2.5.8. Evaluation of dye exhaustion, color strength, and color
fastness
UVevis absorption spectra of EFCS in water were recorded on a
TU-1900 UVevis spectrophotometer. The EFCS solution had
maximum absorption at 295 nm wavelength. It was necessary to
dilute the residual dye solution to the same volume as that of the
initial dye solution. The dye exhaustion was determined by
measuring the absorbance (lmax ¼ 295 nm) of the initial and final
dye solutions. The dye exhaustion percentage E (%) was calculated
through the following equation: