The effect of additives on zinc deposited from zinc sulfate solutions

Abstract

Zinc is industrially electrowon from acid zinc sulfate solutions at ambient temperatures. Some refiningagents are usually added to improve the deposit qualities. Gelatin is a traditional additive, but other additives are also used. In the investigation described here, the basic parameters of deposition (e.g., current density, acid concentration, and zinc concentration) were optimized. Gelatin and a tetraalkylammonium salt (T AS) were used separately and in combination as grain refiners of the cathodic deposits. Current efficiency determination experiments were perf.ormed to investigate the role of these additives. Scanning electron micrographs of the cathodic deposits were obtained to examine the surface qualities of deposits at certain conditions. Results showed that gelatin is generally a better refiner,although T AS may be used in concentrations of 0.074 mg/l to 1 mg/l. A mixture of the two additives resulted in a decrease of current efficiency. 100

Electrodeposition of zinc and composite zinc–yttria stabilized zirconia coatings

“…It is suggested that the electric field provides electrophoretic motion of charged gelatin to the cathode surface and zinc deposition is influenced by the adsorbed gelatin. The observed changes in deposit microstructure can result from increases in the cathode overpotential arising from gelatin adsorption (Afifi et al, 1992).…”

“…Generally, it is difficult to stabilize particles in solutions of metal salts due to their high ionic concentration (Biest and Vandeperre, 1999). It has been suggested that gelatin was protonated and positively charged (Afifi et al, 1992) in the acidic environment. The protonated gelatin macromolecules then adsorbed on the ceramic particle surfaces promoting electrosteric stabilization of the ceramic particles, which is less sensitive to high ionic concentrations.…”

Effect of Additives on Electrodeposition of Nanocrystalline Zinc from Acidic Sulfate Solutions

“…Obviously, all these compounds are common additives for zinc electroplating. [20][21][22][23][24][25][26][27][28][29][30] The following results attempted gradually to show their effect and coeffect on the preparation of nanocrystalline zinc coatings on steel specimens. By the way, a small amount of ethanol or methanol was generally used to dissolve BA in aqueous solutions, 27,28 but the pre-experiments found that these two compounds did not dissolve BA fully in the base solution S 0 , mainly due to the high concentration of zinc sulfate.…”

The Effect of Direct and Pulsed Current in the Presence of Surfactants on the Electrodeposition of Zn–SiC Nanocomposite Coatings

“…Organic molecules such as animal-derived glues, gelatin, and gums are widely used in the industry [28,29]. They act in zinc electrodeposition mainly as dendrite inhibitors, grain refiners, and brighteners [31,32]. Gelatin (G) and gum arabic (GA) have also been widely used as dispersants, namely, to avoid the agglomeration of inert particles in aqueous solutions [27,[33][34][35].…”