Abstract
The adsorption of dye sunset yellow (SY) on both raw and functionalized chitosan (CTN and CTNF) was investigated using statistical physics theory. Adsorption data of SY dye on CTN and CTN-F were experimentally obtained at 298–328 K. Statistical physics modeling analysis demonstrated that the adsorption capacities at 298–328 K of both systems were similar. This theoretical evidence explained that the functionalization of the raw chitosan via 3-aminopropyltriethoxysilane did not improve the adsorbent performance. It was also concluded that the SY dye interacted via the same orientation on CTN and CTNF. The effect of the temperature on the adsorption capacity was studied and results indicated that the SY dye adsorption on CTN and CTN-F adsorbents was endothermic. Dye adsorption capacities were due to the similarity in the number of the attracted SY dye molecules per adsorption site and the density of this receptor site. The interactions between SY dye and adsorbents (CTN and CTNF) and also between SY dye molecules were understood via the calculation of adsorption energies. Physical interactions were the responsible of the dye adsorption mechanism using adsorbents CTN and CTN-F.
•Adsorption of sunset yellow dye on a raw and functionalized chitosan was investigated.•Impact of adsorbent functionalization was analyzed via statistical physics calculations.•Physical interactions were responsible for the endothermic dye adsorption.