Kinetic and thermodynamics of the removal of Zn2+ and Cu2+ from aqueous solution by sulphate and phosphate-modified Bentonite clay

摘要: Abstract The modification of pristine Bentonite clay with sulphate and phosphate anions was found to increase its cation-exchange capacity (CEC), adsorption overall pseudo-second order kinetic rate constant for the Cu2+ Zn2+. Modification anion decreased specific surface area clay. Phosphate-modified give highest both metal ions. process observed be endothermic spontaneous in nature ions Zn2+ being more adsorbed. increased spontaneity process. effective confirmed from hypochromic shifts range 13–18 cm−1 which is typical physisorption while by hyperchromic chemisorption infrared red region using Fourier transformed spectroscopy (FTIR). Using model efficiency indicator, data were show very strong fit implying that basically chemisorption.