Mechanism of Silver Nanoparticles Deposition by Electrolysis and Electroless Methods on a Graphite Substrate

This study shows a silver electrodeposition model (EDM) on a graphite ‎substrate. The electrolyte was a 0.01 M solution of pure silver and chromium nitrate using an ‎electrolyzing cell. EDC with current density up to 20 mA/cm2 and 15 mV and pulse current were studied. Results revealed that silver deposited at a ‎rate of 0.515 mg/cm2/min with 12 mA /cm2 that decreases to 0.21 and 0.16 mg/cm2.min ‎with the decrease of current density to 6 and 5 mA/cm2 respectively. The model postulates that ‎silver ions (a) were first hydrated before diffusing (b) from the solution bulk to ‎the cathode vicinity, the next step (c) involved the chemical adsorption of these ions on certain ‎accessible sites of the graphite substrate (anode), the discharged entities (d) adhere to the graphite ‎surface by Van der Vales force. Silver ions are deposited because the ‎discharge potential of silver is low (0.38 mV) as compared to other metal ions like chromium (0.82 mV). Pulse ‎current controls silver deposition due to flexibility in controlling steps (a) - (c) of the ‎deposition mechanisms.

Effect of Anolyte on Background Microflora, Salmonella, and Listeria monocytogenes on Catfish Fillets†

Near-neutral electrolyzed water (anolyte), having a pH of 6.0 to 6.5 ± 0.02, oxidation reduction potential of greater than 700 mV, and a residual chlorine level of 10 to 200 ppm, was reported to have a potential use to decontaminate food surfaces. An electrolyzing cell was developed that is capable of producing neutral electrolyzed water containing a chlorine level of greater than 700 ppm in the form of hypochlorous acid (anolyte). Anolyte with a chlorine level of 300 ppm was used to determine its effect on Salmonella and Listeria monocytogenes cells after a 3-min contact. Transmission electron micrograph results showed disruption of the outer cellular membrane for both bacteria. The anolyte (300 ppm) was used as a washing solution to decontaminate catfish fillets inoculated with either Salmonella or L. monocytogenes. After a 3-min contact time with the anolyte, there was a 1-log reduction for Salmonella, and after 8 days of refrigerated storage (4°C), this bacterial reduction was maintained. There was no reduction of L. monocytogenes on the catfish fillet surfaces. The anolyte was an effective wash solution for Salmonella reduction on the catfish fillet surfaces.