Boosting the Adsorption of Congo Red Dye onto Zr/Cu Bimetallic Organic Frameworks

Congo red (CR), a persistent anthropogenic pollutant, poses substantial environmental and human health hazards due to its carcinogenicity, mutagenicity, systemic toxicity, and recalcitrance to biodegradation. In this study, a series of UiO-66 (Cu/Zr) bimetallic metal-organic frameworks (MOFs) were fabricated via a facile one-step hydrothermal route for CR adsorption from synthetic wastewater. Characterization confirmed the well-defined crystalline structure of the materials, and SEM-EDS elemental mapping demonstrated the homogeneous distribution of Cu within the UiO-66 framework. Adsorption experiments for CR under varied conditions revealed the enhanced adsorption properties of bimetallic MOFs. Optimal performance occurred at pH 8 and 40 °C, where UiO-66-0.5Cu achieved a maximum capacity of 499 mg·g^-1, which was significantly surpassing the pristine UiO-66 (268 mg·g^-1). And the adsorption equilibrium was attained within 180 min. Kinetic analysis indicated close adherence to the pseudo-second-order model (<i>R</i> ² = 0.9997), confirming the potential of Zr/Cu bimetallic frameworks for dye wastewater remediation.