Dual hydrophobic modification on MIL-101(Cr) with outstanding toluene removal under high relative humidity

The volatile organic compounds (VOCs) removed in the presence of atmospheric moisture using metal-organic framework (MOF) MIL-101(Cr) powder had been grievously restricted by the need for powder shaping and poor moisture stability. In this study, a dual modification was employed to conquer these issues. We firstly crystallized MIL-101(Cr) on the inner surface of amine grafting macroporous polyacrylate (PA-NH2) spheres using an in-situ confined growth strategy. The average size of MIL-101(Cr) crystals decreased by 15 times by reducing the nucleation energy barrier through high surface energy induced by interface engineering and enrichment of precursor solution on the interior surface with nanoscale roughness of carrier. Further hydrophobic composite P-MIL-101(Cr)@PA-NH2 was subsequently empoldered with the adoption of chemical vapor deposition (CVD) by polydimethylsiloxane (PDMS). The static adsorption capacity of water on P-MIL-101(Cr)@PA-NH2 was greatly diminished by 87.39 %, which was attributed to the change in the way of clustering of water molecules. The breakthrough results of competitive adsorption also showed that the working capacity of hydrophobic composites was 6.3 times that of the pristine MIL-101(Cr) powder under the conditions of 1000 mg/m3 toluene and 50 % RH, while maintaining 81.1 % of the original adsorption capacity after being exposed to the humid atmosphere for 30 days, showing excellent structural stability and outstanding adsorption performance. The brilliant performance of the present adsorbent made it promising for practical application in VOC capture.