Preparation、Characterization And Process Improvement Of Highly Selective Ion Exchange Membrane

As a high-tech separation method,membrane separation technology has the advantages of no phase change,low separation temperature,good selectivity and low energy consumption during the separation process.An ion exchange membrane is a kind of separation membrane,which consists of three main parts: a polymer skeleton,a fixed group,and a movable ion on a radical.According to its fixed group charge,it can be divided into two kinds of ion exchange membranes: yin and yang.Since the surface of the cation exchange membrane is negatively charged,in the electrolytic cell model,the cations in the anode compartment can pass through the positive membrane to reach the cathode side solution under the action of the electric field force,while the anions cannot penetrate the membrane.On the other hand,the anion membrane also has the ability to allow the anion to migrate through the membrane and block the cation transmission.This ability is called the selective transmission performance of the ion exchange membrane.However,the current domestic and international commercial ion-exchange membranes only have a selective transmission performance of 88% to 96%.During the separation process,some counter-charge ions still penetrate the membrane at the same time,which greatly limits the application effect of ion-exchange membranes.Under the background of "High-selection membrane and membrane refining industrialization technology development",This paper studies how to improve the selectivity of the cation exchange membrane by improving the membrane production process in the electrowinning cobalt process involving ion exchange membranes,and increase the inhibition rate of chloride ions,thereby reducing the chlorine pollution to the environment.The experiment establishes an evaluation system for ion exchange membrane evaluation;changes the process parameters such as raw material mix ratio,processing temperature,time,pressure,etc.,and iteratively produces ion exchange membranes.It discusses how to improve ion exchange membrane selective permeability under classical techniques.And look forward that high-performance ion exchange membranes suitable for membrane metallurgy can be obtained through improved processes.The experimental design contains three parts,summarized as follows:Enrich and quantify the characterization system of ion exchange membranes.The ion exchange membrane has no fixed industry testing standards.This experiment starts from the three major categories of indicators: general performance,electrical performance and mass transfer performance.The performance characterization method of the ion exchange membrane is subdivided into 9 subcategories test methods.Based on the actual requirements of ionexchange membranes,five indexes,including bursting resistance,ion exchange capacity,and chloride ion inhibition rate etc.,were selected as representative parameters.Through proper formula transformation,the parameters of the indicators were uniformly assigned to 0~1.The values of the five-dimensional indicators were plotted on a radar chart.The overall performance of the ion exchange membrane was quantified by the square of the product of the area and the perimeter of the graph presented in the ion exchange membrane radar chart.The feasibility of improving the performance of ion exchange membranes by classical techniques was studied.In the experiment,the most widely used HDPE binder and 001×7 styrene resin were selected as the research materials.By changing the blending ratio,processing temperature and hot-pressing time parameters,the performance of the modified ion exchange membrane was observed through the analysis found that improved process recipes and parameters have a certain degree of improvement in the performance of ion exchange membranes.The performance of ion exchange membranes prepared under conditions of 75% ion exchange resin,processing temperature of 140°C,and hot-pressing time of 30 minutes is comparable with Ionsep? MC-C film has a certain degree of improvement.Explored the feasibility of new materials and new process conditions to improve the performance of ion exchange membranes.The experiment analyzes the ion exchange resin and binder materials of the two major components of the existing ion exchange membrane,and comprehensively considers the compatibility of the material,the processability,the performance of the material itself,the availability,and the environmental protection performance.The combination of various materials such as HDPE,LLDPE,PVC,PVDF,silane cross-linked polyethylene,001×7,001×12,and D001×8 was selected to verify the performance of the new material after film formation and tried to Analyze the reasons for its performance and find new materials to improve the performance of ion exchange membranes.Studies have shown that the use of silane cross-linked polyethylene and D001 × 8 material made of ion exchange membrane in the best performance of several ion exchange membranes,indicating that increase the compatibility of the two materials,improve the resin ion exchange capacity,appropriate to improve the material cross-linked The direction of the degree helps to improve the film forming performance of the new material.