Hen Feather: A Remarkable Adsorbent for Dye Removal - Green Chemistry for Dyes Removal from Wastewater - page 450

variation is observed in the values of the rate constants with the change
in temperature.

11.6.3.3 Elucidation of Reaction Mechanism

In order to ascertain the operative mechanisms of the undertaken systems
as particle diffusion or film diffusion, B t versus time graphs are plotted.
In the cases of adsorption of Azo dyes Amaranth and Tartrazine, lin-
earity of the line is deviated at all the temperatures, thereby suggesting
involvement of a film diffusion mechanism as the rate-determining step.
Figure 11.18 represents typical time versus B t plot in the lower as well as
higher concentration ranges for the Amaranth-Hen Feather system, while

Table 11.7 Rate constant values for the removal of Azo Dyes at different
temperatures.

Adsorbate Adsorbent Rate Constant Unit of Rate

Constant

30°C 40°C 50°C

Amaranth Hen Feather 2.2 × 10 -2 2.3 × 10 -2 2.4 × 10 -2 min -1

Tartrazine Hen Feather 4.1 × 10 -4 2.4 × 10 -4 4.1 × 10 -4 sec -1

Figure 11.18 Correlation of time versus B t for Amaranth-Hen Feather system at different
concentrations at 30 C.