What is the difference between mass transfer and diffusion?

Answer 1

https://www.wyzant.com/resources/answers/596663/what-is-the-difference-between-mass-transfer-and-diffusion

Answer 2

From Wikipedia:

Some common examples of mass transfer processes are the evaporation of water from a pond to the atmosphere, the purification of blood in the kidneys and liver, and the distillation of alcohol. In industrial processes, mass transfer operations include separation of chemical components in distillation columns, absorbers such as scrubbers or stripping, adsorbers such as activated carbon beds, and liquid-liquid extraction. Mass transfer is often coupled to additional transport processes, for instance in industrial cooling towers. These towers couple heat transfer to mass transfer by allowing hot water to flow in contact with air. The water is cooled by expelling some of its content in the form of water vapour.

Diffusion is the movement of particles from an area of higher concentration to one of lower concentration. It is powered by the motion of particles which creates collisions.

Answer 3

Diffusion is a form of mass transfer. Both terms are used to describe the spread or aggregation of solutes in a fluid.

Mass transfer is the transport of mass from one place to another. Diffusion is the even distribution of solutes molecules throughout the fluid or liquid. The main difference between mass transfer and diffusion is that mass transfer may or may not involve a concentration gradient whereas diffusion does involve the movement of a solute down a concentration gradient.

 Example of mass transfer: evaporation of a liquid phase to a vapor phase

Example of diffusion: movement of dye molecules from an area of high concentration to one of lower concentration.