Adsorbent nanoarchitectonics of mMnO2/nFeOOH/KIT-6 for As(iii) adsorption from wastewater

Abstract

A manganese dioxide and ferric hydroxide doped KIT-6 adsorbent (8MnO₂/FeOOH/KIT-6) was prepared and employed for As(III) adsorption. The studies indicated that the large surface area, particular pore structure and the synergy interaction between FeOOH and MnO₂ endow the adsorbent with excellent adsorption performance. The adsorption rate of 8MnO₂/FeOOH/KIT-6 for As(III) could reach 92% when the As(III) initial concentration was 20 mg L⁻¹ and the adsorbent dose was 1 g L⁻¹, at pH 1. During five consecutive cycles, 8MnO₂/FeOOH/KIT-6 exhibited good stability, and the adsorption rate was consistently above 90%. The adsorption capacity of the 8MnO₂/FeOOH/KIT-6 for As(III) was 39.77 mg g⁻¹ when 10 mg of adsorbent and 10 mL of As(III) ion solution (20 mg L⁻¹) were used at pH 1 and 303 K. The adsorption of As(III) on 8MnO₂/FeOOH/KIT-6 was a spontaneous process and in line with the pseudo-second-order kinetic model. More importantly, 8MnO₂/FeOOH/KIT-6 showed excellent selectivity in a complex system, for example Cl⁻, NO₃⁻, SO₄²⁻, SiO₃²⁻ or Ge⁴⁺ coexisting with As(III) in wastewater.