RESUMO

The urgent need for a simple and cost-effective thermochemical process to produce biochar has prompted this study. The aim was to develop a straightforward thermochemical process under O2-limited conditions for the production of coconut-based biochar (CBB) and to assess its ability to remove methylene blue (MB) through adsorption, comparing it with CBB produced by slow pyrolysis. CBBs were obtained under different atmospheric conditions (O2-limited, muffle furnace biochar (MFB); and inert, pyrolytic reactor biochar (PRB)), at 350, 500, and 700 °C, and for 30 and 90'. MFB and PRB were characterized using FTIR, RAMAN, SEM, EDS, and XRD analyses. Adsorption tests were conducted using 1.0 g L-1 of MFB and PRB, 10 mg L-1 of MB at 25 °C for 48 h. Characterization revealed that atmospheric conditions significantly influenced the yield and structural features of the materials. PRB exhibited higher yields and larger cavities than MFB, but quite similar spectral features. Adsorption tests indicated that MFB and PRB had qt values of 33.1 and 9.2 mg g-1, respectively, which were obtained at 700 °C and 90', and 700 °C and 30', respectively. This alternative method produced an innovative and promising lignocellulose-based material with great potential to be used as a biosorbent.

Assuntos

Carvão Vegetal , Cocos , Lignina , Cocos/química , Carvão Vegetal/química , Lignina/química , Adsorção , Azul de Metileno/química , Temperatura

RESUMO

Catalytic biomass pyrolysis is one of the most promising routes for obtaining bio-sustainable products that replace petroleum derivatives. This study evaluates the production of aromatic compounds (benzene, toluene, and xylene (BTX)) from the catalytic pyrolysis of lignocellulosic biomass (Pinus radiata (PR) and Eucalyptus globulus (EG)). Chilean natural zeolite (NZ) was used as a catalyst for pyrolysis reactions, which was modified by double ion exchange (H2NZ) and transition metals impregnation (Cu5H2NZ and Ni5H2NZ). The catalysts were characterized by nitrogen adsorption, X-ray diffraction (XRD), ammonium programmed desorption (TPD-NH3), and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS). Analytical pyrolysis coupled with gas chromatography/mass spectrometry (Py-GC/MS) allowed us to study the influence of natural and modified zeolite catalysts on BTX production. XRD analysis confirmed the presence of metal oxides (CuO and NiO) in the zeolite framework, and SEM-EDS confirmed successful metal impregnation (6.20% for Cu5H2NZ and 6.97% for Ni5H2NZ). Py-GC/MS revealed a reduction in oxygenated compounds such as esters, ketones, and phenols, along with an increase in aromatic compounds in PR from 2.92% w/w (without catalyst) to 20.89% w/w with Ni5H2NZ at a biomass/catalyst ratio of 1/5, and in EG from 2.69% w/w (without catalyst) to 30.53% w/w with Ni5H2NZ at a biomass/catalyst ratio of 1/2.5. These increases can be attributed to acidic sites within the catalyst pores or on their surface, facilitating deoxygenation reactions such as dehydration, decarboxylation, decarbonylation, aldol condensation, and aromatization. Overall, this study demonstrated that the catalytic biomass pyrolysis process using Chilean natural zeolite modified with double ion exchange and impregnated with transition metals (Cu and Ni) could be highly advantageous for achieving significant conversion of oxygenated compounds into hydrocarbons and, consequently, improving the quality of the condensed pyrolysis vapors.

RESUMO

The methanation of CO2 is of great interest in power-to-gas systems and contributes to the mitigation of climate change through carbon dioxide capture and the subsequent production of high-added-value products. This study investigated CO2 methanation with three Ni catalysts supported on Al2O3 and ZrO2, which were simulated using a mathematical model of a packed bed reactor designed based on their chemical kinetics reported in the literature. The simulated reactive system was fed with syngas obtained from residual coffee pulp obtained after a solvent phytochemical extraction process under several gasification conditions. The results reflect a high degree of influence of the catalyst support, preparation method, and syngas composition on CO2 and H2 conversions and CH4 selectivity. For all the syngas compositions, the Ni/ZrO2 catalysts showed the best values for CO2 conversion and H2 conversion for the Ni/Al2O3 catalyst except in gasification at 700 °C and using the Ni/ZrO2p catalyst.

