零价铁和六价在固体-液体界面和溶液中的反应热力学
1College of Materials and Metallurgy, Inner Mongolia University of Science and Technology, Baotou 014010, P. R. China.
Langmuir : the ACS journal of surfaces and colloids
|March 14, 2024
概括
零价铁 (Fe) 通过所有pH水平的固体-液体界面的自发氧化还原反应有效地修复六价 (CrVI). 在溶液中,Cr (VI) 减少Fe是pH依赖的,在酸性和性条件下很容易发生.
科学领域:
- 环境化学环境化学
- 材料科学 材料科学 材料科学
- 化学热力学化学热力学
背景情况:
- 六价 (Cr(VI)) 对环境和健康构成重大风险.
- 零价铁 (Fe0) 已被认为具有通过吸附和减少修复CrVI的潜力.
- 了解反应机制和热力学可行性对于有效的Cr (VI) 整治策略至关重要.
研究的目的:
- 在固体-液体界面和溶液中研究Fe0和Cr(VI) 之间的反应热力学.
- 为了确定pH值对物种分布和反应自发性的影响.
- 阐明了通过Fe0进行Cr(VI) 补救的化学原理.
主要方法:
- 使用了平衡热力学方法.
- 计算了水中Cr (VI),Cr (III),Fe (II) 和Fe (III) 的物种分布函数.
- 根据物种分布,确定了可信的反应途径.
- 使用范特霍夫方程的热力学计算评估了反应自发性.
主要成果:
- 在固体-液体界面,氧化还原反应 (2Cr(VI) + 3Fe0 → 2Cr(III) + 3Fe(II)) 在pH值0-14之间是自发的,由Fe0氧化驱动.
- 在溶液中,由于水的电离,反应 (Cr(VI) + 3Fe(II) → Cr(III) + 3Fe(III)) 在pH 6-7时是非自发的.
- 这种溶液反应在pH值0-5和8-14时是自发的,由酸中和促进.
结论:
- Fe0是Cr (VI) 修复的高效减少剂,特别是在固体-液体界面.
- 溶液中Cr(VI) 降解的pH依赖性自发性凸显了溶液化学在修复过程中的重要性.
- 这项研究提供了关于Cr (VI) 用Fe () 修复的热力学优势的基本见解,有助于设计优化处理系统.
更多相关视频
07:44Determining the Chemical Composition of Corrosion Inhibitor/Metal Interfaces with XPS: Minimizing Post Immersion Oxidation
Published on: March 15, 2017
15.8K
10:42Combining Solid-state and Solution-based Techniques: Synthesis and Reactivity of ChalcogenidoplumbatesII or IV
Published on: December 29, 2016
10.7K
相关概念视频
02:58Properties of Transition Metals
25.8K
Transition metals are defined as those elements that have partially filled d orbitals. As shown in Figure 1, the d-block elements in groups 3–12 are transition elements. The f-block elements, also called inner transition metals (the lanthanides and actinides), also meet this criterion because the d orbital is partially occupied before the f orbitals.
25.8K
01:23Redox Equilibria: Overview
564
A reduction-oxidation reaction is commonly called a redox reaction. In a redox reaction, electrons are transferred from one species to another rather than being shared between or among atoms. The reducing agent or reductant is the species that loses electrons and gets oxidized in the process. The species that gains electrons and gets reduced in the process is the oxidizing agent or oxidant. Redox reactions are represented as two separate equations called half-reactions, where one equation...
564
02:21Chemical and Solubility Equilibria
4.1K
The free energy change associated with dissolving a solute in a liter of solvent is called the free energy of a solution, ΔGsolution. The overall ΔGsolution is expressed as the balance of ΔGinteraction against the always-favorable free-energy of mixing, ΔGmixing. Solution formation is favorable if ΔGsolution is less than zero, whereas it is unfavorable if ΔGsolution is greater than zero. In short, for a solution to form and complete dissolution to take place,...
4.1K
02:59The Nernst Equation
40.8K
Nonstandard Reaction Conditions
The interconnection between standard cell potentials and various thermodynamic parameters such as the standard free energy change ΔG° and equilibrium constant K has been previously explored. For example, a redox reaction involving zinc(II) and tin(II) ions at 1 M concentration with Eºcell = +0.291 V and ΔG° = −56.2 kJ is spontaneous.
The interconnection between standard cell potentials and various thermodynamic parameters such as the standard free energy change ΔG° and equilibrium constant K has been previously explored. For example, a redox reaction involving zinc(II) and tin(II) ions at 1 M concentration with Eºcell = +0.291 V and ΔG° = −56.2 kJ is spontaneous.
40.8K
03:25Free Energy Changes for Nonstandard States
11.4K
The free energy change for a process taking place with reactants and products present under nonstandard conditions (pressures other than 1 bar; concentrations other than 1 M) is related to the standard free energy change according to this equation:
where R is the gas constant (8.314 J/K·mol), T is the absolute temperature in kelvin, and Q is the reaction quotient. This equation may be used to predict the spontaneity of a process under any given set of conditions.
Reaction Quotient...
where R is the gas constant (8.314 J/K·mol), T is the absolute temperature in kelvin, and Q is the reaction quotient. This equation may be used to predict the spontaneity of a process under any given set of conditions.
Reaction Quotient...
11.4K
01:14Zeroth Law of Thermodynamics
5.0K
Experimentally, if object A is in equilibrium with object B, and object B is in equilibrium with object C, then object A is in equilibrium with object C. That statement of transitivity is called the "zeroth law of thermodynamics." For example, a cold metal block and a hot metal block are both placed on a metal plate at room temperature. Eventually, the cold block and the plate will be in thermal equilibrium. In addition, the hot block and the plate will be in thermal equilibrium.
5.0K