Multi-functional Magnesium Hydroxide Coating for Iron Nanoparticles Towards Prolonged Reactivity in Cr(VI) Removal from Aqueous Solutions

In this study, the reactive performance of magnesium hydroxide-coated iron nanoparticles (Fe-0 @Mg(OH)(2)) was investigated for the removal of hexavalent chromium (Cr(VI)) from aqueous solutions. Short-and long-term progressive-release of Fe-0 @Mg(OH)(2) reactivity was evaluated through several batch tests. The Multifunctional effect of the environmentally-friendly Mg(OH)(2) coating shell was represented by the progressive shell-dissolution in water and preventing the rapid corrosion of Fe-0-core, which resulted in a controlled release of Fe0 reactivity towards Cr(VI). Fe-0 @Mg(OH)(2) showed good performance in preserving Fe-0 long-term reactivity within a wide range of pH (3.0 - 9.0) and temperature (15-55 ?). The long-term investigation of Fe-0 @Mg(OH)(2) performance towards Cr(VI) removal confirmed the progressive and maintained reactivity, represented by the continuous release of Fe(0 )electrons, to achieve 100% removal efficiency of 40 mg/L initial Cr(VI) concentration over 50 days reaction time, to be reported for the first time in the literature. Fe-0 @Mg(OH)(2) showed high regeneration abilities up to 5 cycles with 1.36 times average enhancement in Cr(VI) removal efficiency compared to that of Fe-0. Moreover, Fe-0 @Mg(OH)(2 )achieved an increase in the shelf-live longevity performance up to 30 days without any storing solution with 90% final Cr(VI) removal efficiency after 180 min reaction time.