One-pot synthesis of a novel P-doped ferrihydrite nanoparticles for efficient removal of Pb(Ⅱ) from aqueous solutions: Performance and mechanism

Abstract

The developments of environmentally friendly and efficient heavy metal adsorbents face challenges. A new adsorbent, P-doped ferrihydrite (P-FH) was designed to remove Pb(Ⅱ) from the aqueous solution. Various techniques are implemented to characterize P-FH. P-FH was confirmed the formation of the second-line ferrihydrite phase by X-ray diffraction. Scanning electron microscopy (SEM) indicated that P-FH composed of a large number of uniform nanoparticles with a specific surface area (SBET) of 431.2 m2/g, and it is an ultra-small mesoporous material. Batch adsorption experiments showed that adsorption capacity of P-FH for Pb(II) increases with the increase of pH value or temperature. P-FH possesses a high adsorption capacity of 246.8 mg/g (25 ℃, pH = 6) for Pb(Ⅱ) in solution, which is very competitive compared with other representative adsorbents. The adsorption process of Pb(Ⅱ) onto P-FH is more in line with the pseudo-second-order kinetic model and the Freundlich adsorption isotherm model. Moreover, P-FH has a high selectivity for Pb(II) adsorption. Cation exchange, complexation electrostatic attraction jointly contributed to the efficient adsorption of Pb(Ⅱ) on P-FH from aqueous solution. Additionally, a high adsorption rate of 81% was held after six sorption-regeneration cycles. This work provides a simple one-pot method to prepare an environmentally friendly adsorbent for Pb(Ⅱ) efficient adsorption.