Rahul Chetry | ALES Graduate Seminar

Event details: A graduate exam seminar is a presentation of the student’s final research project for their degree.
This is an ALES MSc Final Exam Seminar by Rahul Chetry. This seminar is open to the general public to attend.

MSc with Drs. Roopesh Syamaladevi and Aman Ullah.

Zoom Meeting: https://ualberta-ca.zoom.us/j/92682999271?pwd=7yjaqrACw75CiO7VLy5okbdXeGgH2b.1
Meeting ID: 926 8299 9271 Passcode: 980400

Thesis Topic: 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. The conventional water treatment methods have certain drawbacks, necessitating the exploration for innovative water treatment methods. This study investigated the inactivation of Escherichia coli AW 1.7 in water by the application of light pulses with different wavelengths, including ultraviolet-A (UV-A, 365 nm), near UV-visible (NUV-Vis, 395 nm), and blue (455 nm) light, emitted from light-emitting diodes (LED) 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 UV-A, NUV-Vis, and blue light emitted from LED for 10 and 20 min. Results demonstrated that all the LED treatments for 10 and 20 min with GO NP concentrations of 0.2% and 0.3% resulted in the inactivation of E. coli, below the limit of detection (LOD) (>5 log CFU/mL reduction). In the case of NC (0.2 and 0.3%), LED treatment using UV-A was more effective on the photocatalytic inactivation with >5 log CFU/mL reduction in the E. coli population. For the individual LED treatments, UV-A was more effective compared to NUV-Vis and blue light treatments on the inactivation of E. coli. The higher oxidation-reduction potential, electrical conductivity, and lower pH of water contributed to the greater E. coli inactivation when GO was used in combination with LED treatments. The Fourier-transform infrared spectroscopy analysis of LED-treated GO showed partial photoreduction of the oxygen-containing functional groups, whereas the structure of NC remained relatively unchanged. Significant E. coli inactivation (p-value <0.05) was observed in water with NP at different concentrations, particularly with GO NP, showing their antimicrobial properties even without LED treatment. The study suggests the photocatalytic antibacterial potential of GO and NC, highlighting their application in water treatment.