How to Measure the Diffusivity of Alginate Beads
- 1). Measure the radius of a bead. Write this down. For example, suppose you measure a bead and it turns out to be 0.21 centimeters in radius.
- 2). Look up the binding density for the type of bead you are measuring. This can be found in a calculation of diffusivities chart you can find online. For example, for a bead composed of 2 percent calcium alginate has a binding density of 3.69.
- 3). Substitute the values discovered in the previous steps into the equation below to calculate the diffusivity of the bead. The symbol Co stands for binding density and the symbol R stands for radius (in centimeters), and the symbol “R^2” means the square of the radius.
D = 32.88 * Co *(R^2/6) - 4). Calculate the equation after substitution. For example, for a 2 percent calcium alginate bead that is 2 centimeters in radius, the substituted equation looks like this:
D = 32.88 * 3.69 * (0.21^2/6) - 5). Enter the values into a calculator. The result is the diffusivity of the bead. The result is shown below:
D = 0.89 cm^2/s
Source...