RESUMO
Bioethanol is recognized today as the most coveted biofuel, not only because of its tendency to reduce greenhouse gas emissions and other undesirable impacts associated with climate change, but also because of the simplicity of its methodology. This study evaluated bioethanol production from cocoa waste hydrolysates at the laboratory scale and, then evaluating the environmental impact associated with this production. Acid treatment was carried out on the hydrolysate in order to make it more accessible to ethanol-producing microorganisms. The cocoa hydrolysate was converted on a laboratory scale into bioethanol. The Ca, Mg, K and Na content of the substrate were respectively 78.4 ± 0.04; 109.59 ± 0.03; 1541.53 ± 0.08 and 195.05 ± 0.12 mg/L. The iron and total phosphorus contents were found to be at 14.06 ± 0.07 and 97.54 ± 0.01 mg/L respectively. The hydrolysate's biochemical oxygen demand (BOD 5) was 1080 ± 0.01 mg/L. A two per cent alcohol yield was obtained from 50 mL of substrate. Environmental impacts were assessed and quantified using SimaPro software version 9.1.1.1, Ecoinvent v.3.6 database, ReCiPe Midpoint v.1.04 method and openLCA sustainable development software. A total of 15 impact factors were assessed and quantified. The categories with more significant impacts in the agricultural phase were land use (1.70 E+04 m2a crop eq), global warming (3.41 E+03 kg CO2eq) and terrestrial ecotoxicity (7.23 E+03 kg 1,4-DCB), which were the major hotspots observed in the lab-scale biomass-to-bioethanol conversion phase due, to the use of electricity, distilled water and chemicals. The result of this work has shown that the cocoa-based hydrolysate is a suitable substrate for the sustainable production of liquid biofuels.
RESUMO
From recent research, lignocellulosic materials assert themselves as good precursors for the manufacture of highly carbonaceous and porous materials. Hence, the perspective of this work is the preparation of the low-cost activated carbons (ACs) based on puck shells (Afrostyrax lepidophyllus) with a large surface area. To achieve this, chemical activation using phosphoric acid and sodium hydroxide as an activating agent was carried out. The response surface methodology through Box-Behnken design was used to optimize the preparation conditions. Box-Behnken design was used to optimize the preparation conditions. The factors whose influences have been studied are the concentration of activating agent (0.5-1.5 mol l-1), the carbonization temperature (300-500°C) and the residence time (30-100 min). The AC obtained by phosphoric acid was named CRP and impregnated with sodium hydroxide CRB. The ideal conditions for the preparation of the ACs obtained from the maximum iodine number (647.29 for CRP and 575.15 mg g-1 for CRB) were: 1.5 mol l-1 for the concentration of activating agent at a carbonization temperature of 500°C during 62 min for CRP and 0.85 mol l-1 for the concentration of activating agent at a carbonization temperature of 500°C during 59 min for CRB. These two materials prepared were characterized by several techniques pH at the point of zero charge (pHpzc), Boehm titration, Fourier transform infrared spectroscopy, XRD analysis, BET method, Raman spectroscopy and scanning electron microscopy, which confirmed the acidic nature of CRP and the basic nature of CRB carbons. The specific surface of the micropores was 509.05 and 27.53 m2 g-1, respectively. It provides a new valorization of agricultural waste for the preparation of effective-cost microporous ACs as an adsorbent that can be applied in water treatment industries.
