Enhanced adsorption of methylene blue and congo red from aqueous solutions by MCM-41/HKUST-1 composites

Abstract

Impregnation of mesoporous silica MCM-41 on metal organic framework type HKUST-1 or often called CuBTC (BTC = 1,3,5- benzenetricarboxylate) has been successfully carried out by solvothermal methods in a solvent mixture of water, ethanol and N,Ndimethylformamide (DMF). The XRD patterns of the obtained solids showed that MCM-41/HKUST-1 composites had the same crystalline phase as pure as HKUST-1. SEM images revealed that the impregnation of the mesoporous silica to HKUST-1 did not alter the surface morphology of the original HKUST-1, which had octahedral shapes. In addition, the thermal stability of the MCM-41/HKUST-1 composites reached 302 °C, increased by 292 °C in comparison to the HKUST-1, even though the impregnation process resulted in a decreased in the specific surface area of the composites. Furthermore, MCM-41/HKUST-1 composites showed outstanding performance as adsorbent of methylene blue and Congo red in aqueous solutions. Results of adsorption studies showed that a pseudo-second order kinetics and Langmuir isotherm were observed for both types of dyes.