The Role of Electrolyte Additives on Passivation Behaviour During Copper Electrorefining

Additives, such as chloride, thiourea and glue, are commonly added to electrorefining electrolyte to control deposition structure and morphology. Very few studies have been performed to observe their effects on anode passivation. Chronopotentiometry was utilized to observe the passivation behaviour of commercial copper anodes in synthetic electrolyte. The effect of chloride, thiourea and glue were investigated individually. A simulated electrolyte containing all three additives was used in conjunction with twenty commercial copper anode samples to determine possible interactions between additives and anode composition

The Effect of Copper, Acid, and Temperature on the Diffusion Coefficient of Cupric Ions in Simulated Electrorefining Electrolytes

Deposition and dissolution processes involved in copper electrorefining are significantly affected by the diffusion coefficient of copper within an electrolyte. It is believed that the diffusion coefficient of cupric ions under conditions similar to those encountered in commercial electrolytes is not precisely known. The effects of copper, acid, and temperature on copper diffusivity were measured for simulated industrial electrolytes. Copper and acid concentrations tested were 35-70 and 160-250 g L−1, respectively. Temperature was varied from 40°C to 65°C. Increasing the copper and acid concentrations slightly decreased the diffusivity of copper. The diffusion coefficient of cupric ions increased with increasing temperature according to the Arrhenius relationship. An activation energy of 19.2 kJ mol−1 was calculated from the data. The diffusivity data was utilized in a simple one-dimensional finite difference model. The model indicates that saturation of copper sulfate occurs very rapidly at the high current densities (3820 A m−2) used in accelerated passivation experiments

On-Site Visual Detection of Hydrogen Sulfide in Air Based on Enhancing the Stability of Gold Nanoparticles

We have described a simple and low-cost visual method for on-site detection of hydrogen sulfide (H2S) in air based on the antiaggregation of gold nanoparticles (AuNPs). The bubbling of H2S into a weak alkaline buffer solution leads to the formation of HS-, which can stabilize the AuNPs and ensure the AuNPs maintain their red color even in a Tris buffer solution containing 80 mM NaCl with the presence of Tween 80. The stabilization of the AuNPs is attributed to the adsorption of negatively charged S2- on the AuNPs surface. In contrast, without the bubbling of H2S, AuNPs aggregate and change color from red to blue. Under optimal conditions, the proposed method exhibits excellent visual sensitivity with a naked-eye detectable limit of 0.5 ppm (v/v), making the on-site detection of H2S possible. This method also possesses good selectivity toward H2S over other gases by using a simple SO2 removal device. The successful determination of the concentrations of H2S in local;We have described a simple and low-cost visual method for on-site detection of hydrogen sulfide (H2S) in air based on the antiaggregation of gold nanoparticles (AuNPs). The bubbling of H2S into a weak alkaline buffer solution leads to the formation of HS-, which can stabilize the AuNPs and ensure the AuNPs maintain their red color even in a Tris buffer solution containing 80 mM NaCl with the presence of Tween 80. The stabilization of the AuNPs is attributed to the adsorption of negatively charged S2- on the AuNPs surface. In contrast, without the bubbling of H2S, AuNPs aggregate and change color from red to blue. Under optimal conditions, the proposed method exhibits excellent visual sensitivity with a naked-eye detectable limit of 0.5 ppm (v/v), making the on-site detection of H2S possible. This method also possesses good selectivity toward H2S over other gases by using a simple SO2 removal device. The successful determination of the concentrations of H2S in loca