Three kinds of apatite adsorbents prepared by co-precipitation for Pb (II) and Cd (II) removal from wastewater: performance, competitive effects and mechanisms

Abstract

Heavy metal pollution in water bodies is a serious environmental problem continuously, which requires urgently seeking an efficient and cost-effective solution. Apatite as the most abundant phosphate on earth exhibits remarkable adsorption effect on heavy metals. Based on this, three kinds of apatite adsorbents were prepared in this study by titration co-precipitation method for the removal of heavy metals Pb (II) and Cd (II) from water. In the single system, the maximum adsorption capacity of hydroxyapatite (Hap), chlorapatite (Clap), and fluorapatite (Fap) for Pb (II) was 1597.16 mg/g, 1477.82 mg/g, and 1455.99 mg/g, for Cd (II) were Hap (107.18 mg/g), Clap (79.08 mg/g) and Fap (15.8 mg/g). Pb (II) was more competitive than Cd (II) in binary metal system. Apatite adsorbents mainly remove Pb (II) and Cd (II) from solution by dissolution precipitation, electrostatic attraction, surface complexation and ion exchange. The results of this study show that the three kinds of apatite adsorbents exhibited excellent adsorption performance for Pb (II), and also had a certain removal effect for Cd (II). Therefore, the three kinds of apatite have certain application prospects in heavy metal wastewater treatment.