Synthesis of copper-based metal-organic framework for adsorptive removal of crystal violet dye from model industrial effluent

Industrialization and anthropogenic activities have aggravated this global challenge of water pollution. Toxic dyes are being discharged into the water, polluting it. Conventional adsorbents failed to eliminate these dyes. Metal-organic frameworks (MOFs) have been investigated as promising adsorbents for wastewater treatment owing to their high surface area, water stability, and strong dye adsorption capabilities. Owing to its promising potential as an adsorbent, this study presents a novel copper-based MOF synthesized using glutaric acid and orthophenylenediamine, offering enhanced adsorption capacity for crystal violet dye compared to conventional adsorbents. As-synthesized Cu (II) MOF was investigated using different analytical techniques such as FTIR, SEM and mapping, XRD, Raman, and BET analysis. The average particle size was 25.64 nm while stretching vibration at 618 cm⁻¹ in the FTIR fingerprint region was ascribed to the Cu–O bond. Batch adsorption study was shown as a function of contact time, concentration, dose, pH and point zero charge, kinetics, thermodynamics, and isotherms. The calculated equilibrium adsorption capacity (Qe) value was 181 mg/g at the optimized condition of pH 7, 35 ppm dye concentration, and agitation time of 50 min, which is better than previous reports. A substantial adsorption extent was observed at neutral pH (pH 7). Owing to the kinetic analysis, an adsorption process is best described by pseudo-second-order. R² (correlation coefficient) values of 0.99 imply a linear data fit to the Langmuir isotherm. The rate constant, K value, was 0.07021 (g(mg⁻¹ min⁻¹) ^-1) for CV dye. The adsorption process was spontaneous by the thermodynamic analysis. The recyclability of the adsorbent was confirmed by using it for five consecutive cycles. Furthermore, the Cu -MOF was applied to model industrial wastewater and showed promising results. These results illustrate that Cu (II) MOF can be used as an efficient, cost-effective adsorbent in crystal violet dye from wastewater.