Nitrate removal from aqueous solutions by magnetic cationic hydrogel: Effect of electrostatic adsorption and mechanism
Nitrate removal from aqueous solutions by magnetic cationic hydrogel: Effect of electrostatic adsorption and mechanism
复制标题
磁性阳离子水凝胶从水溶液中去除硝酸盐：静电吸附的效果和机理
DOI：
10.1016/j.jes.2020.01.029
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发表时间：
2020
影响因子：
6.9
通讯作者：
Hao Haotian
中科院分区：
文献类型：
--
作者：
Li Junyi;Dong Shuoxun;Wang Yili;Dou Xiaomin;Hao Haotian
过量的硝酸盐（NO3−）是地表水和地下水中最严重的污染物之一。在这项研究中，一种类型的磁性阳离子水凝胶（MCH）用于NO3−吸附，并在本文中进行了很好的表征。其吸附能力与pH值有很大的关系，当pH值为5.2-8.8时，NO3−-的最大吸附量为95.88 ± 1.24 mg/g。均相表面扩散模型的拟合结果表明，表面/膜扩散控制了吸附速率，NO3-在30 min内接近MCH颗粒中心。液相扩散系数Ds为1.15 × 10 - 6cm ~ 2/min，外传质系数kF为4.5 × 10 - 6cm ~ 2/min。采用该磁分离器对NO3-浓度为10 mg/L的地表水进行处理，发现最佳磁分离时间为1.6 min。MCH在吸附-再生过程中的高效传质和磁分离特性有利于其在地表水处理中的应用。此外，对所涉及机制的研究表明，-N+（CH 3）3基团和NO3−通过静电相互作用在吸附中发生回旋。进一步发现NO3−和氯之间发生离子交换。
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 pH-dependent and achieves the optimal adsorption (maximum NO3−-adsorption capacity is 95.88 ± 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 are 1.15 × 10−6cm2/min and 4.5 × 10−6cm/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)3groups and NO3−are convoluted in adsorption via electrostatic interactions. It is further found that ion exchange between NO3−and chlorine occurs.