State Key Laboratory of Urban Water Resource and Environment, School of environment, Harbin Institute of Technology, Harbin 150090, PR China.
School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, PR China.
J Hazard Mater. 2021 May 5;409:125024. doi: 10.1016/j.jhazmat.2020.125024. Epub 2021 Jan 2.
Magnetite-coating biochar (MBC) is a promising remediator for antibiotic contamination. Accurate models describing the sorption affinity are required to better understand the role of minerals. In this study, the presence of magnetite led to the improvements of oxygen-containing groups (i.e. C˭O) and regulation of π-systems within BC. Based on Dubinin-Ashtakhov (DA) model, the differences of site energy (E) and sorption heterogeneity (σ*) led to the variances between sorption capacities of sulfonamides (SAs). The positive correlations between E and the oxygen content or pore volume of MBCs indicated that π-π interactions, H-bonding, and pore-filling may act as the high energy sites. Moreover, σ* was related to the distribution of magnetite on BC and their porosities. These results suggested that compared to BCs, the coating minerals improved the π-interaction assisted H-bonding and proton configuration of antibiotic when sorbing on MBC. The negative correlations between the E of different SAs with their molecular sizes and solubilities resulted from steric effects and competition with water, which further confirmed the proposed high energy sites on MBCs. This study provided the insightful information of site energy distribution and understanding of fate and transport of organic pollutants on BC when the iron minerals were embedded or coated.
磁铁矿涂层生物炭 (MBC) 是一种很有前途的抗生素污染修复剂。为了更好地了解矿物质的作用，需要准确的模型来描述其吸附亲和力。本研究中，磁铁矿的存在改善了生物炭中的含氧基团（如 C˭O）和π 体系的调节。基于杜宾纳-阿斯哈科夫 (DA) 模型，位点能 (E) 和吸附异质性 (σ*) 的差异导致了磺胺类抗生素 (SAs) 吸附容量的差异。E 与 MBC 中氧含量或孔体积之间的正相关表明，π-π 相互作用、氢键和孔填充可能作为高能位点。此外，σ* 与磁铁矿在生物炭上的分布及其孔隙率有关。这些结果表明，与生物炭相比，涂层矿物质在 MBC 吸附抗生素时，改善了 π-相互作用辅助氢键和质子构象。不同磺胺类抗生素的 E 与它们的分子大小和溶解度之间的负相关，是由于空间位阻效应和与水的竞争，进一步证实了 MBC 上提出的高能位点。本研究提供了关于铁矿物质嵌入或涂层时，生物炭上有机污染物的位点能分布和归宿及传输的深入信息。
