In-situ synthesis of ZIF-8@GO composites for efficient aqueous dye removal: a systematic study of performance and...

The integration of two-dimensional (2D) graphene oxide (GO) with zinc-based metal-organic frameworks (MOFs) offers significant potential for environmental remediation. In this study, an in-situ synthesized ZIF-8@GO composite was developed, where ZIF-8 crystals are uniformly dispersed on GO nanosheets to enhance adsorption performance and structural stability. The composite was applied for the removal of malachite green (MG) dye from aqueous solutions, achieving a maximum removal efficiency of ~ 97% under favorable conditions. A systematic parametric investigation was conducted to evaluate the influence of key operational variables, including pH, adsorbent amount, contact time, initial dye concentration, and temperature, on adsorption performance. The adsorption behavior was best described by the Freundlich isotherm indicating monolayer adsorption, while kinetic analysis followed a pseudo-second-order model. Thermodynamic analysis revealed that the adsorption process is spontaneous and endothermic. The ZIF-8@GO composite exhibited excellent reusability, maintaining high removal efficiency over eight cycles. Furthermore, its applicability was validated in real-water systems and competitive adsorption conditions, demonstrating strong selectivity toward MG dye. With a maximum adsorption capacity of (q_max) 211.4 mg g⁻¹ at 298 K, this study highlights a scalable, stable, and efficient adsorbent platform for practical wastewater treatment applications.