Fixed-bed Reactor for Water Microbial Disinfection via Supported ZnO Glass Nanocomposites

Abstract

Zinc Oxide (ZnO) has been widely used as a disinfectant in many applications due to its low cost, stability, and long-lasting effect. The aim of this project is to demonstrate and model water microbial disinfection in a fixed-bed reactor implementing ZnO-glass (40wt %) fused with Na2CO3, SiO2, B2O3, ZnO, and Al2O3. The ZnO-glass powder was immobilized on borosilicate glass beads with a spray gun operating at less than 2 bar using a suspension containing a predetermined amount of ZnO-glass, PEG, and 15mL of a solution containing PEG, ethanol, water, and HNO3. The sprayed beads were annealed at 450oC for 4 hours. Characterization techniques such as SEM and SEM-EDX are used to study the morphology of the surface of the glass beads. These beads were used in a homemade fixed-bed reactor to investigate the antimicrobial properties of the ZnO-glass powder. Viable and non-viable cells were tracked using a flow cytometer. A preliminary test was done showing the possible disinfection effect of the immobilized ZnO-glass beads, however, improvements on the material properties and cell quantification techniques are still required. A kinetic model was developed based on proposed surface adsorption and reaction mechanisms describing the disinfection dynamics in terms of viable and non-viable cells. The proposed model was simplified and preliminarily calibrated against data from a similar disinfection system using n-Ag as well as from our ZnO-glass experiments. The outlook of this project will be directed toward improving the functionalization method to obtain highly stable films on the beads, and leaching can be eliminated. Besides understanding the expected reaction mechanisms, finding bottlenecks, and improving the experimental design.

Date of Award	Dec 2022
Original language	American English
Supervisor	Jorge Rodriguez (Supervisor)