Journal of Ecology and Rural Environment ›› 2018, Vol. 34 ›› Issue (4): 356-362.doi: 10.11934/j.issn.1673-4831.2018.04.009

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Adsorption Characteristics of Low Concentration Nitrate-Nitrogen Onto Modified Macrophytes Biochar

LI San-shan1, WANG Chu-chu1, HE Xiao-yun2, REN Li-man1, GUO Qiong1, YANG Liu-yan1   

  1. 1. School of the Environment, Nanjing University/State Key Laboratory of Pollution Control and Resource Reuse, Nanjing 210046, China;
    2. Zhejiang Environmental Monitoring Centre, Hangzhou 310012, China
  • Received:2017-09-13 Online:2018-04-25 Published:2018-04-17


To remove the low concentration nitrate in water and eliminate eutrophication, the biochar was prepared from three kinds of macrophytes, including Thalia dealbata, Typha orientalis and Phragmites australis, and then were modified by ferric chloride. FTIR and SEM-EDS results of the biochar and equilibrium adsorption tests show that the Fe-O was formed on the surface of the modified biochar which greatly enhanced biochar's adsorption performance to the nitrate-nitrogen. The nitrate was absorbed rapidly in 4 hours and then reached equilibrium slowly in 24 hours. The equilibrium adsorption capacity of the modified Typha orientalis biochar was the highest, which reached up to 1.747 mg·g-1. The adsorption performance of low concentration nitrate onto three kinds of modified macrophytes biochar fitted well to pseudo-second-order equation and Freundlich equation, indicating that inhomogeneous polymolecular layer chemisorption occurred on the surface of modified biochar. The initial pH of the solution in the range of 3.0-9.0 has little effect on the adsorption performance of nitrate, and the most appropriate pH is neutral. At the initial nitrate-nitrogen concentration of 2 mg·L-1, the most appropriate dosages of the three kinds of modified macrophytes biochar are 1.50, 1.14, and 1.22 g·L-1 for iron modified biochar of Thalia dealbata, Typha orientalis and Phragmites australis, respectively. Therefore, the iron modified macrophytes biochar can not only effectively remove the nitrate-nitrogen in water, but also realize resource utilization of the macrophytes, which has a promising application prospect.

Key words: biochar, hydrophyte, adsorption, modification, low concentration nitrate-nitrogen

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