Novel eco-friendly self-healing nanozirconium vanadate@alginate hybrid microcapsules for corrosion prevention

Abstract

Nanozirconium vanadate (nZV) was synthesized and encapsulated in calcium alginate as a novel composite material to be used as an eco-friendly and novel self-healing coating. Physicochemical characterizations of the synthesized nanozirconium vanadate, and nanozirconium vanadate/alginate composite microcapsules (nZV@A) were conducted to confirm size and sphericity (129.95 µm ± 12.8, 0.82 ± 0.094), elemental composition, and microcapsule cross sectional analysis. The self-healing mechanism of nZV@A is initiated by an ion-exchange process that transforms the microcapsules from a stiff state to gel-like due to Ca^2+/Na⁺ competition at alginate guluronic junction of the microcapsules, enabling the release of nZV leading to the formation of protective barriers and zirconium oxide films, effectively preventing corrosion and simultaneously facilitating the formation of pentavalent hydrates of vanadium, for self-healing. Electrochemical analysis and self-healing tests were examined in 3.5 wt% of NaCl solution at room temperature to investigate the protective capability of the novel ZV-CA/EP coating compared with the blank epoxy coating for steel substrates. The coating of the zirconium vanadate composite showed excellent barrier protection as well as remarkable self-healing capabilities.