Nitrate removal from aqueous solutions by magnetic cationic hydrogel:Effect of electrostatic adsorption and mechanism  

作　　者：Junyi Li Shuoxun Dong Yili Wang Xiaomin Dou Haotian Hao 

机构地区：[1]College of Environmental Science and Engineering,Beijing Key Lab for Source Control Technology of Water Pollution,Beijing Forestry University,Beijing 100083,China [2]Center for Water and Ecology,State Key Joint Laboratory of Environment Simulation and Pollution Control,School of Environment,Tsinghua University,Beijing 100084,China [3]Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,Beijing 100085,China

出　　处：《Journal of Environmental Sciences》2020年第5期177-188,共12页环境科学学报（英文版）

基　　金：supported by the National Key Research and Development Program of China(No.2017YFC0505303);the China Major Science and Technology Project of Water Pollution Control and Management,China(No.2017ZX07202003);the National Natural Science Foundation of China(Nos.51478041 and 51678053)

摘　　要：Excessive nitrate(NO3-)is among the most problematic surface water and groundwater pollutants.In this study,a type of magnetic cationic hydrogel(MCH)is employed for NO3-adsorption and well characterized herein.Its adsorption capacity is considerably pHdependent and achieves the optimal adsorption(maximum NO3--adsorption capacity is95.88±1.24 mg/g)when the pH level is 5.2-8.8.The fitting result using the homogeneous surface diffusion model indicates that the surface/film diffusion controls the adsorption rate,and NO3-approaches the center of MCH particles within 30 min.The diffusion coefficient(Ds)and external mass transfer coefficient(kF)in the liquid phase are1.15×10-6 cm2/min and 4.5×10-6 cm/min,respectively.The MCH is employed to treat surface water that contains 10 mg/L of NO3-,and it is found that the optimal magnetic separation time is 1.6 min.The high-efficiency mass transfer and magnetic separation of MCH during the adsorption-regeneration process favors its application in surface water treatment.Furthermore,the study of the mechanism involved reveals that both-N+(CH3)3 groups and NO3-are convoluted in adsorption via electrostatic interactions.It is further found that ion exchange between NO3-and chlorine occurs.

关 键 词：ADSORPTION Nitrate removal Low concentration Electrical stern layer Magnetic cationic hydrogel 

分 类 号：X52[环境科学与工程—环境工程]