Adsorption of heavy metals using cysteine-modified pillared montmorillonite: Mechanisms and characteristics

IF 5.3 2区地球科学 Q2 CHEMISTRY, PHYSICAL

Applied Clay Science Pub Date : 2025-07-03 DOI:10.1016/j.clay.2025.107923

Chao Hu , Feiyu Teng , Xinjia Yin , Pu Wang , Bianyang He , Lei Zhu

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引用次数: 0

Abstract

Montmorillonite enhanced its adsorption performance through the modification with organic and inorganic materials. Among various modifiers, cysteine was known for its significant ability to bind heavy metals due to the presence of thiol and amino functional groups. This study used X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and a series of adsorption experiments to examine the interaction between FeCl₃-AlCl₃ pillared montmorillonite (PMt) and cysteine (Cys), and to investigate the adsorption characteristics and mechanisms of the composite of pillared montmorillonite and cysteine (P-Mt-Cys) toward heavy metals. The XRD and FTIR results indicated that cysteine intercalated into the layers of the pillared montmorillonite and, through its functional groups, dominated the surface of the P-Mt-Cys composite. The pillaring material slowed down the rate at which cysteine entered the montmorillonite and established pH 5.0 as the optimal electrochemical condition for cysteine intercalation. The adsorption of cysteine onto PMt followed a pseudo-second-order kinetic model, and the Dubinin-Radushkevich (D-R) isothermal adsorption model provided a good fit for the data. In the pH range of 5.0–5.5, P-Mt-Cys exhibited superior adsorption of Cu(II) compared to unmodified Mt. and PMt. The adsorption of Cu(II) on P-Mt-Cys reached equilibrium within 120 min. The Freundlich isothermal adsorption model best described the multilayer adsorption of Cu(II), with a maximum adsorption capacity of 27.02 mg g⁻¹ at an equilibrium concentration of 81.91 mg L⁻¹. The adsorption process was exothermic and spontaneous, and the adsorption amount decreased as the temperature increased. Additionally, both the enthalpy change and entropy change were negative. These findings established the foundation for understanding the adsorption characteristics of heavy metals and offered a reference for further studies on the Mt-Cys-heavy metal system.

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半胱氨酸修饰柱状蒙脱土对重金属的吸附：机理与特性

通过对蒙脱土进行有机和无机改性，提高了其吸附性能。在各种修饰剂中，由于巯基和氨基官能团的存在，半胱氨酸以其结合重金属的显著能力而闻名。本研究采用x射线衍射（XRD）、傅里叶变换红外光谱（FTIR）及一系列吸附实验，考察了FeCl3-AlCl3柱状蒙脱土（PMt）与半胱氨酸（Cys）的相互作用，探讨了柱状蒙脱土与半胱氨酸（P-Mt-Cys）复合材料对重金属的吸附特性及机理。XRD和FTIR结果表明，半胱氨酸嵌入柱状蒙脱土层中，并通过其官能团主导了P-Mt-Cys复合材料的表面。柱状材料减缓了半胱氨酸进入蒙脱土的速度，并确定pH 5.0为半胱氨酸嵌入的最佳电化学条件。半胱氨酸在PMt上的吸附符合准二级动力学模型，其中Dubinin-Radushkevich （D-R）等温吸附模型与实验数据吻合较好。在5.0 ~ 5.5的pH范围内，P-Mt-Cys对Cu（II）的吸附效果优于未改性的mt和PMt。P-Mt-Cys对Cu（II）的吸附在120 min内达到平衡，Freundlich等温吸附模型最能描述Cu（II）的多层吸附，在平衡浓度为81.91 mg L−1时，最大吸附量为27.02 mg g−1。吸附过程为放热自发吸附过程，吸附量随温度升高而减小。焓变和熵变均为负。这些发现为了解mt - cys -重金属吸附特性奠定了基础，并为进一步研究mt - cys -重金属体系提供了参考。

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来源期刊

Applied Clay Science 地学-矿物学

CiteScore

10.30

自引率

10.70%

发文量

289

审稿时长

39 days

期刊介绍： Applied Clay Science aims to be an international journal attracting high quality scientific papers on clays and clay minerals, including research papers, reviews, and technical notes. The journal covers typical subjects of Fundamental and Applied Clay Science such as: • Synthesis and purification • Structural, crystallographic and mineralogical properties of clays and clay minerals • Thermal properties of clays and clay minerals • Physico-chemical properties including i) surface and interface properties; ii) thermodynamic properties; iii) mechanical properties • Interaction with water, with polar and apolar molecules • Colloidal properties and rheology • Adsorption, Intercalation, Ionic exchange • Genesis and deposits of clay minerals • Geology and geochemistry of clays • Modification of clays and clay minerals properties by thermal and physical treatments • Modification by chemical treatments with organic and inorganic molecules(organoclays, pillared clays) • Modification by biological microorganisms. etc...