Faculty of Environmental Science & Engineering, Kunming University of Science & Technology, Kunming 650500, Yunnan, China.
Yunnan Academy of Eco-environmental Sciences, Kunming, Yunnan 650034, China.
Environ Sci Process Impacts. 2020 May 28;22(5):1287-1294. doi: 10.1039/d0em00102c.
The sorption characteristics of ionizable organic contaminants on biochars are currently unclear, largely because of the different mineral content and pH of the investigated biochars. This study examines the sorption of sulfamethoxazole (SMX) on a number of biochars with different ash contents (KCl and Ca-containing minerals), surface areas (SAs), and acid-basic properties. SMX sorption on biochars produced at 200 °C showed higher sorption compared to sorption on biochars produced above 300 °C due to the hydrophobic effect, hydrogen bonds, and π-π electron donor-acceptor interactions (π-π EDA interactions) resulting from a larger fraction of neutral SMX present in the sorption system. Under alkaline conditions, less sorption nonlinearity was observed, probably resulting from the limited contact between the dissociated SMX- and the negatively charged surface of biochars. Significant sorption observed at alkaline pH was attributed to the negative charge assisted hydrogen-bond (-(CAHB)). When the pyrolysis temperature increased above 400 °C, the increase in the SA of the biochars facilitated apparent sorption. Ca-containing minerals in biochars may provide additional sorption sites for SMX- through electrostatic interactions. This study indicates that the overall sorption of SMX was governed by a combination of factors such as the surface charge, functional groups, SA, and mineral composition of biochars.
目前，对于可离子化有机污染物在生物炭上的吸附特性还不清楚，这主要是因为研究中生物炭的矿物质含量和 pH 值不同。本研究考察了一系列灰分含量（含 KCl 和 Ca 的矿物质）、比表面积（SA）和酸碱性质不同的生物炭对磺胺甲恶唑（SMX）的吸附作用。由于疏水性效应、氢键和π-π 电子供体-受体相互作用（π-π EDA 相互作用），在吸附体系中存在更多中性 SMX 部分，导致 200°C 下制备的生物炭对 SMX 的吸附作用高于 300°C 下制备的生物炭。在碱性条件下，观察到较少的吸附非线性，可能是由于解离的 SMX-与生物炭带负电荷的表面之间接触有限。在碱性 pH 值下观察到的显著吸附归因于负电荷辅助氢键（-(CAHB)）。当热解温度高于 400°C 时，生物炭的 SA 增加促进了明显的吸附。生物炭中的含 Ca 矿物质可能通过静电相互作用为 SMX-提供额外的吸附位点。本研究表明，SMX 的总体吸附是由生物炭的表面电荷、官能团、SA 和矿物质组成等多种因素共同作用的结果。
