Silver Nanoparticles Synthesis
Silver nanoparticles (AgNPs) are very popular nanomaterial. In addition to the abundance of silver in the earth crust, silver nanoparticles also have a broad spectrum of bactericidal activity, surface plasmon resonance absorption, and low cost of manufacturing. For these reasons, AgNPs have been used in many application, such as antimicrobial agent, part of environmental treatments, such as air, water, and surface disinfection, and as chemical sensors for ammonia, chlorine dioxide, herbicides, copper ions, and lead.
The AgNPs synthesized by chemical reduction method. Chemical reduction method is preferable because of its convenience factor, relatively low cost, and likely to be produced on a large scale. The reducing agent will reduce the positive silver ion from the precursor solution to become zero charged silver particles which further will become AgNPs. The stabilizing agent was used to form a system, which can protect the AgNPs and prevent aggregation. Many studies have been conducted by using different chemicals as reducing and stabilizing agents. However, AgNPs synthesis by using only one chemical as both reducing and stabilizing agent is preferable than using two different chemicals. Some previous study had been conducted by using benzoic acid derivatives with hydroxy phenolic group as reducing and stabilizing agent in the AgNPs synthesis. However, the use of benzoic acid derivatives with amino and hydroxyl phenolic groups has not been performed yet.
In order to discover the role of each functional group in benzoic acid derivative, p-aminosalicylic acid was used in this research as reducing and stabilizing agent in AgNPs synthesis. The amino and hydroxyl phenolic groups were predicted to reduce the Ag+ ions to become Ag0, and the carboxylate groups will stabilize the formed AgNPs. This study critically examines the effect of the amino group addition or substitution on the benzoic acid derivatives as both reducing agents of Ag+ to Ag0 and as stabilizing agents for the formed AgNPs. Furthermore, a comparison was made with existing research which used other benzoic acid derivative in AgNPs syntheses, such as hydroxybenzoic acid and dihydroxibenzoic acid. The parameter examined includes the particle size, shape, and stability. In addition, the AgNPs formation and stability mechanism by p-aminosalicylic acid were also proposed based on the FTIR spectra of synthesized AgNPs.