Modified magnetite adsorbent (Zr–La@Fe3O4) for nitrilotrismethylenephosphonate (NTMP) removal and recovery from wastewater

Abstract

Organic phosphonate in wastewater is an important resource but may cause eutrophication world widely. The removal and recovery of phosphonate is therefore essential but little research was done in this regard. In this study, a novel zirconium-lanthanum modified magnetite adsorbent (Zr–La@Fe3O4) was developed for the removal and recovery of nitrilotrismethylenephosphonate (NTMP) from wastewater. The NTMP adsorption capacity and desorption efficiency were investigated under various conditions, while the characterization of the novel adsorbent was also performed. The results showed that 99% NTMP removal efficiency was achieved using Zr–La@Fe3O4 adsorbent. In addition, using different initial concentrations of NTMP, the highest adsorption capacities obtained at equilibrium stage were 16 mg/L to 77 mg/L. Isotherm model of NTMP adsorption on Zr–La@Fe3O4 was well illustrated by the Langmuir model (R2 = 0.994), while the pseudo-second-order model (R2 = 0.893) was well demonstrated in the kinetics study. Besides, acid pH conditions (3, 4, 5, 6) could promoted the NTMP adsorption. Nevertheless, the NTMP adsorption capacity was decreased with the increase of adsorbent dosage. A higher desorption efficiency was found with 1 mol/L NaOH solution, achieving 38.53% DE of NTMP, and then decreased with the increasing number of cycles in the reusability experiment. This novel adsorbent demonstrated potential for removal and recovery of NTMP and to become a promising technology for further research.