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

Authors

Parisa Ahmadi, Azam Ahmadi, Mahnaz Tabibiazar, Samin Hamidi, Mohammad Reza Afshar Mogaddam, Soghra Ramezani

Published in

Scientific reports. Jul 05, 2026. Epub Jul 05, 2026.

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.

PMID:
42402645
Bibliographic data and abstract were imported from PubMed on 06 Jul 2026.

Read full publication at:
Please sign in to see all details.

Stats

1-terrible, 9-excellent. How would you rate this publication? Sign in in to submit your rating.

Post a comment

You need to be signed in to post comments. You can sign in here.

Comments

There are no comments yet.