Graphene oxide assisted ZIF-90 composite with enhanced n-hexane vapor adsorption capacity, efficiency and rate

Highlights: • Larger pore diameter and smaller particle size of ZIF-90 was synthesized by reflux method. • The adsorption efficiency and rate of mesoporous ZIF-90 for n-hexane vapor was up to 99% and 0.53 mg g^-1s^-1separately. • The novel composites ZIF-90/GO were first synthesized successfully. • The adsorption capacity and rate of ZIF-90/GO for n-hexane vapor was increased by 72% and 11%, respectively. • The higher adsorption efficiency (106%) of ZIF-90/GO was detected due to its excellent thermal conduction performance. -- Abstract: Zeolitic imidazolate framework-90 (ZIF-90) synthesized by solvothermal method reveals large BET surface area and high n-hexane vapor adsorption capacity. However, the adsorption rate and efficiency for n-hexane vapor are far from expectation, which affect the industrial applications. Thus, a green and efficient method using triethylamine (TEA) was developed to prepare a new ZIF-90 with large pore diameter to increase the adsorption rate and efficiency dramatically. Notably, the average pore diameter of the new ZIF-90 was up to 3.66 nm, which was more than twice larger than that reported one using previous method. On the other hand, the resulting samples with larger pore limited the adsorption capacity for n-hexane vapor. Therefore, graphene oxide (GO) was further employed as filler to modify the ZIF-90 based on its high BET surface area and thermal conductivity. The resulting ZIF-90/GO composite with both higher adsorption capacity and rate for n-hexane vapor was optimized, which was 72% and 11% higher than that of the pristine ZIF-90, respectively. More importantly, the ZIF-90/GO composite possessed a more stable structure for n-hexane vapor adsorption, which endowed it a potential prospect in the purification field.