MgO-embedded S-doped porous biochar composites for efficient removal Cd(II) and Pb(II) in water: DFT studies and mechanistic insights

文献类型： 外文期刊

第一作者： Hao, Peixin

作者： Hao, Peixin;Fu, Haichao;Ma, Shuanglong;Li, Guangxin;Sui, Fuqing;Li, Chang;Zhao, Peng;Hao, Peixin;Fu, Haichao;Ma, Shuanglong;Li, Guangxin;Sui, Fuqing;Li, Chang;Zhao, Peng;Xue, Weijie;Xiong, Shiwu;Duan, Ran

作者机构：

关键词： Sodium thiosulfate; Magnesium oxide; Cotton straw biochar; Heavy metals; Density functional theory

期刊名称：SEPARATION AND PURIFICATION TECHNOLOGY （ 影响因子：9.0； 五年影响因子：8.5 ）

ISSN： 1383-5866

年卷期： 2025 年 363 卷

页码：

收录情况： SCI

摘要： A novel modification strategy for biochar utilizes sodium thiosulfate (Na2S2O3) activation combined with magnesium chloride (MgCl2) impregnation to produce magnesium oxide (MgO)-loaded sulfur (S)-doped cotton straw biochar (MgO-S-BC). MgO-S-BC exhibits a highly porous structure, substantial MgO loading capacity, and abundant S surface motifs, enabling efficient removal of Cd(II) and Pb(II) from aqueous solutions. The MgO-S-BC demonstrated maximum adsorption capacities of 630 mg/g for Cd(II), and 2022 mg/g for Pb(II) in monometallic system by Langmuir models. The kinetic and isotherm studies, multiple characterizations, and speciation analysis indicated that precipitation and ion-exchange were the primary mechanisms for the adsorption of Cd(II) and Pb (II) by MgO-S-BC. Density functional theory (DFT) calculations revealed that the O-top and hollow of MgO were the most stable adsorption sites for Cd(II) and Pb(II) adsorption, respectively, compared to other sites (Mg-top, bridge, and S). Projected density of states (PDOS) analysis further confirmed that the affinity of MgO-S-BC for Pb (II) was greater than that for Cd(II). S-groups enhance the surface complexation and precipitation capabilities of biochar for Cd(II) and Pb(II). Additionally, column adsorption tests, ion interference tests, regeneration experiments, and cost analysis demonstrated that MgO-S-BC had a high removal efficiency for heavy metals, highlighting its potential for practical applications.

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