Highly Efficient Removal of Congo red from Wastewater by Nano-Cao

Nano-CaO with high surface area of 120 m² · g^?1 has been used as adsorbents for Congo red adsorption from wastewater. The maximum adsorption capability of Congo red on nano-CaO reached 357.14 mg · g^?1 in 10 min, while the maximum capability on commercial CaO was only 238.66 mg · g^?1 in 30 min. In comparison with commercial CaO, some published metal oxides for Congo red adsorption such as Fe₂O₃, NiO, MgO, and Mn₂O₃, etc., the Nano-CaO exhibited much more favorable adsorptive property. In addition, the effects of pH, salt concentration, and temperature were also investigated, and these factors played significant roles for Congo red adsorption on Nano-CaO.