| Summary: | 碩士 === 國立成功大學 === 化學工程學系碩博士班 === 98 === In this study, we modified iron oxide (BT4) by using KMnO4 to prepare a new adsorbent-MBT4 which was used to removal arsenite (As(III)) from water solution. We detected the concentration variation of As(III) and Mn in the solution to investigate the adsorption mechanism.
We take appraisement and analysis for iron oxide (BT4). The result of XRD showed that BT4 contained lots of amorphous goethite (α-FeOOH). The particle size range was 0.125~0.25 mm.The Specific surface area of BT4 was 154 m2/g by using BET analysis.
When the feed Fe/Mn molar ratio (FeCl2/KMnO4) increased, the capacity of Mn loading on MBT4 decreased. We also found that BT4 could react with MnO4- by itself. The capacity of Mn loading on MBT4 was 1.24 mg/g after 24 hours of the reaction.
The As adsorption capacity of MBT4 was 12.82 mg/g which is higher than that of BT4 (10.87 mg/g). Three models were used to describe the adsorption kinetics. Pseudo-second-order rate equation and the second-order rate equation were more suitable than the first-order Lagergren equation . For adsorption isotherm, Freundlich Model was better than Langmuir Model. The competition of nitrate, sulfate and phosphate with arsenate was also studied. Phosphate and sulfate decreased the arsenate removal efficiency. Nitrate had no obvious effect on the adsorption of arsenite. The mechanism of removal As(III) by MBT4 was proposed. Intially, As(III) was oxidateed by Mn oxide on MBT4. As(III) was transformed into As(V).Finally, MBT4 adsorbed As(V).
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