In-situ construction of layered double hydroxides/flue gas desulfurization gypsum hetero-composites for enhancing phosphate adsorption and green utilization

Abstract

Based on the concept of “waste treats waste”, developing affordable and robust technologies for the effective adsorption and sustainable utilization of phosphorus is very important. Through in-suit constructed magnesium–aluminum hydrotalcite (MgAl-LDH) /flue gas desulfurization gypsum (FGDG) heterointerface composites (MgAl-LDH@FGDG), the excellent stable adsorption performance on phosphate over a wide pH range (4∼12) was obtained, and the maximum adsorption capacity reached 137.71 mg·g−1 at 318 K at pH = 5.2, over ten and five thousand times higher than that of MgAl-LDH and FGDG, respectively. The composite can significantly enhance the active sites, the active Ca2+ derived from FGDG, and the heterointerface effect to form a multi-adsorbed coupling mechanism by chemical precipitation, electrostatic interaction, ion exchange, and ligand exchange for phosphate removal effectively, which can be used as a sustainable fertilizer with potential green utilization value for environmental remediation. This provides a new effective strategy to remove pollutants and utilize sustainably and ecologically.

Keywords

• In-situ construction
• MgAl-LDH@FGDG
• Phosphate
• Adsorption
• Green utilization