Unravelling the sorption mechanism of two organic dyes (Indigo Carmine and Orange II) onto Al-Fum MOF: Kinetic and isotherm scrutinization

This study aims to synthesize and characterize a fumarate-Al-based Metal-Organic Framework (Al-Fum MOF) to evaluate its adsorption properties towards two organic dyes, namely: Indigo Carmine (IC) and Orange II (OII). The Al-Fum MOF was synthesized by a non-solvothermal method and characterized by XRD, FTIR, EDX, TGA, N 2 sorption and pH PZC . The results of this work show that the pseudo-second-order model better describes the adsorption process for both dyes. The plausible mechanisms reveal a duality between the physisorption phenomenon and physicochemical interactions, the latter being predominant. The optimal conditions for adsorption were determined using centered composite experimental designs, resulting in error percentages below 2 %: for IC (pH 3, concentration of 84.7 mg/L and adsorbent mass of 25 mg) and for OII (pH 3, concentration of 100 mg/L and adsorbent mass of 25 g). The adsorbed amounts were 33.8 and 22.9 mg/g for IC and OII, respectively. The regeneration of Al-Fum MOF was studied and the results suggest that the material can remain active during several use cycles. This study contributes to the advancement of knowledge on adsorbent materials for wastewater treatment and highlights the potential of Al-Fum MOF for practical applications. However, further studies are needed to evaluate the application of Al-Fum MOF to real and complex wastewater.