Publications by Stefanos Giannakis

Photo-Fenton inactivation of MS2 bacteriophage at alkaline pH by Fe salts or nm to μm-sized oxides, and the Janus-faced effects of natural organic matter in surface waters

César Pulgarin, Stefanos Giannakis, Ogadimma Cassandra Oji-Okoro, Giulio Farinelli

In this study, MS2 bacteriophage was inactivated by homogeneous and heterogeneous photo-Fenton processes in an alkaline matrix (pH 8) using low concentrations of H2O2 and iron forms (1 mg/L), including Fe(II), Fe(III), and Fe (hydr)oxides. As a reference, ...

Elsevier2024

Acids from fruits generate photoactive Fe-complexes, enhancing solar disinfection of water (SODIS): A systematic study of the novel " fruto-Fenton " process, effective over a wide pH range (4-9)

César Pulgarin, Aline Laetitia Schaub, Stefanos Giannakis, Giulio Farinelli, Mona Kohantorabi

This study aimed to enhance solar disinfection (SODIS) by the photo-Fenton process, operated at natural pH, through the re-utilization of fruit wastes. For this purpose, pure organic acids present in fruits and alimentary wastes were tested and compared wi ...

Pergamon-Elsevier Science Ltd2024

Homogeneous vs. heterogeneous photo-Fenton elimination of antibiotic-resistant bacteria bearing intracellular or extracellular resistance: Do resistance mechanisms interfere with disinfection pathways?

César Pulgarin, Stefanos Giannakis, Truong-Thien Melvin Le, Jérémie Decker

The present study aimed to fill the knowledge gap between the implications of intracellular and extracellular antibiotic resistance mechanisms may inflict on the inactivation pathways of the photo-Fenton process under mild conditions. It was thus designed ...

Elsevier Sci Ltd2024

Bacterial inactivation in sunlit surface waters is dominated by reactive species that emanate from the synergy between light, iron, and natural organic matter

César Pulgarin, Stefanos Giannakis, Jun Ma, Da Wang, Shuang Song

In this study, the synergistic and antagonistic effects of Fe species and coexisting natural organic matter (NOM) on the efficacy of solar light disinfection of water are investigated. Different initial iron species (Fe2+/Fe3+) and naturalorganic matter ty ...

Elsevier2023

Sunshine and a pinch of tropical soils: A natural, low-cost photo-Fenton variation for safer water, assisted by H2O2 or percabonate

Michaël Bensimon, César Pulgarin, Stefanos Giannakis, Jérémie Decker, Thomas Guillaume

Clean water is essential for human survival, but access to safe drinking water remains a challenge in resource -limited regions. Herein, we explored a low-cost but effective solution for water potabilization using natural iron sources from soils along with ...

ELSEVIER2023

Identifying the mediators of intracellular E. coli inactivation under UVA light: The (photo) Fenton process and singlet oxygen

César Pulgarin, Stefanos Giannakis

Solar disinfection (SODIS) was probed for its underlying mechanism. When Escherichia coli was exposed to UVA irradiation, the dominant solar fraction acting in SODIS process, cells exhibited a shoulder before death ensued. This profile resembles cell killi ...

PERGAMON-ELSEVIER SCIENCE LTD2022

Effective removal of the rotifer Brachionus calyciflorus from a Chlorella vulgaris microalgal culture by homogeneous solar photo-Fenton at neutral pH

Horst Pick, Christian Ludwig, Adrian Pulgarin, Stefanos Giannakis, Jérémie Decker, Dominik Refardt, Jiahua Chen

In this study, a citrate-modified photo-Fenton process was successfully applied to decontaminate a Chlorella vulgaris microalgae culture spiked with the rotifer Brachionus calyciflorus (5 individuals mL−1). The applied treatment (1 mg L−1 Fe2+, 20 mg L−1 H ...

2022

Mechanistic modelling of solar disinfection (SODIS) kinetics of Escherichia coli, enhanced with H2O2 - part 1: The dark side of peroxide

César Pulgarin, Stefanos Giannakis, Ling Feng

The present bi-partite work describes the development and validation of a mechanistic kinetic model of SODIS E. coli inactivation, enhanced with H2O2. In this first part, the mechanism of the baseline dark phenomena is modelled. A mechanistic model involvi ...

ELSEVIER SCIENCE SA2022

Superior visible light-mediated catalytic activity of a novel N-doped, Fe3O4-incorporating MgO nanosheet in presence of PMS: Imidacloprid degradation and implications on simultaneous bacterial inactivation

Stefanos Giannakis, Jérémie Decker

Impressive Imidacloprid (IMD) degradation and bacterial inactivation were attained through the photocatalytic activation of peroxymonosulfate (PMS) via a novel, N-doped MgO@Fe3O4, under visible light. After complete characterization (XPS, XRD, FT-IR, FE-SE ...

ELSEVIER2022

Mechanistic modelling of solar disinfection (SODIS) kinetics of Escherichia coli, enhanced with H2O2 - Part 2: Shine on you, crazy peroxide

César Pulgarin, Stefanos Giannakis, Ling Feng

In this second part of the development of a mechanistic kinetic model of the solar inactivation of E. coli enhanced with hydrogen peroxide, we evaluate the mechanisms based on photonic inactivation and integrate them into the kinetic model of the dark proc ...

