Kinetic Investigation of Reaction between Metallic Silver and Nitric Acid Solutions in the Range 7.22−14.44 M

Abstract

In this study, the reaction kinetics between metallic silver and nitric acid solutions was investigated by taking into consideration the parameters of temperature, solid-to-liquid ratio, particle size, stirring speed, nitric acid concentration, and addition of sodium nitrite. It was determined that the dissolution rate of the process increased with decreasing particle size, solid-to-liquid ratio, and acid concentration, and increasing reaction temperature and stirring speed. It was found that the amount of sodium nitrite in the solution has no significant effect on the dissolution rate. In the present study, the examination of shrinking core models of fluid−solid systems showed that the dissolution of metallic silver in the range of 7.22−14.44 M nitric acid solutions was controlled by the film diffusion. The following semiempirical model, which represented well the process, was developed by statistical methods: 1 − (1 − X)1/2 (5271.13)(D)-0.548(S/L)-0.3(W)0.851(C)-3.41e-18.81/ RT t, where D is the particle size, C the acid concentration, S/L the solid-to-liquid ratio, T the reaction temperature, W the stirring speed, and t the reaction time. The activation energy of the process was found to be 18.81 kJ mol-1.

Silver Ion Mediated Shape Control of Platinum Nanoparticles: Removal of Silver by Selective Etching Leads to Increased Catalytic Activity

“…This is in agreement with studies of highly dispersed Pt-Ag catalysts on silica gel; in that study, rates of 1-hexene hydrogenation decreased exponentially with increasing Ag content . The dependence of etching on temperature, HNO 3 concentration, and silver particle size (mm-range) is well-documented [24][25][26][27] . The reaction proceeds with the overall stoichiometry at HNO 3 concentrations between 3.8 and 4.9 M:…”

Kinetic Investigation of Reaction Between Metallic Silver and Nitric Acid Solutions

“…But in the acid concentration range between 4.04 and 7.22 M, the dissolution increased rapidly due to the presence of enough HNO 3 to react with the metal. However, the dissolution rate decreased at acid concentrations above 7.22 M [10]. Using the data of the present study and a former study [10], the dissolution of metallic silver in 4.04±14.44 M HNO 3 concentrations was plotted in concentration versus conversion fraction in Fig.…”

“…pressure and in the presence of oxygen) [9]. Özmetin et al [10] studied the kinetics of reaction between metallic silver and nitric acid solutions from 7.22 to 14.44 M, and found that the dissolution rate was controlled by film diffusion. He also determined that the dissolution rate of the process increased with decreasing particle size, solid-to-liquid ratio and acid concentration, and with increasing reaction temperature and stirring speed, and the activation energy of the process was calculated to be 18.81 kJ mol ±1 .…”

Electrochemical characterization of carbon coated bundle-type silicon nanorod for anode material in lithium ion secondary batteries

“…(2) and (3) represent the simultaneous reactions occurred at anode [13,30,31]. After the Ag dendrites were formed, Ag dendrites were then removed by the HNO 3 solution which effectively dissolved the remaining Ag metal to form AgNO 3 salt and water [32]. Based on these reactions, the metal-assisted chemical etching on silicon powder renders a nanostructured formation which comprises a mesoporous material.…”