Peroxydisulfate activation by photo-generated charges on mesoporous carbon nitride for removal of chlorophenols

Photogenerated charges were found to involve in activation of peroxydisulfate (PDS) on mesoporous carbon nitride (MCN) with Lewis basic sites under visible light irradiation. Photogenerated hole (h+), superoxide radical (O2 center dot- ) and singlet oxygen (1O2) were verified as the most important active species for 2,4,6-trichlorophenol (TCP) removal. Lewis basic sites of MCN induced the interface hydrolysis of PDS to produce hydroperoxyl anions (HOO- ) and peroxide ions (O22- ), which was further reacted with h+ to generate O2 center dot- and 1O2 predominantly. The efficiently separated electron (e- ) was responsible for the nucleophilic attack toward the C-Cl bond of TCP. Moreover, the electrical energy per order (EEO) of vis/MCN/PDS (3.75 x 106 kW h m- 3 order- 1) was an order of magnitude lower than that of UV/PDS (3.14 x 107 kW h m- 3 order-1). This work highlighted the metalfree MCN with Lewis basic sites as a photocatalyst to activate PDS and elucidated a new strategy of PDS activation for chlorophenol pollutants removal.

Automated summary

Photogenerated charges are involved in activating peroxydisulfate (PDS) on mesoporous carbon nitride (MCN) with Lewis basic sites under visible light irradiation, producing important active species for the removal of 2,4,6-trichlorophenol (TCP). The Lewis basic sites of MCN induce PDS interface hydrolysis, generating hydroperoxyl anions and peroxide ions that react with photogenerated holes to produce superoxide radicals and singlet oxygen. The separated electrons are responsible for attacking the C-Cl bond of TCP, with a lower electrical energy per order for vis/MCN/PDS compared to UV/PDS.