Municipal green waste promotes iron release from steelmaking slag in water

Shortage of soluble Fe in seawater is a limiting condition for benthic seaweeds growth. Utilizing steelmaking slag as the Fe source for seaweeds growth has been proposed. Aiming to find a cost-effective method to promote Fe release, we investigate the effect of adding municipal green wastes. By conducting leaching experiments in freshwater, a sharp improvement in Fe release was observed with the addition of tangerine peel together with steelmaking slag. The flavonoids supplied from the tangerine peel, vicenin-2, apigenin, hesperidin, vitexin, hesperetin and diosmin were observed to have a promotion effect on Fe release. Formation of stable flavonoid-Fe(II) chelates changes the thermodynamic property of Fe(II) in water and disturbs the equilibrium between Fe(II) in slag and Fe(II) in water, which promotes Fe release from slag. These results demonstrate the feasibility to develop a technology for Fe supply in seawater by utilizing the mixture of steelmaking slag and municipal green wastes.