Buriti pellets were used as adsorbents for the removal of Copper (II) metal and Methylene Blue dye. The adsorbent was characterized by the FTIR, SEM/EDS, NMR, TGA/DTA and PCZ technique. The effect of different factors such as solution pH, particle size and contact time were tested. After optimization of the experimental conditions, adsorption studies were conducted and the results adjusted to the models to the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models. The FTIR showed the main functional groups present in the adsorbent as O-H, C=O and COOH. The SEM/EDS analysis showed a heterogeneous surface and confirmed the presence of Cu after the adsorption. 13C NMR spectrum identified the constituents of buriti fiber which were cellulose and lignin. Thermal analysis TGA/DTA obtained the thermal behavior of the material with information regarding thermal stability and residue content. The PCZ was 6.2 pH value at which the total biomass surface charge was zero. For Cu (II) the optimum pH was 4.5 using 30 min as the time needed to reach equilibrium and temperature of 25 °C. The model that best fit the experimental data by the linear regression method was Langmuir with R2 of 0.9903 with qmáx of 14.20 mg/g and the non-linear regression method applying the error squares sum function (ERRSQ) The model that best fit was Freundlich with ERRSQ of 0.0475. For the methylene blue dye the ideal pH was between 6 and 8, contact time of 30 min and the kinetic model of pseudosecond order was better fitted to the experimental data. The Dubinin-Radushkevich adsorption model had better applicability according to the linear regression method with R2 of 0.9982 and with the energy value (E) less than 8 kJ/mol indicating that the adsorption process is physical in nature. By the nonlinear regression method applying the sum of error squares (ERRSQ) function, the model that best fit was Langmuir with ERRSQ of 0.008. Buriti fibers are very efficient lignocellulosic residues in the adsorption of effluents, being a renewable, biodegradable alternative and of low cost.
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