Relative Empirical Evaluation of the Aqueous Sequestration of Methylene Blue Using Benzene-1,4-dicarboxylic Acid-Linked Lanthanum and Zinc Metal Organic Frameworks

摘要

Two metal-organic frameworks (MOFs), lanthanum- 1,4-benzene dicarboxylate (LaBDC) and zinc-1,4-benzene dicarboxylate (ZnBDC) were synthesized via the reflux-controlled solvothermal process. The characterization of both adsorbents confirmed the physicochemical properties of well-defined surface morphology with high porosity and thermal stability greater than 450 ℃. Adsorption of methylene blue (MB) using both MOFs showed that the rate of MB removal reached equilibrium at 120 and 30 min for LaBDC and ZnBDC, respectively. The MB adsorption was pH dependent with optimum adsorption at pH 12, and the adsorption data trend fitted the fractal pseudo-second-order model (FPSOM), Langmuir and Freundlich adsorption isotherm models, and MB adsorption capacities of LaBDC and ZnBDC are 35.0 and 55.0 mg/g, respectively. The process is physisorption, spontaneous, and feasible. The ZnBDC MOF had a better potential for the removal of MB from an aqueous solution than LaBDC. Both MOFs have the potential to sequester MB from aqueous phases but can be enhanced for better performance.