Innovative CuZnCr-BTC Framework for Enhanced Congo Red Dye Removal in Sustainable Wastewater Treatment

Abstract

Dye-contaminated wastewater poses a significant threat to environmental and human health, necessitating the development of efficient and reusable adsorbent materials. Metal–organic frameworks (MOFs) have emerged as promising candidates owing to their high surface area, tunable porosity, and chemical stability. In this study, a novel trimetallic copper–zinc–chromium MOF based on benzene-1, 3, 5-tricarboxylate (CuZnCr-BTC) was synthesized via a solvothermal method, and its adsorption performance was evaluated for the removal of Congo Red dye from aqueous media. The synthesized MOF displayed a cubic morphology with particle sizes ranging from 200 to 400 nm, as confirmed by scanning electron microscopy (SEM) and complementary characterization techniques. Batch adsorption experiments were conducted under varying operational conditions. The CuZnCr-BTC MOF achieved a maximum dye removal efficiency of 93.3% at an adsorbent dose of 30 mg, dye concentration of 100 mg/L, pH 7, temperature of 35 °C, and contact time of 60 min. Adsorption kinetics followed a pseudo-second-order model (R² = 0.996), while equilibrium data were best fitted by the Langmuir isotherm model (R² = 0.998), suggesting monolayer adsorption with a maximum adsorption capacity of 280 mg/g. Additionally, the MOF maintained approximately 87% of its removal efficiency after six regeneration cycles, indicating excellent reusability. These results demonstrate that the trimetallic CuZnCr-BTC MOF is a robust, cost-effective, and reusable adsorbent for wastewater dye removal applications, with promising implications for large-scale environmental remediation.