What does moisture sorption isotherm mean?

What does moisture sorption isotherm mean?

A moisture sorption isotherm is a graph showing how water activity (aw) changes as water is adsorbed into and desorbed from a product held at constant temperature. This relationship is complex and unique for each product.

What is meant by sorption?

Sorption can be defined as a phenomenon of fixation or capture of a gas or a vapor (sorbate) by a substance in condensed state (solid or liquid) called sorbent [124]. From: Solar Energy Materials and Solar Cells, 2014.

How is isotherm sorption measured?

Measurement of sorption isotherms In the manometric methods, the vapour pressure of water is measured when it is in equilibrium with a sample at given moisture content. In the hygrometric methods, the equilibrium relative humidity with a sample at a given moisture content is measured.

What is GAB model?

The GAB (Guggenheim–Anderson–de Boer) and BET (Brunauer–Emmett–Teller) are the most common models used for the determination of the sorption isotherms for different materials. The GAB model is represented by constant C and K. Constant C is a positive value that represents the total heat of the first layer of sorption.

What are the 2 types of adsorption?

There are two types of adsorption: Physical adsorption and Chemisorption. When there is adsorption of gases on a solid, two types of forces are operating.

What is sorption give example?

Sorption is defined as the phenomenon in which one substance get attached to another. Sorbate is the substance that gets attached while the sorbent is the substance on which the sorbate gets attached to. An example of sorption is sponge dipped in water.

What is sorption curve?

At equilibrium, the relationship between water content and equilibrium relative humidity of a material can be displayed graphically by a curve, the so-called moisture sorption isotherm. This relationship between water activity and moisture content at a given temperature is called the moisture sorption isotherm.

What is critical moisture content?

The critical moisture content is the average material moisture content at which the drying rate begins to decline. A prototype drying test should be conducted to determine the critical moisture content. The critical point (B) occurs when the superficial moisture has evaporated. In porous solids point B of Fig.

What is called isotherm?

Isotherm, line drawn on a map or chart joining points with the same temperature. Isotherms are commonly used in meteorology to show the distribution of temperature at the Earth’s surface or on a chart indicating constant level or constant pressure.