Metal-free photo-activation of peroxymonosulfate using graphene supported graphitic carbon nitride for enhancing photocatalytic activity

[Display omitted] •Graphitic carbon nitride based metal-free photocatalyst was fabricated.•The peroxymonosulpahte activation enhanced photocatalytic process.•SO4•− formation enhanced the malathion degradation.•The photocatalyst exhibited significant bacterial disinfection. In this work, graphene supported graphitic carbon nitride (g-C3N4, GCN) photocatalyst was used for photo activation of peroxymonosulfate (PMS) oxidant. Coupling with graphene (Gr) upgraded photocatalytic performance of g-C3N4 (GCN), as graphene increased surface area, acted as a sink/support material and reduced charge carriers recombination. PMS assisted photodegradation processes had superior malathion pesticide degradation efficiency in 5 h. Peroxymonosulfate activation by graphene supported graphitic carbon nitride (Gr/GCN/PMS) exhibited higher malathion degradation than other photocatalysts and followed the removal order: 94% (Gr/GCN/PMS) > 72% (Gr/GCN) > 65% (GCN/PMS) > 45% (GCN) > 30% (Gr). Likewise, 94% removal of Escherichia coli (E. coli) was observed by Gr/GCN nanocomposite in 6 h under visible light. Scavenging studies confirmed the important role of holes (h+), hydroxyl (•OH) and superoxide (SO4•−) radicals in photodegradation processes which was further validated by possible mechanism.