School of Agricultural Engineering and Food Science, Shandong University of Technology, Zibo, Shandong 255000, China.
School of Resources and Environmental Engineering, Shandong University of Technology, Zibo, Shandong 255000, China E-mail:
Water Sci Technol. 2019 Nov;80(10):2003-2012. doi: 10.2166/wst.2020.033.
To remove NO-N from water, coconut shell biochar (CSB) was modified by a solution of FeCl, a solution of AlCl and a mixture solution of FeCl and AlCl respectively. The obtained modified biochar with the best effect of NO-N adsorption was screened out to explore the adsorption behavior and mechanism of NO-N removal by batch experiments and kinetics and thermodynamics and correlated characterization. The results indicated that the mixture solution of FeCl- and AlCl- modified CSB (Fe-Al/CSB) showed the best adsorption performance for NO-N removal. Iron and aluminum elements existed on the surface of Fe-Al/CSB in the form of FeOOH, FeO, Fe, and AlO respectively. The adsorption process could reach equilibrium in 20 min. An acidic condition was favorable for NO-N adsorption. The presence of coexisting anions was not conducive for NO-N adsorption. The quasi-second-order model and Freundlich model could be well fitted in the adsorption process. The maximum adsorption capacity of Fe-Al/CSB fitted by the Langmuir model could reach 34.20 mg/g. The adsorption of NO-N by Fe-Al/CSB was an endothermic and spontaneous process. Ligand exchange and chemical redox reaction were the NO-N adsorption mechanisms which led to NO-N adsorption by Fe-Al/CSB.
为了去除水中的硝态氮，采用 FeCl 溶液、AlCl 溶液和 FeCl-AlCl 混合溶液分别对椰子壳生物炭（CSB）进行改性。通过批量实验、动力学和热力学及相关表征，筛选出对硝态氮吸附效果最佳的改性生物炭，探讨了其去除硝态氮的吸附行为和机理。结果表明，FeCl-AlCl 混合溶液改性 CSB（Fe-Al/CSB）对硝态氮去除具有最佳的吸附性能。Fe-Al/CSB 表面的铁、铝元素分别以 FeOOH、FeO、Fe 和 AlO 的形式存在。吸附过程在 20 min 内即可达到平衡。酸性条件有利于硝态氮的吸附。共存阴离子的存在不利于硝态氮的吸附。准二级动力学模型和 Freundlich 模型能够很好地拟合吸附过程。Langmuir 模型拟合的 Fe-Al/CSB 的最大吸附容量可达 34.20 mg/g。Fe-Al/CSB 对硝态氮的吸附是一个吸热自发的过程。配体交换和化学还原反应是导致 Fe-Al/CSB 吸附硝态氮的吸附机制。
