Effects of humic material on the precipitation of calcium phosphate
Effects of humic material on the precipitation of calcium phosphate
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DOI：
10.1016/s0016-7061(03)00207-6
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发表时间：
2004-02-01
期刊：
影响因子：
6.1
通讯作者：
Wilson, MA
中科院分区：
文献类型：
--
作者：
Alvarez, R;Evans, LA;Wilson, MA
土壤有机酸（例如腐殖酸和富富酸）可以通过抑制热力学稳定磷酸钙的形成来影响P肥大土壤中无机磷酸盐的可用性。在这些系统中很重要的磷酸钙相可能包括磷酸非晶钙（Ca-9（PO4）（6）（6）.NH（2）O; ACP），磷酸二硫酸二水合物（Cahpo4.2H（2）O; DCPD，也已知，也已知作为刷子），八钙磷酸盐（Ca8h2（PO4）（6）.5H（2）O; OCP）和热力学最稳定的相，羟基磷灰石（Ca-5（po4）（3）OH; HAP）。在这项研究中，使用pH-STAT自动竞争，傅立叶变换红外（FTIR）和Laser Raman Spectroscopicy对澳大利亚的悉尼盆地衍生而成的这些相的形成。 ，以及X射线衍射（XRD）和元素分析。在pH值高7.4的高饱和条件下，温度为25摄氏度，发现这些土壤蜂窝会延迟不稳定的ACP向热力学上更稳定的OCP转化，从而使其变为apatitic相，类似于结晶性较差的HAP。在5.7的较低pH下，在存在腐殖酸的情况下，ACP最初也被沉淀。但是，这与产生DCPD的无腐殖质解决方案形成鲜明对比。在不存在的情况下，在腐殖质存在下产生的ACP持续更长的时间，然后最终讨论了将其水解为OCR磷酸 - 磷酸 - 磷酸盐相互作用的模式。已经得出结论，腐殖质是磷酸钙转化的地质相关抑制剂，它们可能会通过改变溶液中的结晶行为来改变土壤中磷的可用性。 （c）2003 Elsevier B.V.保留所有权利。
Soil organic acids such as humic and fulvic acids can play an important role in influencing inorganic phosphate availability in P-fertilized soils by inhibiting formation of thermodynamically stable calcium phosphates. Calcium phosphate phases which are important in these systems may include amorphous calcium phosphate (Ca-9(PO4)(6).nH(2)O; ACP), dicalcium phosphate dihydrate (CaHPO4.2H(2)O; DCPD, also known as brushite), octacalcium phosphate (Ca8H2(PO4)(6).5H(2)O; OCP) and the thermodynamically most stable phase, hydroxyapatite (Ca-5(PO4)(3)OH; HAp). In this study, the formation of these phases in the presence of soil humic acids derived from the Sydney Basin in New South Wales, Australia has been examined using the combined techniques of pH-stat autotitration, Fourier transform infrared (FTIR) and laser Raman spectroscopy, as well as X-ray diffraction (XRD) and elemental analyses. Under conditions of high supersaturation at a pH of 7.4 and a temperature of 25 degreesC, it was found that these soil humics delay the transformation of unstable ACP to thermodynamically more stable OCP and thence to an apatitic phase resembling poorly crystalline HAp. At the lower pH of 5.7, and in the presence of humic acids, ACP was also precipitated initially. However, this was in contrast to the humic-free solutions which produced DCPD. ACP produced in the presence of humic materials persisted longer than DCPD in their absence, before ultimately hydrolyzing to OCR Modes of humic-calcium phosphate interaction are discussed. It has been concluded that humic materials are geologically relevant inhibitors of calcium phosphate transformation and that they may modify, the availability of phosphorus in soils by changing crystallisation behaviour from solution. (C) 2003 Elsevier B.V. All rights reserved.