Method for preparing high activity and long service negative charged colloidal nanometer silver

Abstract

The present invention prepares negatively charged nanometer colloidal silver particle with high activity and long life with water solution of silver nitrate in 169.0-340 mg / l concentration, water solution of tannic acid in 9-20 g / l concentration, water solution of sodium carbonate in 9.5-10.5 g / l concentration and high purity water in conductivity lower than 0.2x10<-6> S / cm, and through heating the silver nitrate solution to near the boiling point, and dropping tannic acid solution and sodium carbonate solution successively while stirring. Compared with available technology, the negatively charged nanometer colloidal silver particle of the present invention has the advantages of high stability, shelf life over 4 years, low preparation cost and enhanced surface spectrum effect.

Description

technical field [0001] The invention relates to a method for preparing negatively charged colloidal nano-silver, which belongs to the field of nanotechnology and metal nanoparticle colloid preparation methods. Background technique [0002] Silver nanocolloids are widely used in surface-enhanced spectroscopy research, public security criminal investigation, forensic science, and biomedicine. Traditional silver colloids have several preparation methods, the most commonly used is the chemical reduction method, that is, the surface positively charged colloidal nano-silver (also known as gray silver colloid) prepared by trisodium citrate reducing silver acid; Colloidal nano-silver (also known as yellow silver colloid) was prepared by reducing silver nitrate. The above two methods are all electropositive nano-silver. Recently, people also use pulsed laser to irradiate metals (gold, silver, copper, etc.) to produce nano-metal particles, and disperse them into aqueous solution to o...

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Problems solved by technology

Moreover, many properties of the colloid are changing during this period, which brings great inconvenience to the use, and often creates uncertainty in the use effect, such as the repeatability and reliability of the surface-enhanced Raman spectrum, public security criminal investigation and the stability and reliability of forensic test results

On the other hand, since the prepared silver colloids are all positively charged on the surface, some molecules cannot be adsorbed on the surface of silver nanoparticles, so that the surface-enhanced Raman scattering spectrum cannot be obtained.

The above two reasons are the key to the difficulty of practical application of surface-enhanced Raman scattering technology.