Synthesis of nanosized silver particles by chemical reduction method

Synthesis of nanosized silver particles by chemical reduction using formald ehyde in aqueous solution was studied in this work. Effects of several proc essing variables such as quantities of alkaline solution and formaldehyde a nd reaction time were investigated. Effects of protective agents such as PV P (polyvinyl-pyrrolidone) and PVA (polyvinyl alcohol) were also included. T he products were mainly characterized for its particle size distribution to provide information on the optimal conditions of synthesis and sufficient stability against coagulation. Our results indicated that for [AgNO3]=0.01 M solution, the addition of [formaldehyde]/[AgNO3]=4, [NaOH]/[AgNO3]=1 and [Na2CO3]/[Ag]=1, together with PVP/Ag weight ratio of 9.27 or PVA/Ag weight ratio of 3.37, could produce silver colloids having sizes between 7 and 20 nm. The suspension was stable for at least 24 h. Silver particles can be e asily collected through centrifuge and filtration when the solution is mixe d with sufficient amount of acetone. The wet precipitate can be redispersed for further applications with increase in particle size. (C) 2000 Elsevier Science S.A. All rights reserved.