Antibacterial Efficacy of Light-Activated Graphene Oxide Nanoparticles and Nanochitosan in Water

Abstract

Water quality is a crucial aspect of public health, and microbial contamination remains a significant challenge, necessitating the exploration of innovative water treatment methods. This study investigated the inactivation of Escherichia coli AW 1.7 in water driven by light-emitting diodes (LED) emitting UV-A (365 nm), near UV-visible (395 nm), and blue (455 nm) light in combination with graphene oxide (GO) nanoparticles (NP) and nanochitosan (NC). E. coli inoculum was added to NP solutions (0.2 and 0.3 % of GO and NC) and treated with the LED for 10 and 20 min. Results demonstrated that all GO treatments with different LED reduced E. coli populations below the limit of detection (LOD) (>5 log CFU/mL). In the case of NC (0.2 and 0.3%), UV-A was more effective on the photocatalytic inactivation with >5 log CFU/mL reduction in the E. coli population. The combination of NP, H2O2, and 365 nm LED also gave significant (p-value <0.05) E. coli reductions. Among individual LED treatments, UV-A was more effective in inactivating the E. coli. The higher oxidation-reduction potential (ORP), electrical conductivity, and lower pH contributed to the greater E. coli inactivation with GO and LED combination treatments. The Fourier-transform infrared spectroscopy showed partial photoreduction of oxygen-containing functional groups in GO, while the structure of NC remained relatively unchanged. The study suggests the photocatalytic antibacterial potential of GO and NC, highlighting their application in water treatment.