Study On The Synthesis Of Five Clay Mineral Colloids And Their Adsorption Characteristics Of Cd²⁺, Pb²⁺,Zn²⁺

In these days, it is hot to study remediation of polluted soil and water in the field of environmental science and geochemistry. To study on the adsorption characteristics of heavy metal on soil mineral colloids, we have studied the synthesis of the five mineral colloids and their adsorption characteristics of Cd2+, Pb2+, Zn2+.First, we synthesized five mineral colloids and analysized their Fourier Transform Infrared spectrometries (FT-IR), X-ray Diffraction scanning spectrums (XRD), then concluded that these five mineral colloids is deserved. These five mineral colloids are goethite, aluminum hydroxide, manganese hydroxide colloid, Hydroxyaluminosilicate-and Hydroxyaluminum-Montmorillonite Complexes.Next we studied the thermodynamics of cadmium (Cd), plumbum (Pb), zinc (Zn) adsorption on the five mineral colloids, the results showed that Cd2+, Pb2+, Zn2+are easy to adsorb on these five mineral colloids and hard to desorb. Then fit Linear, Freundlich, Langmuir equations to the adsorption datas, the results showed that the adsorption datas of Cd2+, Pb2+can fit Freundlich equation better, but the adsorption data of Zn2+fit Langmuir equation better.Then the kinetics is discussed and the empirical equations, including the Lagergren first-, and second-order rate equations, Elovich, Two-constant equation and the parabolic diffusion equations were applied to the adsorptive dynamics results. The results showed that adsorption and desorption of Cd2+, Pb2+, Zn2+on each colloid can be divided into two processes, their kinetics curves can fit well with the five empirical equations and fit Lagergren second-order rate equations better. At last, we study the effects of pH on the thermodynamics of Cd2+, Pb2+, Zn2+on mineral colloids. And the results showed that the effects of pH are similar because adsorption mechanisms are basically identical.