| Summary: | 碩士 === 中原大學 === 生物環境工程研究所 === 103 === Mg-Al LDHs intercalated with the organic acid anions (citrate and malate) and adsorbed the heavy metal ions (copper and lead) from aqueous solution have been studied. Mg-Al LDHs was prepared by hydrothermal method and then citrate and malate were intercalated through a coprecipitation technique to form the citrate Mg-Al LDH and malate Mg-Al LDH. All of adsorbents were characterized by SEM, FTIR, zeta potential and XRD. The maximum adsorption capacities of adsorbents under the given conditions were estimated from Langmuir equation. Moreover, the dynamic data were fitted the pseudo-second order kinetic model well. The adsorption mechanisms of test adsorbents toward copper and lead ions were examined.
The results indicated the produced adsorbents could adsorb Cu2+ and Pb2+ rapidly from an aqueous solution. For Mg–Al LDHs, the adsorption capacities mainly result from the surface precipitation. For citrate Mg-Al LDH and malate Mg-Al LDH, the adsorption capacities were mainly attributable to the formation of the citrate–metal and malate–metal complexes in the interlayers of the Mg–Al LDHs. The uptake of Cu2+ and Pb2+ increased in the order Mg–Al LDH<malate•Mg–Al LDH<citrate•Mg–Al LDH. Citrate possesses the relatively higher oxygen content to generate the higher adsorption capacities. Except for the adsorption of copper ion on Mg–Al LDH, the adsorption capacities can increase with the increasing temperature.
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