Controlled synthesis of ZIF-11 with varied particle size: Effective adsorbent for industrial pollutants and host for storages of gaseous CO2, H2 and CH4

Abstract

The present work focuses on the controlled synthesis of ZIF-11 at various temperatures to get different particle sizes having improved surface area and porosity for the storage of CO2/CH4/H2 gases and as an adsorbent for industrial pollutants. Toluene assisted method was employed to synthesize ZIF-11 samples at various temperatures such as 10, 20, 40, 60, 80 and 100 °C and characterized by various spectroscopic techniques and tools. The Brunauer-Emmett-Teller analysis demonstrates that ZIF-11 synthesized at 10 °C (Z10) has highest surface area (1408 m2/g) while that at 100 °C (Z100) has lowest surface area (1027 m2/g). The surface area of ZIF-11 decreases with an increase of the reaction temperature, which may be due to fact that low nucleation rate at lower temperature gives more ordered crystals of ZIF-11. Due to the highest surface area, sample Z10 has been applied for the storage of CO2/CH4/H2 gases; Z10 exhibits 6.49 wt% uptake for CO2(g) and 0.91 wt% for CH4(g) (at 273 K, up to 1 bar), similarly for H2(g) 1.26 wt% uptake is observed at 77 K. Moreover, all samples of ZIF-11 (Z10, Z20, Z40, Z60, Z80 and Z100) have also been explored for the adsorption of congo red (CR) dye. Among them, Z10 shows excellent adsorption ≈100 % of [CR] = 50 ppm dye solution at pH 7.8, and is reusable up to five cycles.