Extraction of hydrocolloids from Pereskia Aculeata Miller: reuse of process residue as activated carbon for the pigment-removal phase

Abstract Hydrocolloids of Pereskia aculeata Miller (OPNH) are potential ingredients in food industry as emulsifiers and stabilizers. The extraction process of OPNH requires the removal of pigments with activated carbon. Because this step is critical to the quality of the ingredient and has an impact on costs, a new activated carbon has been developed with residues from the same process. Residues activated with NaOH and H3PO4 (300 °C, 1 h) were subjected to batch adsorption tests in model solutions of malachite green (MG), carbohydrate and protein. Residue treated with 85% H3PO4 (OPNAC) had higher productivity and MG adsorption capacity, displaying a predominantly microporous surface (MEV/BET) with chemical activation confirmed by TG/FTIR. OPNAC showed higher MG and protein adsorption capacity than the commercial activated carbon (CAC) did. Results for MG-adsorption capacity by OPNAC did not show significant differences in the presence of protein and carbohydrate, presenting the higher affinity of the adsorbent for the dye. Adsorption isotherms showed OPNAC to be more favorable to MG adsorption than CAC, and to have a good fit to Langmuir-Freundlich model. OPNAC made it possible to reduce costs and allowed the sustainability of the process, leading to increased efficiency in selective pigment removal compared with CAC.