Synthesis Of Magnetic Kaolin And The Adsorption Property Of Cu(Ⅱ) And Pb(Ⅱ)

With the unique characteristics of magnetic composite structure and chemical properties, it has broad prospects in heavy metal wastewater treatment, the magnetic kaolin was prepared by co-precipitation phase with low prices and rich source kaolin, the adsorbent was researched by SEM, EDX, BET, FTIR and XRD analysis. The effects of initial concentration, pH and adsorption time on the adsorption behavior were determined by experiments, its adsorption properties were also compared with kaolin and Fe₃O₄, and the mechanisms were investigated by adsorption isotherm model, SEM, FTIR and XRD analysis.The SEM indicated that magnetic kaolin was a tiny particle which in different size, the BET indicated that after the preparation the specific surface area and pore volume are increased, the XRD indicated that the crystal structure of kaolin was not changed, the EDX indicated that the elements content of Si, Al keep unchanged but O increased, the FTIR showed that Fe-O characteristic absorption peaks was appeared.The results showed that the adsorption process reached adsorption equilibrium in 20 min, and at initial Pb²⁺ concentration of 5 mg·L-1, the adsorption removal rate reached 99.48%, the adsorption of Pb²⁺ on magnetic kaolin was well described by the Langmuir adsorption model,the kinetics of adsorption was well fitted by the pseudo-second order kinetic model, the Pb²⁺ adsorption on the magnetic kaolin was mainly controlled by chemical adsorption. The results of single factor experiments indicated that the adsorption process achieved adsorption equilibrium in 30 min, at adsorbent dosage 0.4 g, pH=6, adsorption time of 30 min, and initial Cu²⁺ concentration of 5 mg·L-1, the adsorption removal rate reached 98.18%; The isotherm model follows the Langmuir adsorption model, the adsorption property of magnetic kaolin was better than kaolin; SEM photos indicated that adsorption process was mainly attributed to surface monolayer. Results of XRD, FTIR suggested that Cu²⁺ adsorption mechanism of magnetic kaolin is complexation and coordination reaction with the –OH,-NH and-COOH as the major functioning groups for Cu²⁺ adsorption.The results of adsorption experiments showed that adsorption kinetics was abided by pseudo-second-order equation and intra-particle diffusion model, and exhibited preferential adsorption in single or binary system; In competitive system, magnetic kaolin for Cu²⁺and Pb²⁺ adsorption capacity has weakened, but the adsorption capacity of Cu²⁺ decreased more significantly, respectively, and the adsorption stability of Pb²⁺ on the magnetic kaolin was better than that of Cu²⁺. The thermodynamic parameters indicated that the adsorption is spontaneous, endothermic accompanied by increase in entropy, the adsorption thermodynamic characteristics was influenced by competing ions.