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Waste valorization is an essential aspect of sustainable development. From this perspective, co-hydrothermal carbonization (Co-HTC) is a promising thermochemical process for converting organic waste into hydrochar. Hydrochar is a solid material whose physicochemical properties could make it suitable for adsorbing pollutants such as heavy metals. Accordingly, this work evaluated the hydrochar from Co-HTC of sawdust and non-dewatered sewage sludge as a potential adsorbent of heavy metals at low concentrations. In the context of sustainable drainage systems (SuDS), it is notable that heavy metals are present at very low but still potentially harmful concentrations, which presents a potential opportunity for the application of hydrochar. Thus, three hydrochars (H-180, H-215, and H-250), produced by Co-HTC at 180, 215, and 250 °C, were tested herein for their ability to retain lead (Pb2+). The H-180 presented better performance than other hydrochars (H-215 and H-250), suggesting that chemisorption could be the main adsorption mechanism. Interestingly, the presence of other cationic heavy metals (Cu2+, Zn2+, Cd2+, Cr6+, and Ni2+) did not hinder the Pb2+ adsorption, for which the removal efficiency remained close to 100%. In fact, in such a multi-metal system, hydrochar can be suitable for capturing both lead and cadmium. Therefore, the hydrochar from Co-HTC of sawdust and non-dewatered sewage sludge can be useful for removing heavy metals at low concentrations, such as those found in urban runoff waters. Although further studies are required, these findings suggest hydrochar as a potential material for application in SuDS.

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This study aims to conduct an applied and innovative investigation to enhance the energy quality of wood residues through hydrothermal carbonization pretreatment. For this purpose, the treatment was carried out at three different temperatures: 180, 220, and 240 °C under autogenous pressure. The in natura material and the hydrochars were characterized, and thermogravimetric analyses were performed in an O2 atmosphere with heating rates of 2.5, 5, 10, and 20 °C min-1. The global activation energy for natura biomass combustion was determined to be 112.49 kJ.mol-1. On the other hand, the hydrothermal carbonization process promoted a reduction in this value for the 94.85 kJ.mol-1. The conversion function for the in natura biomass was characterized as 1 - α , order 1, while the hydrochars was 2(1-α) [-ln(1-α)] (1/2), Avrami-Erofe'ev I. Triple kinetic parameters were ascertained, and the conversion curves along with their respective derivatives were modeled, exhibiting minimal deviations between theoretical and experimental data. This facilitated the mathematical representation of the reaction processes and allowed for a comprehensive comparison of the results.

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The synthesis and characterization of a hydrochar/CeO2 composite along with its evaluation in methylene blue degradation under visible light are presented. The methodology consisted of a single-pass hydrothermal method, having as synthesis conditions 9 h of reaction time, 210 °C, autogenous pressure, and a biomass/CeO2 ratio of 100:1. The composite characterization revealed good dispersion of CeO2 in the carbonaceous matrix and significant synergy in the composite activation using visible irradiation. The photodegradation experiments showed an efficiency of 98% for white LED light, 91% for UV light, 96% for solar irradiation, and 85% for blue LED light using as conditions pH 7.0, 50 mg of composite, 50 mL of solution, 10 mg/L of dye initial concentration, and 120 min of contact time. Meanwhile, the reusability experiments evidenced a reuse capacity of up to five times with a constant photodegradation efficiency (99%); moreover, it was determined that the presence of electrolytes at pH below 7.0 during degradation negatively affected methylene blue degradation. Finally, the results of this work demonstrate that the hydrochar/CeO2 composite can be synthesized by a green method and used for the efficient treatment of water contaminated with methylene blue.

