Investigation on open water adsorption performance of multi-walled carbon nanotubes modified MIL-96(Al)

Abstract

An aluminum-based metal-organic framework material MIL-96(Al) was prepared by solvent-thermal synthesis method, and by adding multi-walled carbon nanotubes (MWCNTs) in the preparation process, MWCNT/MIL-96(Al) composite adsorbent was synthesized for the first time. The morphology of the adsorbents was discussed by scanning electron microscopy (SEM). In adsorption experiments under different working conditions, MIL-96(Al) exhibited a stable equilibrium adsorption capacity, while the addition of only 0.50% mass fraction of multi-walled carbon nanotubes increased equilibrium adsorption capacity by approximately 30%. The enhancement ratio of six composite adsorbents compared to MIL-96(Al) in equilibrium adsorption capacities was almost constant under different working conditions. The adsorption rate of MIL-96(Al) could reach up to 0.573 g g−1 h, while that of the composite adsorbents under the same conditions was 0.763 g g−1 h. MIL-96(Al) could be completely desorbed within 40 min at 110 °C, and the optimal desorption temperature of MWCNT/MIL-96(Al) was reduced to 100 °C. The cyclic stability of the seven adsorbents was also confirmed through cyclic regeneration experiments. The experimental results indicated that the MWCNT/MIL-96(Al) composite adsorbent was a potential adsorbent for solar-driven atmospheric water harvesting in arid regions.