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This study evaluated the effects of the temperature and pressure used when compacting banana leaves on viscoelastic properties and briquette quality. Banana leaves with 12.4% of humidity were milled at two ranges of average particle size. The briquetting was carried out in a cylinder-piston device coupled to a universal mechanical test machine, under different compacting temperatures (30 and 120 °C) and pressures (20, 40 and 60 MPa). Several parameters, including compacting module, porosity index, final density, critical density, compacting energy, compression ratio, higher heating value, and energy density, were investigated. The banana leaf particles smaller than 1.7 mm performed better during compaction, with low compacting resistance. Temperature showed less influence on final density than pressure. The increase of pressure contributed to decreasing the compacting module and to achieving denser briquettes. It was not necessary to apply high temperature to obtain briquettes with high final density and energy density. The optimum briquetting process parameters identified can be used to produce briquettes from banana leaves at an industrial scale with an extruder. Briquetting adds value to banana leaf waste and reduces environmental pollution.

Catole coconut (Syagrus cearensis) is produced in abundance in the Northeastern region of Brazil, but still remains relatively unexploited for bioenergy purposes because of the little relevant scientific information available. In this context, this study aims to investigate the kinetics and thermodynamics that describe the pyrolysis of catole coconut through a multi-component approach, aiming to highlight its bioenergy potential. Thermogravimetric analysis of catole coconut was performed in an inert atmosphere with different heating programs (10, 20 and 30 °C min−1) to establish its pyrolysis behavior. The resulting pyrolysis behavior was subjected to deconvolution by the symmetrical Gaussian function to specify three independent components: pseudo-hemicellulose, pseudo-cellulose, and pseudo-lignin. By using four isoconversional methods, the average activation energy estimated is in the range of 124.2–133.5 kJ mol−1 for pseudo−hemicellulose, 159.7–170.1 kJ mol−1 for pseudo−cellulose, and 151.5–162.8 kJ mol−1 for pseudo−lignin. Based on the kinetic compensation effect, the pre-exponential factors were determined to be in the range of 3.5 × 1011–5.4 × 1014 min−1. Statistical results (R2>0.954 and Fit>0.944) indicate that the proposed summative kinetic expression proved to be valuable in reproducing the experimental pyrolysis behavior. The promising findings acquired from this study justify the interest in exploring catole coconut as a new bioenergy feedstock.

The influence of the multi-component composition of cotton and polyester dyeing baths was investigated in a DCMD process using a PTFE membrane, aiming to water reclamation from textile wastewater. The process was evaluated with each auxiliary, solutions combining auxiliary and dye, and residual water from pilot-scale dyeing baths. The salts used in the cotton dyeing bath did not influence the DCMD process, resulting in a similar rejection rate and permeate flux to those in dye solutions. The formic acid employed in the polyester dyeing bath resulted in high permeate fluxes but decreased the permeate quality by almost 33%. The surfactants (detergent and dispersant) demonstrated the most harmful behavior in the process, evidenced by a complete membrane wetting. An absence of synergy of the dyes and auxiliaries influencing the DCMD process was verified for the textile dyeing wastewater. This work enabled identifying the influence of each dyeing bath component in the rejection rate and permeate flux, allowing to find alternatives in mitigating the remaining gaps involving DCMD operation and the MD membranes. This work contributes to consolidating this promising technique in water reclamation from textile wastewater, encouraging research on membrane development and modification or integrated operations involving MD.

An energy performance comparison between a novel thermosyphon-assisted falling film distillation unit and a conventional tray unit was carried out for three mixtures with different relative volatil...

This study analyzed the influence of operational conditions on the Direct Contact Membrane Distillation for synthetic effluents containing reactive and disperse dyes. Results of the permeate flux demonstrated different behavior of the process according to the class of dye. It was found a higher dependence of feed temperature to reactive dye and the analysis of temperature gradient between feed and permeate demonstrated the possibility of operation with higher temperatures in both streams to increase the permeate flux for both dyes. Feed flow rate influenced more the process with reactive dye, while the permeate flow rate determined this behavior for disperse dye. Energy factors showed that the gain output rate and energy efficiency enhanced with the increase of feed temperature, and the energy efficiency increased only with the permeate flow rate (and not with feed flow rate). The water distillation recovery rate was 97.3 % for reactive and 98.7 % for disperse dye; the color rejection of the dyes was over 98 %. These results indicated the adequate functionality of the process for water recovery of textile wastewater, providing an adequate permeate for possible reuse.