RESUMO

Theobroma cacao L. species, cultivated worldwide for its valuable beans, generates up to 72% weight of the fruit as waste. The lack of reutilization technologies in the cocoa agroindustry has hindered the exploitation of valuable bio-components applicable to the generation of high value added bioproducts. One such bioproduct is microfibrillated cellulose (MFC), a biopolymer that stands out for its desirable mechanical properties and biocompatibility in biomedical, packing, 3D printing, and construction applications. In this study, we isolated microfibrillated cellulose (MFC) from cocoa pod husk (CPH) via oxalic acid hydrolysis combined with a steam explosion. MFC isolation started with the Solid/Liquid extraction via Soxhlet, followed by mild citric acid hydrolysis, diluted alkaline hydrolysis, and bleaching pre-treatments. A Response Surface Methodology (RSM) was used to optimize the hydrolysis reaction at levels between 110 and 125 °C, 30-90 min at 5-10% (w/v) oxalic acid concentration. The cellulose-rich fraction was characterized by Fourier-Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) analyses. Characterization analyses revealed a cellulose-rich polymer with fibers ranging from 6 to 10 µm, a maximum thermal degradation temperature of 350 °C, and a crystallinity index of 63.4% (peak height method) and 29.0% (amorphous subtraction method). The optimized hydrolysis conditions were 125 °C, 30 min, at 5% w/v oxalic acid: with a 75.7% yield. These results compare with MFC obtained through highly concentrated inorganic acid hydrolysis from different biomass sources. Thus, we show a reliable and greener alternative chemical treatment for the obtention of MFC.

RESUMO

The growing interest in plant-based food protein sources has provided opportunities for the valorization of agri-food by-products, driving the food industry towards more sustainable development. In this study, three extraction procedures (varying the pH value (7.0 and 11.0) and the addition of salt (0 and 5%)) were investigated to obtain seven different protein fractions (SIPF) from Sacha Inchi oil press-cake (SIPC), which were characterized in terms of their protein content, electrophoretic profile, secondary structure, and techno-functional properties. Extractions at pH 11.0 without salt addition produced the highest values of protein content, extraction yield, protein recovery, and protein concentration increase (84.0%, 24.7%, 36.5%, and 1.5-fold, respectively). Under these extraction conditions, the electrophoretic analysis indicated that most of the SIPC proteins were extracted. SIPF displayed an excellent oil absorption capacity (4.3-9.0 w/w), and interesting foam activity (36.4-133.3%). The solubility and emulsifying activity of the albumin fractions were significantly higher than those of the other fractions (~87 vs. <15.8%, and 280-370 vs. <140 m2/g, respectively). Correlation analysis showed that the secondary structure of the SIPF significantly influences their techno-functional properties. These results indicate that SIPC is a by-product of great potential for protein extraction processes, and as a valorization strategy for technical cycle solutions for the Sacha Inchi productive chain in the circular economy context.

RESUMO

This work aimed to develop a phosphorous-based biorefinery process for obtaining phosphorylated lignocellulosic fractions in a one-pot protocol from coconut fiber. Natural coconut fiber (NCF) was mixed with 85 % m/m H3PO4 at 70 °C for 1 h to yield the modified coconut fiber (MCF), aqueous phase (AP), and coconut fiber lignin (CFL). MCF was characterized by its TAPPI, FTIR, SEM, EDX, TGA, WCA, and P content. AP was characterized regarding its pH, conductivity, glucose, furfural, HMF, total sugars and ASL contents. CFL structure was evaluated by FTIR, 1H, 31P and 1H-13C HSQC NMR, TGA and P content and was compared to that of milled wood lignin (MWL). It was observed that MCF and CFL were phosphorylated during the pulping (0.54 and 0.23 % wt., respectively), while AP has shown high sugar levels, low inhibitor content, and some remaining phosphorous. The phosphorylation of MCF and CFL also showed an enhancement of their thermal and thermo-oxidative properties. The results show that a platform of functional materials such as biosorbents, biofuels, flame retardants, and biocomposites can be created through an eco-friendly, simple, fast, and novel biorefinery process.

