酸性および環中性pHの水中サスペンションのTiO2ナノ粒子に対する酸性アドソープション:表面覆面,表面特異性,およびナノ粒子-ナノ粒子相互作用への影響
Imali A Mudunkotuwa1, Vicki H Grassian
1Department of Chemistry, University of Iowa, Iowa City, Iowa 52246, USA.
Journal of the American Chemical Society
|October 6, 2010
まとめ
二酸化チタン (TiO2) ナノ粒子の上でのリン酸吸収はpHに依存し,表面化学と集積行動に影響を与えます. 表面に閉じ込められたシトラート種は,散発溶液と比較して酸性の変化を示します.
科学分野:
- マテリアルサイエンス 材料科学
- 表面化学について
- ナノテクノロジー ナノテクノロジー
背景:
- リン酸はナノマテリアル合成の安定剤として使用される天然の有機酸です.
- 二酸化チタン (TiO2) アナターゼナノ粒子 (約. 4nm) は,さまざまなアプリケーションで一般的です.
- 表面相互作用を理解することは,ナノ粒子の行動を制御するために重要です.
研究 の 目的:
- 酸の吸附をTiO2アナターゼナノ粒子に調査する.
- 表面覆い,種化,ナノ粒子相互作用に対するpHの影響を決定する.
- 酸の表面化学をTiO2.2で解明する.
主な方法:
- 溶液相アドソルプション測定.
- 弱体化された全反射FTIRスペクトロスコーピー.
- ダイナミックな光散乱とゼータポテンシャル測定.
- pHに依存する研究.
主要な成果:
- TiO2に含まれるチート酸の表面覆いは,pHの上昇とともに減少する.
- シトラートの表面特異は時間に依存し,散発溶液と異なる.
- 吸収されたシトラート種は,酸性pHでも溶液よりもpKa値が低いことを示します.
- ナノ粒子の集積は複雑で,pHと表面化学の影響を受けます.
結論:
- チオ2ナノ粒子の酸吸収と表面特異は,強くpHに依存しています.
- 表面に結合したシトラートの酸性の変化は,ナノ粒子の相互作用と集積に影響を与えます.
- この研究は,ナノマテリアルの振る舞いを支配する表面化学の洞察を提供します.
関連する概念動画
Colloidal precipitates
The high insolubility of some precipitates can result in an unfavorable relative supersaturation. This can lead to colloidal particles with a large surface-to-mass ratio, where adsorption is promoted. For instance, in the precipitation of silver chloride, silver ions are adsorbed on the surface of the colloidal particles, forming a primary layer. This layer attracts ions of opposite charge (such as nitrate ions), forming a diffuse secondary layer of adsorbed ions. This electric double layer...
EDTA: Auxiliary Complexing Reagents
EDTA titrations are usually carried out in highly basic conditions, where the fully deprotonated form of EDTA, Y4−, actively complexes with the free metal ions in the solution. Several metal ions precipitate as hydrous oxide (hydroxides, oxides, or oxyhydroxides) under these conditions, lowering the concentration of free metal ions in the solution. For this reason, auxiliary complexing agents or ligands such as ammonia, tartrate, citrate, or triethanolamine are used in EDTA titrations to...
Adsorption Isotherms I
Adsorption isotherms are mathematical models that describe how molecules in a gas or liquid phase interact with surfaces. Two of the most common isotherm models are the Langmuir and Freundlich isotherms, which relate to Type I monolayer chemisorption. The Langmuir model is based on four key assumptions:• Adsorption cannot exceed monolayer coverage.• All surface sites are equivalent.• Molecules adsorb only at vacant sites.• There are no interactions between adsorbed molecules.Consider the...
Acid–Base Titration: Overview
An acid-base titration is a technique used to determine the concentration of an unknown acid or base, using a titrant of known concentration–either a base for acid titration or an acid for base titration. The process involves gradually adding the titrant, leading to a predictable change in the pH of the solution. This change is plotted on a titration curve, showing how a solution's pH varies with the amount of titrant added. Such curves are instrumental in monitoring the titration's progress...
Factors Affecting Solubility
Compared with pure water, the solubility of an ionic compound is less in aqueous solutions containing a common ion (one also produced by dissolution of the ionic compound). This is an example of a phenomenon known as the common ion effect, which is a consequence of the law of mass action that may be explained using Le Chȃtelier’s principle. Consider the dissolution of silver iodide:
Precipitation Titration: Overview
Precipitation titration involves the reaction of a titrant and an analyte to generate an insoluble precipitate. While precipitation titration uses various precipitating agents, silver nitrate is the most common precipitating reagent; titrations involving Ag+ are called argentometric titrations. Usually, the endpoint in a precipitation titration can be detected by visual indicators.
A precipitation titration curve demonstrates the change in concentration of the titrant or analyte upon adding the...
A precipitation titration curve demonstrates the change in concentration of the titrant or analyte upon adding the...


