The desulfurization performance and mechanisms of mesoporous g-C3N4 as adsorbent in iso-octane solutions are presented. Mesoporous g-C3N4 was synthesized at 600 degrees C with a hard-template method using three types of silica-gels as template agent. XRD diffraction patterns show the interlayer distances of g-C3N4 are enlarged due to the intercalation of H+. The as-prepared adsorbents possess a large sulfur capacities and excellent selective adsorption for thiophene in a benzene/iso-ocatane mixed solution. TPD and regeneration experimental tests demonstrate that the larger sulphur-capacities could attribute to H+-intercalation. The adsorptive mechanisms of the thiophene over mesoporous g-C3N4 are interpreted by a novel donor-acceptor (D-A) interaction, where the donor is the S-atom of thiophene and the acceptor is the C-atoms in g-C3N4 . Gaussian computation indicates the ortho-C atoms of N-atoms bonded with Fr are the main active sites for D-A interactions. (C) 2018 Elsevier B.V. All rights reserved.