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Study of Adsorption and Desorption of Arsenic(III) in Soils with Prussian Blue Modified Electrode
There are higher arsenic content in blackfoot disease endemic village soils of in southwestern coast area in Taiwan. Arsenic will cause toxicity and harm to human body through various pathway, so the determination of arsenic is very important. In this study, we established a basic detective method of arsenic(III) in soils with Prussian blue-modified electrode. Because popularity of organic agriculture at present, we studied adsorption and desorption of arsenic(III) on three different soils (Hsingta, Shiushui and Holi) with blank and compost treatments. The mechanism of specific adsorption of arsenic(III) on Prussian blue was solved by X-ray diffraction and FT-IR spectrometers. The mechanism could be extended to the determination of arsenic(III) with Prussian blue-modified screen-printed carbon electrode that had a good linear calibration curve (R2 = 0.996). Furthermore, the results of determination for different arsenic(III) concentration between electrochemical analysis and inductively coupled plasma emission spectroscopy are also much consistent (R2 = 0.976). The method have high potential and is a new analytical tool for studying arsenic(III) of soils. Sensitivity and detective limits could be improved by coupling with flow injection analysisa, and it had better resolution in determination and researches of arsenic(III) in soils. The results of adorptive experiments showed that soils treated with compost would increase their adsorptive ability of arsenic(III) due to increase organic matter content. However, Hsingta soil became more suprising, adsorptive ability of arsenic(III) decrease in lower concentration range but increase in higer concentration range. We thought the complexation of smectites and organic matter made the major contribution. The order of desorptive proportion were Hsingta > Shiushui > Holi in blank and compost treatments. Shiushui soils was stranger among three soils and its adsorptive ability of arsenic(III) increased apparently after compost treatments, but desorptive proportion didn't increase. That indicated the desorption process was controlled mainly by the types and contents of clay minerals. In conclusion, the novel method provided not only a fast, convenient, accurate and economic determination for arsenic(III) in soils, but also possessed high potential as a new analytical tool to study arsenic(III) of soils. Finally, we could create a brandnew field of soil chemistry researches.
台灣西南沿海是烏腳病的流行區，該地區土壤中砷含量有偏高的情形，砷含量過高會經由各種途徑對人體造成毒性與傷害，因此環境中砷的偵測至為重要。探討與瞭解普魯士藍修飾電極在三價砷偵測上的機制，可作為日後土壤中砷物種偵測上的理論基礎。此外，由於現今有機農法的盛行，農地中常施用大量有機堆肥做為土壤養份的來源，因此試驗中針對三種不同土類土壤(大里系、秀水系及吳厝系)經堆肥處理後對三價砷吸附與脫附情形做進一步的探討。經X-射線繞射儀與傅立葉轉換紅外線吸收光譜儀試驗結果證實三價砷在普魯士藍上的專一性吸附機制，且利用普魯士藍修飾網版印刷碳電極可成功偵測土壤中的三價砷，以電流計法偵測不同濃度三價砷時其標準定量曲線有一良好的線性關係 (R2 = 0.996) ，且樣品的偵測結果與感應耦合電漿放射光譜儀的測值十分吻合(R2 = 0.976)，進一步搭配流動注入系統的偵測方式，可大大提高分析效率，降低偵測極限，應用於土壤中三價砷的研究可得到更好的結果。由土壤三價砷的吸附試驗中發現堆肥處理會增加秀水與后里土壤對三價砷的吸附，且其中以秀水土壤增加情形較為明顯，此與有機質含量的增加有關。對興大土壤而言，堆肥處理後對三價砷的吸附行為較為特別，在低濃度時吸附量會降低，而高濃度時吸附量卻又增加，其受土壤中膨脹性黏土礦物與有機質鍵結所形成的複合物影響較大，複合物會大大影響三價砷的吸附。三種土壤不論有無施用堆肥，在脫附百分率的大小順上依序為興大>秀水>后里，其中秀水土壤雖在施用堆肥後吸附力大小明顯增加，但脫附百分率下降情形卻較不明顯，顯示脫附行為受到土壤黏土礦物成分所影響。利用電化學分析技術進行土壤中三價砷的吸附與脫附試驗結果，得知此技術不僅可達到快速、簡便、準確且經濟的目的外，進一步更提高了污染現址土壤研究的可行性，開拓土壤化學研究的新視野。
|Appears in Collections:||土壤環境科學系|
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