Search

In this work, the techno-economic feasibility of a new process for biodiesel production from crude tall oil (CTO) was investigated. A solid acid-catalyzed (SAC) route based on esterification of free fatty acids (FFA) using a catalytic distillation column (CDC) with Relite CFS as the catalyst was employed. CTO purification was needed to achieve biodiesel standard specifications. A base case and an alternative process for CTO purification from four and three distillation columns were designed, optimized and techno-economically assessed. The alternative process was technically feasible for biodiesel production and also more economical and eco-friendly. Therefore, this process was investigated for biodiesel production by the SAC process using a CDC and a catalytic divided-wall column (CDWC). The CDWC process was not technically feasible, so that the CDC process was globally optimized based on six inputs. Finally, the effect of CTO composition was also investigated, so that a final design was obtained for biodiesel production using CTO coming from the United States of America, Canada and Scandinavia.

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.

The activated biochar is a carbonaceous material obtained from thermal degradation of biomass with high adsorption potential. On the other hand, the high production cost has still limited its use in large-scale, so that low-cost raw materials derived from biomass have been encouraged. For instance, waste from palm oil industry, such as palm endocarp (Elaeis guineenses), has shown high potential to produce cheaper activated carbon since high amount of palm residues are annually generated worldwide. Moreover, as far as we know, Elaeis guineensis-biochar activated by ZnCl2 has not been tested as an adsorbent for methylene blue (MB) removal. In addition, optimization studies on activation variables focused on maximizing MB removal are still scarce. This work aims to investigate the adsorption capacity of the Elaeis guineensis-activated carbon for MB removal and to find optimized conditions. Thermo-chemical activation was carried out using ZnCl2. Temperature ( $$T$$ ), activation time ( $$t$$ ) and particle size ( $$PS$$ ) were the variables evaluated through a full factorial design. The optimal condition was obtained based on central composite design (CCD) and surface response methodology (RSM) techniques. Kinetic and equilibrium studies were also carried out. CCD and RSM predicted an optimal MB removal of 93.2% adopting 0.05 g of activated biochar, PS = 65 mesh, $$T\hspace{0.17em}$$ = 700 °C and $$t\hspace{0.17em}$$ = 3 h. Kinetic and adsorption equilibrium results agreed to pseudo second-order model and Langmuir’s model, respectively. Finally, Elaeis guineensis showed to be a promising feedstock to produce activated biochar aiming MB removal from water and wastewater.

The use of renewable sources has been an alternative to decrease the negative environmental impacts of fossil fuels. In this context, bioethanol from sugarcane has proved to be a successful option to gasoline. However, bioethanol purification through conventional distillation requires high-energy demand. For this reason, energy balance calculations are very useful to estimate steam demand. As a result, simpler alternatives for estimation of steam consumption from spreadsheet calculations have been encouraged. In contrast, many efforts have focused to solve complex flowsheets including tear streams, which increases convergence complexity for each change on feed composition and additional components. In this work, mathematical models were fitted to bioethanol–water mixture property data and applied to energy balance calculations involved in the conventional process for hydrated bioethanol purification. Total steam consumption was obtained for volume percentages of bioethanol in the wine feed stream of 6, 8 and 10 °GL considering potential losses found in the industrial reality. The calculated data were compared to simulations carried out in the Aspen Plus® software. Similar values of total steam consumption were found comparing the two approaches, where the average absolute relative deviation was kept below 5%. Moreover, simulated temperature and composition profiles agreed to process data. Finally, mathematical models and energy balance calculations proved to be a simpler and faster alternative to estimate total steam consumption involved in the hydrated bioethanol purification from wine.

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 phase equilibrium of interest in biodiesel production by reactive distillation was modeled. Mixtures were composed of the main components found in esterification and transesterification reactions. The pure component thermophysical properties of acylglycerols were predicted and evaluated by comparison with available experimental data. Databanks of vapour-liquid equilibrium, liquid-liquid equilibrium and vapour-liquid-liquid equilibrium experimental data were created for the mixtures in the biodiesel production process. The experimental data evaluated were then used to develop a rigorous thermodynamic modeling using the NRTL model. Three binary interaction parameter sets were regressed. Two NRTL parameter sets can be used to simulate the catalytic distillation column of interest in the production of biodiesel from residual oil and fats by a solid acid catalyzed process. The third parameter set is useful to simulate the reactive distillation column applicable in the biodiesel production by the homogeneous alkali catalyzed process. The phase behavior of the mixtures studied was correctly described by the proposed modeling for pressures up to 750 kPa. The proposed phase equilibrium modeling was then validated against experimental results reported for biodiesel production by reactive distillation.

In order to provide new isobaric vapor−liquid equilibrium (VLE) data for ethanol-biodiesel systems, experimental boiling points for mixtures of ethanol + biodiesel from soybean oil (SB) and frying oil (FB) were measured. UNIFAC and NRTL models were used to predict and correlate the data, in order to better represent the VLE in process simulation. VLE data were measured with a Fischer type ebulliometer. Reliability and reproducibility were evaluated with VLE data for ethanol + water system at 101.32 kPa. These data also proved to be thermodynamically consistent based on the area test. The boiling temperatures for ethanol + biodiesel systems agreed with other results reported at same pressure for SB and for biodiesel from sunflower seed oil (SSB). The thermodynamic modelling using the NRTL model obtained lower AAD values than those from UNIFAC, assuring better safety in the design and simulations steps of a biodiesel production plant.

Tooth decay affects most of the population in developed countries. The multifactorial etiology of the disease includes multiple bacterial species, S. mutans is the main pathogen associated with the disease. This bacterium adheres to the tooth surface and allows the colonization of other microorganisms resulting in dental biofilm. Several therapeutic agents are available to treat or prevent tooth decay, but none, with the exception of fluoride, has significantly influenced the disease’s global burden. Moreover, the probable development of resistance of microorganisms to existing antibacterial agents and the scarcity of good antimicrobial agents motivates this effort for innovation. The detailed knowledge obtained in recent years on the S. mutans allowed the identification of potential targets in this microorganism, enabling the development of specific drugs to combat tooth decay. Thus, the identification of potential targets in these pathogens is the first step in the discovery process of new therapeutic agents. Currently, the experimental assays used for this purpose are expensive and time consuming. In contrast, bioinformatics methods to predict drug targets are cheap, quick and workaday in the biotechnology. This article will review the potential drug targets in S. mutans, as well as the bioinformatics methods used to identify these targets and effective drugs for specific pharmacological treatment of dental caries.

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).