Corrosion Chemistry: Introduction and Theories

The breakdown of a material due to chemical or electrochemical reactions with its surroundings. This gradual deterioration often starts at the surface and can lead to significant damage.

Corrosion is an electrochemical process, similar to a galvanic cell, where oxidation occurs at the anode and reduction occurs at the cathode.

The area of a metal where oxidation takes place, releasing electrons and forming metal ions. The metal at the anode undergoes corrosion.

The area of a metal where reduction occurs, accepting electrons and forming new compounds. The metal at the cathode does not corrode.

The loss of electrons from a metal atom, resulting in the formation of a positive ion. This occurs at the anodic area of the metal during corrosion.

The gain of electrons by a substance, often at the cathodic area during corrosion. It helps to maintain the electrochemical balance in the process.

The process of forming ions from neutral atoms through the loss of electrons, often during corrosion. For example, iron becomes ferrous ions (Fe2+).

Corrosion is a significant problem with major economic costs and environmental impact.

This type of corrosion occurs when a metal is exposed to different oxygen concentrations. The area with lower oxygen concentration becomes anodic and corrodes, while the area with higher oxygen concentration becomes cathodic and remains protected.

A form of differential aeration corrosion that occurs in partially filled water tanks. The area below the waterline has less oxygen and becomes anodic, corroding. The area above the waterline has more oxygen and is cathodic.

This occurs when dust particles or oil drops settle on a metal surface, creating areas with lower oxygen concentration. These areas become anodic, leading to localized corrosion.

The process where a metal loses electrons and forms positive ions, leading to corrosion. It happens at the anode.

The process where a metal gains electrons and forms negative ions, preventing corrosion. It happens at the cathode.

When two different metals are in contact, the metal with lower reduction potential corrodes, while the metal with higher reduction potential remains protected. This occurs because the metal with lower reduction potential loses electrons more readily.

The tendency of a metal to undergo reduction; a higher reduction potential means the metal is more resistant to corrosion.

E-waste is a major environmental hazard, it should be managed sustainably to protect health and the environment.

Burning e-waste releases harmful pollutants into the air, contributing to air pollution.

E-waste can directly harm wildlife through ingestion, entanglement, or habitat destruction.

E-waste contains toxic materials like lead, cadmium, and mercury, which can lead to various health issues if improperly handled.

E-waste disposal methods include landfilling, incineration, recycling, metal recovery through acid treatment, and reuse.

Landfilling, though economical, isn't ideal for e-waste due to potential leakage of toxins into the environment.

Recycling and reuse are preferred e-waste management methods as they minimize resource consumption and pollution.

E-waste is a significant environmental concern, and proper management through recycling and reuse is crucial for a sustainable future.

Corrosion Penetration Rate (CPR) is a measure of how quickly a material corrodes in millimeters per year (mmpy) or mils per year (mpy). It indicates the depth of corrosion per unit of time.

The formula for calculating CPR in mmpy is: CPR = (K * W) / (ρ * A * t), where K is a constant, W is the weight loss in milligrams, ρ is the density in g/cm³, A is the area in cm², and t is the time in hours.

The formula for calculating CPR in mpy is similar to mmpy, but with a different constant (K) and the area A measured in square inches.

The weight loss of a material due to corrosion can be measured in grams (g) or milligrams (mg).

The density (ρ) is a property of a material that describes its mass per unit volume. For carbon steel, a common density is 7.8 g/cm³.

The area (A) exposed to corrosion is calculated in square centimeters (cm²) or square inches (in²), depending on the desired CPR unit (mmpy or mpy).

The time (t) for which the material is exposed to corrosion is measured in hours.

The constant (K) is a conversion factor specific to the unit of CPR being calculated (mmpy or mpy).

A mixture of nitric acid (HNO3) and hydrochloric acid (HCl), typically in a 1:3 ratio by volume, used to dissolve noble metals like gold.

The process of dissolving a substance, like gold, in a liquid solvent, often using a chemical reaction.

Iron sulfate (FeSO4) is used to precipitate gold out of the aqua regia solution, forming solid gold. This reaction is driven by the reduction of gold ions (Au3+) to elemental gold (Au) by iron ions (Fe2+).

Sulfuric acid (H2SO4) is added to accelerate the removal of nitric acid (HNO3) from the gold solution, preventing unwanted reactions and improving the purity of the extracted gold.

During the gold extraction process, the solution containing gold is heated to 100°C to ensure the complete drying of the gold powder. This removes any residual moisture and ensures purity.

A method that reduces waste volume significantly by burning it, potentially generating heat usable for energy production. Some ash may also be used in agriculture.

A method that aims to reduce waste by reusing materials instead of discarding them. It's often used for electronic devices, extracting valuable metals for future use.

A method for managing waste that involves recovering resources from discarded materials to manufacture new products. It reduces landfill waste and saves resources.

The process of extracting metals from electronic waste through chemical reactions in a liquid solution, often using acids to dissolve the metals of interest.

The initial step in extracting metals from electronic waste, involving breaking down the material into smaller pieces for easier processing.

A crucial step in the hydrometallurgical process where metals from electronic waste are dissolved in a liquid using a strong acidic solution.

The process of separating and concentrating metals from the liquid solution after leaching, using techniques like deposition, solvent extraction, adsorption, and ion exchange.

The recovery of valuable metals like gold, copper, aluminum, lead, and others from discarded electronic devices, promoting resource conservation and reducing environmental impact.