Assuntos

Cocos , Lignina , Lignina/química , Açúcares , Glucose , Biomassa

RESUMO

Solar driven semiconductor-based photoreforming of biomass derivatives, such as glycerol is a sustainable alternative towards green hydrogen evolution concerted with production of chemical feedstocks. In this work, we have investigated the influence of the pH of the hydrothermal treatment on the efficiency of Bi2WO6 as photocatalyst in the glycerol photoreforming. Bi2WO6 is pointed as a promising material for this application due its adequate band gap and the ability to promote hole transfer directly to glycerol without formation of non-selective ⋅OH radicals. Samples prepared at neutral to moderate alkaline conditions (pH = 7-9) are highly crystalline, while those prepared in acidic media (pH = 0-2) exhibit higher concentrations of oxygen vacancies. At pH = 13, the non-stoichiometric Bi(III)-rich phase Bi3.84W0.16O6.24 is formed. All samples were fully characterized towards their optical and morphological properties. UV-Vis irradiation of the photocatalysts modified with 1% m/m Pt and in the presence of 5% v/v aqueous glycerol solution leads to H2 evolution and glycerol oxidation. The sample prepared at pH = 0 exhibited the highest photonic efficiency (ξ) for H2 evolution (1.4 ± 0.1%) among the investigated samples with 99% selectivity for simultaneous formic acid formation. Similar performance was observed for the non-stoichiometric Bi3.84W0.16O6.24 sample (ξ = 1.2 ± 0.1% and 88% selectivity for formic acid), whereas the more crystalline sample prepared at pH = 9 was less active (ξ = 0.9 ± 0.1%) and leads to multiple oxidation products. The different behaviors were rationalized based on the role of oxygen vacancies as active adsorption and redox sites at the semiconductor surface, stablishing clear relationships between the semiconductor structure and its photocatalytic performance. The present work contributes for the rational development of specific photocatalysts for glycerol photoreforming.

Assuntos

Glicerol , Processos Fotoquímicos , Catálise , Formiatos , Glicerol/química , Concentração de Íons de Hidrogênio , Oxigênio/química

RESUMO

Water management and treatment are high concern fields with several challenges due to increasing pollutants produced by human activity. It is imperative to find integral solutions and strategic measures with robust remediation. Landfill leachate production is a high concern emerging problem. Especially in low middle-income countries due to no proper local waste disposition regulation and non-engineered implemented methods to dispose of urban waste. These landfills can accumulate electronic waste and release heavy metals during the degradation process. Similar phenomena include expired pharmaceuticals like antibiotics. All these pollutants accumulated in leachate made it hard to dispose of or treat. Leachate produced in non-engineered landfills can permeate soils and reach groundwater, dragging different contaminants, including antibiotics and heavy metals, which eventually can affect the environment, changing soil properties and affecting wildlife. The presence of antibiotics in the environment is a problem with particular interest to solve, mainly to avoid the development of antibiotic-resistant microorganisms, which represent a future risk for human health with possible epidemic implications. It has been reported that the use of contaminated water with heavy metals to produce and grow vegetables is a risk for consumers, heavy metals effects in humans can include carcinogenic induction. This work explores the opportunities to use leachate as a source of nutrients to grow microalgae. Microalgae stand out as an alternative to bioremediate leachate, at the same time, microalgae produce high-value compounds that can be used in bioplastic, biofuels, and other industrial applications.

