Magnetic biochar-supported layered double hydroxide for simultaneous remediation of As and Cd in soil: Effectiveness, retention durability, and insight into a new immobilization mechanism

文献类型： 外文期刊

第一作者： Lyu, Peng

作者： Lyu, Peng;Li, Lianfang;Zhu, Changxiong;Lyu, Peng;Li, Lianfang;Huang, Jinli;Ye, Jing;Zhu, Changxiong

作者机构：

关键词： Modified biochar; Arsenic and cadmium; Simultaneous immobilization; Durability and stability; Ca-Mg-Al layered double hydroxide

期刊名称：JOURNAL OF CLEANER PRODUCTION （ 影响因子：11.1； 五年影响因子：11.0 ）

ISSN： 0959-6526

年卷期： 2024 年 434 卷

页码：

收录情况： SCI

摘要： Immobilization/stabilization is a common technique for remediating As and Cd-contaminated soil. However, the effectiveness of employed stabilizer plays a crucial role in determining the fate of these contaminants. This study investigated the effectiveness and durability of a magnetic biochar-supported Ca-Mg-Al layered double hydroxide composite (FLBC) and its components in simultaneous remediation of As and Cd in Phaeozem (BS) and Krasnozem soils (RS). Results demonstrated that 5 wt% FLBC amendment immobilized >85% of As and Cd and converted them into immobile fractions even in a reduction environment. Moreover, FLBC treatment effectively resisted leaching of As and Cd by > 70% under acidic rainwater filtration, thus displaying excellent retention durability. The new immobilization mechanisms were proved using transmission electron microscope technol-ogy, where layered double hydroxide (LDH) acted as a nano-bridge to bind FLBC and soil colloids ensuring FLBC stability and synergistic immobilization. During this process, X-ray photoelectron analysis demonstrated the re-oxidation of As(III) to As(V) driven by ferric reduction that resulted in the formation of multiple stable species on the soil surface via the confirmation of X-ray absorption near fine structure and extended X-ray absorption fine structure. This species included Ca/Fe/Cd-As(V) and gamma-Cd(OH)2 co-precipitation, as well as As(V)-O-Fe(III)/Ca and As-Fe tridentate-hexanuclear corner-sharing complexes. Furthermore, FLBC amendment favored the immobilization of As and Cd in RS soil compared to BS soil due to a weaker reduction potential and an increased participation of metal-(hydr)oxides for As and Cd complexation. This study provides valuable references for predicting the impact of LDH-coupled magnetic biochar technology on the fate of As and Cd in actual soil environments.

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