Waiting
Login-Verarbeitung ...

Trial ends in Request Full Access Tell Your Colleague About Jove

5.21: Types of Coprecipitation

TABLE OF
CONTENTS
JoVE Core
Analytical Chemistry

Ein Abonnement für JoVE ist erforderlich, um diesen Inhalt ansehen zu können. Melden Sie sich an oder starten Sie Ihre kostenlose Testversion.

Education
Types of Coprecipitation
 
TRANSCRIPT

5.21: Types of Coprecipitation

Coprecipitation is the contamination of a precipitate by otherwise soluble species and occurs via different processes. In colloidal precipitates, coprecipitation occurs via surface adsorption. For instance, barium sulfate has a primary layer of adsorbed barium ions and a secondary layer of nitrate counterions. This results in contamination of the precipitate by barium nitrate.

Sometimes, ions in a crystal lattice can undergo isomorphous replacement by inclusions of similar charge and size. For example, during the precipitation of cadmium sulfide, manganese in the solution can replace cadmium to form a mixed crystal. Similarly, magnesium ammonium phosphate can be contaminated by potassium ions in the solution, resulting in mixed crystals of magnesium potassium phosphate. The formation of mixed crystals can be prevented by removing the interfering ion or using a different precipitant.

Coprecipitation can also occur via occlusion, where foreign ions are trapped within the growing lattice. Similarly, pockets of solution are trapped between adjacent crystals in mechanical entrapment. Slow precipitation can minimize occlusion, whereas rapid dissolution and reprecipitation in a clean, fresh solvent can remove it.

Tags

Keywords: Coprecipitation Surface Adsorption Isomorphous Replacement Mixed Crystals Occlusion Mechanical Entrapment Precipitate Contamination

Get cutting-edge science videos from JoVE sent straight to your inbox every month.

Waiting X
Simple Hit Counter