Room-temperature synthesis of hydrophobic/oleophilic ZIF-90-CF3/melamine foam composite for the efficient removal of organic compounds from wastewater

To overcome the shortage of conventional synthetic methods, such as long reaction time at high temperature and pressure (HTP) or poor performance at room temperature and pressure (RTP), a facile and economical strategy was employed to prepare high-performance ZIF-90 for the first time at RTP only by adding triethylamine (TEA). Herein, we successfully prepared ZIF-90 nanocrystals by a two-step stirring method within several minutes (5-30 min) and their structure parameters (e.g., BET surface areas, 916-1235 m(2).g(-1)) were also tuned simultaneously, which were much better than reported samples prepared at RTP. Afterwards, by changing functional ligands, hydrophobic ZIF-90-CF3 with low surface energy was also designed. With the ligand side of aldehyde (-CHO) and trifluoromethyl (-CF3) groups on ZIF-90 and ZIF-90-CF3, the water vapor uptakes and adsorption heats decreased from 7.9 to 0.79 mmol.g(-1) and 20.6 to 2.6 kJ.mmol(-1), respectively. Additionally, a shaped ZIF90-CF3/melamine foam (MF) composite with both hydrophobic and oleophilic properties exhibited extraordinary organic compounds (OCs)-water separation ability, including a high adsorption capacity (40.1-108.7 g.g(-1)) towards various OCs. Furthermore, owing to its excellent compressibility and mechanical stability, the ZIF-90CF(3)/MF composite can be regenerated by slightly squeezing the adsorbed OCs, indicating the potential for possible commercialisation of the derived MOF/MF composites for the efficient purification of wastewater.

Automated summary

A new method was employed to prepare high-performance ZIF-90 nanocrystals at room temperature and pressure by adding triethylamine, successfully tuning their structure parameters. Additionally, a hydrophobic ZIF-90-CF3 was designed to reduce water vapor uptake and adsorption heat, showing high adsorption capacity towards OCs. The ZIF-90CF(3)/MF composite demonstrated excellent OCs-water separation ability, compressibility, and mechanical stability, with potential for commercialization in wastewater purification.