...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>The journal of physical chemistry, C. Nanomaterials and interfaces >Integrated Molecular and Microscopic Scale Insight into Morphology and Ion Dynamics in Ca2+-Mediated Natural Organic Matter Floccs
【24h】

Integrated Molecular and Microscopic Scale Insight into Morphology and Ion Dynamics in Ca2+-Mediated Natural Organic Matter Floccs

机译：在CA2 +介导的天然有机物质FLOCC中集成分子和微观规模洞察的形态和离子动力学

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

Combined X-ray diffraction (XRD), helium ion microscopy (HeIM), and Ca-43 nuclear magnetic resonance (NMR) results provide novel insight into the nano- and microstructure of flocculated NOM; the molecular-scale interaction among natural organic matter (NOM), dissolved Ca2+ ions, and water in NOM floccs; and the effects of pH and ionic strength on these characteristics. Suwannee River humic acid (HA), fulvic acid (FA), and NOM flocculated from Ca2+ bearing solutions share similar morphological characteristics on the 100 nm to micron scales, including micron-sized equant fragments and rounded, rough areas with features on the 100 nm scale. HeIM suggests that the NOM floccs are built from a fundamental spheroidal structure that is similar to 10 nm in diameter, in agreement with published AFM and small-angle X-ray scattering results. Calcium is incorporated into these floccs at 100% relative humidity in a wide range of disordered structural environments, with basic pH leading to shorter mean Ca-O distances and lower mean coordination numbers with respect to floccs formed under acidic conditions. The NMR results show that dynamical processes involving water and Ca2+ occurring at frequencies >10(4) Hz are important for hydrated OM floccs, in agreement with published molecular dynamics simulations of OM in solution. From the NMR results, we find evidence for two Ca2+ dynamic averaging mechanisms: one related to rapid exchange (>100 kHz) between surface proximity-restricted (those within 5 angstrom of a surface) and bulk solution environments when excess Ca2+ is present in the pore solution when pore water is unfrozen and a second consisting of intermediate scale (tens of kHz) site exchange among strongly sorbed inner-sphere sites when excess Ca2+ is absent and the carboxylic and phenolic functional groups of the NOM are deprotonated.
机译：组合X射线衍射（XRD），氦离子显微镜（Heim）和Ca-43核磁共振（NMR）结果提供了对絮凝NOM的纳米和微观结构的新颖洞察力;在NOM FLOCC中的天然有机物（NOM），溶解CA2 +离子和水中的分子级相互作用; pH和离子强度对这些特性的影响。 Suwannee河腐殖酸（HA），Fulvic酸（FA）和来自CA2 +轴承溶液的NOM絮凝在100nm到微米鳞片上的相似形态特征，包括微米尺寸的秤和圆形，粗糙区域，具有100nm的特征规模。 Heim表明，NOM Floccs由基本的球形结构构成，与直径为10nm，与发表的AFM和小角度X射线散射结果一致。钙在各种无序的结构环境中以100％相对湿度掺入这些FLOCC中，碱性pH导致较短的平均CA-O距离和相对于在酸性条件下形成的FLOCC的较低平均配位数。 NMR结果表明，涉及水和Ca2 +在频率下发生的动态过程> 10（4）Hz对于水合OM Froccs是重要的，同时与解决方案中的OM的发布分子动力学模拟很重要。从NMR结果中，我们发现两个CA2 +动态平均机制的证据：与在表面接近限制（表面5埃内的5埃内）之间的快速交换（> 100 kHz）和批量溶液环境存在的证据当孔隙水未充气时孔隙溶液，当不存在过量的CA2 +时，强烈的内侧内球位点之间的中间尺度（数十kHz）位点交换，并且羧酸含有NOM的羧酸和酚醛官能团被剥去溶栓。

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