General Principles of Material Reversibility
Reversibility of industrial and agro-industrial processes: principles, diagnostics and applications

In classical thermodynamics (Carnot, Clausius), a reversible process is one that occurs at equilibrium, without the production of entropy. This definition pertains to energy exchanges and chemical transformations.

The definition used in this article is distinct: material reversibility refers to the ability of a flow or a material to return to a functional state after transformation, through technically feasible separation and purification processes. It does not imply the absence of energy dissipation, but rather assesses the degree to which material can be recovered within an industrial or natural cycle. This distinction is maintained throughout the article.