Porous Pr(OH)3 nanowires as novel high-performance adsorbents for phosphate removal

• Porous Pr(OH)3 nanowires were utilized in phosphate removal for the first time.
• The adsorption capacity estimated by Langmuir model was 129.0 mg P/g at 25 °C.
• The adsorption was chemisorption; and it was spontaneous and exothermic.
• The presence of Cl−, HCO3−, or NO3− had neglectable effects on P adsorption.
• The adsorbent could work efficiently in a wide pH range of 3–10.

Porous Pr(OH)3 nanowires (NWs), which were synthesized via an electrodeposition approach, were utilized in phosphate removal for the first time. Our prepared porous Pr(OH)3 NWs exhibited superior phosphate removal performances, due to their large surface area, unique porous structure, and abundant hydroxyl groups as active sites. Their phosphate adsorption equilibrium data were well described by utilizing the Langmuir isotherm model (R2 ⩾ 0.996), with a maximum phosphate adsorption capacity of 128.96 mg P/g at 25 °C. The thermodynamic study showed that the phosphate adsorption of Pr(OH)3 NWs was a spontaneous and exothermic process. On the other hand, the phosphate adsorption kinetics was well described with the use of the pseudo-second-order model, suggesting the adsorption process be chemisorption. In the pH range of 3.0–10.0, the high adsorption capacities of Pr(OH)3 NWs were observed; whilst, the presence of Cl−, HCO3−, or NO3− did not dramatically affect the phosphate uptake. Our experimental results strongly suggest that the use of porous Pr(OH)3 NWs hold a great potential in achieving highly efficient phosphate removal in practical water treatment.