Sorption behavior and mechanism of iminodiacetic acid resin for cadmium

The sorption of Cd(Ⅱ) with iminodiacetic acid resin(D401) was investigated.The results show that D401 has a good sorption ability for Cd(Ⅱ) in the HAcNaAc medium at pH=5.73.The statically saturated sorption capacity of resin is 363mg/g and 0.5mol/L HCl can be used as an eluant;the elution percentage is 100%,the sorption rate constant is k_(298)=2.05×10~(-5)s~(-1),and the apparent sorption activation energy of D401 for Cd(Ⅱ) is 18.0kJ/mol.The sorption behavior of D401 for Cd(Ⅱ) obeys the Freundlich isotherm.The sorption thermodynamic parameters of D401 for Cd(Ⅱ) are: enthalpy change ΔH=3.08kJ/mol,free energy change ΔG =-7.62kJ/mol,entropy change ΔS =35.9J/(mol·K),respectively.The coordination molar ratio of the functional group of D401 to Cd(Ⅱ) is 1∶1.The sorption mechanism of D401 for Cd(Ⅱ)was confirmed by chemical analysis and IR spectrometry.