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In this study, cucurbit[8]uril(CB[8]) was utilized as a kind of new adsorbent to remove Pb~(2+) ions from aqueous solution. With the solution p H increased from 2 to 6, the removal efficiency of adsorption increased from 55.6% to 74.5%correspondingly. The uptake of Pb~(2+) increased rapidly in the initial 30 min, and then the adsorption rate became slower. The Pseudo-second order model could be used to interpret the adsorption kinetics satisfactorily;and the rate determining step in Pb~(2+) adsorption onto CB[8] was the external mass transfer step. Equilibrium isotherm study reveals that the Langmuir model gave a better fitting result than Freundlich model. The maximum adsorption capacity calculated by the Langmuir model was 152.67 mg/g for 298 K, 149.70 mg/g for 313 K and 136.42 mg/g for 323 K, respectively.The adsorption is a spontaneous process of exothermic nature. The effect of the adsorbent dosage and the influences of solution p H and co-existing cations were also investigated.The CB[8] was synthesized and characterized by ~(1)H NMR, IR, ESI-MS spectra, SEM-EDAX,Zeta-potential and BET-analysis. The adsorption mechanism was due to the coordination between CB[8] molecule and Pb~(2+) ions.
In this study, cucurbit [8] uril (CB [8]) was utilized as a kind of new adsorbent to remove Pb ~ (2+) ions from aqueous solution. With the solution p H increased from 2 to 6, the removal efficiency The increase of Pb ~ (2+) increased rapidly in the initial 30 min, and then the adsorption rate became slower. The Pseudo-second order model could be used to interpret the adsorption kinetics satisfactorily; and the rate determining step in Pb ~ (2+) adsorption onto CB [8] was the external mass transfer step. Equilibrium isotherm study reveals that the Langmuir model gave a better fit result than Freundlich model. The maximum adsorption capacity calculated by the Langmuir model was 152.67 mg / g for 298 K, 149.70 mg / g for 313 K and 136.42 mg / g for 323 K, respectively. The effect of the adsorbent dosage and the influences of solution p H and co-existing cations were also investigated.T The adsorption mechanism was due to the coordination between CB [8] molecule (H NMR, IR, ESI-MS spectra, SEM- EDAX, Zeta-potential and BET- and Pb ~ (2+) ions.