Name: ion exchange resins and charged molecules
Uploaded: 2024-04-04T10:51:25.000Z
Duration: 1 min 17 s
Channel: JoVE

이온 교환은 반대 전하를 띤 고정상과 관련된 모바일 또는 '활성' 이온과 가역적으로 교환하여 용액에서 하전된 분자를 분리합니다.
고정상은 일반적으로 다공성이지만 불용성 고체이며, 예를 들어 이온 작용기를 지니는 많은 수의 단량체를 갖는 고분자량을 갖는 가교 유기 중합체와 같습니다.
활성 양이온이 있는 음이온 중합체는 양이온 교환기인 반면 활성 음이온이 있는 양이온 중합체는 음이온 교환기입니다.
양이온 및 음이온 교환기는 작용기에 따라 약한 것과 강한 것으로 더 분류됩니다.
이온 교환기에 부착된 이동 이온은 용액으로 이동하고 평형에 도달할 때까지 용액에서 유사하게 전하를 띤 이온으로 대체됩니다.
질량 작용 법칙을 이온 교환 평형에 적용하면 반응에 대한 선택성 계수가 표현됩니다.
소진된 양이온 및 음이온 교환기는 각각 과도한 산성 또는 염기성 용액으로 세척하여 재생됩니다.

이온 교환

Ion Exchange

이온 교환 크로마토그래피는 반대로 전하를 띤 고정상과 관련된 이동성 또는 '활성' 이온과 가역적으로 교환하여 용액에서 전하를 띤 분자를 분리합니다. 이 방법은 이온을 분리하고, 물을 연화 및 탈이온화하고, 용액을 정제하는 데 사용할 수 있습니다. 이온 교환 컬럼을 구성하는 폴리머는 고분자량이며 화학적으로 안정한 폴리머이며 가교 결합되어 다공성이고 본질적으로 불용성입니다. 이는 또한 산성 또는 염기성 그룹으로 기능화됩니다. 산성 그룹으로 관능화되면 컬럼이나 수지는 양이온 교환기로 알려져 있으며 양이온 반대 이온을 갖는 음전하 폴리머를 포함합니다. 이를 통해 이동상에서 양이온이 교환될 수 있습니다. 염기성 그룹으로 관능화될 때 컬럼 또는 수지는 음이온 교환기로 알려져 있으며, 이는 음이온 반대 이온과 용액의 음이온 교환으로 양전하를 띤 폴리머를 포함합니다.

이온 교환 중에 고체상 폴리머와 관련된 반대 이온이 용액에 들어가는 반면 용액의 이온은 그 자리에서 폴리머와 상호 작용합니다. 이온 교환 능력은 가교 정도가 증가하고 폴리머의 이온 교환 그룹 수가 증가함에 따라 증가합니다. 이 교환은 가역적이며 평형이 확립될 때까지 계속됩니다.

산성 양이온 교환체는 폴리스티렌 설폰산에서 볼 수 있는 설폰산(−SO3H)과 같은 강산 또는 폴리(메틸 메틸아크릴)산에서 볼 수 있는 카르복실산(-COOH)과 같은 약산으로 기능화될 수 있습니다. 마찬가지로 음이온 교환체는 강하거나 약한 것으로 분류됩니다. 강한 음이온 교환체는 종종 폴리스티렌 4차 암모늄 클로라이드의 것과 같은 4차 암모늄 그룹(−CH2N(CH3)3+)을 포함하고, 약한 음이온 교환체는 종종 폴리스티렌 3차 아민 수산화물과 같은 치환된 아민(−NH3+)으로 기능화됩니다.

이온 교환은 하전 분자를 용액과 관련된 모바일 또는 '활성' 이온과 가역적으로 교환하여 분리하는 것입니다.

Education

교육

JoVE Core

Analytical Chemistry

분석 화학

Unit 1

제1단원

Introduction to Separation Methods

분리 방법 입문

KEY TERMS AND CONCEPTS

주요 용어 및 개념

ion exchange resins and charged molecules

Ion exchange chromatography separates charged molecules from a solution by swapping them with mobile, or active, ions on a stationary phase. It is used to separate ions, soften and deionize water, and purify solutions. The method depends on a solid column made of high-molecular-weight, chemically stable polymers that are crosslinked to make them porous and essentially insoluble.

These polymers are functionalized with either acidic or basic groups. When acidic groups are present, the resin is a cation exchanger. It has a negatively charged polymer with positive counterions, so it can exchange cations from the mobile phase.

