Photocatalytic Bactericidal Performance of LaFeO3 under Solar Light: Kinetics, Spectroscopic and Mechanistic Evaluation

Nazmiye Birben,Renato Pelosato,Miray Bekbolet,Ezgi Lale,Ceyda Uyguner Demirel,Isabella Natali Sora

doi:10.3390/w13091135

Nazmiye Birben, Renato Pelosato + Show 4 more

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https://doi.org/10.3390/w13091135

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Abstract

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.

Highlights

Microbial contamination in drinking water is a serious concern in many low-income countries
The solar photocatalytic bactericidal performance of a perovskite photocatalyst specimen, such as lanthanum orthoferrites (LaFeO3), to inactivate pathogenic microorganism as E. coli in aqueous medium was discussed by addressing the effects of various aqueous medium conditions
Saline solution was selected as the medium in solar photocatalytic inactivation (SPCI) of E. coli to exclude all interfering species either as ultra-pure water or presence of common water constituents

Summary

Introduction

Microbial contamination in drinking water is a serious concern in many low-income countries. Pathogenic microorganisms present in water mainly include viruses, bacteria, parasites, etc. Diseases related to contamination of drinking water constitute a major problem for human health. It is necessary to develop processes of microbial disinfection of water that combine high efficiency with simplicity of management and costeffectiveness. Microbial disinfection of water is achieved through chlorination, ozonation, chloramination, the use of chlorine dioxide or UV radiation [1,2]. When TiO2, suspended in water, is irradiated with UV light, hydroxyl radicals are generated. These promote the oxidation of the organic substances and/or the inactivation of pathogenic microorganisms, such as bacteria, viruses and parasites

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