ABSTRACT
In this work, a combination of mechanical and chemical pretreatments using urea on corn residues (leaves and stems) was evaluated to obtain total reducing sugars (TRSs). The residues were characterized via high-performance liquid chromatography (HPLC) to quantify biomass composition. During the mechanical pretreatment, the particle size of the biomass was reduced to 0.5, 1, and 2 mm. The chemical pretreatment was performed with urea solution at different concentrations (2, 5, and 10% w/v) and a fixed biomass-to-solvent ratio of 1:25 (g/mL) as well as stirring at 150 rpm for 20 h. The effect of temperature on the pretreatment results was evaluated by varying such operating variables in 30 and 50 °C. After both pretreatments, hydrolysis was carried out in an autoclave using sulfuric acid at 1% v/v at 121 °C for 1 h. The content of TRS was quantified using 3,5-dinitrosalicylic acid (DNS) method and biomass after pretreatment was characterized via Fourier transform infrared (FT-IR). For both leaves and stems, the HPLC technique reported the presence of 47.4 g of cellulose, 40.04 g of hemicellulose, and 26.38 g of lignin. It was found that the highest amount of TRS (36.50 g/L) was obtained with a urea concentration of 2% at 50 °C using a particle size of 0.5 mm. The production of TRS was significantly higher for pretreated biomass than that for raw corn residues, confirming the importance of both mechanical and chemical pretreatments to reach better delignification results.
ABSTRACT
Nowadays, green-chemistry principles offer an approach that fits to ensure chemical process sustainability by the use of low-cost renewable raw materials, waste prevention, inherent safer designs, among others. Based on this motivation, this study presents a novel methodology for sustainable process design that comprises the synthesis of a multifeedstock optimal biorefinery under simultaneous optimization of economic and environmental targets and further sustainability evaluation using the sustainability weighted return on investment metric (SWROIM). The first step of the proposed method is the formulation of an optimization model to generate the most suitable process alternatives. The model took into account various biomasses as available raw materials for production of ethanol, butanol, succinic acid, among others. Process technologies such as fermentation, anaerobic digestion, gasification, among others, were considered for biorefinery design. Once the model synthesizes the optimal biorefinery, we used environmental, safety, economic, and energy analyses to assess the process, which is a case study for north Colombia. Process simulation generated the data needed (extended mass and energy balances, property estimation, and modeling of downstream) to develop the process analysis stage via the Aspen Plus software. Results for the environmental and economic analyses showed that the assumption considered to solve the optimization problem was adequate, yielding promising environmental and economic outcomes. Finally, the overall sustainability evaluation showed a SWROIM of 27.29%, indicating that the case study showed higher weighted performance compared to the return on investment (ROI) metric of 14.33%.
ABSTRACT
The biodiesel from lignocellulosic materials has been widely recognized as an alternative fuel to meet energy requirements worldwide, facing fossil fuel depletion, and emerging energy policies. In this work, the biorefinery approach was applied for biodiesel production from jatropha and palm oils in order to make it economically competitive by the utilization of residual biomass as the feedstock for obtaining hydrogen via steam reforming of glycerol and gasification. The linear chains for hydrogen and diesel were simulated using UniSim software and main stream properties were collected from the literature or predicted by correlations. The proposed scheme of biorefinery was analyzed through environmental and techno-economic assessment to identify the feasibility of this process to be implemented. Three different blends of oils (JO10-PO90, JO20-PO80, and JO30-PO70) were considered in the environmental analysis to determine alternatives for reducing potential environmental impacts (PEIs). It was found that the acidification potential highly contributed to the environmental impacts attributed to the use of fossil fuels for heating requirements, and JO30-PO70 blend exhibited the lowest PEI value. The economic indicators were calculated to be 8,455,147.29 $USD and 33.18% for the net present value and internal rate of return, respectively. These results revealed that the proposed combined biomass biorefinery is feasible to be scaled up without causing significant negative impacts on the environment.
ABSTRACT
These days, there is a need to develop novel and emerging processing pathways that permit production of value-added substances and fuels considering sustainability aspects. In this sense, levulinic acid (LA) is one of the most promising biorefinery products. This paper presents environmental and safety assessments of LA production via acid-catalyzed dehydration (ACD) of biomass. The process was modeled by using Aspen Plus process simulation software based on a capacity of 132 000 tons per annum of banana rachis (main raw material). Likewise, environmental and safety assessments were developed. Parameters such as heats of reaction, explosivity, toxicity of substances, and operational conditions along with extended mass and energy balances were used to perform safety and environmental analyses. In this regard, the modeled topology showed an inherent safety index (ISI) score of 24 with an equal contribution of 12 points for both chemical inherent safety index (CIS) and process inherent safety index (PIS). ACD showed a good safety performance, with moderate concerns related to the handling of formic acid. Moreover, the waste reduction algorithm (WAR) was used to assess environmental performance and estimate potential environmental impacts (PEIs) of the simulated topology. It was performed considering four case studies to determine the influence of mass streams (case 1), product streams (case 2), energy streams (case 3), and simultaneous products and energy contribution (case 4). This analysis showed that for this process, the total inletting flow of impacts that enter was less than the amount of these that leave the system according to a generation rate of the PEI for case 1 (-1.89 × 102 PEI/h) and case 3 (-1.83 × 102 PEI/h). From the environmental viewpoint, the major concern is associated with the photochemical oxidation potential category because of the handling of volatile organic compounds through the process.