Efficient removal of As(III) via the synergistic effect of oxidation and absorption by FeOOH@MnO2@CAM nano-hybrid adsorption membrane

Due to the neutral charge of As(III) oxy-ions that make approaching the traditional adsorbent very improbable compared to the As(V) case, making it harder to be separated. To enhance the adsorption of As(III), the FeOOH coated cellulose acetate (CA) membrane doped with MnO2 nanoparticles (FeOOH@MnO2@CAM) was fabricated and then to removes As(III) in water through the synergistic effect of oxidation and adsorption, and the maximum adsorption capacity can reach 50.34 mg/g. FeOOH@MnO2@CAM was fabricated with CA as a substrate by dipping-precipitation phase inversion and hydrothermal method. Langmuir and pseudo-second-order model showed that As(III) was adsorbed by chemical interactions through the monolayer and thermodynamic showed that As(III) adsorption was an exothermic and spontaneous process. The results of the pH study showed that as the pH increases from 3 to 11, the adsorption capacity of As(III) decreases from 50.34 to 14.32 mg/g, which was attributed to the acidic environment promoting the protonation of the surface of FeOOH@MnO2@CAM, which increases the electrostatic attraction, and the alkaline environment increases electrostatic repulsion due to deprotonation. The competitive ions exhibited the PO43- significantly reduce the adsorption capacity As(III), and as the PO43- content increases, the adsorption capacity of As(III) decreases from 29.76 to 18.57 mg/g, which was attributed to the similar chemical properties of PO43- and arsenate. Importantly, FeOOH@MnO2@CAM still maintains an adsorption capacity of 20.19 mg/g after seven cycles, demonstrating that it is a kind of environmentally friendly material to remove As(III) in the water environment. (C) 2020 Elsevier Ltd. All rights reserved.