Lin Zhaohua, Wang Ruikun, Tan Shiteng, Zhang Kai, Yin Qianqian, Zhao Zhenghui, Gao Peng
Department of Power Engineering, North China Electric Power University, Baoding, 071003, Hebei, China; Hebei Key Laboratory of Low Carbon and High Efficiency Power Generation Technology, North China Electric Power University, Baoding, 071003, Hebei, China; Baoding Key Laboratory of Low Carbon and High Efficiency Power Generation Technology, North China Electric Power University, Baoding, 071003, Hebei, China.
Department of Power Engineering, North China Electric Power University, Baoding, 071003, Hebei, China; Hebei Key Laboratory of Low Carbon and High Efficiency Power Generation Technology, North China Electric Power University, Baoding, 071003, Hebei, China; Baoding Key Laboratory of Low Carbon and High Efficiency Power Generation Technology, North China Electric Power University, Baoding, 071003, Hebei, China.
J Environ Manage. 2023 May 15;334:117503. doi: 10.1016/j.jenvman.2023.117503. Epub 2023 Feb 14.
Dye wastewater has become one of the main risk sources of environmental pollution due to its high toxicity and difficulty in degradation. Hydrochar prepared by hydrothermal carbonization (HTC) of biomass has abundant surface oxygen-containing functional groups, and therefore is used as an adsorbent to remove water pollutants. The adsorption performance of hydrochar can be enhanced after improving its surface characteristics through nitrogen-doping (N-doping). In this study, wastewater rich in nitrogen sources such as urea, melamine and ammonium chloride were selected as the water source for the preparation of HTC feedstock. The N atoms were doped in the hydrochar with a content of 3.87%-5.70%, and mainly in the form of pyridinic-N, pyrrolic-N and graphitic-N, which changed the acidity and basicity of the hydrochar surface. The N-doped hydrochar adsorbed methylene blue (MB) and congo red (CR) in wastewater through pore filling, Lewis acid-base interaction, hydrogen bond, and π-π interaction, and the maximum adsorption capacities of those were obtained with 57.52 mg/g and 62.19 mg/g, respectively. However, the adsorption performance of N-doped hydrochar was considerably affected by the acid-base property of the wastewater. In a basic environment, the surface carboxyl of the hydrochar exhibited a high negative charge and thus an enhanced electrostatic interaction with MB. Whereas, the hydrochar surface was positively charged in an acid environment by binding H, resulting in an enhanced electrostatic interaction with CR. Therefore, the adsorption efficiency of MB and CR by N-doped hydrochar can be tuned by adjusting the nitrogen source and the pH of the wastewater.
染料废水因其高毒性和难降解性已成为环境污染的主要风险源之一。通过生物质水热碳化（HTC）制备的水炭具有丰富的表面含氧官能团，因此被用作吸附剂来去除水中污染物。通过氮掺杂（N掺杂）改善其表面特性后，水炭的吸附性能可以得到增强。在本研究中，选择富含尿素、三聚氰胺和氯化铵等氮源的废水作为制备HTC原料的水源。N原子以3.87%-5.70%的含量掺杂在水炭中，主要以吡啶氮、吡咯氮和石墨氮的形式存在，这改变了水炭表面的酸碱性。N掺杂水炭通过孔隙填充、Lewis酸碱相互作用、氢键和π-π相互作用吸附废水中的亚甲基蓝（MB）和刚果红（CR），其最大吸附容量分别为57.52 mg/g和62.19 mg/g。然而，N掺杂水炭的吸附性能受废水酸碱性质的影响很大。在碱性环境中，水炭表面的羧基表现出高负电荷，因此与MB的静电相互作用增强。而在酸性环境中，水炭表面通过结合H带正电荷，导致与CR的静电相互作用增强。因此，通过调节氮源和废水的pH值，可以调节N掺杂水炭对MB和CR的吸附效率。
