- 學位論文
生物吸附劑吸附重金屬後以酸與鹽類 脫附再生之研究
Regeneration of Heavy Metals on Biosorbents by acid and salt
摘要
本篇研究主要是柚子皮、百香果殼、甘蔗渣等三種生物吸附劑，吸附重金屬後在不同條件下之再生效率，先利用其表面富含之COOH官能基分別對Cu2+、Pb2+、Zn2+進行吸附，再藉由不同濃度之酸(HCl、HNO3)與鹽類(KCl、NaCl)進行脫附再生試驗，探討不同吸附劑與金屬間之脫附效率。再生試驗後的生物吸附劑利用掃描式電子顯微鏡(SEM)觀察外部型態，FTIR觀察官能基的圖譜變化，同時藉由陽離子交換能力(CEC)去測定脫附後的生物附劑，再利用穿透式電子顯微鏡(TEM)去觀察生物吸附劑在脫附後有無孔洞的產生，進以確定在脫附/再生試驗後，生物吸附劑之表面性質。 實驗結果顯示柚子皮與百香果殼具有較高的脫附效率，而甘蔗渣在Pb2+的再生試驗中也有良好的脫附效果，脫附後之生物吸附劑上的COOH官能基變化，也可以藉由FTIR圖譜觀察確認。所得結果顯示在經過酸類(HCl、HNO3)連續脫附/再生後，其表面的官能基與結構發生改變，其陽離子交換能力隨著再生次數增加而減少，對重金屬脫附效果為：Cu2+=Zn2＞Pb2+，生物吸附劑的脫附效果為：柚子皮 > 百香果殼 > 甘蔗渣。最佳之脫附條件為1M HCl，其效率可達98.82%，這顯示出生物吸附劑能有效應用於重金屬回收。
並列摘要
The primary purpose of study is to examine desorption rates of heavy metal ions on fibrous materials, such as citrus maxima, passion fruit shell and sugarcane bagasse, under given conditions. The biosorbents with bio-rich COOH functional groups are used to adsorb Cu2+, Pb2+ , Zn2+ and then they were regenarated using HCl、HNO3、KCl and NaCl with difference concentrations. In order to understand the effects of surface characteristics on the desorption rates,we use scanning electron microscopy image, FTIR spectra, cation exchange capacities and transmission electron microscopy image to observe difference between before and after desorption. Moreover, we can demonstrate the realationship of the surface characteristics of biosorbents and regeneration rates. The results indicate citrus maxima and passion fruit shell have the high desorption rates, and sugarcane bagasse can generate high desorption rates toward lead ions. After desorption, we can observe the change in functional groups by FTIR spectra. Result revealed that the functional groups and the surface structures have been destoryed using regenerants of HCl and HNO3. The cation exchange capacities of the biosorbents significantly decrease with the continuous regeneration of acids. The estimated desorption rate is in the following descreasing order: Cu2+=Zn2＞Pb2+. The desorption rates for all heavy metals are the following order: citrus maxima > passion fruit shell > sugarcane bagasse. 1M of HCl can produce the best desorption concentration, leading to the desorption rate up to 98.82%. The result indicated that biosorbents could be applied to recovery heavy metals in aqueous solutions.