| pH对磷钾铝石形成的影响 |
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| 作者姓名： | ZHOU Jian-Min P. M. HUANG |
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| 作者单位： | [1]DepartmentofPlantNutrition,ChinaAgriculturalUniversity,Beijing100094,China [2]DepartmentofPlantNutrition,ChinaAgriculturalUniversity,Beijing100094,China |
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| 基金项目： | Project supported by a grant of Potash and Phosphate Institute of Canada and grant GP2383-Huang of the Natural Sciences and Engineering Research Council of Canada. |
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| 摘 要： | Effects of column temperature and flow rate on separation of organic acids were studied by determining nine low-molecular-weight organic acids on reversed-phase C18 column using high performace liquid chromatography(HPLC) with a wavelength of UV(ultraviolet)214 nm and a mobile phase of 18 mmol L^-1 KH2PO4 buffer solution (pH2.1).The thermal stabiltiy of organic acids was determined by comparing the recoveries of organic acids in different temperature treatments.The relationships between column temperature,flow rate or solvent pH and retention time were analyzed.At low solvent pH,separatioin efficiency of organic acids was increased by raising the flow rate of the solvent because of lowering the retention time or organic acids.High column temperature was unfavorable for the separation of organic acids.The separating effect can be enhanced through reducing column temperature in organic acid determination due to increasing retention time.High thermal stability of organic acids with low concentrations was observed at temperature of 40℃-45℃,Sensitivity and separation effect of organic acid determination by HPLC were clearly improved by a combination of raising flow rate and lowering column temperature at low solvent pH.
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| 关 键 词： | HPLC法 根渗出物 有机酸 测定条件 |
Influence of pH on formation of taranakites |
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| ZHOU Jian-Min,P. M. HUANG.Influence of pH on formation of taranakites[J].Pedosphere,1999,9(1):35-44. |
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| Authors: | ZHOU Jian-Min and P M HUANG |
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| Institution: | [1]DepartmentofPlantNutrition,ChinaAgriculturalUniversity,Beijing100094,China [2]DepartmentofPlantNutrition,ChinaAgriculturalUniversity,Beijing100094,China |
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| Abstract: | Monoammonium phosphate (1 mol L-1), monopotassium phosphate (1 mol L-1) and aluminum chloride (5 × 10-3 mol L-1) were used to investigate the influence of pH on the formation of NH4-taranakite and K-taranakite in systems with a high NH4H2PO4 or KH2PO4 concentration. The experimental data indicated that the reaction products of aluminum with NH4H2PO4 or KH2PO4 changed with the pH in the systems. In a pH range of 2.5 to 10.0, as the pH increased, the products in either ammonium or potassium system followed the sequence: taranakite, amorphous (NH4, K)2AlH(PO4)2·4H2O, and then crystalline (NH4, K)AlPO4OH·2H2O. However, the pH ranges of the formation of these products in ammonium system were different from potassium system. NH4-taranakite formed from pH 2.75 to pH 5.75, whereas K-taranakite formed in the pH range of 3.00 to 5.00. From the theoretical calculation by a computer program (GEOCHEM version 2.0), NH4-taranakite and K-taranakite could form at the pH from 1.50 to 8.30 and from 1.25 to 8.45, respectively. These pH ranges were much wider than the experimental results. The difference between the experimental data and theoretical data was attributed to the lack of kinetic data and/or the incompleteness and inaccuracy of the thermodynamic data in the data base of the program. The pH ranges of the formation of the taranakites indicated that the taranakites could exist in the immediate vicinity of phosphate fertilizer zone as reaction products of phosphate fertilizers with soils, especially acidic soils, resulting in the fixation of not only phosphate but also nitrogen and/or potassium in soils. |
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| Keywords: | ammonium pH phosphate fertilizer potassium taranakite |
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