Abstract
Chocolate is obtained from Theobroma cacao L., which is in high demand worldwide. However, industrialization generates quantities of waste ranging from cocoa pods, mucilage, and seed shells. Shells are sources of lignocellulosic residues rich in hemicellulose, cellulose, and lignin. These are useful as feedstock in the production of adsorbents for the removal of pollutants from water. Therefore, the objective of this study was to synthesize and characterize a biosorbent from cocoa shell, evaluating the effect of alkaline treatment on the properties of the material. From cocoa fruits obtained from the “Montes de Maria”, municipality of “Maria La Baja” in the department of Bolivar, Colombia, South America. The raw material was selected, washed, cut and dried in a tray at room temperature. The shells were classified according to their size (< 0.212 mm, 0.150 mm and 0.106 mm). Then, one part was subjected to alkaline treatment by immersing them in a 0.1 M NaOH solution, 60 min, room temperature and another part of the samples was not treated with an alkaline solution. Once the biosorbent was obtained, it was analyzed using scanning electron microscopy and X-ray spectroscopy. The SEM images showed that the samples without alkaline treatment do not have high porosity and have smooth surfaces, which is to be expected since when performing the alkaline treatment, it is expected that the modifications can improve the general adsorption properties of the natural form of the biomaterials; that is, increase the surface area and the number and diversity of functional groups, improve their adsorption capacity, and improve particle size, pore size, pore volume and morphology, stability, others. EDS analysis showed the presence of carbon and oxygen in the samples, and iron, potassium, chlorine, and gold were also found in most of them; and very few samples showed the presence of magnesium, bromine, and calcium. In conclusion, alkaline treatment made it possible to obtain high-porosity bioadsorbents that can be used to remove contaminants from water.
