Comparative Study of Corrosion Behaviour of Several Metals and Alloys Exposed to Brines

In tannery industries, before the tanning process, the hides are preserved through a curing stage. This involves applying 40–50% of common salt (NaCl) based on the fresh weight of the hide. One of the byproducts of the curing stage is contaminated salt, which is usually landfilled. In this work, the reclamation of this waste was achieved through iron-driven electrocoagulation of salt-derived brine (SdB) using iron electrodes. A current density of 371 A·m−2 was applied for 16 min, yielding 88% removal of total organic carbon (TOC). The upscaling of this process requires suitable materials. Given that NaCl is highly corrosive to metal structures, this work investigated the corrosion resistance of different metals and alloys (aluminium, brass, carbon-steel, copper, AISI 304L and AISI 316L stainless steels) when exposed to SdB. The corrosion resistance was evaluated using different electrochemical techniques, including polarisation curves and electrochemical impedance spectroscopy (EIS). These measurements were made after immersing the metallic alloys in SdB for one hour and one month. The corrosion resistances of the six metals and alloys, ranked from highest to lowest, were as follows: AISI 316L > AISI 304 > aluminium > carbon-steel > brass > copper. This research provides valuable insights for future pilot-scale researchers and up-scaling efforts. By improving the circularity of the tannery industry and enhancing their competitiveness against conventional treatments, this work contributes to the advancement of the tannery industry.