DEVELOPMENT OF STEP-BY-STEP METHOD FOR PRODUCING SILVER NANOPARTICLES BY CITRATE METHOD

The article presents an algorithm for developing a step-by-step method for producing silver nanoparticles 30-35 nm in size, taking into account the establishment at each stage of the necessary ratio of concentrations and volumes of reagents. In the work, silver nitrate and sodium citrate anhydrous were used by "Sigma-Aldrich" (USA). All test solutions were prepared by the gravimetric method. To weigh the reagents, we used Adventurer electronic analytical balances ("OHAUS", USA) (with a resolution of 0.0001 g). The size and density of silver nanoparticles were estimated using a JEM-1011 electron transmission microscope ("Jeol", Japan). In the course of the study, a direct dependence of the size of the nanoparticles on the concentration of solutions of sodium citrate and silver nitrate was established. According to the results of the first stage, the concentration ratio of AgNO3 : Na3C6H5O7 - 1 : 0.75 was chosen for testing the synthesis of colloidal silver nanoparticles. At the second stage, the influence of the ratios of the volumes of reagents on the conditionability of the obtained series was evaluated. The best result was obtained in the series with the volume ratio of AgNO3 : Na3C6H5O7 - 5 : 1, where single conglomerates were observed, and the particle shape was regular and round. At the next stage, the optimal boiling time of the colloidal solution after the appearance of a light yellow color was experimentally determined. With an increase in the boiling time of the solution, stabilization of particles occurs, thereby aggregative stability is observed. The most appropriate reagent mixing mode using a magnetic stirrer was selected: after the appearance of a light yellow color, the number of revolutions was changed from 375 to 500 rpm and the temperature regime was decreased from 300 degrees C to 200 degrees C.