ELSEVIER SCIENCE SA2022

SODIS potential: A novel parameter to assess the suitability of solar water disinfection worldwide

César Pulgarin, Sofia Samoili, Stefanos Giannakis, Giulio Farinelli

This paper studies the worldwide applicability of solar water disinfection (SODIS) technology through a novel parameter: the SODIS potential. This parameter is defined as the inverse ratio between the required exposure time to achieve a four log disinfecti ...

ELSEVIER SCIENCE SA2021

Natural iron ligands promote a metal-based oxidation mechanism for the Fenton reaction in water environments

César Pulgarin, Stefanos Giannakis, Giulio Farinelli

The Fenton reaction is an effective advanced oxidation process occurring in nature and applied in engineering processes toward the degradation of harmful substances, including contaminants of emerging concern. The traditional Fenton application can be rema ...

ELSEVIER2020

Visible light plays a significant role during bacterial inactivation by the photo-fenton process, even at sub-critical light intensities

César Pulgarin, Rosa Mosteo, David Muzard, Cristina del Socorro Lonfat, Stefanos Giannakis, Angelica Varon Lopez

The aim of this research is to clarify the contribution of sunlight wavelengths, irradiance and Fe2+/H2O2 during bacterial disinfection by the photo-Fenton process in clear surface waters. We considered different solar spectrum distributions (visible, UVA- ...

PERGAMON-ELSEVIER SCIENCE LTD2020

Insights into the Photocatalytic Bacterial Inactivation by Flower-Like Bi2WO6 under Solar or Visible Light, Through in Situ Monitoring and Determination of Reactive Oxygen Species (ROS)

Juan Kiwi, César Pulgarin, Sami Rtimi, Stefanos Giannakis, Minoo Karbasi

This study addresses the visible light-induced bacterial inactivation kinetics over a Bi2WO6 synthesized catalyst. The systematic investigation was undertaken with Bi2WO6 prepared by the complexation of Bi with acetic acid (carboxylate) leading to a flower ...

2020

Detrimental vs. beneficial influence of ions during solar (SODIS) and photo-Fenton disinfection of E. coli in water: (Bi)carbonate, chloride, nitrate and nitrite effects

César Pulgarin, Stefanos Giannakis

In this work, we studied the effect of inorganic ions occurring in natural waters on E. coli inactivation by solar and photo-Fenton processes, two crucial methods for drinking water treatment in sunny or developing countries. HCO3-, Cl-, SO42-, NO3-, NO2- ...

2020

Improving visible light photocatalytic inactivation of E. coli by inducing highly efficient radical pathways through peroxymonosulfate activation using 3-D, surface-enhanced, reduced graphene oxide (rGO) aerogels

César Pulgarin, Stefanos Giannakis, Minoo Karbasi

In this work, we synthesized highly porous reduced graphene oxide foams, presenting augmented antibacterial activity in presence/absence of peroxymonosulfate (PMS). To date, this is the first investigation of photocatalytic PMS disinfection by 3D-rGO mater ...

ELSEVIER SCIENCE SA2020

A novel proposition for a citrate-modified photo-Fenton process against bacterial contamination of microalgae cultures

César Pulgarin, Christian Ludwig, Adrian Pulgarin, Stefanos Giannakis, Dominik Refardt

This study reports the first attempt of a citrate-modified photo-Fenton (PF) application at near-neutral pH (7.5–8.5, tap water) to disinfect Escherichia coli (as model bacterium), in Chlorella vulgaris cultures. The conditions are aimed towards bacterial ...

2020

Unfolding the action mode of light and homogeneous vs. heterogeneous photo-Fenton in bacteria disinfection and concurrent elimination of micropollutants in urban wastewater, mediated by iron oxides in Raceway Pond Reactors

Dominique Grandjean, César Pulgarin, Florian Frédéric Vincent Breider, Stefanos Giannakis, Irene De La Obra Jimenez

In this work, iron oxides have been proposed as low-cost heterogeneous photo-Fenton catalysts for the simultaneous disinfection and reduction of microcontaminant load from urban wastewater in raceway pond reactors at near-neutral pH. The objective was not ...

2020

Employing bacterial mutations for the elucidation of photo-Fenton disinfection: Focus on the intracellular and extracellular inactivation mechanisms induced by UVA and H2O2

César Pulgarin, Stefanos Giannakis, Ling Feng, Da Wang

The bacterial inactivation mechanisms by solar light and the photo-Fenton process is still a matter of debate. In this study, we bring evidence towards the elucidation of the mechanisms that govern photo-Fenton disinfection at near-neutral pH. With the use ...

PERGAMON-ELSEVIER SCIENCE LTD2020

Solar-assisted bacterial disinfection and removal of contaminants of emerging concern by Fe2+-activated HSO5- vs. S2O82- in drinking water

Luiz Felippe De Alencastro, Dominique Grandjean, César Pulgarin, Miloch Marjanovic, Stefanos Giannakis, Mona Kohantorabi

2019