Preparation of Size Controlled Silver on Carbon from E-waste by Chemical and Electro-Kinetic Processes

Preparation of size controlled nano-particles of silver catalyst on carbon substrate from e-waste has been investigated. Chemical route was developed by extraction of the metals available in nitric acid followed by treatment with hydrofluoric acid. Silver metal particles deposited with an average size 4-10nm. A stabilizer concentration of 10-40g/l was used. The average size of the prepared silver decreased with increase of the anode current density. Size uniformity of the silver nano-particles was improved distinctly at higher current density no more than 20mA. Grain size increased with EK time whereby aggregation of particles was observed after 6h of reaction. The chemical method involves adsorption of silver nitrate on the carbon substrate. Adsorbed silver ions were directly reduced to metal particles using hydrazine hydrate. Another alternative method is by treatment with ammonia followed by heating the carbon loadedsilver hydroxide at 980°C. The product was characterized with the help of XRD, XRF, ICP, SEM and TEM techniques. Keywords—e-waste, silver catalyst, metals recovery, electrokinetic process.