Corrosion mechanism of (NH4)

There are two reasons why ammonia corrodes metals: first, ammonia can form complex ions with metal ions, and second, the atmosphere contains a large amount of oxygen. To explain it more specifically, since ammonia can form relatively stable complex ions with many metal ions, this reduces the standard electrode potential between the metal ions and the metallic elements. In terms of high school chemistry, this means that the metals become more easily oxidized. Furthermore, since Earth’s atmosphere is an oxidizing atmosphere, metals become more susceptible to oxidation, which is the phenomenon of corrosion. To be more precise, it is oxygen in the atmosphere that actually corrodes metals, while ammonia facilitates the corrosion process. For example, copper containers cannot be used to hold ammonia, as this leads to the formation of copper(II) tetraammine ions.

The original poster please clarify what material is being corroded by NH4+ The mechanisms by which NH4+ corrodes copper and iron are different.

3# ask123456 Steel structure or concrete

Concrete is acidic, while ammonia is alkaline; therefore, a reaction occurs

What LZ meant is (NH4+), not ammonia water; generally, in the presence of (NH4+), the solution can have two possible states. I don’t know whether LZ is testing everyone’s basic knowledge or if they really don’t understand it

NH4+ is the ammonium ion, a cation; it must be present in solution along with an anion in order to maintain charge neutrality. Assume for now that the anion is chloride (assuming the same for sulfate as well). Because ammonium ions readily decompose into ammonia and hydrogen ions, as shown in the following equation: NH4+ -----> NH3 + H+. If ammonia becomes saturated in the solution, it will evaporate, leaving behind hydrogen ions which, together with chloride ions in the solution, have an effect similar to that of hydrochloric acid. In the case of corroded concrete, concrete is a mixture of calcium carbonate, calcium silicate, aluminum silicate, and similar substances; when it reacts with hydrochloric acid, calcium carbonate produces carbon dioxide, silicic acid, calcium chloride, aluminum hydroxide, and so on. . . These products are relatively loose and porous substances without cohesive forces. Thus, it causes concrete corrosion. Regarding steel, its reaction with hydrochloric acid is the principle by which iron and acid produce hydrogen gas (hydrogen evolution). Another principle is the oxidation involving oxygen in the air (oxygen absorption).

Amine corrosion refers to the general and/or localized corrosion that occurs primarily in carbon steel during amine treatment processes. Corrosion is not caused by the amine itself, but by dissolved acidic gases (carbon dioxide and hydrogen sulfide), amine degradation products, heat-resistant amine salts (HSAS), and other contaminants. Key factors: a) Corrosion depends on design and operating procedures, amine type, amine concentration, contaminants, temperature, and velocity. b) Amine corrosion is closely related to the operation of the equipment. With a few exceptions, carbon steel is suitable for most components in properly designed and operated devices. Most problems can be traced to defective design, poor operating procedures, or solution contamination. c) Corrosion also depends on the type of amine used. Generally, alkanolamines can be arranged in order of increasing corrosivity as follows: mon ethanolamine (MEA), diethylene glycol amine (DGA), diisopropyl amine (DIPA), diethanolamine (DEA), and methyldiethanolamine (MDEA). d) Poorly basic solutions are generally not corrosive, as they have low electrical conductivity and/or a high pH value. However, when the heat-resistant amine salt (HSAS) aggregates in excess of about 2%, the corrosion rate can increase significantly depending on the concentration of the amine solution. e) Ammonia, hydrogen sulfide, and HCN (hydrogen cyanide) accelerate the corrosion of the condenser at the top of the regeneration tower, as well as the outlet pipes, reflux pipes, valves, and pumps. f) The corrosion rate increases with rising temperature, especially in environments using amine-rich solutions. If the pressure drop is high enough, temperatures above around 220°F (104°C) can cause acidic gases to flash and lead to severe localized corrosion. g) The process fluid velocity affects the amine corrosion rate and erosion characteristics. Corrosion is generally uniform, yet high speeds and strong turbulence can cause localized thickness loss. For carbon steel, the typical speed limit is generally set at 3–6 fps for amine-rich solutions, and around 20 fps for amine-poor solutions.

How is the NH4 ion detected in solution?