LAUSR

Abstract This work aims to evaluate the Cr(VI) removal efficiency and adsorption capacity of the raw coconut fiber from synthetic aqueous solutions through the operational parameters as well as to represent the mechanisms of removal by kinetic and isotherm models. The experimental study was conducted in batch system and the optimum conditions for the adsorption of this metal by the biomass were according to: pH 2, contact time of 270 min, and 10 g/L of adsorbent dosage concentration. The removal efficiency obtained for Cr(VI) solutions was 99.2% at concentrations of 25–50 mg/L. For the highest concentrations, the removal decreased from 96.3% to 74.4%, when Cr(VI) solutions ranged from 100 mg/L to 250 mg/L, respectively. The adsorption kinetics was applied and showed a good agreement for pseudo-second-order and Elovich models, which point out a chemisorption. For the adsorption capacity at equilibrium conditions, the best fit was for the Redlich–Peterson isotherm indicating favorable adsorption and monolayer coverage.