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This work studied the auxin-like activity of liquid and solid hydrochar from aboveground corn biomass prepared using hydrothermal carbonization (HTC). Understanding the action of organic compounds in regulating plant metabolism is important to develop strategies to improve plant growth and production. Bioassays were performed by testing liquid hydrochar concentrations in the range of 0.0557-5570.0 mg carbon L-1; and solid hydrochar (via extracted dissolved organic matter, DOM) in the range of 0.026-2600.0 mg carbon L-1, using seeds of Lactuca sativa. SEM, ATR-FTIR, and Py-GC/MS were applied to assess the effect of HTC on hydrochar production/composition. Liquid hydrochar presented an intense bioactivity, completely inhibiting the germination of testing seeds at higher concentrations. Liquid hydrochar also was considerably more bioactive. Py-GC/MS allowed the identification of the molecules involved in IAA-like effects: carboxylic acids (linear and aromatic) and amino acids. The concentration of more bioactive molecules, rather than their simple presence in the hydrochar fraction, determined the bio-stimulating effect, besides an excellent linear regression between the auxin-like effect and the concentration of active molecules.

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The generation of wastewater due to human activities are the main responsible for environmental problems. These problems are caused by the large amount of organic and inorganic pollutants related to the presence of pesticides, metals, pathogens, drugs and dyes. The photosynthetic treatment of effluents emerges as a sustainable and low-cost alternative for developing wastewater treatment systems based on a circular economy. Chemical compounds present in wastewater can be recovered and reused as a source of nutrients in microalgae cultivation to produce value-added bioproducts. The microalgal biomass produced in the cultivation with effluents has the potential to produce biochar. Biochar is carbon-rich charcoal that can be obtained by converting microalgae biomass through thermal decomposition of organic raw material under limited oxygen supply conditions. Pyrolysis, torrefaction, and hydrothermal carbonization are processes used for biochar synthesis. The application of microalgal biochar as an adsorbent material to remove several compounds present in effluents is an effective and fast treatment. This effectiveness is usually related to the unique physicochemical characteristics of the biochar, such as the presence of functional groups, ion exchange capacity, thermal stability, and high surface area, volume, and pore area. In addition, biochar can be reused in the adsorption process or applied in agriculture for soil correction. In this context, this review article describes the production, characterization, and use of microalgae biochar through a sustainable approach to wastewater treatment, emphasizing its potential in the circular economy. In addition, the article approaches the potential of microalgal biochar as an adsorbent material and its reuse after the adsorption of contaminants, as well as highlights the challenges and future perspectives on this topic.

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The development of industrial process in line with the circular economy and the environmental, social and corporate governance (ESG) is the foundation for sustainable economic development. Alternatives that make feasible the transformation of residues in added value products are promising and contribute to the repositioning of the industry towards sustainability, due to financial leverage obtained from lesser operational costs when compared with conventional processes, therefore increasing the company competitivity. In this study, it is presented a promising and innovative technology for the recycling of agro-industrial residues, the sugarcane bagasse and the high-pressure water boiler effluent, in the development of a low-cost adsorbent (HC-T) using the hydrothermal carbonization processes and its application in the adsorption of herbicide Diuron and Methylene Blue dye from synthetic contaminated water. The hydrothermal carbonization was performed in a Teflon contained inside a sealed stainless-steel reactor self-pressurized at 200°C, biomass-to-effluent (m/v) ratio of 1:3 and 24 h. The synthesized material (HC) was activated in an oven at 450°C for 10 min, thus being named adsorbent (HC-T) and characterized by textural, structural and spectroscopic analyses. The low-cost adsorbent HC-T presented an 11-time-fold increase in surface area and ∼40% increase in total pore volume in comparison with the HC material. The kinetic and isotherm adsorption experiment results highlighted that the HC-T was effective as a low-cost adsorbent for the removal of herbicide Diuron and Methylene Blue dye from synthetic contaminated waters, with an adsorption capacity of 35.07 (63.25% removal) and 307.09 mg g-1 (36,47% removal), respectively.

