The use of PWHM and Mie methods in estimation of colloidal silver particle size obtained by chemical precipitation with sodium borohydride

Damir Barbir,Mario Mehes,Pero Dabic

doi:10.2298/hemind190719031b

Abstract

Unique antibacterial properties of silver have been known since the time of Egyptian pharaohs. With the discovery of antibiotics at the beginning of the twentieth century, silver is mostly pushed out from conventional medicine. However, with the excessive use of antibiotics, antibiotic-resistant super bacteria have appeared. Therefore, there is an increased interest in studying the antibacterial effects of colloidal silver. In this paper, the influence of various concentrations of silver nitrate on formation of colloidal silver particles in the solution was investigated. Colloidal silver was prepared by a chemical precipitation method using sodium borohydride as a reducing agent. As influence factors, color of the solution, Tyndall effect, UV/Vis absorption, and nanoparticle size estimated by PWHM (Peak Width at Half Maximum) and Mie methods were used. By increasing the silver concentration, color of the solution ranged from light yellow to dark yellow. All solutions showed Tyndall's effect equally. By the UV/Vis analysis it was found that the solutions absorbed radiation in the wavelength range 390-402 nm, and the intensity increased with increasing silver nitrate concentrations. By the PWHM and Mie methods silver nanoparticle sizes were estimated in the range 12-20 nm.

Highlights

Since the time of the Egyptian and Roman Empires, silver was used to preserve drinking water from microbial contamination
We have investigated influence of the silver nitrate concentration on colloidal silver synthesis
Colloidal silver was synthesized by using N, N'-dimethylformamide and a peak at 410 nm was obtained with a width of 66 nm while transmission electron microscopy (TEM) analysis has shown that the particle size was in the range

Summary

INTRODUCTION

Since the time of the Egyptian and Roman Empires, silver was used to preserve drinking water from microbial contamination. The most common chemical method of silver nanoparticle synthesis is chemical reduction based on the use of organic and inorganic reducers. Nanoparticle size can be estimated by using UV/Vis spectroscopy and PWHM (Peak Width at Half Maximum) analysis [22]. The PWHM or FWHM (Full Width at Half Maximum) can be used to estimate the nanoparticle size distribution in a solution. From the Mie theory it is possible to calculate scattering (Csca) (eq 1) and extinction (Cext) cross sections for an arbitrary spherical particle (eq 2):. To determine the actual concentration, shape and size of silver nanoparticles in a solution, more complex analysis methods are used, such as atomic emission spectrometry, electron microscopy, XRD (X-ray Diffraction) and AFM (Atomic Force Microscope). Estimation of silver nanoparticle size was performed by using PWHM and Mie methods

EXPERIMENTAL

RESULTS AND DISCUSSION

CONCLUSION