School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China.
School of Environmental and Municipal Engineering, Tianjin Chengjian University, Tianjin, 300384, China.
J Environ Manage. 2022 Feb 15;304:114297. doi: 10.1016/j.jenvman.2021.114297. Epub 2021 Dec 20.
A magnetic nitrogen-doped sludge-based biochar (NAlSB-Fe-Si) was prepared based on waterworks sludge for raw material and dicyandiamide for nitrogen source to adsorb methylene blue (MB) from water. And the magnetic particles loaded on the adsorbent were obtained through functionalizing iron and silicon ions which were extracted from the biochar by acid and alkali impregnation. Physicochemical properties of sludge-based biochar (SB) were analyzed by SEM, BET, FTIR, XRD, XPS and VSM. Compared with the original biochar, NAlSB-Fe-Si had richer pore structure and higher pore volume, and the SiO and FeO loading made the specific surface area increased by 200%. Possible adsorption mechanism was proposed by exploring the initial pH, MB concentration and reaction time. Results revealed that alkaline environment was more conducive to the rapid removal of cationic dyes such as MB. Pseudo-second-order kinetic model and intra-particle diffusion model could describe the adsorption behavior of MB on NAlSB-Fe-Si. The fitting results of Langmuir model showed that adsorption temperature is positively correlated with adsorption capacity, and the maximum adsorption capacity of MB on nitrogen-doped sludge-based biochar (NSB) and NAlSB-Fe-Si at 25 °C was 26.47 and 300.36 mg/g, respectively. Finally, the MB removal rate of NAlSB-Fe-Si could still reach 70% after four cycles, indicating that the composite was an efficient cationic dye adsorbent, and its preparation could be regarded as a way of resource utilization of waterworks sludge.
以自来水厂污泥为原料，双氰胺为氮源，制备了一种磁性氮掺杂污泥基生物炭（NAlSB-Fe-Si），用于从水中吸附亚甲基蓝（MB）。通过酸碱浸渍从生物炭中提取铁和硅离子并对其进行功能化，将负载在吸附剂上的磁性颗粒。采用 SEM、BET、FTIR、XRD、XPS 和 VSM 对污泥基生物炭（SB）的理化性质进行了分析。与原始生物炭相比，NAlSB-Fe-Si 具有更丰富的孔结构和更高的孔体积，SiO 和 FeO 的负载使比表面积增加了 200%。通过探索初始 pH 值、MB 浓度和反应时间，提出了可能的吸附机理。结果表明，碱性环境更有利于阳离子染料如 MB 的快速去除。准二级动力学模型和内扩散模型可以描述 MB 在 NAlSB-Fe-Si 上的吸附行为。Langmuir 模型的拟合结果表明，吸附温度与吸附容量呈正相关，在 25°C 下，MB 对氮掺杂污泥基生物炭（NSB）和 NAlSB-Fe-Si 的最大吸附容量分别为 26.47 和 300.36 mg/g。最后，NAlSB-Fe-Si 在经过四次循环后，MB 的去除率仍能达到 70%，表明该复合材料是一种高效的阳离子染料吸附剂，其制备可视为自来水厂污泥资源利用的一种途径。
