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National Chung Hsing University Institutional Repository - NCHUIR > 農業暨自然資源學院 > 土壤環境科學系 > 依資料類型分類 > 碩博士論文 >  載鐵物質 (DESFERRIOXAMINE-B) 與含磷鐵鋁礦物之間的化學反應機制

Please use this identifier to cite or link to this item: http://nchuir.lib.nchu.edu.tw/handle/309270000/151645

標題: 載鐵物質 (DESFERRIOXAMINE-B) 與含磷鐵鋁礦物之間的化學反應機制
REACTION MECHANISM OF DESFERRIOXAMINE-B WITH Al AND Fe MINERALS CONTAINING PHOSPHORUS
作者: 韋飛斯
Thomas, Wi-Afedzi
Contributors: 黃政恆
Huang, Jang-Hung
土壤環境科學系所
關鍵字: 去鐵胺;載鐵物質;磷酸根;針鐵礦;水鋁礦;赤鐵礦;配位基促進溶解現象;吸附;活化能
Desferrioxamine-B (DFO-B);siderophore;phosphate;goethite;gibbsite;hematite;ligand-promoted dissolution;adsorption;activation energy
日期: 2013
Issue Date: 2013-11-07 11:39:26 (UTC+8)
Publisher: 土壤環境科學系所
摘要: 植物從土壤中攝取養分受到植物根系與土壤之物理、生物化學性質交互作用的複雜過程影響。單子葉禾本科植物的根分泌可鉗合三價鐵且對鐵親和力高的載鐵物質 (phytosiderophores, PSs) 來溶解土壤中的鐵,進而影響磷等其他營養元素在土壤中的移動。本研究目的為:探討載鐵物質之一的去鐵胺 (desferrioxamine-B, DFO-B) 與含鐵、鋁或磷礦物 (紅磷鐵礦 (strengite, FePO4∙2H2O) 、磷酸鋁石 (variscite, AlPO4∙2H2O)) 與已吸附磷的針鐵礦 (goethite, α-FeOOH)、水鋁礦 (gibbsite, α-Al(OH)3)、赤鐵礦 (hematite, α-Fe2O3) 交互作用下礦物表面溶出的情形,進而來瞭解載鐵物質在植物吸收磷可能扮演的角色。實驗結果顯示:擬一級速率方程式適合用於說明DFO-B促進含鐵、鋁或磷礦物的溶解情形,其中溶解的速率常數與DFO-B被吸附的量有相關性。在 pH 4 下,DFO-B隨著針鐵礦、水鋁礦與赤鐵礦表面所吸附磷含量的增加而加速礦物的溶解速率。然而,在 pH 9下,礦物表面磷吸附量的增加卻抑制礦物表面的溶出,可能是因 pH 9 環境下,磷酸根在礦物表面形成了較穩定的結構,使DFO-B不易溶解礦物表面。根據 Arrhenius 方程式,在不同溫度與 pH 下,DFO-B與不同礦物反應之活化能 (activation energies, Ea) 也顯示:在 pH 9 下的反應之活化能高於 pH 4 下的活化能,表示磷酸根與礦物表面在 pH 9 下形成了DFO-B難以鉗合的形式,進而抑制了礦物表面的溶解。針對含鐵磷或鋁磷的礦物研究發現:DFO-B的存在促進紅磷鐵礦與磷酸鋁石溶解的現象。其中,因為磷酸鋁石表面吸附較多的DFO-B,造成磷酸鋁石溶解速率較紅磷鐵礦溶解速率快。
Nutrient uptake of plants from soil is a complex process determined by the interactions of the plant roots with the soil and the combination of physical and biochemical properties of the soil. The roots of graminaceous monocots secrete phytosiderophores (PSs), which are chelating agents with a high affinity for Fe(III), to dissolve Fe(III) in soil. The release of PSs can potentially mobilize nutrients, such as P, associated with Fe in soil. To understand the potential role of PSs in regulating the P acquisition of plants, this study investigated the interactions of desferrioxamine-B (DFO-B) siderophore with some major Fe, Al and P - containing minerals, including strengite (FePO4∙2H2O), variscite (AlPO4∙2H2O), and phosphate-loaded goethite (α-FeOOH), gibbsite (α-Al(OH)3) and hematite (α-Fe2O3). The pseudo-first-order rate constant was determined for the DFO-B – promoted dissolution of each mineral and subsequently normalized to the corresponding amount of adsorbed siderophore to calculate the mass-normalized dissolution rate. Apparent activation energies (Ea) were calculated from the mass-normalized dissolution rates of each mineral obtained at different temperatures using the Arrhenius equation. Increasing the loading of adsorbed P on all three oxides (i.e., goethite, hematite and gibbsite) resulted in an increase in the dissolution rates of the minerals but a decrease in dissolution rates at pH 9. The rate inhibition at pH 9 is attributed to the presence of binuclear surface complexes, in which much more energy is required to remove simultaneously two center atoms from the crystalline lattice than it is to remove solely one center (i.e. in the case of mononuclear complexes at pH 4). Higher Ea values at pH 9 than at pH 4, supports our hypothesis that the existence of stronger adsorbed phosphate complexes hinder the smooth release of the metal-ion-center. DFO-B -promoted dissolution of strengite and variscite studies show that dissolution was enhanced in the presence of DFO-B. Higher dissolution rates for variscite than strengite is attributed to the higher adsorbed concentrations of DFO-B on variscite than on strengite.
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