Simultaneous and efficient removal of multiple heavy metal(loid)s from aqueous solutions using Fe/Mn (hydr)oxide and phosphate mineral composites synthesized by regulating the proportion of Fe(II), Fe(III), Mn(II) and PO43.

In this work, a novel adsorbent FMPs consisting of Fe/Mn (hydr)oxides and phosphate minerals was synthesized by regulating the proportion of Fe(II), Fe(III), Mn(II) and PO43-, and its removal behaviors and possible mechanisms for Cd(II), Pb(II), Cu(II), Zn(II), As(III), Sb(III), As(V) and Sb(V) were systematically investigated. Batch adsorption experiments revealed that the adsorption process of FMPs to these metal(loid) ions conformed to pseudo-second-order (R2 > 0.99) and Redlich-Peterson (R2 > 0.94) models in the mono-component system, demonstrating a hybrid chemical reaction-adsorption process. In addition, the solution pH and ionic strength could affect the adsorption capacity of FMPs to heavy metal(loid)s with varying degrees. Besides, FMPs presented feasible stability and reusability even after four cycles. Combining the macroscopic and microscopic characteristics, the adsorption mechanisms of FMPs mainly included surface complexation, electrostatic adsorption, inner-sphere complexation, hydrogen bonding, redox and pore-filling. In a multi-component system, FMPs exhibited an excellent affinity for capturing Pb(II) and Sb(III/V). This work provides an alternative method for designing and developing a series of novel adsorbent in removing multiple heavy metal(loid)s from wastewater, and demonstrated its application prospect in the remediation of multi-metal(loid) composite polluted water.