Please use this identifier to cite or link to this item:
Effect of Fulvic Acid on Adsorption of Mn onto Manganese-Coated Sand
|關鍵字:||Manganese-coated sand;錳砂;Fulvic acid;Adsorption;黃酸;吸附||出版社:||環境工程學系||摘要:||
以螢光光譜儀分析自行製備的黃酸，於Ex/Em = 334/408 nm可得最佳發光強度，但螢光強度受到pH值變化的影響而有些許改變。添加錳離子於黃酸溶液中，會減弱螢光強度但幅度不大，與其金屬特性有關。當黃酸濃度提高至100 mg C/L時，較易與錳發生錯合，可觀察到螢光減弱量較為明顯。提高錳的添加量卻無法促成錯合反應發生，且改變系統pH值對黃酸與錳的錯合反應影響亦不大。當黃酸濃度為10 mg C/L，吸附百分比約為25 %，換算成單位重量每克人工錳砂可吸附黃酸的量為0.05 mg C/g錳砂。
恆溫動力試驗中錳離子初期之吸附速率非常快速，於2小時已有85 %的錳吸附量，4小時後吸附速率漸趨緩慢，反應近乎達到平衡，最後共有96.7 %的錳被錳砂吸附。當系統中的黃酸濃度上升，吸附率明顯下降，但吸附率隨pH值上升而增加。由競爭吸附結果可知，鐵離子確實會與錳離子在人工錳砂表面競爭吸附位址，且隨著添加的鐵離子濃度愈高，競爭效果愈顯著；但系統中有黃酸存在，部分鐵離子可能會與黃酸發生錯合，而減輕競爭效應。
This study was conducted to investigate the effect of dissolved organic matters on the removal of iron and manganese from water by artificial manganese-coated sand in fast filtration process. Several experiments were conducted, such as surface analyses of manganese-coated sand, the extraction of fulvic acid and its characterization, and batch adsorption tests.
In XRD analysis, there were not only MnO2 but also Mn2O3 and Mn(OH)4 on the surface of manganese-coated sand. By SEM, it's shown that the surface of manganese-coated sand was very rough and filled with granular manganese oxides. Owing to clusters of manganese oxides on the surface of silica sand, manganese-coated sand was more porous than silica sand.
The fluorescence intensity maximum was situated at the wavelength of (excitation/emission) 334/408 nm. Besides, fluorescence intensity was slightly sensitive to pH variation. Addition of Mn2+ slightly quenched fulvic acid fluorescence. It's easily observed spectroscopic changes associated with Mn2+ complexation when the concentration of fulvic acid reached 100 mg C/L. But higher concentration of Mn2+ couldn't result in complexation. The complexation of Mn2+ with FA is pH-indepenent. 25 percentage of fulvic acid was adsorbed on the surface of manganese-coated sand (0.05 mg C/g-sand ).
In adsorption kinetic experiment, the adsorption rate was high in early period. The amount of Mn adsorbed was 85% in first two hours, and the rate slowed down after four hours. Then the adsorption came into equilibrium, and 96.7% of Mn was adsorbed totally. The adsorption of Mn decreased with the increase of FA concentration but increased with increasing pH. The results of competitive adsorption indicated that Fe indeed competed with Mn for adsorption sites on the surface of manganese- coated sand. Adsorption of Mn decreased with the increase of Fe concentration. But in the presence of fulvic acid, the competition was slightly reduced due to fulvic acid-Fe ion complexation.
|Appears in Collections:||環境工程學系所|
Show full item record
TAIR Related Article
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.