Selective removal of phosphate in waters using a novel of cation adsorbent: Zirconium phosphate (ZrP) behavior and mechanism

Control of excessive phosphates is a crucial environmental issue, resulting in eutrophication of water bodies. Among the available technology, adsorption stands out as the most attractive treatment option. Amorphous zirconium phosphate (ZrP), is generally acknowledged to be cation exchanger, little is known the sorption behaviors toward anionic pollutants. In the present study, ZrP was fabricated and the enhanced sorption properties towards anion-phosphate were explored. The uptake of phosphate onto ZrP was examined and common used anion-exchange resin (D201) and zirconium dioxide particles were introduced for references with coexistence of common anions (SO42-, NO3- and Cl− ions), the results indicated that both ZrP and ZrO2 exhibited more favorable sorption performances than D-201, which might ascribed to the information of inner-sphere complex. FT-IR spectrum measurement validated that the immobilization of phosphate mainly driven through Zr–O bonds and phosphate complexation, while the sulfate, nitrate and chloride uptake onto ZrP might be attributed to the electrostatic interaction. XPS investigation further proved the strongly specific affinity between ZrP and phosphate over other common anions with larger binding energy shifts. Moreover, the fast sorption kinetic equilibrium was also observed and the data could be well described by the pseudo-first-order model. The used ZrP particles were readily to efficient regeneration by sodium hydroxide solution for repeated use at least five cycles. All the results suggest that ZrP is a promising adsorbent for enhanced sequestration of phosphates in waters.

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• ZrP known as cation exchanger exhibits selective sorption towards P(V) anion.
• P(V  ) uptake shows slight influences with other anions SO42-/NO3-/Cl- at high levels.
• The exhausted ZrP were readily to efficient regeneration by 5% NaOH solution.