MIL-Ti metal-organic frameworks (MOFs) nanomaterials as superior adsorbents: Synthesis and ultrasound-aided dye adsorption from multicomponent wastewater systems

Herein, 1,4-benzenedicarboxylate (BDC) and 2-amino-1,4-benzenedicarboxylate (NH2-BDC) as organic linkers and tetraisopropyl orthotitanate as a metal source were used to synthesize several metal-organic frameworks (MOFs) nanomaterials. Five Materials Institut Lavoisiers (MILs) as MOFs include MIL-125(Ti), NH2-MIL-125(Ti) and three MILs with different organic linkers molar ratios (BDC/NH2-BDC: 75/25, 50/50 and 25/75 denoted as MIL-X1, MIL-X2 and MIL-X3, respectively). The synthesized nanomaterials were used for ultrasound-aided adsorption of cationic dyes (Basic Red 46 (BR46), Basic Blue 41 (BB41) and Methylene Blue (MB)) from single and multicomponent (binary) systems. The BET, XRD, FTIR, SEM, TEM, TGA and zeta potential were used for characterizing the MILs. Dye removal followed pseudo-second order kinetics with constant rate of 0.20833, 0.00481 and 0.00051 mg/g min for BR46, BB41 and MB, respectively. In addition dye adsorption obeyed the Langmuir isotherm model and the experimental dye adsorption capacity for BR46, BB41 and MB was 1296, 1257 and 862 mg/g, respectively. The synthesized MIL showed high reusability and stability over three cycles. The adsorption thermodynamics data presented that dye removal was a spontaneous, endothermic and physical reaction. The free Gibbs energy for dye removal by the NH2-MIL-125(Ti) at 308K was −19.424, −15.721 and −17.413 kJ/mol for BR46, BB41 and MB, respectively.