| Summary: | 碩士 === 中原大學 === 環境工程學系 === 105 === Mg-Al layered double hydroxides (Mg-Al LDHs) was produced using a co-precipitation method and intercalated with amino acids including phenylalanine, tyrosine and serine. The obtained materials were used to adsorb the cationic heavy metals (Cr3+) and the oxyanion (Cr6+) from aqueous solution under solution pH 4 and 5. The adsorbents were characterized by XPS, SEM, FTIR and XRD. The maximum adsorption capacities of adsorbents under the given conditions were estimated from Langmuir equation. Moreover, the potential adsorption mechanisms of the adsorbents toward the heavy metal ions were elucidated.
The results indicated Mg-Al LDHs have been synthesized and amino acids have been entered the interlayer. The molar ratio of Mg and Al is 3 according to the result in XPS. In addition, carbonate was found in the interlayer through FTIR. As a result, the adsorbents can adsorb chromium ion through the complexation reaction. Dichromate can be adsorbed through anion exchange process. The produced adsorbents can generate the high adsorptive amount for the target pollutants.
The relatively higher adsorption amount for dichromate was found under pH 4. The solution pH increases to 5 that favor the adsorption of chromium ion. The high intercalated concentrations of amino acid lead to the higher adsorptive amount for chromium ion. The low intercalated concentrations can increase the adsorptive amount for dichromate. The maximum capacity of chromium ion and dichromate were found phenylalanine and tyrosine intercalation, respectively.
The advantage of this experimental adsorbent is to develop an adsorbent to simultaneously adsorb anionic chromate and cationic trivalent chromium at the same time. The produced materials used are low cost and high adsorption capacity. Compared with ion exchange resin, the adsorbents possess the advantage in the low cost.
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