Assuntos

Metais Pesados , Microalgas , Eliminação de Resíduos , Poluentes Químicos da Água , Poluentes da Água , Antibacterianos/metabolismo , Biodegradação Ambiental , Humanos , Metais Pesados/análise , Microalgas/metabolismo , Solo , Instalações de Eliminação de Resíduos , Poluentes da Água/metabolismo , Poluentes Químicos da Água/análise

RESUMO

To better understand the production of enzymes of industrial interest from microorganisms with biotechnological potential using lignocellulosic biomass, we evaluated the production of endoglucanase and xylanase from Aspergillus tamarii. CAZymes domains were evaluated in the genome, and a screening of the enzymatic potential of A. tamarii in various agricultural biomasses was done. The enzymatic profile could be associated with the biomass complexity, with increased biomass recalcitrance yielding higher activity. A time-course profile defined 48 h of cultivation as the best period for cultivating A. tamarii in sugarcane bagasse reached 12.05 IU/mg for endoglucanase and 74.86 IU/mg for xylanase. Using 0.1% (w/v) tryptone as the only nitrogen source and 12 µmol/L CuSO4 addition had an overall positive effect on the enzymatic activity and protein production. A 22 factorial central composite design was used then to investigate the simultaneous influence of tryptone and CuSO4 on enzyme activity. Tryptone strongly affected enzymatic activity, decreasing endoglucanase activity but increasing xylanase activity. CuSO4 supplementation was advantageous for endoglucanases, increasing their activity, and it had a negative effect on xylanases. But overall, the experimental design increased the enzymatic activity of all biomasses used. For the clean cotton residue, the experimental design was able to reach the highest enzyme activity for endoglucanase and xylanase, with 1.195 IU/mL and 6.353 IU/mL, respectively. More experimental studies are required to investigate how the biomass induction effect impacts enzyme production.

Assuntos

Celulase , Saccharum , Aspergillus , Biomassa , Celulose/metabolismo , Endo-1,4-beta-Xilanases/genética , Hidrólise , Lignina , Nitrogênio/metabolismo , Saccharum/química , Saccharum/metabolismo

RESUMO

Since 2014, Mexican Caribbean coasts have experienced an atypical massive arrival of pelagic Sargassum accumulated on the shores triggers economic losses, public health problems, and ecosystem damaging near the coastline. Mechanical harvesting has been implemented ending in landfills. Since Sargassum algae represent abundant biomass in tropical regions of the world, it has shown potential as a feedstock to supply bioprocesses focused on obtaining high-value compounds and bioproducts. Nevertheless, there is a lack of data on the biochemical composition of Sargassum biomass from Mexican Caribbean coasts to propose valorization pathways. This study conducted a biochemical and elemental characterization of Sargassum biomass and compared, through statistical analysis, the effect of the season (dry and wet), place of collection (from the beach and shallow water), and method of extraction (Microwave-Assisted Extraction and Enzyme Assisted Extraction) on biomass composition. The biomass composition, expressed in dry weight basis, revealed 5-7% moisture content, 24-31 % ash, 2.6-3.8 % lipids, 1.8-7.0 %, total carbohydrates, 3-11 % total proteins, 1.5-2.31 mgGAg-1 total phenolic compounds (TPC), 2.7-2.9 kcal g-1 calorific power, and metals such as As (30-146.3 ppm), Fe (16.5-45 ppm), P (197-472 ppm). The most influential factor on the compositional content of Sargassum biomass was the season of the year, followed by the extraction method and the place of collection of Sargassum. These results will elucidate information on the biotechnological potential of Sargassum biomass from the Mexican Caribbean, contributing to sustainability challenges of the region, minimizing waste, and making the most of resources.

Assuntos

Sargassum , Biomassa , Região do Caribe , Ecossistema , Estações do Ano

RESUMO

As a consequence of intense industrialization in the last few decades, the amount of agro-industrial wastes has increasing, where new forms of valorization are crucial. In this work, five residual biomasses from Maranhão (Brazil) were investigated as supports for immobilization of lipase from Thermomyces lanuginosus (TLL). The new biocatalysts BM-TLL (babaçu mesocarp) and RH-TLL (rice husk) showed immobilization efficiencies >98% and hydrolytic activities of 5.331 U g-1 and 4.608 U g-1, respectively, against 142 U g-1 by Lipozyme® TL IM. High esterification activities were also found, with 141.4 U g-1 and 396.4 U g-1 from BM-TLL and RH-TLL, respectively, against 113.5 U g-1 by TL IM. Results of porosimetry, SEM, and BET demonstrated BM and RH supports are mesoporous materials with large hydrophobic area, allowing a mixture of hydrophobic adsorption and confinement, resulting in hyperactivation of TLL. These biocatalysts were applied in the production of hexyl laurate, where RH-TLL was able to generate 94% conversion in 4 h. Desorption with Triton X-100 and NaCl confirmed that new biocatalysts were more efficient with 5 times less protein than commercial TL IM. All results demonstrated that residual biomass was able to produce robust and stable biocatalysts containing immobilized TLL with better results than commercial preparations.

