Effect of chelating solubilization via different alkanolamines on the dissolution properties of steel slag

This work aims to investigate the solubilizing ability of alkanolamines on steel slag (SS) and the chelating ability of alkanolamines with metal ions. In this paper, the chelation effect of four alkanolamines, including triethanolamine (TEA), triisopropanolamine (TIPA), diethanol-isopropanolamine (DEIPA), and methyl diethanolamine (MDEA), and metal ions on the dissolution of SS was investigated. The conductivity meter, pH meter, X-ray powder diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP-AES), total organic carbon (TOC) and isothermal calorimetry were used to investigate the solubilizing ability of SS impacted by alkanolamines. Additionally, the conductivity meter and chemical precipitation method (CPM) were used to investigate and explore the chelating ability of alkanolamines interacting with the metal ions. Finally, the nuclear magnetic resonance hydrogen ((HNMR)-H-1) spectroscopy was adopted to investigate the chelating mechanism between alkanolamines and metal ions. The results showed that the alkanolamines increased the elemental concentrations of [Ca], [Al], [Fe] and [Si] in the liquid phase of SS through chelating and promoted the dissolution of the mineral phase of C3S, C2S and C(4)AF in SS. Among the different alkanolamines, DEIPA was present in the liquid phase for the longest time and possessed a more sustained ability to chelating metal ions. The result also shows that alkanolamines can chelate the Ca2+ , Al3+ and Fe3+ in solution. The chelating ability of tertiary alkanolamines were stronger than the secondary alkanolamine. And the alkanolamine with asymmetric molecular structure have stronger chelating ability than those with symmetric molecular structure. Tertiary alkanolamines form ternary five-ring structure with metal ion through nitrogen and oxygen atoms.

Automated summary

This study investigates the solubilizing ability of alkanolamines on steel slag and their chelating ability with metal ions. The results show that alkanolamines can increase the elemental concentrations in the liquid phase and promote the dissolution of specific mineral phases in steel slag. Among the alkanolamines tested, DEIPA exhibits the strongest and most sustained ability to chelate metal ions. Additionally, alkanolamines can chelate Ca2+, Al3+, and Fe3+ ions, with tertiary alkanolamines showing stronger chelating ability compared to secondary alkanolamines. Alkanolamines with an asymmetric molecular structure also exhibit stronger chelating ability than those with a symmetric molecular structure.