Nanoporous composites of activated carbon-metal organic frameworks for organic dye adsorption: Synthesis, adsorption mechanism and kinetics studies

Abstract Activated carbon (AC) is an inert adsorbent material that has widely been used in water treatment or removing of environmental pollutants from water. In order to improve the adsorption of AC, which highly depends on its pore size and surface area, we prepared highly porous adsorbent composites of activated carbon (AC)/chromium-based MOF (MIL-101(Cr)). The composite has a high specific surface area of 2440 m2 g−1 and total pore volume of 1.27 cm3 g−1. To show the efficiency of the composite as an adsorbent, the removal kinetics of anionic dyes (Direct Red 31 and Acid Blue 92) from aqueous solutions dependent on the amount of composite, adsorption time, concentration of dye and pH is demonstrated. It is shown that the kinetics of organic dye removal by AC@MIL-101(Cr) composite is faster than MIL-101(Cr) under near neutral pH conditions. The half-time of removal is about 3 min while about 85% of the dye is removed after 5 min. This study provides new idea into the design and synthesis of highly efficient nanoporous adsorbent based on MOFs for removal of pollutants as well as organic dyes from wastewater.