Facile Synthesis of Hierarchically Structured MIL-53(Al) With Superior Properties Using An Environmentally-Friendly Ultrasonic Method For Separating Lead Ions From Aqueous Solutions

The present study aims to investigate novel ultrasonic synthesized MIL-53(Al) and its applications in adsorption. Both conventional and ultrasonic methods were used to synthesized Mil-53(Al). The ultrasonic-assisted synthesis procedure results in reducing synthesis time to 24 hours; however, Compared to that conventional method takes 3 days to create the framework. Applying ultrasonic waves also increases surface area to 50% more than the ones synthesized by the conventional method, as well as creating the hierarchical MIL-53(Al) structure (meso- and micro-) pores. To this end, XRD, FESEM, BET, and FTIR analyses were employed to identify and characterize MIL-53(Al). The unique structure and high MIL-53(Al) yield lead to effective adsorption among MOF and lead ions. The optimum conditions for removing lead were 6.0 pH, 20 mg/l concentration, 60.0 min contact time, 0.04g adsorbent dose, and 318k temperature with 97.63% removal of the lead ions. The experimental adsorption equilibrium and kinetic data fitted the Langmuir isotherm and pseudo-second-order kinetic models, respectively. Moreover, the use of ultrasonic synthesized MIL-53(Al), for the first time as a novel adsorbent in heavy metal removal, pointed to the great potential of this new environmentally-friendly adsorbent in removing lead ions from aqueous solutions.