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Interest on the use of lignocellulosic waste from second-generation (2G) ethanol industry has increased each year, where biochar and bio-oil production by pyrolysis is a relevant alternative. Biochar has high energy, adsorption capacity and soil enrichment potential, while bio-oil has applications for the pharmaceutical, chemical and fuel industries. Nonetheless, research on pyrolysis of this residue has not been reported, nor has the characterization of the bio-oil produced been profiled. Besides this, few studies on biochar and bio-oil produced from sugarcane bagasse have analyzed the effects of temperature and heating rate on yield. This work investigates the production and characterization of biochar and bio-oil by pyrolysis from this 2G waste. Temperature (500–700 °C) and heating rate (5–15 °C min−1) were the variables evaluated using a full factorial design (FFD), while biochar and bio-oil yields were the responses investigated. Characterization was carried out by thermogravimetric analysis, physical and chemical analyses, Fourier transform infrared spectroscopy, dispersive energy X-ray fluorescence spectroscopy (EDS) and gas chromatography–mass spectrometry (GC–MS). From FFD results, linear models were successfully fit to the responses. Maximum biochar and bio-oil yields of 40.3% and 39.0% were found for a set of temperature-heating rates of 500 °C-5 °C min−1 and 700 °C-15 °C min−1, respectively, in agreement with residue from first-generation ethanol process. The biochar presented low content of ash, volatile materials and moisture as well as high fixed carbon content and heating values, showing high energy potential. The bio-oil exhibited alternativity as source of phenols (53.2%) for industry based on the GC–MS results.

Liquid-liquid equilibrium tie line data were determined at 373.15 K for a model hydrocarbon mixture consisting of hexadecane + xylenes + pyrene with the solvents sulfolane and diethylene glycol (DEG), and also with the solvent combination N-methylpyrrolidone/ethylene glycol (NMP/EG). The measured data were used to estimate binary interaction parameters of the UNIQUAC model. All solvents presented comparable selectivities for pyrene relative to xylenes. Pyrene partition ratios greater than unity were observed for sulfolane only. As a result, from a selectivity/capacity viewpoint, when compared to NMP/EG and DEG, sulfolane is potentially the best suited solvent for extraction of pyrene. Selectivities greater than unity were observed for all solvents studied. Therefore, pyrene, a polycyclic aromatic hydrocarbon, can be selectively removed from oil containing monocyclic aromatic hydrocarbons such as xylenes.

Three solid acid-catalyzed (SAC) processes for biodiesel production from residual oil and fats (ROFs) with HWSi/Al2O3 as catalyst were designed and optimized using Aspen Plus: simultaneous esterification, transesterification, and methanol separation based on catalytic distillation (CD) (process A) and catalytic absorption (CA) (process B), where CA has not yet been investigated in these conditions; and hydro-esterification industrial process using CD (process C1). For the first time, processes A, B and C based on SAC route were optimized and compared regarding to techno-economic and environmental aspects. Processes A and B were the most economically and eco-friendly options. Compared to process B, process A was the best option due to simpler flowsheet. Process A2 presented 25.6, 60.1, 4.6, 8.6, 52.6 and 62.8% lower capital, utilities ( C u t i l ), operation, total annualized ( T A C ), waste treatment ( C w a s t e ) and CO2 emission costs than process C1. A global optimization developed for process A saved 430 k$/year on T A C . After a heat integration, process B presented 4.9 and 10.8% lower C u t i l and C w a s t e than process A. Process A was also designed for FFA levels of 5–25 wt%, where the biodiesel break-even price remained competitive (0.48–0.75 $/kg) with diesel price.

An innovative integrated process of ethanol dehydration and ethylic biodiesel production based on absorption and reactive distillation processes was demonstrated by experimental validated simulation and optimization using Aspen Plus® and Statistica® software, respectively. Glycerol, a byproduct of the transesterification of triacylglycerols, was adopted as solvent for ethanol purification. Experimental and simulated results of the absorption process step were compared and showed no significant difference from t-test with 95% of confidence level. The optimal conditions of the processes were obtained using a multivariate analysis. For the absorption process, the optimized parameters were solvent feed stream temperature, T = 27 °C; number of stages, N = 6; and solvent-to-feed ratio, S / F = 1.5, 1.4 and 1.0 for ethanol mass fractions on feed stream of 0.8800, 0.9380 and 0.9910. The optimal parameters of the reactive distillation column (RDC) for biodiesel production were ethanol-to-oil molar ratio, M R = 12; N = 6; total reflux ratio; and residence time to number of stages ratio, t / N = 8 min/stage. The integrated process produced anhydrous ethanol with mass purity above 99.9%, oil conversion ( X o i l ) above 99%, and biodiesel yield of 98%. Moreover, X o i l > 96.5% was also obtained for a lower value of M R = 7 adopting t / N = 8 min/stage. Finally, the integrated process proved to be a potential economically attractive technology for ethylic biodiesel production, since reactive distillation and absorption columns were coupled based on the concept of process intensification.

The technical and economic feasibility of an alternative process for biodiesel production from residual oil and fats (ROF) was compared to two cases of the conventional two-step alkali-catalyzed process. A reliable set of thermophysical properties, kinetic data, and a rigorous thermodynamic modeling were used in the simulations. The alternative process employed liquid–liquid extraction to separate the free fatty acids from triacylglycerols, with methanol as the solvent. Both processes were found to be technically feasible based on a design specification of 99.65% esters for the product. The alternative process proved to be slightly more economically viable than the conventional process based on the selected economic indicators and thus is a promising alternative for biodiesel production from ROF.

The liquid-liquid extraction of free fatty acids (FFA) from residual oils and fats for biodiesel production, employing methanol as the solvent, has been optimized using process simulation and response surface methodology. The parameters investigated were temperature, number of stages and solvent-to-feed ratio (S/F). Responses evaluated were FFA mass fraction in the oil-rich phase ( w FFA B) and total cost, using yellow and brown greases as the raw materials. Quadratic and linear models were fitted for w FFA B and cost responses, respectively. The optimal conditions satisfying technical ( w FFA B ≤ 0.5%) and economic (minimum cost, including capital and operation costs, except for raw material cost) criteria were 321 K, 6 stages, S/F = 1.27, w FFA B = 0.41%, cost = $84.93/ton (yellow grease), and 318 K, 6 stages, S/F = 1.32, w FFA B = 0.49%, cost = $102.89/ton (brown grease).