3.2 Improved adsorption performance
The adsorption performance of membrane adsorber with CR and MB, as well as its kinetic parameters are shown in Figure 6 . The specific details of the kinetic model parameters are illustrated in Table S1 . It can be seen that compared with the HKUST-1 powder, the adsorption capacity and the adsorption rate of the HP-HKUST-1 powder for CR and MB can be increased obviously. Specifically, for the HP-HKUST-1 powder, the adsorption capacity (qt ) for CR with 458 mg g-1 and for MB with 227 mg g-1 can be achieved within 70 min. However, for the HKUST-1 powder, the adsorption capacity for CR with only 155 mg g-1 and for MB with only 90 mg g-1can be achieved within 70 min. Compared with the HKUST-1 powder , the equilibrium adsorption capacity (qe ) for both CR and MB can be increased about three times by the HP-HKUST-1 powder. In term of the adsorption rate constant (k2 ), the value can be increased about twice for both CR and MB adsorption. The increase of the adsorption capacity can be attributed to the increase of the adsorption active sites after the mesopores introduced into HKUST-1. The adsorption by HKUST-1 for CR and MB is mainly based on the formation of hydrogen bonds between the open oxygen active sites and the adsorbate, the superposition of van der Waals forces, electrostatic forces, π-π bonds, as well as the coordination bonds between the unsaturated metal copper ion active sites of HKUST-1 and the adsorbates, as shown in Figure 7 28. The surface area of the HKUST-1 can be increased after the introduce of the mesopores in HKUST-1, leading to the increase of adsorption amount for CR and MB owing to van der Waals forces and electrostatic forces. More unsaturated metal active sites and oxygen active sites can be exposed as mesopores introduced into HKUST-1, leading to an additional adsorption amount owing to hydrogen bonds and coordination bonds as shown inFigure 7 . Specifically, for CR adsorption, more unsaturated Cu2+ are appeared as lattice vacancies generated in the topological structure of HP-HKUST-1, leading an additional adsorption interaction produced by coordination bond between Cu2+ and the N and O atoms of CR set off. Besides, the interaction of electrostatic forces between Cu2+ and the -SO3- of CR can be enhanced as a lager surface area of HP-HKUST-1. Moreover, the interaction of π-π bonds can be also enhanced since volume-filling adsorption can occur during the adsorption of HP-HKUST-1 in addition to monolayer and multilayer adsorption with the introduce of mesopores29. For MB adsorption, coordination bond between Cu2+ and the N atoms of MB will occur with the introduce of mesopores. In addition, the interaction of π-π bonds can be enhanced for the reason of volume-filling adsorption.