Highly efficient unsymmetrical dimethylhydrazine removal from wastewater using MIL-53(Al)-derived carbons: Adsorption performance and mechanisms exploration

Abstract

In this study, novel MOF-derived porous carbons (C@Al2O3s) with high adsorption capacity for unsymmetrical dimethylhydrazine (UDMH) were synthesized via a solvothermal and carbonization method using MIL-53(Al) as precursors. The MOF-derived carbon prepared at 1000 °C (C@Al2O3-1000) had a higher specific surface area and mesoporous surface area (267.18 m2/g, 131.96 m2/g) compared to nanoparticles carbonized at 600 °C (207.74 m2/g, 119.99 m2/g) and 800 °C (236.31 m2/g, 123.02 m2/g). The UDHM adsorption of C@Al2O3s followed the pseudo-second-order kinetics model and the Langmuir isotherm model. The maximum adsorption capacity for UDMH of C@Al2O3-1000 reached 275.93 mg/g, which was the highest among the reported UDMH adsorbents so far. Adsorption thermodynamics calculations showed that the UDHM adsorption by C@Al2O3s was a thermodynamically favorable process. Besides, C@Al2O3s had wide pH adaptability (pH = 4–12) and good resistance to ionic strength, humic acid, and water qualities. C@Al2O3-1000 exhibited excellent recyclability and removal efficiency after eight adsorption-desorption cycles. Further characterizations and discussions concluded that the UDMH adsorption performance of C@Al2O3-1000 mainly depended on the electrostatic interaction, hydrogen bonding, and hierarchical porous structure.