Environmental photochemistry in hematite-oxalate system: Fe(III)-Oxalate complex photolysis and ROS generation

• Published in: Applied catalysis. B, Environmental Vol. 283; p. 119645
• Main Authors: Xu, Tianyuan, Fang, Yumin, Tong, Tianyi, Xia, Yabei, Liu, Xiao, Zhang, Lizhi
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.04.2021; Elsevier BV
• Subjects: Carbon dioxide; Charge transfer; Decontamination; Hematite; Interfacial reaction; Iron; Liquid-solid interfaces; Mineralization; Oxalate; Oxalates; Oxalic acid; Oxides; Photochemicals; Photochemistry; Photodegradation; Photodissociation; Photolysis; Reaction mechanisms; Reactive oxygen species; Sulfadimidine; Hematite; Reactive oxygen species; Photodissociation; Interfacial reaction; Oxalate
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2020.119645

[Display omitted] •The interactions between Ox and Ht are investigated by in-situ ATR-FTIR.•Fe(III)-Ox complex photolysis is first proved to follow photodissociation mechanism.•No electrons transfer between Fe(III) and Ox during Fe(III)-Ox complex photolysis.•Per Fe(III)-Ox complex generates two CO2− radicals in Ht-Ox system.•More O2− and OH are produced in Ht-Ox than that in Fe3+-Ox homogeneous system. Oxalates, together with iron (hydr)oxides, play important roles in environmental decontamination by photochemical generation of reactive oxygen species (ROS). However, comprehending reaction mechanism about photolytic behaviors across solid-liquid interface is scarce. Here, the photochemical properties of hematite-oxalate system were investigated from complexation, photolysis, and ROS generation tests. Results implied adsorbed oxalate on hematite surface was detached via non-reductive dissolution by irradiating light. Then, the photolysis of Fe(III)-oxalate complexes on hematite surface or dissolved in solution was followed by photodissociation mechanism, in which per Fe(III)-oxalate complex led to two CO2− formation. Moreover, O2−/OOH and OH amounts induced by photodissociation mechanism were much higher than that by classic intramolecular ligand-to-metal charge transfer mechanism in Fe3+-Ox homogeneous system. The photo-degradation and mineralization of sulfadimidine (5 mg/L) reached 95 % and 59 % within 2 h using hematite-Ox system. These findings can help in implementing environmental remediation by utilizing iron (hydr)oxides and oxalate in natural environment.