Effective ultrasound-assisted removal of heavy metal ions As(III), Hg(II), and Pb(II) from aqueous solution by new MgO/CuO and MgO/MnO2 nanocomposites

A series of new (MgO) _x CuO and (MgO) _x MnO₂ nanocomposites were prepared and used as adsorbent for removal of As³⁺, Hg²⁺, and Pb²⁺ ions from aqueous solution with high capacity and detection limit. These nanocomposites were synthesized with different molar ratios by sonochemical method in alkaline solution using polyvinylpyrrolidone as a capping agent and were characterized by FTIR, AAS, UV–Vis spectroscopy, and TEM and SEM imaging. The maximum heavy metal ions adsorption was achieved for (MgO)_0.32CuO and (MgO)_2.9MnO₂ nanocomposites assisted by 3-min sonication using ultrasound. Adsorbent capacity of (MgO)_0.32CuO reached 500.0 mg/g and detection limit was 0.1 ppb for As³⁺. Also (MgO)_2.9MnO₂ nanocomposite adsorbed 457.1 mg/g of Hg²⁺ and 461.2 mg/g of Pb²⁺. Extremely low detection limits of 1.5 and 2.0 ppb were obtained for Hg(II) and Pb(II) ions, respectively, which are much lower than the WHO allowable limits. So, these nanocomposites should be excellent candidate for heavy metal removal with advantage of high capacity, high sensitivity, cost effectiveness and easy preparation.