Small molecule diffusion into Iota-Carrageenan gel was studied by using steady-state fluorescence (SSF) technique. Pyranine, dissolved in water was used as fluorescence probe. Fluorescence emission intensity, I_p, and scattered light intensity, I_sc, were monitored to study diffusion and swelling processes at various temperatures respectively. Fickian and Li-Tanaka models were elaborated to produce diffusion, D, and collective diffusion, D₀, coefficients. Diffusion and swelling activation energies were also obtained and found to be 20.5 kj mol^-1 and 28.2 kj mol^-1, respectively.

Key words: Fluorescence; Carrageenan; Diffusion; and Gel.