Assuntos

Enzimas Imobilizadas/química , Eurotiales/enzimologia , Proteínas Fúngicas/química , Resíduos Industriais , Ácidos Láuricos/química , Lipase/química , Adsorção , Agricultura/métodos , Algoritmos , Biocatálise , Brasil , Enzimas Imobilizadas/metabolismo , Esterificação , Proteínas Fúngicas/metabolismo , Hidrólise , Interações Hidrofóbicas e Hidrofílicas , Ácidos Láuricos/síntese química , Ácidos Láuricos/metabolismo , Lignina/química , Lignina/metabolismo , Lignina/ultraestrutura , Lipase/metabolismo , Microscopia Eletrônica de Varredura , Modelos Químicos

RESUMO

In this work, ultrasound was applied for the conversion of tannic acid into gallic acid using only diluted H2O2 as reagent. Experiments were carried out using several types of ultrasonic horns operating at 20 kHz (VC750W processor). The following experimental conditions were evaluated: H2O2 concentration (0.2 to 8.5 mol L-1), horn type (10 to 25 mm of diameter), ultrasound amplitude (20 to 70%), sonication time (10 to 45 min), tannic acid concentration (170 to 1360 mg L-1), and reaction temperature (50 to 90 °C). Gallic acid production was monitored with ultra-performance liquid chromatography with high-resolution time-of-flight mass spectrometry (UPLC-ToF-MS). The isolated gallic acid was confirmed with nuclear magnetic resonance (1H and 13C NMR). It is important to emphasize that this study was developed as a proof of concept to demonstrate the potential of ultrasound for tannic acid conversion into gallic acid using just diluted H2O2. Under selected conditions gallic acid production yield was 128 ± 4 mg g-1 of initial tannic acid (using 170 mg L-1 of tannic acid as starting material). Reaction time was set as 30 min, which was carried out using 1 mol L-1 H2O2 and ultrasound amplitude of 50% at 90 °C. At silent conditions (mechanical stirring, from 100 to 1000 rpm), gallic acid production was halved (less than 78 ± 4 mg g-1 of initial tannic acid).

RESUMO

Wheat is one of the most important crops worldwide. Mexicali, Baja California, is an important wheat producer in Mexico with an average production of 507,543 t. Wheat straw is generated as a residue which could be used for different purposes such as bioenergy, heat and power generation. In this work, an assessment and potential site determination of a biomass power plant operating with wheat straw as fuel was performed. Aspen Plus was used to evaluate a plant capacity of at least 10 MW considering the physicochemical properties and an higher heating value of 14.86 MJ kg-1 of the wheat straw from the region. The combustion produced 39.76 MW, and the overall plant efficiency was 25.52%. The development of the multi-criteria geographic information system model allowed us to assess and analyse four factors and three restrictions to determine the potential site for the biomass power plant. The factors were raw material, wheat crops, electric transmission lines, paths and roads, water canals and aqueducts, while the restrictions were localities, Ramsar sites and faults. The biomass power plant is technically and geographically feasible. The geographical coordinates of the potential site of the biomass power plant that fulfils all the criteria are 32°29'29.72″N and 115°15'39.45″W.

