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Lanthanum orthoferrites are a versatile class of catalysts. Here, the photocatalytic bactericidal performance of LaFeO3 (LF) to inactivate pathogenic microorganisms, i.e., Escherichia coli (E. coli), in water under simulated solar irradiation conditions was investigated. Various competing and contributing factors were covered to visualize the reaction medium consisting of E. coli K12 cells, organic sub-fractions formed by cell destruction, and LF surface. LF solar photocatalytic inactivation (SPCI) kinetics revealed the highest inactivation rate in ultrapure water as expected, followed by distilled water (DW), aqueous solution containing anions and cations (WM) and saline solution (SS). Characterization of the released organic matter was achieved by UV-vis and fluorescence spectroscopic techniques as well as organic carbon contents (DOC). Upon SPCI, significant amounts of K+ along with released protein contents were detected expressing cell wall destruction and lysis. Under the specified experimental conditions, in the presence of released intracellular organic and inorganic components via cell lysis, a significant count of E. coli was still present in SS, whereas almost all bacteria were removed in other matrices due to various challenging reasons. Based on the presented data, SPCI of E. coli using LF as a novel photocatalyst was successfully demonstrated as an alternative and promising method for disinfection purposes.

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Humic acids represent a major fraction of natural organic matter (NOM) in aquatic environments. Having undefined composition and complex ill-defined structures, their presence in natural waters is undesirable. In this study, solar photocatalytic activity of synthesized Fe-doped TiO2 photocatalysts was investigated for the degradation of a 100 kDa molecular size fraction of humic acid. For this purpose, catalysts comprised of 5 different molar ratios of Fe/Ti were prepared by in-situ sol gel method and characterized by FTIR and Raman spectroscopy. Optimum loadings of the catalysts were determined and the kinetics of humic acid removal was investigated focusing on UV–vis spectroscopic parameters. Moreover, fluorescence techniques such as excitation-emission matrix (EEM) were also acquired for elucidating induced structural changes of humic acid during photocatalytic degradation. Results revealed that, using photocatalysts prepared by in-situ sol-gel method 20 to 25% removal of humic acid could be attained after photocatalytic treatment of 120 min.