Preparation of activated carbons from cocoa shells and siriguela seeds using H3PO4 and ZnCL2 as activating agents for BSA and α-lactalbumin adsorption

• H3PO4 and ZnCl2 were tested to produce activated carbons from agroindustrial wastes.
• H3PO4 was more effective in modifying the structure of the precursors.
• H3PO4 improve the carbon textural properties.
• Tests realized: Effect of pH; Mass influence; Contact time; Adsorption isotherms.
• Non-linear models were tested and successfully fitted to the experimental data.

The aim of this work was to prepare activated carbons from cocoa shells and siriguela seeds and to evaluate the whey protein adsorption on produced activated carbon. The residues were impregnated with ZnCl2 and H3PO4. DTA/TG and FTIR were performed with this material. Carbonization was performed under nitrogen flow for 40 min at 500 °C and the obtained activated carbons were washed, dried and stored. The resulting carbons were characterized regarding their textural properties. Additionally, an adsorption study was performed, using BSA and α-lactalbumin. The activated carbons showed surface areas higher than 642 m2·g−1. Impregnation with H3PO4 was more effective in modifying the structure of the precursors and carbon textural properties and this action was favorable for the adsorption of the protein α-lactalbumin. Impregnation with ZnCl2 resulted in activated carbons which were more effective in the adsorption of BSA. In both cases, use of the siriguela seed as a precursor in the production of activated carbon was favorable. The pseudo second-order model was fitted satisfactorily to the time equilibrium experimental data, for both proteins. The Toth model represents most efficiently α-lactalbumin adsorption experimental data and the Langmuir model was considered the most satisfactory for the adsorption of BSA.