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Microbial resistance to drugs is a public health problem; therefore, there is a search for alternatives to replace conventional products with natural agents. One of the potential antimicrobial agents is wood vinegar derived from the carbonization of lignocellulosic raw materials. The objectives of the present work were to evaluate the antibacterial and antifungal action of two kinds of wood vinegar (WV), one of Eucalyptus urograndis wood and another of Bambusa vulgaris biomass, and determine their chemical profile. The antimicrobial effect was assessed against Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella enteritidis, Escherichia coli, Streptococcus agalactiae, and Candida albicans. The minimum inhibitory concentration and the minimum bactericidal and fungicidal concentrations were determined. Micrographs of the microorganisms before and after exposure to both kinds of wood vinegar were obtained by scanning electron microscopy. The chemical profile of the eucalyptus and bamboo vinegar was carried out by gas chromatography and mass spectrometry (GC/MS). Both types of WV presented significant antimicrobial activity, with the bamboo one having a higher efficiency. Both studied pyroligneous extracts seem promising for developing natural antimicrobials due to their efficiency against pathogens. GC/MS analyses demonstrated that the chemical profiles of both kinds of WV were similar but with some significant differences. The major component of the eucalyptus vinegar was furfural (17.2%), while the bamboo WV was phenol (15.3%). Several compounds in both WVs have proven antimicrobial activity, such as acetic acid, furfural, phenol, cresols, guaiacol, and xylenols. Together, they are the major in the chemical composition of the organic fraction of both WVs. Bamboo vinegar had a more expressive content of organic acids. Micrographs of microorganisms taken after exposure to both kinds of wood vinegar displayed several cell modifications. The potential of both types of wood vinegar as a basis for natural antimicrobial products seems feasible due to their proven effect on inhibiting the microorganisms' growth assessed in this experiment.

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A heteroscedastic regression based on the odd log-logistic Marshall-Olkin normal (OLLMON) distribution is defined by extending previous models. Some structural properties of this distribution are presented. The estimation of the parameters is addressed by maximum likelihood. For different parameter settings, sample sizes and some scenarios, various simulations investigate the performance of the heteroscedastic OLLMON regression. We use residual analysis to detect influential observations and to check the model assumptions. The new regression explains the mass loss of different wood species in civil construction in Brazil.

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Climate change is the world's greatest challenge today, the reason why it is urgent to optimize industrial processes and find new renewable energy sources. Hydrothermal carbonization (HTC) is one of the Waste-to-Energy technologies with greater projections due to its operative advantages. However, for its large-scale implementation, there are challenges related to the variability of the composition of the waste biomass and the seasonal and geographical availability. This research applied the Life Cycle Analysis methodology to evaluate the environmental impacts caused by three biomasses blends as raw material in the HTC process at laboratory scale. The blends analyzed considered different organic fractions of municipal solid waste (food and pruning) and sewage sludge. The results showed that blend 1 had a lower environmental impact for the case of production in the experimental laboratory level, compared with blends 2 and 3. This is mainly due to its greater calorific value and mass yield, which allows obtaining more hydrochar compared with the other blends, increasing the energy efficiency of the process. Also, between 87.94% and 98.00% of the energy reduction is required to obtain neutral impacts regarding the energy requirements in the experimental laboratory level scenario and the Chilean energy matrix. The processing of blends in HTC has excellent potential in a context where municipal solid wastes have been disposed in sanitary landfills or dumps, as in most emerging countries. Since this study incorporated data from the literature, future studies should perform an elemental analysis to provide experimental and differentiated data.

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This article presents a forensic case of an unusual illegal cremation of a person using a process colloquially known as the "microwave oven" practice in Brazil. The microwave process involves two actions: placing the victim in a tire stack and then setting the structure on fire using flammable substances to accelerate the progression. A similar practice, identified as "necklacing", has also been reported in other countries such as South Africa. This report presents a case of microwave oven cremation of a body found in a rural area of Minas Gerais, Brazil. The forensic work helped determine the biological profile and identity of the victim using radiological comparisons. Although the microwave oven cremation practice is rare, it can impose challenges for investigators. Therefore, fully understanding this practice can be helpful to the academic and forensic communities.

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The hydrothermal carbonization (HTC) optimization of oat husk was performed using a response surface methodology. Furthermore, anaerobic digestion (AD) of spent liquor and hydrochar addition were evaluated in the biomethane potential (BMP) test. Results found that temperature influences the most in the studied responses (i.e., mass yield (MY) and higher heating value (HHV)). Optimal hydrochar MY (53.8%) and HHV (21.5 MJ/kg) were obtained for 219.2 °C, 30 min, and 0.08 of biomass/water ratio. A successful prediction capability of the optimization approach was observed, archiving an error < 1% between predicted and validated responses. The BMP experiment showed the feasibility of spent liquor as a potential substrate to be treated by AD (144 NmLCH4/gCOD). Hydrochar boosted the methane production of spent liquor increasing up to 17% compared to digestion with no hydrochar addition. These findings provide new insights regarding oat husk valorization by integrating HTC and AD for energy production.

