Preparation of PEI-DTC and its adsorption performance on Pb2+,Cu,Zn2+
The optimum preparation conditions of PEI-DTC were obtained by taking the adsorption amount of Pb2+as the evaluation index,and the morphology and structure of PEI-DTC were characterized by SEM and FT-IR.The effects of adsorption duration,pH,oscillation speed,and material dosage on the adsorption effect of PEI-DTC to Pb2+,Cu2+,and Zn2+were investigated,and the kinetic,thermodynamic characteristics of the adsorption process,and reuse performance of PEI-DTC were analyzed.The results showed that the optimum preparation conditions of PEI-DTC were m(PEI)/m(glutaraldehyde)=2∶1,m(PEI)/m(NaBH)=3∶1,m(PEI)/m(CS2)=3∶1 when 30％PEI solution was used.The prepared PEI-DTC material had a granular and honeycomb structure with a large specific surface area.The adsorption effect of PEI-DTC on Pb2+,Cu2+,and Zn2+showed a trend of increasing and then stabilizing with the increase of adsorption time and pH,Pb2+,Cu2+showed a better adsorption effect at the oscillations speed of 100 r·min-1,and Zn2+showed a better adsorption effect at the oscillations speed of 150 r·min-1.Pb2+was nearly completely adsorbed at PEI-DTC dosage of 0.03 g,while the removal rates of Cu2+and Zn2+still increased at PEI-DTC dosage of 0.08 g.The removal rates of Pb2+,Zn2+,and Cu2+by PEI-DTC under suitable adsorption conditions were 97.62％,14.79％,and 78.92％,respectively,with the corresponding adsorption amounts of 4.005 mmol·g-1,0.509 mmol·g-1,and 4.658 mmol·g-1,respectively.The adsorption process conformed to Langmuir adsorption isothermal and the quasi-second-order kinetic model.Moreover,Pb2+,Cu2+,and Zn2+adsorption was a spontaneous and endothermic process.The regeneration rate still maintained at 81.14％after four cycles of reuse.
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