Model for Gold Nanoparticle Synthesis: Effect of pH and Reaction Time

The synthesis of gold nanoparticles is dependent on both the concentration of trisodium citrate dihydrate and the time that it interacts with tetrachloroauric acid. A wide range of gold nanoparticles with various sizes and dispersity can be produced based on control variables, such as time of reaction and acid concentration, using a similar approach to that of the Turkevich model. In this model, the pH of the solution decreases slightly throughout the reaction (0.005 unit/min) due to the chemical interactions between trisodium citrate dihydrate and tetrachloroauric acid. Dicarboxy acetone is formed during citrate oxidization, resulting in gold nuclei formation over time. In addition, gold nanoparticle nucleation causes pH fluctuation over time based on gold nanoparticle sizes. An inverse correlation (coefficient of smaller than -0.97) was calculated between the pH and reaction time at different ratios of trisodium citrate dihydrate to tetrachloroauric acid. Regression analysis was used to develop a model for the prediction of the size of gold nanoparticles ranging from 18 to 38 nm based on the concentration of trisodium citrate dihydrate and the reaction time.

Automated summary

The synthesis of gold nanoparticles relies on the concentration of trisodium citrate dihydrate and the interaction time with tetrachloroauric acid, enabling the production of gold nanoparticles with diverse sizes and dispersity through control variables. The chemical reactions between trisodium citrate dihydrate and tetrachloroauric acid lead to a slight decrease in pH throughout the synthesis process. The nucleation of gold nanoparticles causes pH fluctuation over time, with a negative correlation between pH and reaction time demonstrated at different ratios of trisodium citrate dihydrate to tetrachloroauric acid.