Ligand selectivity and competitive adsorption of heavy metals using beta cyclodextrin-based metal organic framework and crosslinked polymers

06/07/2026

AI Summary

Synthesised and characterised CA-βCD, AA-βCD and βCD-MOF via FTIR, XRD, SEM, BET and zeta potential analyses.
In multicomponent tests (1 g/L, 100 mg/L, pH 6) βCD-MOF outperformed polymers, removing Cu ~80%, Pb ~40% and Cd ~20%.
Single-component tests showed near quantitative removal; Langmuir capacities Cd 142.85, Pb 136.99, Cu 120.48 mg g-1, but competitive adsorption favoured Cu.

AI Summary

In the multicomponent system (adsorbent dosage 1 g/L, initial metal concentration 100 mg/L, pH 6.0 at 25℃), βCD-MOF exhibited the highest removal efficiency, particularly for Cu2+ (~ 80%), followed by Pb2+ (~ 40%) and Cd2+ (~ 20%), outperforming AA-βCD and CA-βCD.

Single-component experiments using βCD-MOF (as optimal adsorbent, 3 g/L) revealed excellent removal efficiencies, Cd2+: 99.93%, Pb2+: 97.02%, Cu2+: 96.30%.

Basic summary

Sci Rep. 2026 Jul 5. doi: 10.1038/s41598-026-61163-9. Online ahead of print.

ABSTRACT

Considering the significant threats posed by heavy metals (HMs) to ecosystems and public health, the aim of the current study was the synthesis and characterization of β-cyclodextrin-based adsorbents, including citric acid crosslinked βCD (CA-βCD), adipic acid crosslinked βCD (AA-βCD), and βCD-based metal-organic framework (βCD-MOF), and evaluation of their efficacy in the removal of Pb²⁺, Cd²⁺, and Cu²⁺ ions. The synthesized polymers were analyzed by FTIR, XRD, SEM, BET, and zeta potential methods to assess their structural, morphological, and surface characteristics. In the multicomponent system (adsorbent dosage 1 g/L, initial metal concentration 100 mg/L, pH 6.0 at 25℃), βCD-MOF exhibited the highest removal efficiency, particularly for Cu²⁺ (~ 80%), followed by Pb²⁺ (~ 40%) and Cd²⁺ (~ 20%), outperforming AA-βCD and CA-βCD. The preferential adsorption of copper is attributed to its smaller ionic radius and higher charge density, which enhance electrostatic interactions with polymer ligands. Single-component experiments using βCD-MOF (as optimal adsorbent, 3 g/L) revealed excellent removal efficiencies, Cd²⁺: 99.93%, Pb²⁺: 97.02%, Cu²⁺: 96.30%. Interestingly, while Cd²⁺ was most efficiently removed alone, despite its larger hydrated radius and higher pKa₁, competitive adsorption favored Cu²⁺, indicating ligand selectivity shifts under mixed conditions. Equilibrium data were best fitted by the Langmuir model, with maximum single-state adsorption capacities of 142.85, 136.99, and 120.48 mg/g for Cd²⁺, Pb²⁺, and Cu²⁺, respectively. The results of real water treatments demonstrated positive relationship between water hardness and Cd²⁺ removal efficiency using βCD-MOF adsorbents. These findings highlighted the role of βCD-MOF as a promising candidate for scalable water purification technologies.