Assuntos

Sistemas de Informação Geográfica , Triticum , Biomassa , México , Centrais Elétricas

RESUMO

Activated biocarbons were prepared using biomass wastes: sugarcane bagasse, coconut shell and endocarp of babassu coconut; as a renewable source of low-cost raw materials and without prior treatments. These activated biocarbons were characterized by textural analysis, solid-state 13C nuclear magnetic resonance spectroscopy, X-ray diffraction and scanning electronic microscopy. Textural analysis results revealed that those activated biocarbons were microporous, with specific surface area values of 547, 991 and 1,068 m2 g-1 from sugarcane bagasse, coconut shell and endocarp of babassu coconut, respectively. The innovation of this work was to evaluate which biomass residue was able to offer the best performance in removing 2,4-dichlorophenoxyacetic acid herbicide (2,4-D) from water by adsorption. Adsorption process of 2,4-D was investigated and the Langmuir and Redlich-Peterson models described best the adsorption process, with R2 values within 0.96-0.99. The 2,4-D removal performance were 97% and 99% for the coconut and babassu biocarbons, respectively. qM parameter values obtained from Langmuir model were 153.9, 233.0 and 235.5 mg g-1 using sugarcane bagasse, coconut shell and endocarp of babassu, respectively. In addition, the adsorption kinetics were described nicely by the second-order model and the Gibbs free energy parameter values were negative, pointing to a spontaneous adsorption, as well.

Assuntos

Ácido 2,4-Diclorofenoxiacético/isolamento & purificação , Resíduos Industriais , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Ácido 2,4-Diclorofenoxiacético/química , Adsorção , Agricultura , Biomassa , Celulose/química , Cocos/química , Herbicidas/química , Herbicidas/isolamento & purificação , Concentração de Íons de Hidrogênio , Cinética , Espectroscopia de Ressonância Magnética , Microscopia Eletrônica de Varredura , Saccharum/química , Termodinâmica , Poluentes Químicos da Água/química , Difração de Raios X

RESUMO

Pressed palm oil mesocarp fibers (PPOMF) are by-products from oil palm industry and represents a potential source of lignocellulosic biomass. In order to add value to this agro-waste, dewaxed palm oil acetosolv lignin (DPOAL) was extracted under eco-friendly pulping method. The chemical composition and structural characteristics of DPOAL were investigated. The results showed elevated yield (48.5%) and high purity (94.3%), besides a moderate average molecular weight (1394 g mol-1) and narrow polydispersity index (1.88). Structural characterization via FT-IR, 1H13C HSQC and 31P NMR indicated that DPOAL was a typical HGS-type lignin. In addition, to increase the phenolic hydroxyl contents and improve DPOAL's antioxidant properties through a simple method, a fractionation process with methanol, ethanol and acetone was carried out, obtaining the methanol (MeOH-F), ethanol (EtOH-F) and acetone (ACT-F) soluble fractions. These were characterized by FT-IR, DSC, 1H13C HSQC and 31P NMR, which showed higher values of phenolic and aliphatic hydroxyls groups compared to DPOAL. The antioxidant activity was evaluated by the free radical scavenging activity of 2,2­diphenyl­1­picrylhydrazyl radicals (DPPH·) and compared with commercial antioxidants, such as BHT and Irganox 1010. Interestingly, lignin samples had significantly lower IC50 values compared to commercial antioxidants, what suggests a great potential as novel natural antioxidant.

Assuntos

Antioxidantes/química , Antioxidantes/farmacologia , Lignina/química , Lignina/farmacologia , Óleo de Palmeira/química , Solventes/química , Concentração Inibidora 50

RESUMO

Sugarcane bagasse and hydroponic lettuce roots were used as biosorbents for the removal of Cu(II), Fe(II), Mn(II), and Zn(II) from multielemental solutions and lake water, in batch processes. These biomasses were studied in natura (lettuce roots, NLR, and sugarcane bagasse, NSB) and chemically modified with HNO3 (lettuce roots, MLR, and sugarcane bagasse, MSB). The results showed higher adsorption efficiency for MSB and either NLR or MLR. The maximum adsorption capacities (qmax) in multielemental solution for Cu(II), Fe(II), Mn(II), and Zn(II) were 35.86, 31.42, 3.33, and 24.07 mg/g for NLR; 25.36, 27.95, 14.06, and 6.43 mg/g for MLR; 0.92, 3.94, 0.03, and 0.18 mg/g for NSB; and 54.11, 6.52, 16.7, and 1.26 mg/g for MSB, respectively. The kinetic studies with chemically modified biomasses indicated that sorption was achieved in the first 5 min and reached equilibrium around 30 min. Sorption of Cu(II), Fe(II), Mn(II), and Zn(II) in lake water by chemically modified biomasses was 24.31, 14.50, 8.03, and 8.21 mg/g by MLR, and 13.15, 10.50, 6.10, and 5.14 mg/g by MSB, respectively. These biosorbents are promising and low costs agricultural residues, and as for lettuce roots, these showed great potential even with no chemical modification.

