Adsorption and desorption of Cu(II), Zn(II), Pb(II), and Cd(II) on the soils amended with nanoscale hydroxyapatite

Abstract

Adsorption and desorption of Cu(II), Zn(II), Pb(II) and Cd(II) on a Red soil (RS, Udic Ferrosols) and a Wushan soil (WS, Anthrosol) amended with nanoscale hydroxyapatite (nano-HAP) were studied by batch experiments. The adsorption isotherms show that different kinds of heavy metals had different affinity to the soils in the order of Cu(II) > Pb(II) > Cd(II) > Zn(II). The amount of each heavy metal adsorbed on the RS was lower than that on the WS, because the former had lower CEC and pH than the latter. The amendment of nano-HAP in the soils significantly enhanced the adsorption of heavy metals, in comparison with the treatment receiving no nano-HAP. The K f, simulated from the adsorption isotherms, increased from 78 to 2180for Cu(II), 16.6 to 59.5for Zn(II), and 17.9 to174 for Cd(II) on the RS, and from 995 to 6410 for Cu(II), 52.5 to 92.4 for Zn(II), and 59.2 to 199 for Cd(II) on the WS, when 0.20 g nano-HAP was added into 1.00 g soil. The nano-HAP remarkably inhibited desorption of heavy metals from the soils, suggesting that the addition of nano-HAP can significantly reduce the mobilization of heavy metals and increase their geochemical stability in metal contaminated soils. © 2009 American Institute of Chemical Engineers Environ Prog.