Geo- and nano-materials affect the mono-metal and competitive sorption of Cd, Cu, Ni, and Zn in a sewage sludge-treated alkaline soil

Abstract

We evaluated the effect of geomaterials (modified zeolite and bentonite using CaCl2) and nanoparticles (ZnO and MgO) on the mono-metal and competitive sorption of cadmium (Cd), copper (Cu), nickel (Ni), and zinc (Zn) in an alkaline soil treated with three sewage sludges (SSs) collected from Isfahan, Rasht and Shiraz, Iran. The three SSs increased Cu sorption compared to the control. Sorption of Cd and Zn increased by the addition of Isfahan SS, but decreased by that of Rasht SS. Isfahan SS increased significantly the distribution coefficient of Cd, Cu, and Zn by 1.9, 1.2 and 1.5 times, respectively, compared to the control. The geomaterials and nanoparticles increased metal sorption in the SS-amended soil. Zeolite and MgO were the best sorbents for Cu in Rasht and Shiraz SS treated soil, while ZnO and MgO were better in Isfahan SS-treated soil. Bentonite showed the highest Cd sorption capacity in Isfahan SS-treated soil, and MgO in the Shiraz SS-treated soil. ZnO showed the highest sorption capacity for Ni among the three SSs treatments. The nanoparticles showed higher sorption capacity for Zn than the geomaterials. We conclude that zeolite, bentonite, ZnO and MgO could be suitable immobilizing agents for Cd, Cu, Ni, and Zn in SS-amended alkaline soils.