Syagrus oleracea-activated carbon prepared by vacuum pyrolysis for methylene blue adsorption

This work aims to produce activated carbon from the endocarp of Syagrus oleracea by vacuum pyrolysis and evaluate its potential as an adsorbent. The effects of pyrolysis temperature (400 degrees C, 500 degrees C, 600 degrees C, and 700 degrees C), particle diameter (0.467mm, 0.267mm, and lower than 0.234mm), and activation agent (H2SO4, H2PO3, and KOH) on the potential for methylene blue adsorption were investigated. In addition, kinetics and adsorption equilibrium were evaluated. The best condition found was particle diameter <0.234mm, final pyrolysis temperature of 700 degrees C, and using KOH. Adsorption kinetics followed pseudo-second order, with equilibrium reached within 20min. Isotherms followed the Freundlich model. Values of adsorption capacity were in the order of 30mg/g. Thermodynamic parameters indicated that adsorption occurred spontaneously with a reduction in the heterogeneity of the solid interface/solution. The results obtained demonstrate the great adsorption capacity of the activated carbon prepared from endocarp of Syagrus oleracea via vacuum pyrolysis for the removal of up to 98% methylene blue from aqueous solutions.