Equilibrium Isotherms, Thermodynamics, and Kinetic Studies for the Adsorption of Food Azo Dyes onto Chitosan Films

Abstract

The adsorption of FD&C red 2 and FD&C yellow 5 onto chitosan films was evaluated by equilibrium isotherms, thermodynamics and kinetic studies. The effects of temperature (298-328 K), initial dye concentration (50-300 mg L -1 ), stirring rate (50-350 rpm) and contact time (0-120 min) were investigated at pH of 2.0 and 100 mg L -1 of chitosan films. The dyes concentration was determined by spectrophotometry. Freundlich and Langmuir models were used to represent the equilibrium data. The Langmuir model was the more adequate to represent the equilibrium data (R 2 >0.99 and average relative error<2.50%) and the maximum adsorption capacities were 494.13 mg g -1 and 480.00 mg g -1 for FD&C red 2 and FD&C yellow 5, respectively, obtained at 298 K. The R L values ranged from 0.044 to 0.145. The adsorption was exothermic, spontaneous and favorable.For the FD&C red 2, 90% of saturation was attained at 120 min and the Elovich model was the more appropriate. For the FD&C yellow 5, 95% of saturation was attained at 20 min and the pseudo first-order model was the more adequate to fit the kinetic data.Chitosan films were easily separated from the liquid phase after the adsorption process, Downloaded by [Selcuk Universitesi] at 00:18 27 December 2014 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 2providing benefits for industrial applications, and its application range can be extended for azo dyes.

Chitosan based-nanoparticles and nanocapsules: Overview, physicochemical features, applications of a nanofibrous scaffold, and bioprinting

“…Particle size can be obtained using scanning electron microscopy (SEM), sieving test, or using a particle size analyzer. The effect of the particle size, surface area, and pore volume of chitosan on the adsorption of some food azo dyes FD&C red 2 and FD&C yellow 5 was studied before [37]. The particle sizes used were 0.10, 0.18, and 0.26 mm with surfaces of 4.2, 3.4, or 1.6 m 2 /g.…”

Preparation of low-cost functionalized diatomite and its effective removal of ammonia nitrogen from wastewater

“…The kinetic fitting results showed the arrival of the adsorbate from the solution to the adsorbent surface was controlled by surface diffusion, and the only factor that determined the adsorption rate was the concentration of NH + 4 -N because the temperature had little effect. Several research papers have reported the same conclusion that the pseudofirst-order kinetics was more consistent with the adsorption process (Cadaval et al 2015;Guo et al 2019;Hu et al 2020).…”

Enhanced Cr(VI) removal by waste biomass derived nitrogen/oxygen co-doped microporous biocarbon

“…The equilibrium data were further analyzed by Langmuir and Freundlich isotherm models, respectively (Cadaval et al 2015).…”