Quantifying the immobilization mechanisms of heavy metals by Calcium Silicate Hydrate (C-S-H): The case of Cu2+

IF 10.9 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement and Concrete Research Pub Date : 2024-10-10 DOI:10.1016/j.cemconres.2024.107695

Qi Liu , Pan Feng , Lijing Shao , Chen Chen , Xin Liu , Yuefeng Ma , Lizhi Zhang , Guoqing Geng

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Abstract

Understanding the interactions between calcium silicate hydrate (C-S-H) and heavy metals is vital for optimizing the use of solid waste in cementitious materials. This paper introduces an innovative approach to elucidate the immobilization mechanism of Cu²⁺, a representative heavy metal. The roles of Ca²⁺ and OH⁻ in Cu²⁺ immobilization were comprehensively investigated through being treated by C-S-H samples with varying interlayer Ca²⁺ contents via meticulous immersion in ammonium chloride (NH₄Cl). Our results indicate that Cu²⁺ immobilization primarily occurs via complete substitution of interlayer Ca²⁺ and partial substitution of intralayer Ca²⁺, with contributions of 40 % and 59 %, respectively, for a Ca/Si ratio of 1.2. Minor mechanisms like OH⁻ complexation and surface adsorption account for the remaining immobilization. The formation of Si-O-Cu complexes was confirmed by X-ray photoelectron (XPS) and Extended X-ray Absorption Fine Structure (EXAFS) analysis. This study provides a quantitative methodology that informs strategies for sustainable cementitious waste utilization.

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量化硅酸钙水合物（C-S-H）固定重金属的机制：以 Cu2+ 为例

了解水合硅酸钙（C-S-H）与重金属之间的相互作用对于优化水泥基材料中固体废弃物的利用至关重要。本文介绍了一种创新方法来阐明具有代表性的重金属 Cu2+ 的固定化机理。通过将不同层间 Ca2+ 含量的 C-S-H 样品精心浸泡在氯化铵（NH4Cl）中，全面研究了 Ca2+ 和 OH- 在 Cu2+ 固定化过程中的作用。我们的研究结果表明，Cu2+ 固定化主要是通过层间 Ca2+ 的完全置换和层内 Ca2+ 的部分置换实现的，在 Ca/Si 比为 1.2 时，两者的贡献率分别为 40% 和 59%。其余的固定化作用主要来自于一些次要机制，如羟基络合和表面吸附。X 射线光电子（XPS）和扩展 X 射线吸收精细结构（EXAFS）分析证实了 Si-O-Cu 复合物的形成。这项研究提供了一种定量方法，为水泥基废物的可持续利用战略提供了依据。

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来源期刊

Cement and Concrete Research 工程技术-材料科学：综合

CiteScore

20.90

自引率

12.30%

发文量

318

审稿时长

53 days

期刊介绍： Cement and Concrete Research is dedicated to publishing top-notch research on the materials science and engineering of cement, cement composites, mortars, concrete, and related materials incorporating cement or other mineral binders. The journal prioritizes reporting significant findings in research on the properties and performance of cementitious materials. It also covers novel experimental techniques, the latest analytical and modeling methods, examination and diagnosis of actual cement and concrete structures, and the exploration of potential improvements in materials.