Innovative modification of anticorrosive coatings by reusing sludge generated in an electrocoagulation reactor for water treatment: exploring cross-industry sustainability opportunities.

Recycling electrocoagulation sludge generated during water treatment processes is proposed as a sustainable strategy for the functionalization of organic coatings intended for the anti-corrosion protection of metal parts. This strategy is promising in the context of the circular economy. This study explores the functionalization of alumina derived from electrocoagulation sludge with 8-hydroxyquinoline and benzotriazole as corrosion inhibitors to improve the protective properties of a commercial epoxy coating system recommended for marine applications. The functionalized coating system was applied to mild steel coupons and tested in 0.5 M NaCl aqueous solution at room temperature. A multiscale electrochemical characterization approach was used to investigate its effectiveness in the corrosion protection of the coated steel. The results show that benzotriazole-functionalized alumina added to an epoxy resin matrix leads to an improved corrosion resistance of mild steel coupons with artificial defect in the coating (scratch), suggesting its potential use in the fabrication of advanced protective coatings with functionalized action. This demonstrates the feasibility of using micro and nanoparticles based on aluminum waste from water treatment by electrocoagulation as containers for corrosion inhibitors capable of acting as an active protection element against metal corrosion when included in an organic coating.