Figure 6 DFT calculations of PMS activation and durability of SA-Cu-NC (A 1 , B 1 ) The configuration models of Cu-N 4  and Cu-N 2 . (A 2 , B 2 ) Two-dimensional valence-electron density images of Cu-N 4  and Cu-N 2 . (A 3 , B 3 ) PMS adsorption model on Cu site of Cu-N 4  and Cu-N 2 . (A 4 , B 4 ) PMS adsorption model on C site of Cu-N 4  and Cu-N 2 . (C) Effect of inorganic anions and humic acid on BPA degradation in the SA-Cu-NC+PMS system. (D) Kinetics of BPA degradation with various actual water systems in the SA-Cu-NC+PMS system. Reaction conditions: [catalyst] = 0.04 g L −1 , [BPA] 0  = 50 μM, [PMS] 0  = 1.0 mM, [anions] 0  = 10 mM, [HA] 0  = 10 mg (if any), initial pH = 5.8, Temp = 30°C. (E) BPA concentration in a continuous-flow reactor consisting of SA-Cu-NC filled column. Reaction conditions: [catalyst] = 50 mg, [BPA] 0  = 50 μM, [PMS] 0  = 1.0 mM, flow rate = 0.3 mL min −1 .