Preferential capture of phosphate by an Enteromorpha prolifera-based biopolymer encapsulating hydrous zirconium oxide...

Preferential removal of phosphate from aqueous was conducted by a novel biomass-based nanocomposite (EP-N⁺-Zr) with encapsulated hydrous zirconium oxide, and the biopolymer EP-N⁺-Zr features were described. EP-N⁺-Zr exhibited high selective sequestration toward phosphate when humic acid or other competing anions (Cl^-, SO₄^2-, NO₃^-, ClO₄^-) coexisted at relatively high levels. Such excellent performance of EP-N⁺-Zr was attributed to its specific two site structures; the embedded HZO nanoparticles and quaternary ammonia groups [N⁺(CH₂CH₃)₃Cl^-] bonded inside the biomass-Enteromorpha prolifera, which facilitated preferable capture towards phosphate through specific affinity and nonspecific preconcentration of phosphate ions on the basis of the ion exchange, respectively. The maximum adsorption capacity of phosphate (20 °C) as calculated by Langmuir model was 88.5 mg(P)/g. Regeneration tests showed that EP-N⁺-Zr could be recycled at least five times without noticeable capacity losses using binary NaOH-NaCl as eluent.