Some of the most carcinogenic substances (e.g., hexavalent chromium compounds, cadmium or lead salts, whose deposition requires highly-toxic cyanides), were extensively employed in the past for the electrodeposition of protective coatings in the most demanding applications (aggressive environments).
Since the use of these materials has been prohibited by National and European regulations, alternative materials have emerged. Proposed alternatives for hard chromium are NiP, CoP, NiW or CoW. However, these are not good choices, bearing in mind environmental concerns. Zn-based (Zn-Co, Zn-Ni and Zn-Sn) and Al-based (Al-Mn) alloys have been proposed as replacement for Cd-alloys. However, electrodeposition of Al alloys requires the use of ionic liquids.
The use of hazardous chemicals including concentrated acids and alkalis, heavy metals, cyanides and oils will be minimized as much as possible and protective equipment (disposable gloves, eye protection and face masks will be used whenever deemed necessary). Durable electrolytic baths, avoiding short-term precipitation, will be designed. To avoid hazardous chemicals (e.g., boric acid), deep eutectic solvents and ionic liquids will be considered as green electrolytes. Since both have a negligible vapour pressure at room temperature, these solvents are non-volatile and hence do not pollute environment in a significant manner (green electrochemistry).
Gallium is generally considered not to be toxic (unless ingested in large amounts) and although there is less supply risk for Ga than for RE or NM, Ga appears also in the list of “substances of high concern”. The reason for that is the abusive use of Ga especially in the semiconductors industry. If no actions are undertaken, Ga will become amongst the scarcest resources in 2030
Phosphorus is essential as nutrient for plants, animals and humans and is non-replaceable. Phosphorus supplies are limited and prices have been volatile. Hence, concern has arisen about the availability of future phosphorus supplies in the EU and worldwide. For this reason, the European Commission (EC) launched a consultation on how to use phosphorus in a more sustainable way in 2013 and the European Sustainable Phosphorus Platform was also created. Hence, SELECTA will keep in mind this concern by minimizing the use of P in electrodeposition procedures, although some alloys containing P (like CoP, NiP) have been widely used in recent years.