3.1 Characterization of membrane adsorber
In order to demonstrate the successful assembly of HP-HKUST-1 in the pores of the PES membrane, the membrane adsorber with HP-HKUST-1 is characterized. Figure 3(A) shows the XRD spectra of membrane adsorber with HP-HKUST-1 immobilized, which are consistent with the simulation results. The results indicated that HP-HKUST-1 has been successfully immobilized in membrane pores. Besides, no difference of the XRD pattern between the HKUST-1/PES membrane and HP-HKUST-1/PES membrane implied that the addition of organic amine does not affect the crystal structure of HP-HKUST-1. It can be seen that the peak intensity of HP-HKUST-1/PES membrane is not as strong as that of HKUST-1/PES membrane, since the effect of organic amines and lattice defects may lead to the reduced crystallinity of HP-HKUST-1. From the TGA results as shown in Figure S1 , it can be also seen that compared with HKUST-1/PES membrane, an additional weight loss in the range of 170-270 °C for HP-HKUST-1/PES membrane owing to the removal of the ligand N,N,N,N-tetramethylhexanediamine. This phenomenon implied that the introduction of organic amines during the process of immobilizing HP-HKUST-1 is successfully. The FTIR characteristics of membrane adsorber with HP-HKUST-1 immobilization are shown in Figure 3(B) . It can be seen that the antisymmetric stretching vibration absorption peak of the carboxylate appears at 1577 cm-1, the symmetric stretching vibration absorption peaks of the carboxylate appears at 1442 and 1364 cm-1, and the stretching vibration absorption peak of Cu-O bond appears at 762 cm-1. It is worth mentioned that the absorption peak of Cu-N bond at 431 cm-1 may be difficult to distinguish due to the coverage by the out-of-plane wobble vibration absorption peak of COO-, etc. as well as its weak spectral absorption peak25. The XPS characteristics of membrane adsorber with HP-HKUST-1 immobilized are shown in Figure 3 (C, D) . Compared with HKUST-1/PES membrane, a new Cu-N characteristic peak appears at 401.9 eV and the peak of N 1s orbital belonging to Cu-N shifts 0.4 eV to the high binding energy for the HP-HKUST-1/PES membrane, as shown in Figure 3C. Besides, the peak of Cu 2p3/2 orbital shifts 0.7 eV to the low binding energy, as shown in Figure 3D . These phenomena implied that HP-HKUST-1 has been successfully immobilized in PES membrane pores.