Effect of pH and humic acid on the adsorption of cesium onto g-Al2O3

The sorption of cesium onto g-Al2O3 was studied by using batch technique and ultra-filtration method at room temperature, at pH 4.0, 6.0 and 8.0 and ionic strength ranged from 0.001M to 0.1M NaClO4. The pore size of the filter 1000K was used to separate the liquid from the solid phase. UV vis spectrophotometer was used to determine the concentration of humic acid in the solution at wavelength of 254 nm. The sorption of humic acid and Cs on the g-Al2O3 was studied in the pH range from 2 to 12. The sorption of humic acid on the g-Al2O3 was strong (»98% HA was sorbed on the surface of g-Al2O3 below pH 9) and strongly depended on the pH values (above pHzpc the sorption of HA decreased markedly with the increasing of pH), humic acid has a little negative effect on the sorption of cesium. This may be attributed to the formation of HA-Cs complexation in the solution. The sorption of Cs onto g-Al2O3 was weak depending on the pH and independent on the ionic strength. The sorption of Cs onto g-Al2O3 may be contributed to cation exchange and surface complexation mechanism.