deossigenation

Deossigenation, also written as deoxygenation, is the process of removing oxygen from a substance or environment. In chemistry, it refers to reactions that eliminate oxygen atoms from molecules or convert oxygen-bearing groups to other forms, typically by reduction or by decarbonylation or decarboxylation steps. In environmental and physiological contexts, deossigenation can describe the lowering of dissolved oxygen in water, or the loss of oxygen from biological tissues as part of metabolic activity.

Chemical approaches to deossigenation include catalytic and non-catalytic reduction, hydrogenolysis, and hydrodeoxygenation, where oxygenated organic molecules are converted to hydrocarbons with the release of water or CO/CO2. Common reagents include hydrogen gas with metal catalysts, metal hydride reducing agents, and in some industrial settings, reagents that promote decarboxylation or decarbonylation to remove oxygen-containing groups.

Industrial and environmental applications include upgrading biomass-derived feedstocks via hydrodeoxygenation, refining operations that remove oxygen from crude products, steelmaking and metal fabrication where oxide layers are reduced, and water treatment or wine and food packaging where deoxygenation improves stability by limiting oxidative reactions. In physiology and ecology, deossigenation describes reduced oxygen availability in blood or aquatic systems, influencing metabolic processes and ecosystem health.

Deossigenation is influenced by temperature, pressure, hydrogen availability, catalysts, and the chemical structure of the substrate. Accurate terminology distinguishes deoxygenation (removal of oxygen atoms) from oxidation (gain of oxygen) and reduction (gain of electrons).