Ag nanofluids synthesis in presence of citrate at different stirring rotation and their post reaction stability

Abstract

Ag nanofluids have been synthesized by the single pot synthesis method reducing silver nitrate (AgNO3) applying sodium borohydride (NaBH4) as a reducing agent in the presence of trisodium citrate (TSC) in water base fluid. Stirring effect on the synthesis has been studied in terms of rotation per minute (RPM) using a digitally displayed electronically controlled mechanical stirrer and a decreasing tendency of mean particle sizes has been observed on increasing RPM from 250 to 950 at the interval of 100. Time dependent Surface Plasmon Resonance (SPR) Spectra have been recorded by UV-Visible spectrometer from 1 h to 36 h at the interval of almost 12 h and the particle size distribution have been estimated by the deconvolution of the spectra. The size distribution has been quantified correlating deconvoluted peaks and their area under the curves proportionated to that of the entire spectrum. The mean particle sizes have been observed to vary from 20 nm to 100 nm and the variations depend on both RPM and time. The RPM and time dependent area under the curve of each spectrum have been analyzed to find the nanofluid stabilization and 450 has been recorded as most stabilizing RPM accounting by 0.35% change in it. The histograms of particle size distribution have been analyzed by mathematical modeling, arithmetic progression and geometric progression. Histogram that fits arithmetic progression indicates Ag+ seeding by its reduction on Ag nanoparticles to grow bigger particles and histogram that fits geometric progression indicates agglomeration of Ag nanoparticles for sedimentation.