A comprehensive investigation of crystal violet adsorption on ZIF-67 using experimental and statistical approaches

Abstract

The effective removal of synthetic dyes from wastewater remains a significant challenge in environmental remediation due to their complex molecular structures and resistance to biodegradation. In the present study, Zeolitic Imidazolate Framework-67 (ZIF-67) was successfully synthesised via the co-precipitation method and evaluated for the effective adsorption of cationic crystal violet (CV) dye from aqueous solutions. The synthesised composite was comprehensively characterized using several analytical and electron microscopic techniques, viz., XRD, FTIR, SEM-EDS, BET, zeta potential, and pHpzc, confirming its structural, morphological, and surface characteristics. Under optimized conditions (CV concentration: 50 mg L−1, adsorbent dose: 10 mg, pH: 7.0, and contact time: 60 min), ZIF-67 exhibited the maximum adsorption capacity of 698.9 mg g−1. This high adsorption efficiency was attributed to the crystalline nature and large specific surface area of 367.1 m2 g−1. Equilibrium adsorption data were best described by the Freundlich isotherm model, whereas the adsorption kinetics followed the pseudo-second order model. Thermodynamic analysis revealed that the resulting adsorptive mechanism was spontaneous, endothermic, and entropy-driven. Furthermore, the optimal conditions for the batch adsorption experiments were validated using response surface methodology. These findings demonstrate that ZIF-67 is a promising adsorbent for the efficient decontamination of CV from wastewater. © 2026 Indian Chemical Society.