An easily-synthesized low carbon ionic liquid functionalized metal-organic framework composite material to remove Congo red from water

Congo red (CR) is documented as a typical azo dye compound that is widely used for industrial activities such as papermaking, textiles, leather and additives production, making it a main component of COD contaminants in industrial wastewaters. Excessive releases of CR have resulted in adverse impacts on water environments and ecological systems due to its non-biodegradable, toxic and carcinogenic properties. Therefore, the removal of CR from water environments is of important for wastewater treatment. Previous studies have proved that metalorganic frameworks (MOFs) were feasible for CR adsorption, but less stable in water environments. Several functionalized materials have therefore been used to produce MOF-derived composite material for better performance. To simplify the synthesis processes and reduce the energy consumption, an ionic liquid (IL) was used in this study for the synthesis of [BMIM][PF 6 ]/ZIF-8 (BP/Z) composite material. The morphological structure of this material remained stable after the incorporation of IL. The equilibrium time of CR adsorption was 90 min with a maximum adsorption capacity of 1463 mg/g. Isotherm and kinetic studies revealed that the adsorption process was better described by Langmuir and pseudo-second-order model. Our results also presented that the IL/MOF composite material can be used within pH 5 and 6 with the presence of Na+, K+, Mg2+, Ca2+, Cl- and SO4 (2-). It was also proved that the novel IL/MOF composites in this study have great potential to adsorb and remove organic dyes from water.