Synthesis and Application of Cobalt-based Metal-organic Framework for Adsorption of Humic Acid from Water

In this study, the adsorption of humic acid on cobalt based metal-organic framework (Co-MOF) was investigated. Co-MOF was synthesized via solvothermal technique and further characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The characterization results of material confirm the formation of MOF structure. The adsorption kinetics, isotherms, thermodynamics, as well as isosteric heat of adsorption were also investigated by obtaining experimental adsorption data through batch experimentation. Optimum adsorption uptake of ~91 mg g^–1 was attained at pH 6 and 305 K. Regression analysis of experimental results revealed that adsorption kinetics follows a pseudo-second-order kinetic model, and adsorption can reach equilibrium at ~20 min. Adsorption isotherm data can be well fitted with Koble Corrigan isotherm. Thermodynamic parameters demonstrated that the adsorption of humic acid is a spontaneous, endothermic, and physical process, while isosteric heat evaluations revealed the heterogeneous nature of the adsorbent. Overall, the Co-MOF was a promising choice to adsorb humic acid from water.