From the lab to the river: Bimetallic clinoptilolite photocatalyst for antibiotic-resistant bacteria and emerging contaminants removal

Abstract

The presence of contaminants of emerging concern and antibiotic-resistant bacteria in aquatic environments is a major global challenge. Heterogeneous photo-Fenton-type treatments have proven effective; however, affordable and sustainable catalysts are needed to address real-world water treatment challenges. For the first time, we report the efficacy of a heterogeneous bimetallic Fe-Cu clinoptilolite catalyst, which can remove up to 29 contaminants of emerging concern (pharmaceuticals, metabolites, industrial products, herbicides and insecticides) at concentrations ranging from 6.38 to 2358 ng/L, and inactivate naturally occurring bacteria (Escherichia coli and total coliforms) from Guadaíra River water (Spain) to the detection limit of 1 CFU/100 mL. Heterogeneous photo-Fenton (1 g/L of NZ-Fe-Cu catalyst, 2.9 mM H2O2 and visible light: 410–710 nm / 9 W/m2) was the selected method for treating real river water. The successful synthesis of the material was demonstrated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM/EDX). DR-UV-Vis measurements allowed the estimation of the optical band gap, which was used to evaluate the photocatalytic performance of the bimetallic zeolite. X-ray photoelectron spectroscopy (XPS) allowed the determination of the charge of iron and copper cations in the zeolite. The photocatalytic mechanism of this new material was investigated, including hydroxyl radical detection, reusability, and stability (Fe- and Cu-leaching tests). Complete inactivation of antibiotic-resistant bacteria Pseudomonas aeruginosa and Staphilococcus aureus (initial concentration ≈ 106 CFU/mL) without further regrowth for 24 h was achieved. These results highlight the potential of this new catalyst for the decontamination and disinfection of river water, supporting its suitability for reclaimed water in agricultural irrigation and its promising applicability in broader wastewater treatment applications.