Abstract:

High performance cobalt-nitrogen co-doped waste microbiochar (Co-N@MSBC) was prepared from agricultural waste mushroom stick by impregnation-calcination method. The biochar was characterized by scanning electron microscopy (SEM), specific surface area (BET), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Gatifloxacin (GAT) was removed by Co-N@MSBC activated permonosulfate (PMS). The experimental results showed that, compared with PMS, MSBC, MSBC/PMS, Co-N@MSBC, the removal rate of GAT in Co-N@MSBC/PMS system was up to 96.5% within 60min under the best conditions, and remained above 90% removal efficiency at a wide pH range (3—11). Cl^-, $\mathrm{N}{\mathrm{O}}_{\mathrm{3}}^{-}$ and $\mathrm{H}\mathrm{C}{\mathrm{O}}_{\mathrm{3}}^{-}$ had a certain inhibitory effect on the removal of GAT, while ${\mathrm{H}}_{\mathrm{2}}\mathrm{P}{\mathrm{O}}_{\mathrm{4}}^{-}$ had a slight promotion effect. After three cycles of recycling, the GAT removal rate of Co-N@MSBC for tap water and ultra-pure water was still higher than 85%, indicating that it has good stability. The quenching experiments showed that sulfate radicals ($\mathrm{S}{\mathrm{O}}_{\mathrm{4}}^{·-}$), ·hydroxyl radicals (·OH), and singlet oxygen (¹O₂) were involved in the degradation. There was a metastable complex mediated non-free radical pathway. Electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) experiments showed that there was direct electron transfer between ternary systems during GAT removal, which meant PMS, Co-N@MSBC and GAT act as electron acceptor, electron bridge and electron donor, respectively, and doped Co and N promote electron transfer between PMS and Co-N@MSBC.

Key words: cobalt-nitrogen co-doped waste bacterial stick biochar (Co-N@MSBC), advanced oxidation, gatifloxacin (GAT), permonosulfate (PMS), activation

摘要：

以农业废弃物废菌棒为原料，采用浸渍-煅烧法制备高性能的钴氮共掺杂废菌棒生物炭（Co-N@MSBC），对其进行扫描电子显微镜（SEM）、比表面积（BET）、红外光谱（FTIR）、X射线光电子能谱（XPS）表征分析，并用Co-N@MSBC活化过一硫酸盐（PMS）去除加替沙星（GAT）。结果表明，与PMS、MSBC、MSBC/PMS、Co-N@MSBC相比，最佳条件下，Co-N@MSBC/PMS体系在60min内对GAT的去除率高达96.5%，且在宽pH（3~11）范围均保持90%以上的GAT去除率；Cl^-、$\mathrm{N}{\mathrm{O}}_{\mathrm{3}}^{-}$和$\mathrm{H}\mathrm{C}{\mathrm{O}}_{\mathrm{3}}^{-}$对GAT去除有一定抑制作用，${\mathrm{H}}_{\mathrm{2}}\mathrm{P}{\mathrm{O}}_{\mathrm{4}}^{-}$有轻微促进作用。Co-N@MSBC经过3次循环利用后对用自来水和超纯水配置的GAT去除率均高于85%，表明其具有良好的稳定性。淬灭实验表明，硫酸根自由基（$\mathrm{S}{\mathrm{O}}_{\mathrm{4}}^{·-}$）、羟基自由基（·OH）和单线态氧（¹O₂）共同参与降解。体系存在亚稳态络合物介导的非自由基途径。电化学阻抗谱（EIS）和线性扫描伏安法（LSV）研究表明，GAT去除过程中存在三元体系间的直接电子转移，即PMS、Co-N@MSBC和GAT分别充当电子受体、电子桥和电子供体，且掺杂的Co、N促进PMS与Co-N@MSBC之间的电子转移。

关键词: 钴氮共掺杂废菌棒生物炭, 高级氧化, 加替沙星, 过一硫酸盐, 活化