碱改性活性炭纤维电吸附处理RO浓水效果及除盐动力学特性

Electrosorption effect and desalination kinetic characteristics of reverse osmosis concentrated water with alkaline modified activated carbon fiber electrode

针对电吸附技术在反渗透浓水回收利用过程中的吸附效率问题,通过NaOH、KOH、氨水对ACF电极材料进行浸渍改性,采用SEM观察、傅里叶变换红外光谱图分析的方法对改性前后ACF进行了表征;研究了改性前后ACF对反渗透浓水的去除效果和除盐动力学特性;探讨了碱改性前后ACF处理反渗透浓水的除盐机理。结果表明:随着氨水改性ACF比表面积的增加,表面碱性基团增加、酸性基团减少;ACF理化特征的变化与改性剂溶液的酸碱性有关;氨水改性ACF对反渗透浓水中电导率、氨氮、COD均有很好的降低或去除效果,而NaOH改性ACF对UV^254有很好的去除效果;碱改性ACF处理反渗透浓水除盐过程更符合Elovich动力学方程;碱改性ACF电吸附处理反渗透浓水时,对各污染物指标表现出选择性,且与未改性ACF相比,具有更好的降低或去除效果,同时,碱改性ACF电吸附除盐过程是以物理吸附和化学吸附共存的多相吸附过程,也会存在离子交换作用。

In order to solve the problem of electrosorption efficiency in recovery and utilization of reverse osmosis concentrated water(ROCW),activated carbon fiber(ACF)electrode material was impregnated and modified by NaOH,KOH,and ammonia.SEM and FT-IR were used to characterize ACF before and after modification,and the removal effect,desalination kinetics and mechanism of ROCW by pristine and alkali modified ACF were discussed.The results showed that ammonia modified ACF had increased specific surface area and surface alkaline groups,decreased acidic groups,which corresponded to the acidity and alkalinity of the modifier solution.Ammonia modified ACF showed better removal of conductivity,ammonia nitrogen and COD,while NaOH modified ACF showed better UV^254 removal.The ROCW desalination process of alkaline modified ACF could be better described by Elovich kinetic model,and presented selectivity and better removal efficiency for pollutants than pristine ACF.The adsorption process of alkaline modified ACF belongs to physical adsorption,chemical adsorption,and ion exchange.