Novel green synthesis of cluster AgNPs by reduction of Silver (I) by vitamin C in presence of alginate surfactant powder in aqueous media: Characteristics and applications

Abstract

All synthesized AgNPs were characterized by the spherical shape nature; therefore, the cited work aims to present a perspective methodology for obtaining AgNPs of cluster beans for the first time (Alg-AgNPs). This synthesis was performed by stepwise addition of a powder mixture involving vitamin C (0.6 g) as reducing agent and alginate (0.4 g) as sustainable surfactant to solution involving (1 g) of AgNO₃ dissolved in conductivity water at pH of 1–2 whilst stirring the mixture continuously and vigorously for about 10–20 min. The naked eye observations noticed a rapid change in color of Ag (I) solution from colorless into brownish when just gets in touch with the added mixture, then turns rapidly into greyish of colloidal sol aggregates. Such formed aggregates were turned into black crystals by aging or gentle warming. In absence of vitamin C, addition the alginate powder to Ag (I) electrolyte leads to formation of granule grains precipitate. The SEM, TEM and XRD investigations indicated the formation of alginate-based capped AgNPs of clusters beans with particle size of 26.5 nm in the former case and alginate-based Ag(I) granule complex of amorphous phase in the latter ones, respectively. The synthesized Alg-AgNPs were found to have high antimicrobial activity against gram-positive and gram- negative bacteria. Some kinetic studies were performed to follow the growth rates of nanoparticles for shedding some light on the nature of electron-transfer pathway in the rate-determining step. The formed granule complex was applied as starting sample material for determining the alginate capacity as adsorbent biomaterial for binding Ag (I) ion from aqueous solutions. A capacity value of 80.85 mg/g was obtained at 25 °C. The correlation between the alginate capacity and properties of coordinated metal ions involving Ag(I) was examined. The experimental results were interpreted and a tentative formation mechanism of Ag NPs was suggested.