Evaluation of Cocoa Beans Shell Powder as a Bioadsorbent of Congo Red Dye Aqueous Solutions

Abstract

The use of synthetic dyes in the textile, leather, and paper industries is a source of groundwater pollution around the world. There are different methods for the treatment of wastewater that has been contaminated with dyes, among which adsorption with agro-industrial wastes is gaining relevance. In the present study, the adsorption capacity of cocoa bean shell powder was evaluated when it was used as a bioadsorbent for Congo red dye in an aqueous medium. A 24 central factorial design with central and axial points was proposed to determine the adsorption capacity. The factors that were studied were the adsorbent (0.06–0.15 g), Congo red (40–120 mg L−1), pH (3–11), and time (4–36 h). The bioadsorbent was characterized through scanning electron microscopy and Fourier-transform infrared spectroscopy. The effects of the factors on the adsorption capacity for Congo red using cocoa bean shell were nonlinear, and they were modeled with a second-order polynomial (p < 0.05) and with an R2 of 0.84. The bioadsorbent obtained a maximum adsorption of 89.96% in runs. The process of optimization by using the surface response allowed the maximization of the adsorption, and the validation showed that 95.79% adsorption of the dye was obtained.

Factors Affecting Synthetic Dye Adsorption; Desorption Studies: A Review of Results from the Last Five Years (2017–2021)

“…Accordingly, as the initial dye concentration increased, the adsorption capacity of the biosorbent decreased. Referring to other similar studies with Congo red, it was explained that the equilibrium adsorption capacity increases with increasing initial dye concentration, a process controlled by the mechanism of resistance to removal of Congo red [ 160 ].…”

“…Arellano G. Rodríguez et al [ 160 ] reported that a negative linear effect between removal efficiency, amount of bound material and initial concentration occurred when removing Congo red with cocoa bean shells [ 160 ]. Accordingly, as the initial dye concentration increased, the adsorption capacity of the biosorbent decreased.…”

Cocoa Bean Shell: A By-Product with High Potential for Nutritional and Biotechnological Applications

“…Al-Yousef et al, 2021 [118] evaluated the application of CBS as an adsorbent to eliminate ibuprofen (IBP) from water, and the results showed that the adsorption capacity of CBS in removing IBP was significantly higher than other materials, such as biochar, zeolites or even activated carbon. Moreover, Rodriguez-Arellano et al, 2021 [121] assessed the properties of dried CBS powder as an adsorbent for Congo red dye removal in water, achieving a maximum percentage of adsorption of 96% under optimal conditions (40 mg/L of dye concentration, pH 3, 0.11 g of adsorbent/L and 36 h). These authors indicated that the dye attached to the CBS surface, particularly, it was associated with the OH group of phenolic compounds.…”

Adsorption of Brilliant blue FCF (B1) and Allura Red (R40) colorants on cocoa shell: kinetics of the process

“…Cocoa shells (CS) show a good performance in the removal of contaminants, however, studies to remove dye mixtures are scarce. Due to its properties and massive generation, the use of the CS can contribute as an interesting alternative to environmental management in the food industry [15].…”