The present study attempts to explore the energy potential of smoked cigarette butts (SCB) through pyrolysis. For the first time, the pyrolysis characteristics, including the kinetic triplet and the thermodynamic parameters, were investigated using non-isothermal thermogravimetry. Firstly, three pseudo-components were successfully deconvoluted from the multiple-step pyrolysis of SCB using the asymmetrical Fraser-Suzuki function, which corresponds to the devolatilization reactions of retained organic volatile components (PS-1), unburned tobacco (PS-2), and cellulose acetate fibers (PS-3). Posteriorly, the isoconversional methods of Friedman, Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, and Starink were used to obtain the activation energy values, which were lower for PS-1 (from 101.87 to 108.77 kJ mol−1). The frequency factor values for SCB pyrolysis determined by the compensation effect method were 1.77 × 1012 min−1 for PS-1, 9.44 × 1016 min−1 for PS-2, and 9.62 × 1020 min−1 for PS-3. According to the master plot method, the three pseudo-components followed nth-order reaction models. An acceptable correspondence was observed between experimental and reconstructed pyrolysis behavior, proving the representativity and reliability of the obtained kinetic triplets. Both positive values of ΔH and ΔG suggest that the pyrolytic conversion of smoked cigarette butts into biofuels can be considered as a non-spontaneous conversion. These pyrolysis-related findings from SCB can be used to offer a good opportunity for its valorization as an energy commodity instead of a neglected solid residue.

This study presents the first attempt to focus on the cocoa shell pyrolysis in terms of kinetic triplet, thermodynamic parameters, and evolved volatile analysis using the TGA-FTIR technique. For reliable interpretation of the multistep pyrolysis of cocoa shell, the multiple kinetic triplets were adequately estimated by a combined kinetic procedure using five independent parallel reactions with the Vyazovkin isoconversional method, the compensation effect, and the master plot method. According to the results, the multiple kinetic triplets were able to describe the pyrolysis behavior of the cocoa shell with an accuracy of R2 > 0.9446 and the pyrolysis mechanisms exhibited different reaction models (n-order and contracting cylinder). Evolved volatile analysis suggested the presence of high-energy compounds (aromatic) and useful chemicals (aldehyde, ketone, esters, ether, and alcohols). The pre-exponential factors for the five pseudo-components of cocoa shell pyrolysis ranged from 2.56 × 1011 to 8.66 × 1016 min−1 (derived from the compensation effect method), while the values of Ea ranged from 99 to 271 kJ mol−1. From a comparative analysis, it was found that the results from the compensation effect method ensured the overall kinetic expression to be consistent with the experimental cocoa shell pyrolysis behavior. In contrast, the overall kinetic expression using pre-exponential factors derived from Kissinger’s method failed to match the experimental curves. The pyrolytic conversion of cocoa shell into bioenergy appeared as potentially viable (Ea – ΔH ≤ 5.5 kJ mol−1). The promising findings on the cocoa shell pyrolysis can expand the use of this residue in bioenergy applications, consisting of a great attempt toward its valorization.

Around 2.96 million tons of potential feedstocks are generated annually in the form of jackfruit waste, including peels (JP) and seeds (JS). This study assessed the suitability of JP and JS as new feedstocks for combustion and their preliminary potential for bioenergy considering their physicochemical properties, bioenergy indicators, combustion behaviors and emission characteristics. The jackfruit wastes presented attractive features for direct application in combustion, such as their composition of 75.1–81.3 wt.% of volatile solids, 40.8–41.8 wt.% carbon content, a higher heating value of 16.3–17.2 MJ kg−1, and negligible amounts of nitrogen and sulfur. Their ash contents varied from 5.6 wt.% to 6.7 wt.%, similar to that of other biomass fuels. The bioenergy yield obtained for JP and JS were 2.5 TJ ha−1 yr−1 and 0.9 TJ ha−1 yr−1 (dry basis), respectively, which exceed that of well-known bioenergy crops. The use of jackfruit residues as raw material for bioenergy can be highly feasible, given the low CO, CO2 and SO2 emissions, and a considerable equivalence with reference fuels. Combustion properties of JS and JP revealed a favorable burning performance. In conclusion, the highlights of this study provide useful information for the valorization and large-scale application of jackfruit wastes and contribute to their establishment as sustainable and renewable sources of bioenergy.

