A MIL-101 Composite Doped with Porous Carbon from Tobacco Stem for Enhanced Acetone Uptake at Normal Temperature

A high-efficiency adsorbent for acetone under normal temperature was prepared with metal-organic framework MIL-101 doped with porous carbon from tobacco stem (MIL-101/TC) by a solvothermal synthesis method. These synthesized composites were characterized and then investigated for acetone adsorption at 288 and 298 K up to 20 kPa. The isosteric heat of adsorption was estimated from adsorption isotherms of acetone vapor. Temperature programmed desorption (TPD) was employed to calculate the activation energies of acetone desorption on MIL-101/TC and MIL-101. Results of characterization showed that MIL-101/ TC possessed crystal structure and morphology similar to those of MIL-101. Despite the smaller BET surface area, MIL- 101/TC-40 and MIL-101/TC-30 composites had much higher acetone uptakes of 1137 and 1123 mg/g at 18.9 and 18.1 kPa in 288 K, respectively, which increased by 19.8% and 18.3% compared with those of MIL-101 composites. The increase in acetone uptakes was attributed to the associative effect of the enhancement of the surface dispersive forces and the activation of the unsaturated metal sites by TC loading. The isosteric heat of acetone adsorption on MIL-101/TC was much higher than that on MIL-101, and the maximum isosteric adsorption heat on MIL-101/TC-40 was 52 kJ/mol. The activation energy of desorption obtained through TPD ranged from 24.5 to 48.5 kJ/mol. The acetone adsorption isotherms of the composites could be fitted favorably by the L-F and DSLF equations.