When basic groups are present, the resin is an anion exchanger. It has a positively charged polymer with negative counterions, so it can exchange anions from the solution. During ion exchange, the counterions on the solid polymer move into the solution, and ions from the solution take their place.

The exchange is reversible and continues until equilibrium is reached. The ability to exchange ions increases when the polymer has more crosslinking and more ion-exchange groups. Cation exchangers can be strong or weak. Strong cation exchangers often use sulfonic acid groups, such as in polystyrene sulfonic acid, while weak cation exchangers often use carboxylic acid groups, such as in poly(methyl methylacrylic) acid.

Anion exchangers are also classified as strong or weak. Strong anion exchangers often contain quaternary ammonium groups, such as in polystyrene quaternary ammonium chloride. Weak anion exchangers are often functionalized with substituted amines, such as in polystyrene tertiary amine hydroxide.

Ion Exchange Resins and Charged Molecules

ion-exchange-resins-and-charged-molecules

states of matter and phase changes

Heating and Cooling During Phase Changes

Heating and cooling can change a substance from one state of matter to another. These phase changes depend on internal energy, which is the total kinetic energy of particles and the potential energy from their interactions. In the condensed phases, stronger intermolecular forces and the pressure on the substance affect that internal energy. The internal energy is highest in the gaseous state, lowest in the solid state, and in between for the liquid state. Phase transitions happen when...

distillation: vapor&ndash;liquid equilibria

Distillation and Boiling Point Changes

Distillation separates a miscible liquid mixture by using differences in boiling points. It works best when the two liquids have a significant boiling point gap, usually at least 20°C. In this process, the mixture is heated until the more volatile component reaches its bubble point and begins to vaporize. The vapor then rises into a condenser. A condenser is a glass tube with separate inner and outer sections. Cold water flows through the outer section and cools the vapor in the inner section,...

filtration

Filtration Setup and Filtrate Collection

Filtration separates a solid from a liquid by passing a suspension through a porous medium. The solid stays on the filter, and the liquid, called the filtrate, passes through. This makes filtration a physical separation process, not a chemical change. The filtering medium is chosen for the purpose of the separation, the amount of material, and the nature of the precipitate. A good filter medium should be inert, mechanically strong, nonabsorbent toward dissolved materials, and able to let...

centrifugation

Centrifugation for Separating Particles

Centrifugation separates particles in a liquid by using differences in size and density. The sample is placed in centrifugation tubes and spun at high angular velocity. This creates centrifugal force, which makes the different components move at different rates. After spinning, the supernatant, or liquid above the settled material, is decanted. In some cases, the pellet is kept for further purification. In other cases, the supernatant is kept and may be spun again for additional processing. <br...

sublimation

Sublimation in Separation and Purification

Sublimation is the direct change of a solid into a gas. It skips the liquid state. A common example is solid carbon dioxide, or dry ice, which turns into gaseous carbon dioxide at standard pressure and room temperature. The phase diagram shows when sublimation can happen. This process occurs at the solid-gas boundary. It is not seen above the triple point of a substance. The reverse process is deposition, which is when a gas changes directly into a solid. Sublimation and deposition can help...

recrystallization: solid&ndash;solution equilibria

recrystallization-solidsolution-equilibria

Recrystallization for Purifying Solid Compounds

Recrystallization is a way to purify solid compounds by using differences in solubility. It does not involve a chemical reaction. Instead, it relies on physical properties of the desired compound and the impurities. The process is based on solid-solution equilibrium, also called solubility equilibrium. In this equilibrium, a component is split between the solid phase and the solution phase. At equilibrium, the chemical potential of that component is the same in both phases. To begin...

crystal growth: principles of crystallization

crystal-growth-principles-of-crystallization

Crystal Formation Through Supersaturation

Crystal formation through supersaturation begins when a solution contains more dissolved solute than it can normally hold. In crystallization, atoms or molecules line up into a rigid crystal lattice so the system can lower its energy. To start the process, the solute concentration and the solution temperature must be adjusted so the supersaturation ratio, S, is greater than one. Supersaturation can be increased in two main ways. One method is to concentrate the solution by evaporating the...

precipitation and co-precipitation

Selective Ion Separation by Precipitation

Selective ion separation by precipitation is used to isolate ions from a solution. In qualitative inorganic analysis, ions that form sparingly soluble precipitates with the same reagent can be separated by using differences in their solubility products. A solubility product is the limit at which an ionic solid begins to form from dissolved ions. One example is the separation of Cu(II) and Fe(II) ions as insoluble sulfides. Copper(II) sulfide is first precipitated by adding acidic H2S. The acid...

