Nitrilotrismethylenephosphonate sorption from wastewater on zirconium-lanthanum modified magnetite: Reusability and mechanism study

Phosphonates in wastewater is a recalcitrant pollutant when discharge but also have been recognized as an important resource. However, the understanding of their recovery and reuse via adsorption as an efficient solution is very limited so far. Especially, the desorption and reusability of phosphonate including nitrilotrismethylenephosphonate, which is important for adsorption process, has never been thoroughly explored. For this purpose, desorption efficiency, reusability and kinetic desorption study of nitrilotrismethylenephosphonate were systematically investigated in this study. The desorption mechanism was studied by XPS (X-Ray Photoelectron Spectroscopy) analysis. The results showed that both the pseudo second order and pseudo first order were fitted well for nitrilotrismethylenephosphonate desorption. The decreased of organic phosphorus (OP) presented to new findings for conversion of nitrilotrismethylenephosphonate into inorganic ortho-phosphate phosphorus (IP) during Kinetic and reusability (1.5 mol/L NaOH) which was exhibited to lower desorption efficiency of nitrilotrismethylenephosphonate. The highest desorption efficiency of 92.7% and 114.7% were achieved with 3 mol/L NaOH and 0.30 mol/L NaOH + NaCl solution. The reusability was successful in five cycles by 96.1% and 83.4% with 3 mol/L NaOH and 0.30 mol/L NaOH + NaCl. Comparably, higher total phosphorus (TP) 100% efficiency is involved during nitrilotrismethylenephosphonate reusability. The 100% sustained removal efficiency of nitrilotrismethylenephosphonate made the zirconium-lanthanum modified magnetite as a promising aspirant for wastewater treatment. The XPS analysis suggested inner-sphere complexation mechanism. Overall, zirconium-lanthanum modified magnetite has a potential implementation for nitrilotrismethylenephosphonate desorption in practices.