本研究以水熱法製備奈米級鈦酸鈉，應用作為多種金屬離子Sr2+、Co2+、Cs+、Ni2+、Cu2+吸附劑。本研究主要分為四大部分，第一部分探討水熱溫度及前驅物對於水熱合成產物的相組成及形貌、結構變化的影響。實驗結果顯示，水熱溫度會影響產物相組成，在200°C的反應環境下會生成結晶性較高的Na2TinO2n+1 (n= 3, 4, 9)混合相，在110、150 °C的環境中則形成結晶性低的鈦酸鈉水熱中間相。而TiO2前驅物的晶相及粒徑則會影響產物形貌及結構，以5 nm 的amorphous TiO2為前驅物，所得鈦酸鈉產物為奈米纖維狀；使用30 nm的Rutile前驅物所得產物則捲曲為管狀；以25 nm的P25為前驅物，則形成厚度較高的片狀結構水熱產物。
本研究第二部分探討上述不同型態的鈦酸鈉產物，對於Sr2+之批次吸附效果與Sr2+的吸附機制，另加入Co2+、Cs+共存離子以探討離子競爭效應。透過批次吸附實驗結果顯示，本研究所得之鈦酸鈉對於Sr2+最佳飽和吸附量為204.8 mg/g。除此之外，研究結果顯示鈦酸鈉對Sr2+的吸附機制同時含有化學沉澱、化學吸附及離子交換，其中以離子交換為主要離子吸附方式，以Ti-O-Na形式鍵結之Na離子作為主要交換位址，部分殘餘在鈦酸鈉表面之NaOH則會造成Sr(OH)2沈澱。
在吸附動力學實驗結果則表明，鈦酸鈉對Sr2+的吸附模式符合擬二階動力學模式，而吸附過程又可分為兩階段，前期之速率決定步驟由沉澱與化學吸附共同控制，而後時段的速率決定步驟則為離子交換反應。
在離子競爭吸附實驗結果可知，Sr2+、Co2+於單一及三重溶液的環境下的吸附容量總和接近，而二價離子(Sr2+、Co2+)的吸附效率並不受到共存的一價離子(Cs+)影響，推測二價陽離子應佔據相同的吸附位置，且此吸附位址對Co2+具有更高的選擇性吸附效率。
本研究第三部分探討鈦酸鈉於Ni2+、Cu2+的吸附效率及工業廢水的實際應用，鈦酸鈉對於Ni2+、Cu2+的最佳飽和吸附量分別為129.7 mg/g及152. 7 mg/g。以從封裝廠取得含Ni2+與Cu2+之高酸度的工業廢水作為測試對象，研究結果顯示，鈦酸鈉對於Ni2+可到達98 %的去除率，而含Cu2+之工業廢水則僅有21 %左右的去除率，推測 Cu2+ 受到Na+、K+其他離子的競爭影響較為明顯。
本研究第四部份則為鈦酸鈉廢料的脫附及還原，透過酸洗再鹼洗兩步驟可成功將鈦酸鈉廢料還原為可吸附的鈦酸鈉，其中以鹽酸酸洗具有較佳的脱附效率，經酸洗處理後再以氫氧化鈉再生，可使使用過的鈦酸鈉廢料再生，但吸附效率僅有原先的44%。

Sodium titanate was prepared by hydrothermal method using three different starting materials, i.e., amorphous TiO2, Degussa P25, and rutile TiO2. The morphologies of sodium titanate products, where fibrous, tubular and lamellar structures were formed depending on the starting. Sodium titanates in different forms were applied to remove Sr2+ ions from aqueous solution. Their adsorption capacities and mechanisms were investigated. The experimental results presented that the optimal adsorption up to 204.08 mg/g were achieved whereas the adsorption mechanisms were mainly dominated by ion exchange and partially by chemical precipitation.

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