Xu Zhi-Xiang, Song Hao, Li Pei-Jun, Zhu Xuan, Zhang Shu, Wang Qian, Duan Pei-Gao, Hu Xun
School of Energy and Power Engineering, Jiangsu University, Zhenjiang, 212013, China.
School of Energy and Power Engineering, Jiangsu University, Zhenjiang, 212013, China.
J Hazard Mater. 2020 Nov 5;398:122833. doi: 10.1016/j.jhazmat.2020.122833. Epub 2020 May 19.
The high content of nitrogen in hydrochar produced from hydrothermal carbonization (HTC) of sewage sludge (SS) leads to serious NOx pollution when the hydrochar is used as a solid fuel. Mg-Ga layered double hydroxides (LDHs), Mg-Al LDHs and their calcined samples (layered double oxides, LDO) were prepared. The LDHs and LDO all can notably promote the removal of nitrogen element, in which organic-N was transferred to NH-N to cause increasing pH value. Mg-Al LDO showed the highest efficiency for the removal of nitrogen among the catalysts. The thermal decomposition of the N-organic matter with acidic sites in catalyst was the key step to release NH. The key role of basic sites in Mg-Al LDO was that it can effectively destroy the cell wall and extracellular polymeric substances structure. The lipid-like substance did not participate in the carbonization reaction, but they can be absorbed by the hydrochar. Partial SS floc directly transformed to hydrochar according to "solid-solid" reaction. The reaction pathways of remove nitrogen were proposed.
污水污泥（SS）水热碳化（HTC）制备的水热炭中氮含量较高，当将其用作固体燃料时会导致严重的氮氧化物污染。制备了镁镓层状双氢氧化物（LDHs）、镁铝层状双氢氧化物及其煅烧样品（层状双氧化物，LDO）。LDHs和LDO均能显著促进氮元素的去除，其中有机氮转化为氨氮导致pH值升高。镁铝LDO在催化剂中表现出最高的氮去除效率。催化剂中含酸性位点的有机氮物质的热分解是释放氨的关键步骤。镁铝LDO中碱性位点的关键作用在于它能有效破坏细胞壁和胞外聚合物结构。类脂物质不参与碳化反应，但可被水热炭吸附。部分SS絮体根据“固-固”反应直接转化为水热炭。提出了氮去除的反应途径。
