Study On Adsorption Behavior Of Metal Ions In H~+ Form 732 Resin

In China,a serious shortage of water resources,alkaline earth metal ions Mg²⁺ and heavy metal ions Pb²⁺ and Cu²⁺ were present in hard water and industrial wastewater,which could lead to serious problems in industrial and domestic environment.From the perspective of economy,safety and human health,Hard water and heavy metal pollution control without delay.In this paper,the adsorption thermodynamics and kinetics of metal ions such as magnesium,copper and lead in cationic resin?H⁺ form 732-CR?were studied.The adsorption isotherms and adsorption kinetics data of the above three kinds of metal ions?concentration of 5-50 mol·m-3?in H⁺ form 732-CR were measured in the temperature range of 298.15-328.15K.The Langmuir model and the Freundlich model were used to correlate the adsorption isotherm.The results show that the Langmuir adsorption isotherm is in good agreement with the experimental data?linear correlation coefficient R2 is greater than 0.997?,which also shows that the adsorption process is monolayer adsorption.The saturated adsorption capacities of Mg²⁺,Pb²⁺ and Cu²⁺ in the Langmuir model were:40.33,512.8 and 104.2 mg·g-1,respectively.On the basis of this,the adsorption process was thermodynamically analyzed,and the adsorption enthalpy change and entropy change and Gipus free energy of the three metal ions were obtained.The results show that the adsorption process is exothermic and spontaneous.The adsorption kinetics of Mg²⁺ in H⁺ form 732-CR was investigated by Nernst-Planck equation and shrinkage core model?SCM?.The results show that the two kinetic models can be used to describe the adsorption kinetics of Mg²⁺.The diffusion coefficients?DM and DH?of the ion pair and the effective diffusion coefficient?De?were obtained and the relationship between them was discussed.The adsorption kinetics data of Pb²⁺ and Cu²⁺ in H⁺ form 732-CR were analyzed by SCM model,first order and second order dynamic model.The results showed that the metal ion concentration was 0.02 mol·L-1,The ion exchange process of Pb²⁺ and Cu²⁺ with H⁺ form 732-CR conforms to the second-order kinetic model.