• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Applied Surface Science >Role of pH and calcium ions in the adsorption of an alkyl N-aminodimethylphosphonate on steel: An XPS study
【24h】

Role of pH and calcium ions in the adsorption of an alkyl N-aminodimethylphosphonate on steel: An XPS study

机译：pH和钙离子在N-氨基二甲基膦酸烷基酯在钢上的吸附中的作用：XPS研究

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The role of pH and calcium ions in the adsorption of an alkyl N-aminodimethylphosphonate on mild steel (E24) surfaces was investigated by XPS. Fe 2p_(3/2) and O 1s spectra show that the oxide/hydroxide layer developed on the steel surface, immersed in the diphosphonate solution (7 ≤ pH ≤ 13, without Ca~(2+)) or in a filtered cement solution (pH 13, 15.38 mmol l~(-1) of Ca~(2+)), consists of Fe_2O_3, covered by a very thin layer of FeOOH (goethite). The total thickness of the oxide/hydroxide layer is ～3 nm and is independent of the pH and the presence/absence of Ca~(2+). In the absence of Ca~(2+) ions, the N 1s and P 2p spectra reveal that the adsorption of the diphosphonate on the outer layer of FeOOH takes place only for pH lower than the zero charge pH of goethite (7.55). At pH 7, the adsorbed diphosphonate layer is continuous and its equivalent thickness is ～24 A (monolayer). In the presence of Ca~(2+) ions, the C 1s and Ca 2p signals indicate that calcium is present on the steel surface as calcium phosphonate (and Ca(OH)_2, in very small amount). The adsorption of the diphosphonate molecules on the steel surface is promoted in alkaline solution (pH > 7.55) by the doubly charged Ca~(2+) ions that bridge the O~- of goethite and the P-O~- groups of the diphosphonate molecules. The measured values for the Ca/P intensity ratio are in the range 0.75-1, which suggests that the diphosphonate molecules are adsorbed on steel forming a polymer cross-linked by calcium ions through their phosphono groups. In the presence of Ca~(2+) ions in alkaline solution, the adsorbed diphosphonate layer is discontinuous and the surface coverage is found to be ～34%.
机译：通过XPS研究了pH和钙离子在N-氨基二甲基膦酸烷基酯在低碳钢（E24）表面上的吸附作用。 Fe 2p_（3/2）和O 1s光谱表明，钢表面上形成的氧化物/氢氧化物层浸入二膦酸盐溶液（7≤pH≤13，不含Ca〜（2+））或过滤的水泥溶液中（pH 13，Ca.（2+）的15.38 mmol l〜（-1））由Fe_2O_3组成，并被一层非常薄的FeOOH（针铁矿）覆盖。氧化物/氢氧化物层的总厚度约为3 nm，与pH值和Ca〜（2+）的存在与否无关。在不存在Ca〜（2+）离子的情况下，N 1s和P 2p光谱表明，仅当pH值低于针铁矿的零电荷pH值（7.55）时，FeOOH外层上才会发生二膦酸盐的吸附。在pH值为7时，被吸附的二膦酸酯层是连续的，其等效厚度为〜24 A（单层）。在存在Ca〜（2+）离子的情况下，C 1s和Ca 2p信号表明钙以磷酸钙（和Ca（OH）_2的量非常少）形式存在于钢表面。在碱性溶液（pH> 7.55）中，通过双电荷的Ca〜（2+）离子桥接针铁矿的O〜-和二膦酸酯分子的P-O〜-基团促进了二膦酸酯分子在钢表面的吸附。 Ca / P强度比的测量值在0.75-1的范围内，这表明二膦酸酯分子吸附在钢上，形成通过钙离子通过其膦酰基基团交联的聚合物。在碱性溶液中存在Ca〜（2+）离子时，吸附的二膦酸盐层不连续，表面覆盖率为〜34％。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号