This paper aims to offer a new compact, safer, less energy-intensive technological alternative for ethanol-water separation, based on the intensified multi-tube falling film distillation technology. A pilot-scale investigation (with a processing capacity close to 250 kg h−1) proved the practical feasibility of a multi-tube falling film distillation column coupled with a biphasic thermosiphon for the distillation of ethanol and water in obtaining concentrated ethanol (64 wt.% - acceptable for medical applications) from aqueous ethanol (12 wt.%). Notable findings were achieved by using the intensified multi-tube falling film distillation to produce hydrated ethanol with adequate ethanol recovery (∼ 50 %), acceptable energy savings (∼ 15 %) and significant space savings (∼ 63 %) as compared with a conventional tray column, thus justifying its relevance for sugarcane ethanol distilleries. Finally, new research prospects for further improving the separation efficiency of this novel distillation concept are also mentioned in this study, purporting to make such novel intensified distillation process more competitive with conventional distillation columns in the future.

Clean thermochemical conversion of lignocellulosic residues is particularly interesting for both bioenergy production and environmental protection. For this reason, the novelty of this study is to present tamarind residues (husks and seeds) from the tamarind fruit processing industry as new prospective feedstocks for bioenergy production considering their physicochemical properties, combustion performance indexes, and emission patterns. Characterization results confirmed the suitability of tamarind residues as raw materials for combustion with considerable energy contents (~ 17.5 MJ kg−1), ash contents below 2.9 wt.%, and negligible sulfur (

Typical industrial technologies to produce tert-amyl methyl ether (TAME), a gasoline oxygenated additive, require some advanced purification process for methanol recovery from the reactor effluent, due to the presence of the iC5-methanol minimum boiling point azeotrope. Pressure-swing distillation (PSD) is widely used as an efficient method for separating pressure-sensitive azeotropic mixtures in industrial processes. However, it is well known that distillation units are responsible for the highest energy consumption in chemical separation facilities, reaching in some cases to 95% of the total energy cost. Thus, the objective of this work was to perform an optimization methodology of the main design and operational variables of the PSD process applied to the separation of the azeotropic iC5-methanol mixture, considering minimizing the objective function of total annual cost (TAC). For this purpose, Honeywell’s UniSim Design® Suite software was used to simulate the process flowchart and Matlab® was used to perform TAC optimization. The optimized PSD design revealed potential for saving of up to 12% per year in terms of TAC when compared to the non-optimized process, thus proving the feasibility of the optimization methodology for this specific process. Furthermore, it reinforces the main objective of the optimization technique that is to make chemical processes more economically competitive in the industrial sector.

The global interest in sustainable production of chemicals and materials from lignocellulosic biomass is boosted by the need of replacing fossil derivatives. Cellulose nanocrystals may prove to be one of the most promising green materials of modern times due to its intrinsic properties, renewability and abundance. The preliminary steps to obtain pure cellulose fibers are crucial and must be performed carefully. Several chlorine-free treatments have been developed in order to decrease the environment impact of the pulping process. Among all, traditional pulping with sodium hydroxide and hydrogen peroxide is still the most viable method for industries. Based on that, this work is dedicated to propose and optimize chlorine-free purification routes for isolating cellulose nanocrystals from rice husk agroindustrial waste. The novelty addressed here is the application of mild industrially viable process conditions to perform the chlorine-free purification routes, previously unexplored for rice husk as a source of lignocellulosic raw material. Two routes were performed, reducing lignin from 20 to 2.91% and 4.65%. The formation of cellulose nanocrystals was confirmed by the significant increase in crystallinity, ranging from 40.87% of rice husk, to 77.45% for the first route and 66.21% for the second rout, both being cellulose II. Thus, it has been shown the viability to obtain cellulose nanocrystals using a totally chlorine-free technique to extract and bleach cellulose from rice husk under mild process conditions, in order to add value to this residue reducing its volume and impact on the environment.

