herbicides for pigs grass, foxtail, etc.. Currently, the synthesis of these compounds foucuses on using metal ions to reduce the pentachloropyridine in the acidic condition. The drawback is high cost, the reaction rate and the selectivity is lower, at the same time the waste disposal problem is trouble.With the environmental requirements increasing in recent years, polluting chemical process has been gradually replaced by the green synthesis. The dechlorination reaction of chlorinated organic compounds was a very important reaction types in organic synthesis and environmental management showing a broad application prospect.The self-made Zn/Ni-mSA/mCS bipolar membrane was equipped in an electrolyzer to synthesis of 2,3,5,6-tetrachloro-pyridine by the electro-reduction of pentachloropyridine. Metal zinc and nickel alloy was plated on the surface of cation exchange membrane to reduce the cathode solution IR drop. The current efficiency was 70.1%, the yield was 96% att room temperature, current density of 30mA.cm-2, electrolysis time of 40min.