Efficient simultaneous removal of fluoxetine and venlafaxine from aqueous media using a bimetallic NiCu-BTC metal–organic framework

In this study, a bimetallic NiCu-BTC metal–organic framework was synthesized and evaluated as an efficient adsorbent for the simultaneous removal of two widely prescribed antidepressants, fluoxetine and venlafaxine, from aqueous solutions. The synthesized material was comprehensively characterized by XRD, FTIR, FESEM, and BET analyses. Batch adsorption experiments were carried out using binary pharmaceutical solutions to investigate the effects of solution pH, adsorbent dosage, contact time, initial concentration, and coexisting ions on adsorption performance. Under the optimized conditions, rapid adsorption was observed, and equilibrium was achieved within 90 min for fluoxetine and 120 min for venlafaxine. The equilibrium data were analyzed using the extended Langmuir model, yielding maximum adsorption capacities of 82.5 mg g⁻¹ for fluoxetine and 73.4 mg g⁻¹ for venlafaxine under binary adsorption conditions. Kinetic analysis showed that the pseudo-second-order model provided the best fit to the experimental data, while intraparticle diffusion was not identified as the sole rate-limiting step. Also, satisfactory removal efficiencies were achieved in real wastewater samples despite the presence of competing constituents. These results indicated that NiCu-BTC is a reusable adsorbent for the treatment of pharmaceutical-contaminated water.