Ricerc@Sapienza

Abstract: Aims: Ni-Mo alloy coatings could represent a key material for several leading applications
of engineering. Indeed these coatings present excellent physico-chemical characteristics such as
magnetism, wear-resistance, heat-conductivity, and electrocatalytic properties.
Observations: Ni-Mo alloys have been electrowon, with a pH 5.8 sulphate catholyte containing 40 g/l
Ni and Mo in the range 1-4 g/l, sodium citrate and acetic acid, at temperature in the range 25-50°C and
current density in the range 10-100 mA/cm2.

Since indium is considered a strategic material, a study for developing and optimizing a recovery process by electrowinning has been performed. The possibility of using electrolytic baths based on sulfates instead of chlorides has also been evaluated. Nowadays, chlorides are widely used because they generally present greater current efficiencies;however, the dangers of chlorine gasrequireexpensive-sealed systems to avoid human health and environmental issues.

Electrowinning represents a promising methodology for recovery of strategical, scarce metals. In this study, an indium electrowinning process using a sulfate electrolyte on stainless steel, nickel, titanium, aluminum and copper (SS, Ni, Ti, Al and Cu) cathodes was investigated. Firstly, cyclic voltammetry carried out at 15 mV/s scanning rate and 25 °C temperature evaluated the suitability of electrolyte and the surface reactivity on different metal cathodes. Subsequently, indium was deposited using a current density of 25 A/m2 for 22 h at 40 °C and pH 2.3.