Efficacy of silver nanoparticles in capacitive deionization electrodes as antimicrobial agents

Abstract

The availability of clean and safe water is still a big challenge in most parts of the world. Drinking water should be free of harmful microorganisms and should contain the required amount of minerals based on the set standards. In this study, silver nanoparticles (Ag-n) embedded in Activated Carbon (AC) electrodes for capacitive deionization (CDI) were evaluated for desalination and also for anti-microbial activities against Escherichia coli and Salmonella enteritidis. The novel AC/Ag-n electrodes were prepared by mixing Activated Carbon powder together with silver nanoparticles. The morphology, surface functional groups, and porosity were characterized by Scanning Electron Microscope (SEM), Fouriertransform infrared (FT-IR), and nitrogen adsorption studies which affirm the formation of disinfecting electrode material. The desalination and disinfection performance of the fabricated electrodes were evaluated by Capacitive Deionization batch mode experiment using natural water collected from the Nganana stream while applying the potential of 2 V for 3h. The AC/Ag-n Capacitive Deionization (CDI) electrodes achieved 100% Escherichia coli and 98% Salmonella enteritidis removal and 45% salt removal efficiency, and electrosorption capacity of 2.56 mg/g and the ions removal efficiency of 89%, 40%, 2.4%, 57.9%, 50%, 8% and 33% for Na+ , K+ , Ca2+ , Mg2+ , PO4 3- , NO3 - and Clrespectively. The microbial disinfection mechanisms were through electrosorption process and physical contacts with the embedded Ag-n. Thus, it is possible to disinfect the water while also removing salt simultaneously using Capacitive Deionization. Therefore, AC/Ag-n are considered as novel electrode material with an excellent antimicrobial agent for the Capacitive Deionization process.