coagulation

Wastewater Cleanup by Coagulation

Coagulation helps remove colloidal particles from wastewater. Colloids are tiny solid particles suspended in a liquid. They are usually negatively charged, so they attract a compact first layer of positive ions. More counterions gather around them and form an electrical double layer. This charge barrier keeps the particles apart and stabilizes the colloid. These suspended solids can be a problem because they may contain toxins that are hard to remove. Coagulation is used to make the particles...

electrodeposition

Electrodeposition for Metal Ion Separation

Electrodeposition separates metal ions from a solution by using an electric current and an electrolytic cell. The cell has an anode and a cathode. When current flows, oxidation happens at the anode. At the cathode, metal ions gain electrons, undergo reduction, and deposit on the large metal surface. This method works well when metals have very different reduction potentials. Copper and nickel in the same solution can be separated this way. First, the solution is made acidic. Then current is...

extraction: partition and distribution coefficients

extraction-partition-and-distribution-coefficients

Solvent Partitioning in Chemical Extraction

Solvent partitioning in chemical extraction describes how a solute spreads between two immiscible solvents. Immiscible solvents do not mix, such as an aqueous phase and an organic phase. The distribution law, also called Nernst's distribution law or the partition law, explains how that solute is shared at a constant temperature and equilibrium. At equilibrium, the ratio of solute concentrations in the two solvents stays constant. For extraction from water into an organic solvent, this...

extraction: effects of ph

pH Control in Liquid Extraction

pH control in liquid extraction changes how amines and acids move between organic and aqueous phases. The pH of the aqueous phase affects the charge on acidic and basic solutes. The charged form is usually more soluble in the aqueous phase. For a weak base such as an amine, the neutral form is called B. Its partition coefficient, K, describes how the neutral molecule distributes between the two liquids. If the conjugate acid of the amine is soluble only in the aqueous phase, while the base...

extraction: advanced methods

Chelate Extraction for Metal Ion Separation

Chelate extraction is a way to separate metal ions by using an organic ligand, or chelating agent, to form an uncharged metal complex. The chelating agent needs hydrophobic groups, and it must act as a weak acid so it can lose a proton and bind to the metal. Most organic ligands used for this method are not stable in water or are insoluble in the aqueous phase. For that reason, the chelating agent is first placed in the organic phase. It then moves into the aqueous phase, where the...

chromatography: introduction

Chromatography: Separation by Polarity

Chromatography separates compounds by how they divide between a stationary phase and a mobile phase. The stationary phase is the material that holds the compounds for a time. The mobile phase is the solvent that carries the solutes to be analyzed. In column chromatography, a mixture flows through the stationary phase. The compounds separate based on their structure and polarity. Solutes that interact weakly with the stationary phase move faster through the column and exit first. Solutes that...

dialysis

Dialysis Separation by Diffusion

Dialysis separates small molecules from larger ones by diffusion through a semipermeable membrane. It is a purification method used to remove unwanted ions or small organic molecules from a sample while keeping larger analytes in place. The membrane is usually made of cellulose acetate or cellulose nitrate. Its pores are typically about 1 to 5 nm wide. Molecules such as chloride, sodium, and glucose can pass through these pores. Larger molecules, including proteins, hormones, and enzymes, are...

volatilization

Mass Loss in Gravimetric Analysis

Volatilization gravimetry is a way to measure mass loss in a sample by driving off a volatile substance. It helps estimate how much volatile material is present. In this method, a known amount of sample is heated to a high temperature in a crucible or another suitable vessel. As the sample heats, the volatile substance evaporates. The vapor is then completely removed from the crucible, either by continued heating or by bubbling an inert gas through the vessel. The non-volatile part stays...

ion exchange

Ion exchange chromatography separates charged molecules from a solution by swapping them with mobile, or active, ions on a stationary phase. It is used to separate ions, soften and deionize water, and purify solutions. The method depends on a solid column made of high-molecular-weight, chemically stable polymers that are crosslinked to make them porous and essentially insoluble. These polymers are functionalized with either acidic or basic groups. When acidic groups are present, the resin is a...

key terms and concepts

Learn how ion exchange chromatography uses cation and anion exchangers to separate charged molecules, purify solutions, and soften water.

Ion Exchange Resins and Charged Molecules | JoVE K12

analytical chemistry

JoVE Core Analytical Chemistry simplifies complex chemical principles by breaking them down into clear, engaging animations, making topics from SI Units to NMR spectroscopy more accessible and straightforward. Additionally, the scientist-in-action videos highlight the application of these concepts in real-world research conducted in laboratories globally.

Ion Exchange Resins and Charged Molecules

Description

Transcript

Tags