Chitosan composites for thionine dye adsorption

Chitosan (Cs) composites with carbon nanotube (Cs/CNT) and with activated carbon (Cs/AC) were prepared, characterised and applied for adsorption of thionine dye. Optimum adsorption conditions were adsorbent dose 0.1 g, dye concentration 30 mg/L, solution pH 5 and adsorption time 120 min. The overall results confirm the adsorption ability of Cs/CNT > Cs/AC > Cs where the adsorption ability of pure Cs reached 59.3%, 73.7% with Cs/AC and reached its maximum value of 98.5% with Cs/AC adsorbent material. Adsorption isotherm was studied by three isothermal models, and the results indicate the adsorption of thionine dye using the three adsorbents fit Freundlich > Langmuir > Dubinin-Radushkevich (D-R) model. The correlation coefficient (R-2) obtained from Langmuir model did not fit the experimental data of thionine dye where (R-2) obtained from Freundlich model indicate a multilayer adsorption with physicosorption type. The results of D-R isotherm model indicate that the physisorption nature of thionine dye was less than 8 kJ mol(-1) indicating the physisorption nature of adsorption using Cs, Cs/AC and Cs/CNT.

Automated summary

Chitosan composites with carbon nanotube (Cs/CNT) and activated carbon (Cs/AC) were prepared and applied for the adsorption of thionine dye. The adsorption ability of Cs/AC was found to be the highest among the three adsorbents. The adsorption process of Cs, Cs/AC, and Cs/CNT was mainly attributed to physical adsorption, as indicated by the adsorption isotherm models.