Author(s)

Yan Tan ¹, Zhihong Zhang ¹, Jinkun Huang ², Xixin Lu ²

Affiliation(s)

¹ Beijing University of Technology, Beijing, China
² China MCC17 Group Co., Ltd., Hefei, Anhui, China

Corresponding Author

Yan Tan

ABSTRACT

The pollution of water systems by heavy metal ions (Cu²⁺, Zn²⁺, Pb²⁺) poses significant environmental and health risks globally. This study systematically investigates the temperature-dependent adsorption characteristics of bentonite (high CEC, swelling) and kaolinite (stable structure, surface hydroxyls) for these metals. While previous studies have examined pH and concentration effects, we focus on establishing quantitative temperature-adsorption relationships through thermodynamic analysis (ΔG°, ΔH°, ΔS°) and predictive modeling, addressing a critical research gap in optimizing clay-based wastewater treatment under varying thermal conditions. The adsorption characteristics of three heavy metal ions (Cu²⁺, Zn²⁺, and Pb²⁺) on natural clay minerals (bentonite and kaolinite) were examined as a function of temperature (20-40°C) using batch equilibrium techniques. Temperature-dependent adsorption isotherms were quantitatively analyzed to elucidate the underlying mechanisms and subsequently parameterize a predictive adsorption model accounting for thermal effects. Thermodynamic analysis confirmed the exothermic nature of Cu²⁺, Zn²⁺, and Pb²⁺ adsorption on both bentonite and kaolinite, with adsorption capacities decreasing 15-45% across the 20-40°C range, in accordance with Le Chatelier's principle. Structural characterization revealed bentonite's interlayer contraction (d-spacing reduction from 1.5 to 1.0 nm) contributed significantly to its observed thermal sensitivity, contrasted with kaolinite's more stable performance (21% vs 74% KL decrease for Pb²⁺ and Cu²⁺ respectively). Distinct metal-specific behaviors emerged, where Pb²⁺'s strong surface complexation minimized capacity loss (15-25%) compared to Zn²⁺'s hydration-sensitive adsorption (45% reduction). Isotherm modeling demonstrated Langmuir's superiority at lower temperatures (r²>0.99) while Freundlich analysis indicated progressive loss of adsorption favorability (n→1) with heating. Thermodynamic analysis (ΔH = -16.84 to -26.3 kJ/mol) confirms the exothermic nature of adsorption. This study revealed temperature-dependent adsorption behaviors of clay minerals, showing bentonite's greater thermal sensitivity than kaolinite despite its higher Pb²⁺ adsorption capacity. Thermodynamic analysis confirmed exothermic adsorption, with Langmuir and Freundlich models optimally describing low- and high-temperature regimes, respectively. Bentonite's ordered adsorptionsuits 20-30°C Pb²⁺ removal, while kaolinite's surface adsorption performs better under thermal fluctuations.

KEYWORDS

Heavy metal ion adsorption; Temperature effect; Bentonite; Kaolinite

CITE THIS PAPER

Yan Tan, Zhihong Zhang, Jinkun Huang, Xixin Lu. Research on the Adsorption Characteristics of Clay Minerals for Heavy Metal Ions Considering Temperature Effects. Journal of Civil Engineering and Urban Planning (2026). Vol. 8, No.2, 38-45. DOI: http://dx.doi.org/10.23977/jceup.2026.080205.

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