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Chemical Engineering vocabulary · Mass Transfer and Separation Processes

Diffusion

Meaning in chemical engineering, with examples

/dɪˈfjuːʒən/nounCommon term

In chemical engineering, diffusion means: The movement of molecules from an area of high concentration to an area of low concentration caused by their random motion, without any bulk flow.

In Turkish: difüzyon, yayınım

How it is used

Used in mass transfer theory, catalyst design and membranes. Engineers describe it with Fick's law and a diffusion coefficient (diffusivity). Inside porous catalyst pellets, slow pore diffusion can limit the reaction rate.

Example sentences

  1. Smaller catalyst pellets reduce the diffusion path and improve activity.

  2. Diffusion in liquids is about ten thousand times slower than in gases.

Common collocations

  • diffusion coefficient
  • molecular diffusion
  • pore diffusion
  • Fick's law of diffusion
  • mass transferThe movement of a component from one place or phase to another because of a difference in concentration, for example from a gas into a liquid or from a liquid into a solid.
  • catalystA substance that makes a reaction go faster, or more selectively, without being used up itself. In industry it is often a solid in pellets placed in a reactor bed.
  • rate-limiting stepThe slowest step in a series of steps, such as reaction, diffusion or heat removal, which controls how fast the whole process can go.
  • absorptionA separation method in which one or more components of a gas dissolve into a liquid, for example CO2 being removed from gas by an amine solution.

This word in other fields

The same English word can have a different meaning in another field:

More terms: Mass Transfer and Separation Processes

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