新穎材料農業：友善環境農業新穎材料研發與安全評估【土壤環境科學系/劉雨庭副教授/優聘教師】
| 論文篇名 | 英文：Preferential Phosphate Sorption and Al Substitution on Goethite 中文：磷對鋁取代針鐵礦的優先吸附 |
| 期刊名稱 | ENVIRONMENTAL SCIENCE: NANO |
| 發表年份,卷數,起迄頁數 | 2020, in press |
| 作者 | Hsu, Liang-Ching; Tzou, Yu-Min(鄒裕民); Ho, Mon-Shu(何孟書); Sivakumar, Chandrasekar; Cho, Yen-Lin; Li, Wen-Hui; Chiang, Po-Neng; Teah, Heng Yi; Liu, Yu-Ting(劉雨庭)* |
| DOI | 10.1039/C9EN01435G |
| 中文摘要 | 鐵(氫)氧化物在環境中廣泛存在，常含有鋁等雜質。鋁取代針鐵礦(AlG)是鋁和鐵(氫)氧化物最常見的組合之一。本研究測定了Al/(Al+Fe)摩爾比高達17.4%時AlG結構變化與PO4吸附的分子水準機制，並測定了Al與Fe之間的PO4分佈。XRD結果表明，Al更傾向於在針鐵礦較低指數晶面取代Fe，而Fe- XAS和XPS數據分別指出Al會在共邊FeO6八面體鍵上進行取代以及Al更傾向在AlG表面析出。隨著Al/(Al+Fe) mol百分比從0增加到17.4%，PO4的最大吸附容量從135增加到584 mmol kg-1。P-XANES的結果顯示吸附於AlG上PO4對Al優先形成鍵結，亦或者對Al與Fe皆無偏好。密度泛函理論(DFT)結果顯示，相較於純針鐵礦，含12.5 Al mol%的AlG吸附PO4時， supercell的最上層原子層具有更鬆弛Al-O-P角度，Al-O-P角度比對應的Fe-O-P角更小，其暗示AlG表面形成了相對穩定的PO4錯合物。本研究對PO4吸附機制和Fe/Al相關結構變化的提供了新認知，其可用於改善農業活動所導致磷優養化中磷的動力學和質量平衡的評估。 |
| 英文摘要 | Iron (hydr)oxides, which are ubiquitously distributed in the environment, often contain impurities such as Al. Aluminum-substituted goethite (AlG) is a typical assemblage of Al and Fe (hydr)oxides. In this study, the molecular-level mechanisms of PO4 sorption in relation to structural changes in AlG with Al/(Al+Fe) molar ratios up to 17.4% and the PO4 distribution between Al and Fe were determined. While the XRD results showed that Al preferred to substitute for Fe on relatively low-index planes of goethite, the Fe-XAS and XPS data indicated the particular Al substitution in edge-shared FeO6 octahedral linkages and a tendency of Al segregation near the surface of AlG, respectively. The maximum PO4 sorption capacity increased from 135 to 584 mmol kg-1 as Al/(Al+Fe) mol% increased from 0 to 17.4%. Phosphorus-XANES data of PO4 sorbed on AlG showed either preferential PO4 bonding for Al or no preference for Al or Fe. Compared to goethite with adsorbed PO4, the density functional theory (DFT) result of AlG containing 12.5 Al mol% showed more relaxed Al atoms relative to topmost atomic layers of the supercell upon the PO4 adsorption, a smaller Al-O-P angle than the corresponding Fe-O-P angle, and the relatively stable PO4 complex formed on the AlG surface. New insights into the PO4 sorption mechanisms and related structural changes in Al/Fe assemblages could improve the assessment of P dynamics and mass balance in agricultural and PO4-induced-eutrophication systems. |
