Development and Optimization Synthesis of MIL-101(Cr) by Ultrasound Irradiation Using Response Surface Methodology

MIL-101(Cr) stands as one of the extensively researched chromium-based metal–organic frameworks, comprised of chromium metal ions and terephthalic acid ligands. This study introduces an innovative approach to MIL-101(Cr) synthesis by employing ultrasound (UTS) irradiation. Our primary objective revolved around optimizing key operational parameters, namely time and temperature, using the central composite design method. Subsequently, we conducted an in-depth analysis using variance analysis to understand their respective impacts. To predict process behaviour, we developed quadratic equations under varying conditions, achieving a remarkable R2 value of 0.9998 to relate parameters and synthesis yield. Results revealed a more pronounced influence of time variation compared to temperature on the synthesis process. Moreover, we subjected the synthesized MIL-101(Cr) to rigorous characterization using FT-IR, XRD, SEM, TGA, and N2 physisorption techniques. Our findings showcased the synthesized MIL-101(Cr) possessing exceptional characteristics, including an ultra-high specific surface area (2143 m2. g-1), substantial pore size (0.8 cm3.g-1), and excellent thermal, chemical, and water stability. Further examination indicated the presence of microporous windows, mesoporous cages, and uniform octahedral particles ranging in size between 125-260 nm.Notably, our study emphasized the energy efficiency of UTS irradiation over conventional electric (CE) heating, highlighting its potential as a quicker, more efficient, and environmentally friendly alternative to conventional synthesis methods.