This study proposes the use of activated charcoal made from Umbaúba wood as an adsorbent for the removal of naphthenic acid in an aviation kerosene model mixture. The activated charcoal was characterised as mesoporous with a carbon graphite profile and presented pH_pzcequal to 10.5. The best working conditions were obtained for activated charcoal levels of <0.09 mm and 300 r min⁻¹. The system reached the equilibrium after 360 min, without significant statistical difference for the pseudo-first- and pseudo-second-order kinetic models. The Weber–Morris and Boyd models corroborated the conclusion that adsorption is not controlled only by the intraparticle diffusion step. For the equilibrium study, the adsorptive capacity obtained was of 1.1 g g⁻¹, with the Brunauer–Emmett–Teller model better correlating with the experimental data. Given the results obtained, the activated charcoal demonstrated to have a remarkable potential for removing naphthenic acid in an aviation kerosene model mixture.

This work proposes the use of agro-industrial wastes, specifically peanut hull (HP) and orange peel (OP), as adsorbents for dyes, such as Remazol Golden Yellow RNL-150% (RYG), Gray Reactive BF-2R (RG) and Reactive Turquoise Q-G125 (RT). Characterization by Brunauer-Emmett-Teller indicates that the adsorbents are mesoporous, with pH_zpc values of 5.0 for HP and 4.0 for OP. Fourier transform-infrared spectroscopy identified carbonyl and sulphonic groups. The initial pH of the best-adsorbing solution of the three colours was 2.0. Increasing the concentration of the adsorbent promoted an increase in the percentage of removal until saturation of the adsorbent. In a factorial design, the largest value of q was obtained with 0.25 g of the adsorbent, with a particle size of<0.4 mm and a stirring speed of 300 rpm. Such conditions were used in kinetic studies and studies of adsorption equilibrium. The evolution kinetics were rapid in the first few minutes, and after 180 min the system reached equilibrium. The kinetic model that best fit the experimental data to a 95% confidence level for the F test was the pseudo-second-order model for RYG/HP, RG/OP and RT/OP. There was no significant difference between the kinetic models as evaluated by the F test for RYG/OP, RG/HP and RT/HP. The experimental results indicated favourable dye adsorption characteristics for the adsorbents studied. The results of the F test showed that for RYG and RG, there was no significant difference between the two evaluated models. This study suggests that HP and OP are viable alternatives for the treatment of effluents containing RYG, RG and RT dyes.