Monoethylene glycol (MEG) is a desiccant widely used in the Oil and Gas and Sugar Cane Alcohol industries and generates a large volume of MEG-water mixture effluent. This original study explores the use of a new pilot-scale distillation system for separating MEG from a MEG-water mixture. The distillation tests were performed with a single-tube falling film distillation column assisted by a thermosyphon system operating at atmospheric pressure (Destubcal Technology). The results attained high MEG contents, with a MEG loading of 66.00% (m/m), yielding a MEG separation of 88.61%. Additionally, a distillation arrangement with two single-tube falling film distillation columns in series was able to reach values of separation similar to those used by companies in the Oil and Gas sector, while operating at atmospheric pressure. It was also found that Destubcal Technology leads to a 46.93% reduction of the energy required and is more compact than a conventional-industrial distillation column.

A considerable increase in royal palm cultivation as a result of industrialization of canned heart of palm has generated large amounts of renewable lignocellulosic waste, but reuse is still rarely practiced. In this work, for the first time, cellulose nanocrystals (CNCs) were extracted from the leaf sheath discarded from the royal palm harvest. Chlorine-free purification methods were used and strong acid hydrolysis synthesis with different times and temperatures were performed. The purification treatments removed lignin successfully, reducing its content from 10.4% to 1.0%. The formation of spherical and rod-shaped CNCs reached yields between 7.9% and 48.8%, which was confirmed by a significant increase in crystallinity from 38.9% of natural fiber to 63.6% and 79.6% of CNCs, depending on temperature and synthesis duration. The production of CNCs from this underutilized waste has the potential to add value to royal palm tree crops, in addition to significantly reducing the volume of cumulative waste in the environment.

Biofuel produced from biomass is one of the main alternatives for reducing the use of fossil fuels. This work evaluates the ethanol production from different mixtures of banana waste (pseu...

Banana pseudostem is a potential source of lignocellulosic biomass for energy production. Ethanol production from this feedstock is characterized by pre-treatment, hydrolysis, fermentation and ethanol separation. When acid hydrolysis is carried out, a neutralizing step is necessary. This work aims to evaluate different neutralizing agents—barium carbonate, sodium hydroxide, calcium hydroxide, calcium sulfate, and sodium sulfate—and their effect on the ethanol recovery phase by pervaporation. Pervaporation experiments were conducted with a commercial flat-sheet polydimethylsiloxane membrane using a synthetic mixture of ethanol, water, and the residual neutralizing agent as feed. The experiments were compared to a standard solution (ethanol/water) to determine differences in the results due to the presence of neutralizing agents. Membrane swelling with different neutralizing agents was also assessed. Barium carbonate showed the highest potentiality of use in the neutralization process of the hydrolyzed broth of banana pseudostem since it presented the highest ethanol concentration in the permeate (17%) and an increase of approximately 15% of selectivity and 11% of enrichment factor. The results proved that acid hydrolyzed broth of banana pseudostem with the addition of barium carbonate as a neutralizing agent is a potential candidate for ethanol production using pervaporation.

This study investigated the performance of DCMD applied to wastewaters from different stages of the textile process in the same operating system for water reclamation in a single process. High fina...

Various fiber lengths of banana pseudo-stem bagasse (L = 3 and 15 cm) were dehydrated at various temperatures (T = 50 °C, 60 °C, and 70 °C) with and without forced air convection (Sair > 0). The experiments were conducted in a screened bottom tray equipped with a dryer with rising air flow. The effect of dehydrated fiber size (30 mesh, 3 cm, and 15 cm) on the saccharification of the biomass with subsequent alcoholic fermentation of the must was investigated using two different concentrations of reducing sugars (RS = 40 and 90 g/L). In the pretreatment by drying, the temperature (T) was the variable that showed the greatest effect on the productivity of the process (Qd), followed by fiber length (L) and T by L interaction. The use of dehydrated fibers in the form of bran (30 mesh granulometry) in the saccharification process provided the best theoretical average yield based on the stoichiometric conversion of cellulose and hemicellulose in RS (YRS = 37.87%). Fermentation of concentrated must by Saccharomyces cerevisiae up to RS = 90 g/L provided a yield (YP/RS) and productivity (QP) in ethanol of 0.48 g/g and 1.62 g/L/h, respectively. These values were significantly higher (p < 0.05) than those observed in the same fermentation type at RS = 40 g/L (YP/RS = 0.34 g/g, QP = 0.96 g/L/h).

We describe a new configuration for falling film distillation columns: a heating system provided by a vapor chamber along the entire column with the operation at atmospheric pressure. Experimental ...

