Adsorptive removal of reactive dyes from aqueous solution using activated carbon synthesized from waste biomass materials

High-activity mesoporous carbons were prepared from wild almond shells and coir pith by phosphoric acid activation and applied for adsorption of the dyes, C.I. Reactive Red 2 and C.I. Reactive Yellow 145A. The BET surface areas of these activated carbons were found to be 1133.25 and 1210.58 m²/g, respectively. The equilibrium data were best described by the Langmuir isotherm in all the cases. The maximum dye adsorption capacity shown by the activated carbon produced from coir pith was 2022.9 mg/g for C.I. Reactive Red 2 and 1694.3 mg/g for C.I. Reactive Yellow 145A at 60 °C with initial concentration of 1000 mg/L. Pseudo-second-order kinetic model gave a good fit, with the intraparticle diffusion being one of the essential rate-controlling steps. Thermodynamic analysis revealed that the adsorption of both the dyes on activated carbons was spontaneous and endothermic in nature. The t test analysis showed that the difference between adsorption capacities of the produced activated carbons was not significant at 95 % confidence level at all the temperatures studied.

Keywords
Adsorption kinetics; Coir pith; Phosphoric acid activation; Wastewater; Wild almond shell