Assuntos

Celulose , Lactuca , Metais Pesados/química , Raízes de Plantas , Saccharum , Resíduos Sólidos , Purificação da Água/métodos , Adsorção , Agricultura , Biomassa , Recuperação e Remediação Ambiental/métodos , Concentração de Íons de Hidrogênio , Resíduos Industriais , Íons/química , Cinética , Lagos , Água , Poluentes Químicos da Água/química

RESUMO

Sugarcane bagasse and hydroponic lettuce roots were used as biosorbents for Cu(II), Fe(II), Zn(II), and Mn(II) removal from monoelemental solutions in aqueous medium, at pH 5.5, using batch procedures. These biomasses were studied in natura (lettuce roots, NLR, and sugarcane bagasse, NSB) and modified with HNO3 (lettuce roots, MLR, and sugarcane bagasse, MSB). Langmuir, Freundlich, and Dubinin-Radushkevich non-linear isotherm models were used to evaluate the data from the metal ion adsorption assessment. The maximum adsorption capacities (qmax) in monoelemental solution, calculated using the Langmuir isothermal model for Cu(II), Fe(II), Zn(II), and Mn(II), were respectively 24.61, 2.64, 23.04, and 5.92 mg/g for NLR; 2.29, 16.89, 1.97, and 2.88 mg/g for MLR; 0.81, 0.06, 0.83, and 0.46 mg/g for NSB; and 1.35, 2.89, 20.76, and 1.56 mg/g for MSB. The Freundlich n parameter indicated that the adsorption process was favorable for Cu(II) uptake by NLR; Fe(II) retention by MLR and MSB; and Zn(II) sorption by NSB, MLR, and NSB and favorable for all biomasses in the accumulation of Mn(II). The Dubinin-Radushkevich isotherm was applied to estimate the energy (E) and type of adsorption process involved, which was found to be a physical one between analytes and adsorbents. Organic groups such as O-H, C-O-C, CH, and C=O were found in the characterization of the biomass by FTIR. In the determination of the biomass surface charges by using blue methylene and red amaranth dyes, there was a predominance of negative charges.

Assuntos

Celulose , Lactuca , Metais Pesados/química , Raízes de Plantas , Saccharum , Resíduos Sólidos , Purificação da Água/métodos , Adsorção , Agricultura , Biomassa , Compostos Ferrosos/química , Concentração de Íons de Hidrogênio , Resíduos Industriais , Íons/química , Ferro/química , Cinética , Manganês/química , Caules de Planta/química , Água/química , Poluentes Químicos da Água/química , Zinco/química

RESUMO

Recently, supercritical fluid extraction (SFE) has been indicated to be utilized as part of a biorefinery, rather than as a stand-alone technology, since besides extracting added value compounds selectively it has been shown to have a positive effect on the downstream processing of biomass. To this extent, this work evaluates economically the encouraging experimental results regarding the use of SFE during annatto seeds valorization. Additionally, other features were discussed such as the benefits of enhancing the bioactive compounds concentration through physical processes and of integrating the proposed annatto seeds biorefinery to a hypothetical sugarcane biorefinery, which produces its essential inputs, e.g., CO2, ethanol, heat and electricity. For this, first, different configurations were modeled and simulated using the commercial simulator Aspen Plus® to determine the mass and energy balances. Next, each configuration was economically assessed using MATLAB. SFE proved to be decisive to the economic feasibility of the proposed annatto seeds-sugarcane biorefinery concept. SFE pretreatment associated with sequential fine particles separation process enabled higher bixin-rich extract production using low-pressure solvent extraction method employing ethanol, meanwhile tocotrienols-rich extract is obtained as a first product. Nevertheless, the economic evaluation showed that increasing tocotrienols-rich extract production has a more pronounced positive impact on the economic viability of the concept.