Figure 7. Interaction energy between
NO3- and N atom of quaternary ammonium
group at different relative positions (a). Nitrate positions during
removal categorized by total interaction potential (b). Van der Waals
and electrostatic interaction energy between nitrate and MHC (c). Number
of H bonds between NO3- and
coordinating water molecules during removal process (d). Snapshots of
nitrate removal pathway by quaternary ammonium groups (e). O, red; N,
dark blue; H, gray; C, green. Methyl group C atoms on quaternary
ammonium N atoms in (a) were highlighted in light blue.