利用層狀複合金屬氫氧化物即時合成與記憶效應去除水中重鉻酸鹽之研究

Removal of dichromate from water through layer double hydroxides using memory effect and in situ synthesis

鄧羽晴(Yu-Ching Deng)

指導教授 ： 趙煥平

中原大學/工學院/環境工程學系/碩士(2018年)

https://doi.org/10.6840/cycu201800766

摘要

層狀複合金屬氫氧化物的主要成分為二價與三價金屬離子以及陰離子，在本研究中考慮使用常見的Mg2+與Al3+為陽離子金屬，NO3-、CO32-做為可能測試之陰離子，利用即時合成之特性，在控制不同的溶液pH值下，將Mg2+與Al3+配置莫耳比3:1之濃度配合陰離子加入溶液中與不同濃度之鉻酸鹽混合，測試在不同時間下鉻酸鹽濃度變化，計算出吸附速率與最大吸附量。對於記憶效應方面，先以水熱合成法製作出層狀複合金屬氫氧化物，再將合成材料放在不同溫度下鍛燒，冷卻後將產品與鉻酸鹽混合攪拌，在不同時間下測定鉻酸鹽濃度變化，同樣計算出吸附速率與最大吸附容量。
研究結果顯示，LDHs、C300-LDHs、C400-LDHs、C500-LDHs四種吸附劑皆符合Langmuir model，最大吸附量分別為:185.19(mg/g)、222.22(mg/g)、285.71(mg/g)、357.14(mg/g)。動力吸附符合Pseudo second order kinetics，吸附效果: C500-LDHs＞C400-LDHs＞C300-LDHs。即時合成法去除水中重鉻酸鹽之去除效果0.024 mol Mg(NO3)2‧6H2O、0.008 mol Al(NO3)3‧9H2O、0.0672 mol NaOH、0.0044 mol Na2CO3為最佳加藥量。

關鍵字

層狀複合金屬氫氧化物 ； 鉻酸鹽 ； 吸附 ； 記憶效應 ； 即時合成

並列摘要

The LDHs consisted of metal ions with two and three valence electrons, and anions including NO3-、CO32- . In this study, Mg2+ and Al3+ with molar ratio 3:1 and anions are added to solution containing chromate under the various pH values to synthesize LDHs. The adsorption rates and adsorption capacity for chromate are evaluated. For the structural memory effect, the LDHs can be synthesized using hydrothermal method, and then calcine them under different temperatures. The calcined LDHs mixed with chromate solution. The changes in chromate concentration in given period are analyzed. The chromate concentration change was measured at different times, and the adsorption rate and the maximum adsorption capacity were also calculated.
The results showed that the four adsorbents of LDHs, C300-LDHs, C400-LDHs and C500-LDHs were all in accordance with the Langmuir model. The maximum adsorption capacities were: 185.19 (mg / g), 222.22 (mg / g), and 285.71 (mg / g), 357.14 (mg/g). The kinetic adsorption is in accordance with Pseudo second order kinetics, and the adsorption effect is: C500-LDHs> C400-LDHs> C300-LDHs. The in-situ removes the removal effect of dichromate from water 0.024 mol Mg(NO3)2‧6H2O、0.008 mol Al(NO3)3‧9H2O、0.0672 mol NaOH、0.0044 mol Na2CO3 as the best dosage.

並列關鍵字

Layered double hydroxides ； chromate ； adsorption ； structural memory ； in-situ

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