Removal of Basic Blue 41 dyes using Persea americana-activated carbon prepared by phosphoric acid action

Abstract

Adsorption study of Basic Blue 41 dye onto activated carbon from Persea americana nuts with phosphoric acid activation was achieved. The effect of operating parameters, the effect of pH (2–12), adsorbent amount (5–30 mg/50 mL), dye concentration (25–125 mg/L), contact time (0–200 min) and temperature (298–323 K), on the adsorption capacity was examined. The experimental isotherm data were analyzed using Langmuir and Freundlich models, which showed that the best fit was achieved by the Langmuir model with the maximum monolayer adsorption capacity at 625 mg/g. The adsorption kinetic process followed pseudo-second-order kinetics. Thermodynamic evaluation showed that the process was endothermic (ΔH0 = 144.60 kJ/mol) and spontaneous (ΔG0 varied from to −11.64 to −19.50 kJ/mol), while the positive value of entropy (ΔS0 = 524.3 J/mol K) revealed increased randomness at the adsorbent–adsorbate interface. It was found to be a very efficient adsorbent and a promising alternative for dye removal from aqueous solutions.