Morphology control synthesis of Cr-benzenedicarboxylate MOFs for the removal of methylene blue

Propionic acid could efficiently affect the formation of Cr-benzenedicarboxylate metal-organic frameworks (MOFs), giving rise to yielding products with various structures. Generally, nano-sized crystals of MIL-101(Cr) can be prepared with comparatively lower concentration of propionic acid (0.6 ​M), which possessed high porosity (SBET ​= ​2720 ​m2/g). The hierarchically porous (HP) MIL-101(Cr) was obtained with medium concentration of propionic acid (1.2 ​M), and micro-rod like crystals of MIL-88B(Cr) was formed in high concentration of propionic acid (1.8 ​M). Compare to bulk MIL-101(Cr) and nano-sized MIL-101(Cr), HP-MIL-101(Cr) showed much higher uptake of methylene blue (119.1 ​mg/L) in aqueous. This approach can offer a facile and effective pathway to synthesize stable hierarchically porous Cr-benzenedicarboxylate MOF for the applications in pollutant treatment fields.