Equilibrium, kinetics and thermodynamics studies on adsorptive removal of cobalt ions from wastewater using MIL-100(Fe)

This study describes experiments in which MIL-100(Fe) was used to remove Co2+ ions from the waste water. The synthesised adsorbent was characterised by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction, Brunauer-Emmett-Teller (BET) and scanning electron microscope. Statistical analysis was used to investigate the effects of different parameters. From the obtained results, the removal efficiency was enhanced with increasing contact time and pH but decreased with increasing cobalt initial concentration. The maximum removal efficiency of Co+2 was 93.4% under optimum conditions. The equilibrium adsorption data were best fitted to linearly transformed Freundlich isotherm. Adsorption kinetic data followed the pseudo second-order kinetic model. The maximum adsorption capacity of Co+2 on to the MIL-100(Fe) was found to be 119 mg g(-1). The results showed that Delta G of adsorption was negative, while Delta H was positive which showed that the adsorption process was spontaneous and endothermic. The positive value of Delta S showed that disordering and randomness increased at the solid-solution interface of cobalt ions with MIL-100(Fe) particles.