Theoretical study of the interactions between demetallization agent and Ni/V porphyrins and the removal under microwave irradiation

•The S atom in the demetallization agent binds to the metal in metalloporphyrin.•Demetallization agent and metalloporphyrin with 1:1 mol ratio presents better.•Electric field can shorten the S…M bond, facilitating metal removal.•Interaction between demetallization agent and vanadium porphyrins is stronger.•Optimum electric field is proposed to achieve better metal removal efficiency.