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首页> 外文学位 >Natural organic matter at solid/liquid interfaces: Complexation, conformation and colloidal stabilization.
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Natural organic matter at solid/liquid interfaces: Complexation, conformation and colloidal stabilization.

机译：固/液界面的天然有机物：络合，构象和胶体稳定化。

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Natural organic matter (NOM) adsorbs on most particle surfaces and can dominate their surface properties. In most cases, adsorbed NOM increases the colloidal stability of particles. The purpose of this research is to provide a better understanding of the adsorption process and the consequent stabilization effects. A hybrid SC (surface complexation)/SF (Scheutjens and Fleer) model is developed to describe the adsorption of weak polyelectrolytes including NOM on metal oxide surfaces. The hybrid model has the advantage that both the macromolecular nature of NOM and NOM/oxide complexation interactions are addressed.; In the model, the average magnitude of the specific interactions between NOM (polyelectrolyte) functional groups and surface sites, expressed as {dollar}rmchisb{lcub}s{rcub}{dollar}(hyb), varies systematically with surface and NOM (polyelectrolyte) speciation. Over a broad range of solution conditions, good agreement of model simulations and experimental adsorption density is achieved. Of the reactions tested, a 1:1 stoichiometric reaction represented by {dollar}>{dollar}MeOH + L{dollar}sp-{dollar} = {dollar}>{dollar} MeOHL{dollar}sp-{dollar} provides the best representation of the experimental adsorption density data.; Depending on solution chemistry, adsorbed NOM exhibits different conformations at solid/liquid interfaces. At low pH and high ionic strength, adsorbed NOM has an extended conformation. At high pH and low ionic strength, adsorbed NOM exhibits a flat conformation. A detailed description of the conformation of adsorbed NOM at solid/liquid interfaces is described by the model. The effects of pH and ionic strength on adsorbed hydrodynamic layer thickness are predicted well by the model for the oppositely charged case (pH {dollar}{dollar} pH{dollar}rmsb{lcub}pzc{rcub}),{dollar} the contribution of tails to adsorbed hydrodynamic layer thickness is underpredicted by the model.; Depending on solution conditions, adsorbed NOM stabilizes colloidal particles to different extents and by different mechanisms. At high pH and low ion strength, colloidal stability is determined by the electrostatic interactions between ionic diffuse layers on colliding particles. At low pH and high ionic strength, the interactions between adsorbed NOM (polyelectrolyte) segments on colliding particles probably also play a role in determining colloidal stability.
机译：天然有机物（NOM）吸附在大多数颗粒表面上，并可以控制其表面性质。在大多数情况下，吸附的NOM可增加颗粒的胶体稳定性。这项研究的目的是为了更好地理解吸附过程及其带来的稳定作用。建立了混合SC（表面络合）/ SF（Scheutjens和Fleer）模型，以描述包括NOM在内的弱聚电解质在金属氧化物表面上的吸附。混合模型的优点是可以同时解决NOM的大分子性质和NOM /氧化物络合相互作用。在该模型中，NOM（聚电解质）官能团与表面位点之间的特定相互作用的平均幅度表示为{dolrm} rmchisb {lcub} s {rcub} {dollar}（hy​​b），随表面和NOM（聚电解质）而系统地变化。 ）的物种。在宽范围的求解条件下，可以实现模型模拟和实验吸附密度的良好一致性。在测试的反应中，以{美元}> {美元} MeOH + L {美元} sp- {美元} = {美元}> {美元} MeOHL {美元} sp- {美元}表示的1：1化学计量反应可提供实验吸附密度数据的最佳表示。根据溶液的化学性质，吸附的NOM在固/液界面处显示出不同的构型。在低pH和高离子强度下，吸附的NOM具有扩展的构象。在高pH和低离子强度下，吸附的NOM呈现出平坦的构象。该模型详细描述了固/液界面吸附的NOM的构象。对于带相反电荷的情况（pH {dollar} {dollar} pH {dollar} rmsb {lcub} pzc {rcub}）的模型，可以很好地预测pH和离子强度对吸附的水动力层厚度的影响，{dollar}的贡献该模型未充分预测尾部对吸附的水动力层厚度的影响。根据溶液条件的不同，吸附的NOM可通过不同的机理和不同程度地稳定胶体颗粒。在高pH和低离子强度下，胶体稳定性取决于碰撞粒子上离子扩散层之间的静电相互作用。在低pH和高离子强度下，碰撞颗粒上吸附的NOM（聚电解质）链段之间的相互作用也可能在确定胶体稳定性中起作用。

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