By-products from the wax production process from carnauba palm (leaves), from the extraction of oil from macauba seeds (endocarp) and from pine nut production (shell) have been assessed for activated carbon production, using H3PO4 or CaCl2 for their chemical activation. The resulting activated charcoals have been thoroughly characterized by elemental and thermal analysis, X-ray diffraction, infrared spectroscopy, electron scanning microscopy and N2 adsorption behavior. Subsequently, their adsorption capacity for the removal of rhodamine B (RhB) from aqueous solutions has been evaluated by studying different parameters: contact time, pH, adsorbent dose, initial dye concentration and solution temperature. The adsorption of RhB followed Freundlich's model in all cases. Kinetic studies indicate that the pseudo-second order model can be used for describing the dynamics of the adsorption process. Thermodynamic parameters have also been evaluated, indicating its endothermic and spontaneous nature. Finally, a preliminary analysis of the impact of cellulose content in the carbon precursor materials has been conducted, by using a mixture of native cellulose with one of the lignocellulosic materials.

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Compost from poultry hatchery waste (CPHW) was used as an efficient biosorbent for the removal of heavy metals from aqueous solutions. Single and competitive adsorption of Cd(II) and Pb(II) onto CPHW were studied. The optimum pH of the aqueous solution for Cd(II) and Pb(II) adsorption was found to be in the range 3 to 5. The pseudo‐second order model enabled a better description of the adsorption kinetics. Equilibrium data obtained at 25, 35, and 45 °C were better described by the Sips isotherm than by the Freundlich and Langmuir models. The maximum adsorption capacities calculated by applying the Sips isotherm were 32.3 mg/g for Cd(II) and 142.6 mg/g for Pb(II) at 25 °C. In binary metal ion solutions, a decrease in the adsorption capacity for both heavy metals was observed. The single and competitive adsorption tests revealed that the adsorption affinity was higher for Pb(II) than for Cd(II). Thermodynamic parameters such as ΔG0, ΔH0, and ΔS0 indicated that the adsorption was feasible, spontaneous, and endothermic. FTIR spectroscopy characterization showed that carboxyl and hydroxyl groups were involved in the adsorption of the metals. SEM‐EDX analysis confirmed that Cd(II) and Pb(II) may replace Ca(II) from biosorbent surface. Therefore, the results suggest that CPHW can be used as an economical biosorbent for Pb(II) and Cd(II) removal from aqueous solutions.