A Polybenzene Anion Exchange Membrane Based On Click Chemistry Was Used For Diffusion Dialysis Studies

With the development of industry,the discharge of acid wastewater is increasing rapidly.A large amount of waste acid generated from steel processing,titanium processing,electroplating,mining and other industries which can not only cause serious ecological pollution if it is discharged in the water environment without treated timely,but also causes the waste of resources and unreasonable use.Therefore,more and more attention is being paid to the research on the recovery of waste acid,meanwhile,many methods have been developed to deal with the waste acid.However,many treatment options are not affordable for some small and medium-sized enterprises due to their high equipment costs and energy waste.As a method of waste acid recovery and treatment,diffusion dialysis method utilizes osmotic pressure as a driving force to make low valence ions such as hydrogen ions permeate the membrane while metal ions with high valence state are trapped by the membrane,thus achieving the purpose of waste acid recovery.In the diffusion dialysis process,because it does not require additional pressure,it has low energy consumption,simple operation,environmental protection and many other advantages which caused widespread concern.In this paper,polyphenylene oxide(PPO)as the polymer backbone,due to the material has good acid resistance,excellent mechanical strength,easy processing and good thermal stability characteristics.An efficient anion exchange membrane with high hydrogen ion diffusion rate and ion selectivity was prepared by a simple and efficient synthesis method "cick chemistry" method and successfully applied in diffusion dialysis.In the first part of this paper,propyn trimethylamine salt was used as the main functional group and the weakly acidic group propiolic acid as the auxiliary group.The series of polymers PPO-XxYy were synthesized by click chemistry.Afterwards,a transparent and uniform brown anion exchange membrane was obtained by the casting method.Through a series of tests such as water absorption,swelling rate,ion exchange capacity,and diffusion dialysis performance,the obtained PPO-X35Y20 anion exchange membrane has a hydrogen ion permeability of 0.021 m/h and a selectivity of 34.52.And membranes with weakly acidic auxiliary groups have higher hydrogen ion permeability and selectivity than membranes without the addition of auxiliary groups.It is suggested that the introduction of propiolic acid,a weak acid auxiliary group,is helpful to promote the transfer of hydrogen ions and successfully breaks the "trade-off" effect.In the second part of this paper,a series of functional films N-PPO-XxYy were synthesized using propynyl trimethylamine as the main functional group and weakly basic groups N,N-diethyl-l-propyne as auxiliary groups.Its hydrogen ion permeability is up to 0.027 m/h at 30? with a selectivity is up to 67.74 as measured on N-PPO-X3 5Y20.Moreover,compared with PPO-X40 film,that is,a membrane without auxiliary groups.The membrane of N-PPO-X3 5Y5 has a significantly higher performance than a membrane without an auxiliary group,indicating that the weakly basic tertiary amine auxiliary group can greatly promote the hydrogen ion permeability and selectivity.And more than double the performance of commercial membranes DF-120(UH+=0.012m/h,S=22.9).