Removal of phosphate from industrial wastewater using uncalcined MgAl-NO3 layered double hydroxide: batch study and modeling

In this study, the sorption ability of nitrate containing MgAl layered double hydroxide as an anion-exchanger to remove phosphate from a real effluent was investigated. The LDH material was prepared via coprecipitation method and characterized by X-ray diffraction, SEM, Fourier Transform Infrared, BET surface area, and pH(zpc). The effect of physico-chemical key parameters on phosphate removal, such as sorbent dosage, solution pH, initial concentration, and contact time, has been studied in batch mode. The sorption reached equilibrium within 30min. Furthermore, the sorption mechanism of phosphate onto MgAl-NO3 LDH is a combination of both anion-exchange and electrostatic attraction. The equilibrium 8 data were tested using Langmuir, Freundlich, and Dubinin-Radushkevich isotherms. The results show that the Langmuir isotherm describes sufficiently the sorption equilibrium, offering a maximum sorption capacity of 64.10mg/g. Sorption kinetic follows accurately pseudo-second-order reaction. The sorbent reusability shows that regenerated LDH can be reused in subsequent sorption-regeneration cycles with a slight decrease in sorption capacity.