Faculty of Environmental Science & Engineering, Kunming University of Science & Technology, Kunming 650500, China; Yunnan Provincial Key Laboratory of Soil Carbon Sequestration and Pollution Control, Kunming 650500, China; College of Chemistry and Environmental Engineering, Chongqing University of Arts and Sciences, Chongqing 402160, China; Chongqing Key Laboratory of Environmental Materials & Remediation Technologies, Chongqing University of Arts and Sciences, Chongqing 402160, China.
Faculty of Environmental Science & Engineering, Kunming University of Science & Technology, Kunming 650500, China; Yunnan Provincial Key Laboratory of Soil Carbon Sequestration and Pollution Control, Kunming 650500, China.
Sci Total Environ. 2020 Apr 15;713:136663. doi: 10.1016/j.scitotenv.2020.136663. Epub 2020 Jan 13.
The ash content of municipal sewage sludge is generally high. However, the manner in which the composition of ash affects biochar properties and sorption remains unclear. Sewage sludge from two cities, Chongqing and Kunming, were pyrolyzed at different temperatures to produce biochar in this work. The physicochemical properties of biochar were investigated by bulk chemical characteristics (such as FTIR, XPS, Raman analysis, and elemental analysis) and benzene polycarboxylic acid (BPCA) molecular biomarkers, after which they were correlated with sorption characteristics. In comparison with biochar from Chongqing sewage sludge (CSS), biochar from Kunming sewage sludge (KSS) showed stronger polarity, a larger specific surface area (SSA) and more functional groups, but a lower degree of graphitization and aromatization. These differences may result from the higher aluminum (Al) content of KSS. The single-point sorption coefficient K values of biochar derived from CSS and KSS were analyzed together. K was positively correlated with the SSA and pore volume of sewage sludge and biochar produced at 200-300 °C. For biochar produced at 300-700 °C, the K value was positively correlated with the O content, O/C and (O + N)/C. The pyrolysis temperature of 300 °C was a threshold temperature for Cu(II) sorption onto biochar, at which there was a balance between decreased oxygen-containing functional groups and increased SSA. The findings of this study show that higher Al content in sewage sludge was beneficial to pore volume enlargement and functional group retention during the pyrolysis process.
城市污水污泥的灰分含量通常较高。然而，灰分的组成如何影响生物炭的性质和吸附作用尚不清楚。本工作中，采用两种不同的热解温度对来自重庆和昆明的城市污水污泥进行热解，以制备生物炭。采用傅里叶变换红外光谱（FTIR）、X 射线光电子能谱（XPS）、拉曼分析和元素分析等整体化学特性以及苯多羧酸（BPCA）分子标志物研究了生物炭的理化性质，并将其与吸附特性相关联。与来自重庆污水污泥（CSS）的生物炭相比，来自昆明污水污泥（KSS）的生物炭表现出更强的极性、更大的比表面积（SSA）和更多的功能基团，但石墨化和芳构化程度较低。这些差异可能是由于 KSS 中较高的铝（Al）含量所致。还分析了 CSS 和 KSS 来源的生物炭的单点吸附系数 K 值。K 值与污水污泥和在 200-300°C 下制备的生物炭的 SSA 和孔体积呈正相关。对于在 300-700°C 下制备的生物炭，K 值与 O 含量、O/C 和（O+N）/C 呈正相关。300°C 的热解温度是 Cu(II)吸附到生物炭上的一个阈值温度，在该温度下，含氧官能团的减少和 SSA 的增加之间达到平衡。本研究的结果表明，污水污泥中较高的 Al 含量有利于在热解过程中扩大孔体积和保留官能团。
