Heavy metal pollution causes severely adverse impacts on human and ecosystem health. Adsorption is one of the most effective technologies used in the removal of heavy metal ions from contaminated water. However, its widespread applications are limited, owing to its high cost and low adsorbent selectivity. In this study, modified manganese‐containing biochars were synthesized to improve their Pb²⁺ adsorption ability. Fraxinus mandshurica sawdust samples were impregnated with pure water as well as KMnO₄ and MnSO₄ aqueous solutions (FM‐BC, FM‐M7BC, and FM‐M2BC, respectively) for 24 hours at 25°C and pyrolyzed at 400°C. The resulting biochars were characterized using x‐ray diffraction (XRD), scanning electron microscopy (SEM), energy‐dispersive x‐ray analyses (EDX), Fourier‐transform infrared spectroscopy (FTIR), N₂ adsorption‐desorption isotherms, and Boehm titration. Batch adsorption experiments revealed the kinetics and magnitude of Pb²⁺ adsorption onto the biochars. The Pb²⁺ adsorption capacity of FM‐M7BC (156.25 mg · g⁻¹) was significantly higher than those of FM‐M2BC (25.35 mg · g⁻¹) and FM‐BC (11.99 mg · g⁻¹), and based on FTIR and Boehm titration results before and after Pb²⁺ adsorption, an adsorption mechanism was proposed. FM‐M7BC showed the highest adsorption enhancement owing to the strong affinity of MnCO₃ particles and O‐containing groups for Pb²⁺. Additionally, the influence of the different oxidation states of manganese (Mn(VII), and Mn(II)) in the manganese components on the Pb²⁺ adsorption performance of the biochars was extremely strong. FM‐M7BC was an effective adsorbent for removing Pb²⁺.

中文翻译：

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含锰生物炭的制备，表征及其对铅离子的吸附机理

重金属污染对人类和生态系统健康造成严重不利影响。吸附是从污染水中去除重金属离子的最有效技术之一。然而，由于其高成本和低吸附剂选择性，其广泛的应用受到限制。在这项研究中，合成了改良的含锰生物炭以提高其对Pb ^2+的吸附能力。水曲柳锯末样品用纯水以及KMnO ₄和MnSO ₄浸渍水溶液（分别为FM-BC，FM-M7BC和FM-M2BC）在25°C下放置24小时，然后在400°C下热解。使用X射线衍射（XRD），扫描电子显微镜（SEM），能量色散X射线分析（EDX），傅立叶变换红外光谱（FTIR），N ₂吸附-解吸等温线和Boehm对所得生物炭进行表征滴定。分批吸附实验揭示了Pb ²⁺吸附到生物炭上的动力学和大小。FM‐M7BC（156.25 mg·g ^-1）的Pb ²⁺吸附容量显着高于FM‐M2BC（25.35 mg·g ^-1）和FM‐BC（11.99 mg·g ^-1）的Pb ²⁺吸附量，铅前后的FTIR和Boehm滴定结果²⁺吸附，提出了一种吸附机理。由于MnCO ₃颗粒和含O的基团对Pb ²⁺具有很强的亲和力，因此FM‐M7BC表现出最高的吸附增强作用。此外，锰组分中锰（Mn（VII）和Mn（II））的不同氧化态对生物炭Pb ²⁺吸附性能的影响非常强烈。FM‐M7BC是去除Pb ²⁺的有效吸附剂。