Iridium carbon is a carbon-based catalyst containing iridium, which can improve the efficiency and selectivity of chemical reactions, but it can be deactivated or polluted after use, causing iridium waste and environmental harm. Therefore, it is of great significance to extract iridium from iridium carbon, which can not only save resources, but also protect the environment.
The principle of iridium carbon** is to use the different properties of iridium and carbon to separate iridium from the carbon matrix through physical or chemical methods, and then purify and reuse. There are many ways to use iridium carbon**, mainly including the following:
Incineration method: This is a simple and direct method, which is to burn iridium carbon at a high temperature to completely oxidize the carbon and organic matter, leaving the metal powder of iridium, and then dissolving and refining it with acid or alkali to obtain pure iridium. The advantage of this method is that it is easy to operate and has a high rate, but the disadvantage is that it consumes a lot of energy, produces a large amount of waste gas and wastewater, pollutes the environment, and has a certain volatile loss of iridium.
Precipitation method: This is a method that uses chemical reactions, that is, iridium carbon is treated with acid or oxidant to form water-soluble complexes or salts of iridium, and then the hydroxide or metal of iridium is precipitated with alkali or reducing agent, and then filtered, dried and calcined to obtain metal powder of iridium. The advantage of this method is that the reaction conditions are mild and the rate is high, but the disadvantage is that a large number of chemical reagents need to be added, which will introduce impurities, increase the difficulty of subsequent purification, and will produce a large amount of salty wastewater, which is polluting to the environment.
Extraction: This is a method of using solvents, that is, the iridium carbon is treated with acid or oxidant to form water-soluble complexes or salts of iridium, and then extracted with organic solvents to transfer iridium from the aqueous phase to the organic phase, and then the iridium is transferred from the organic phase to the aqueous phase with a reverse extractant, and finally the metal powder of iridium is obtained by precipitation or electrolysis. The advantage of this method is that the separation effect is good, the first rate is high, and the solvent can be recycled, but the disadvantage is that the appropriate extractant and reverse extractant need to be selected, and the extractant is generally toxic, flammable and volatile, and the operation should pay attention to safety, and will cause a certain amount of solvent loss.
Adsorption method: This is a method of using adsorbents, that is, iridium carbon is treated with acid or oxidant to form water-soluble complexes or salts of iridium, and then adsorbed with adsorbents such as activated carbon, ion exchange resin or magnesium silicate, and the iridium is separated from the aqueous phase, and then desorbed with acid or reducing agent to obtain metal powder of iridium. The advantages of this method are that the operation is simple, environmentally friendly, and the adsorbent can be recycled, but the disadvantage is that the adsorption efficiency and selectivity are not high, and the regeneration and desorption of the adsorbent need to consume energy and chemical reagents.