Synthesis of copper coordinated dithiooxamide metal organic framework and its performance assessment in the adsorptive removal of tartrazine from water

•Cu-DTO MOF was synthesized via precipitation method.•Fast adsorptive removal of tartrazine was observed within 30 min.•Both intra-particle and film diffusion were rate limiting factors.•Cu-DTO MOF demonstrated good reusability.

Copper coordinated dithiooxamide metal-organic framework (Cu-DTO MOF) was synthesized and applied for the removal of tartrazine from aqueous solutions. The properties of Cu-DTO MOF were extensively examined through different instrumentation techniques including Fourier transform infra red spectroscopy (FTIR), X- ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), energy dispersive X-ray analysis (EDX), atomic force microscopy (AFM), N2 adsorption-desorption for surface area analysis, thermo-gravimetric analysis (DTA/TGA/DTG) and zeta potential analysis (pHZPC). The effects of various process parameters such as pH, temperature, ionic strength, contact time and initial dye concentration were systematically studied. The interpretation of sorption kinetic data suggest that pseudo-second order model represents data more appropriately. Moreover, consideration of intraparticle diffusion model suggested that both film diffusion and pore diffusion phenomenon dictate the adsorption process. The equilibrium isotherm data agrees well with Freundlich model and the highest adsorption capacity of the synthesized MOF for removal of tartrazine was found to be 309.2 mg/g at 323 K. Thermodynamic parameters like change in free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) were also calculated and it was observed that the sorption process was spontaneous and endothermic in nature. Desorption study recommended that the regenerated adsorbent can be effectively used without significant loss in adsorption capacity upto five cycles.

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