The Study On Surface Coating Of Ion Exchange Membrane

Nowadays,the ion exchange membrane based process is widely used,especially in the biochemical,pharmaceutical,food,environmental protection and chemical industry and many other areas.This process is a highly efficient economic water treatment technology.It uses natural or synthetic polymer materials to prepare a film with special separation properties,to separate specific substances,such as organic molecules,inorganic ions,heavy metals using the external pressure difference,the concentration difference,the potential difference as a driving force.Membrane separation technology has been widely used in material separation,chemical production,environmental protection and other fields,and has formed a huge market billions of dollars each year.The core of membrane separation technology is the membrane,in different areas use different membranes.In this paper,the cation exchange membrane is studied in the process of cobalt alloy electrodeposition.Cation exchange membrane contains negatively charged acidic active groups.The ionized ions in the aqueous solution are positively charged.After the dissociation of the counterions the membrane was electronegatous,and formed electric field attracts the cations in the meantime resist the anions.Membrane plays an important role in the membrane cobalt electrodeposition process.But the commodity exchange membrane whether at home or abroad the selection permeability rate is only 88% to 96%.In the separation process some counterions still can go through the membrane and result in the production of chlorine.In this paper,through the modification experiment of the product ion exchange membrane,the related performance test can clearly see that the coating modification process can significantly improve the performance of the ion exchange membrane,making the modified film more suitable for industrial applications demand.After simple PVDF nanoparticles coating,the two kinds of nanoparticles have the lowest moisture content at 0.5% content,the highest water content of nano-TiO2 particles at 2.5%,the maximum water content of nano-Al2O3 particles at 2%;the two kinds of nanoparticles are 2% of the ion exchange capacity of the largest;membrane resistance are the lowest at 3%,but at 1.5% when the most effective reduction;leakage rate of 3% in the lowest.PVDF nanoparticles after plasma modification,moisture content,ion exchange capacity,membrane resistance,leakage rate of the performance of a substantial increase in the number of nanoparticles and the corresponding relationship between the number of changes in the performance of gentle,small differences.Under the same irradiation power(1w)conditions,10 min for the best time.The moisture content and ion exchange capacity of PDA-coated cation exchange membrane increased with the prolongation of immersion time.Among them,18 h was the most effective soaking time,and increased rapidly after 18 h,but increased slowly after 18 h.Changes in membrane resistance are also the same,before 18 h to reduce rapidly,after 18 h slow down.The ion leakage rate showed a tendency to decrease first and then increase,which was higher than that of the original membrane before and after the increase.The change in leakage rate is not only related to the nature of the PDA coating itself,but also to the coated cation exchange membrane.PVDF nanoparticles simple coating coating and the original membrane for the physical combination of the original film has little effect,and can get a good modification effect.Plasma irradiation of PVDF nanoparticles coating makes the test performance of the membrane greatly improved,the coating and the original membrane between the establishment of the combination of chemical bonds,the whole film is more complete,the modified effect is stable.PDA coating to introduce new active groups,easy to operate.The radiation intensity and the radiation time of the plasma have great influence on the modification effect of the membrane,and should be strictly controlled according to the experimental requirements,and it may cause fatal damage to the membrane.The three modification methods have a good effect on improving the performance of the ion exchange membrane,which can make the modified film better adapt to the application requirements.