Structure-modulated CaFe-LDHs with superior simultaneous removal of deleterious anions and corrosion protection of steel rebar.

The three anionic species; chloride (Cl), sulfate (SO ), and carbonate (CO ), are typical chemical factors that environmentally accelerate failure of concrete structures with steel rebar through long-term exposure. Efficient removal of these deleterious anions at the early stage of penetration is crucial to enhance the lifespan and durability of concrete structures. Here, we synthesize CaFe-layered double hydroxide (CaFe-LDHs) by a simple one-step co-precipitation technique and structural modulation by calcination process. It is applied for the removal of Cl, SO , and CO anions as well as corrosion inhibition on steel rebar in aqueous solutions. The synthesized CaFe-LDHs with phase transfer show notable improvement of removal capacity ( ) toward Cl and SO over 3.4 times and over 5.69 times, respectably, then those of previous literatures. Furthermore, the steel rebar exposed to an aqueous solution containing the three anionic sources shows a fast corrosion rate (1876.56 × 10 mm per year), which can be remarkably inhibited showing 98.83% of corrosion inhibition efficiency when it is surrounded by those CaFe-LDHs. The novel adsorption mechanisms of these CaFe-LDHs-induced crystals and corresponding corrosion protection properties are elucidated drawing on synergy of memory effects and chemical reactions.