Based on previous results and a new proposal for the configuration of falling film distillation columns heated by a vapor chamber operating at atmospheric pressure, the present study analyzed a dif...

Engaged in the global trend towards more energy-efficient and sustainable technologies, our research team has developed a falling film distillation apparatus with an innovative heat supply through a two-phase closed thermosyphon. In order to evaluate the performance of this energy-intensified distillation process, a supervised machine learning (ML) predictive model based on artificial neural networks is implemented for the separation of the ethanol–water binary mixture. The feed temperature, the evaporator temperature, and the feed flow rate are the three input variables of the model, whereas the ethanol mass fraction in the distillate, the distillate mass flow rate, the recovery factor, and the separation factor are the four performance indicators evaluated. The feed-forward ML has been trained, tested, and validated using a total dataset of 64 experimental runs carried out in the pilot-scale unit, covering a wide operating range of the input variables. Despite the high non-linearity, the ML approach was capable of modeling this new process accurately. The optimal topology of the ML model was achieved with a network arrangement of 10 neurons within 1 hidden layer (3:10:4), with a correlation coefficient (R) greater than 0.95 for all data. The predictive abilities of the ML model were harnessed to investigate the individual and synergistic interaction effects of the operating variables by plotting generalization graphs. Finally, the optimal operating conditions were evaluated by the genetic algorithm (GA) technique, being the feed temperature of 90.6 °C, the evaporator temperature of 109.6 °C, and the feed flow rate of 26.3 L/h, the process operating values that led the maximum of the four performance indicators, simultaneously. Under these operating conditions, a distillate mass flow rate of 4.9 kg/h, with 50.6%wt ethanol-enriched, a recovery factor of 84.9%, and a separation factor of 57.4 have been achieved, showing the high-performance feasibility of the pilot-scale unit.

Techniques using membranes for the treatment of wastewaters usually promote higher quality of treated water when compared to other processes. Among them, pervaporation has advantages in terms of selectivity in addition to low working pressure, which can prevent clogging problems. Polysulfone and polyurethane have complementary characteristics and are interesting in the context of membranes for industrial applications. In this sense, the aim of this work was to prepare and characterize polysulfone/polyurethane-based membranes and tested them with a simulated wastewater containing the reactive black dye and sodium chloride by pervaporation. In their manufacture, thermal treatment (at 60°C) and photo-radiation treatment (using ultraviolet light) were also applied. The characterizations were performed using different analytical tools. In general, it was possible to verify that all membranes have a dense layer. The thermal analysis allowed to define that the indicated working temperature is below 50°C. With respect to the simulated wastewater treatment, all membranes reached 100% selectivity. Concerning the saline solution, the mean selectivity was around 98.5%. Moreover, the permeate flow values were within the range presented by commercial membranes ranging from 1.6 to 2.4 kg m

The manufacturing of electrospun mats from preceramic polymers is complex due to low and disperse molecular chain entanglements and a large number of operating parameters. Here, the electrospinning of polysilazane and polysilazane/polyacrylonitrile (PAN) solutions was evaluated and optimized. The reduction in Berry's number from 94 to 22 indicated the positive effect of adding organic polymer on the polysilazane chains to obtain homogeneous fibers. A fractional factorial design was first implemented to screen out the three most significant factors affecting the fiber diameter. Then, a response surface model was developed using the Box-Behnken design to obtain a quantitative relationship between operating parameters and fiber diameter. Finally, the models were used to find the optimal conditions that yield the thinnest fiber. For polysilazane, the feed rate showed a positive effect, while for polysilazane/PAN an interaction between the feed rate and the tip-to-collector-distance was the most significant factor, with a positive effect. The verification of the models was accomplished through model validation. The addition of PAN to polysilazane reduced fiber diameter from 1.79 ± 0.26 μm to 0.57 ± 0.04 μm. The polysilazane/PAN pyrolyzed at 1000°C (SiCN_PAN) could shield more than 50% of electromagnetic energy from 100 MHz to 4.5 GHz. In addition to the presence of carbon-rich regions derived from PAN, thinner diameters caused an increase of interfaces between the voids and electrospun fibers, which intensified multi-reflection for dissipating electromagnetic energy. Owing to the optimized design, the SiCN_PAN fibers with satisfying electromagnetic shielding properties could meet advanced requirements of lightweight hybrid materials from aerospace to defense applications.