Background: In the last decade, research in the field of contaminants of emerging concern
proliferated while special interest was focused on antibiotic-resistant bacteria, antibiotic resistance
genes as widespread pollutants. Advanced oxidation processes have gained an essential attraction in
the field of antibiotics degradation and bacteria inactivation
Methods: Photocatalysts in the form of sol-gel based TiO2-Ag-xerogel and green synthesized
nanocomposites TiO2-Ag compared with regard to their bacteria inactivation performances and effect
on antibiotic resistance behaviour of target strain. Experiments were carried out at parallel plate
reactor configuration under UV-A irradiation with an energy equivalent of solar conditions. PEG 600
and Cydonia oblanga seed extract were used as chemical and bio-chemical reducing-stabilizing
agents respectively for the synthesis of TiO2-Ag nano-composite.
Results: Photocatalyst type/size based alterations in antibiotic resistance profile of intact and post
treatment bacteria cells were examined. Besides the improvement in bacteria inactivation kinetics,
photocatalytic disinfection with Ag doped xerogels and TiO2-Ag nanocomposites have triggered
alterations on E.coli DSM-498 resistance to tetracycline and aminoglycoside antibiotics.
Conclusion: Cydonia oblanga seed extract is proved to be a promising green substitute for the TiO2-
Ag chemical synthesis procedure. Considering the aspects of the economic and environmental impact
of nano-composite photocatalyst synthesis, cost reduction is achievable both in the sense of
production and disposal. The complexity of water matrix must be considered in a way to determine
the wide range applicability of the green synthesis of a nano-composite at the pilot scale.
Keywords: Ag-TiO2 nanocomposite, antibiotic resistance, antibiotics, E. coli, green synthesis, photocatalysis, xerogels.
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