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No in-depth investigation exists on the feasibility of integrating hydrothermal carbonization (HTC) and pelletization into the process of making spent mushroom substrate (SMS), an agro-food residue from the commercial mushroom industry, into an adsorbent for post-combustion CO2 removal. Therefore, this study analyzed if it could be possible for systematically converting low-pressure hydrochars of various SMSs into carbon-adsorbing mini-capsules. Sources of SMS included paddy straw and achiote capsule shell from Pleurotus ostreatus; eucalyptus sawdust and grassy straw from Lentinula edodes; and compost containing peat or soil as casing layer from Agaricus subrufescens. The eucalyptus sawdust and grassy straw from L. edodes outperformed the other biomaterials in adsorbing CO2, and thus effectively encapsuled most of the gas, 8.25 mmol g-1 and 8.10 mmol g-1, respectively. They contained mostly hetero-atoms of O and N, requiring less unit energy to bind acidic molecules of CO2 at the alkaline sites. The amount of unit energy the pore-filling process demanded at 25 °C was 12.65 kJ mol-1, an attribute of self-sustaining and saleable physisorption. A negative 6.80 kJ mol-1 free energy validated both spontaneity and exothermal of biocarbons at steady-state atmosphere. The major findings and innovations of our study support utilizing SMS as an adsorbent as a carbon capture, storage and utilization networking. Our insights into the physisorption-chemisorption on SMS are timely and relevant to help manage the re-use of SMS, and thus bring the global mushroom industry closer to environmental sustainability and toward a lower carbon society and circular economy.

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Hydrochar is a carbon-based material that can be used as soil amendment. Since the physical-chemical properties of hydrochar are mainly assigned to process parameters, we aimed at evaluating the organic fraction of different hydrochars through 13C-NMR and off-line TMAH-GC/MS. Four hydrochars produced with sugarcane bagasse, vinasse and sulfuric or phosphoric acids were analyzed to elucidate the main molecular features. Germination and initial growth of maize seedlings were assessed using hydrochar water-soluble fraction to evaluate their potential use as growth promoters. The hydrochars prepared with phosphoric acid showed larger amounts of bioavailable lignin-derived structures. Although no differences were shown about the percentage of maize seeds germination, the hydrochar produced with phosphoric acid promoted a better seedling growth. For this sample, the greatest relative percentage of benzene derivatives and phenolic compounds were associated to hormone-like effects, responsible for stimulating shoot and root elongation. The reactions parameters proved to be determinant for the organic composition of hydrochar, exerting a strict influence on molecular features and plant growth response.

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Organic matter plays many roles in the soil ecosystem. One property of the substance concerns the metal complexation and interaction with organic contaminants. In this sense, the humic substances (HS), a heterogeneous mixture of compounds, naturally derived from degradation of biomass, have been widely studied in environmental sciences. Recent advances showed a new way to produce humic-like substances (HLS) through hydrothermal carbonization of biomass. Thus, this study aimed to evaluate the HLS of hydrochars, produced by using a mixture of sugarcane bagasse and vinasse with sulfuric acid added (1 and 4% v/v), and to assess their interactions with metal ions, (Fe(III), Al(III), Cu(II) and Co(II)) using EEM-PARAFAC and a two-dimensional FTIR correlation analysis. The results were compared to the humic substances extracted from the Amazonian Anthrosol, as a model of anthropogenic organic matter. NMR analysis showed that humic-like extracts from hydrochar are mainly hydrophobic, while the soil has a greater contribution of polar moieties. The HLS and HS showed similar complexation capacities for Fe(III), Al(III) and Cu(II) assays. For Co(II) HLS exhibited larger affinities than HS. Two-dimensional correlation analysis FTIR showed that chemical groups may undergo conformational alteration with metal additions to achieve more stable arrangements (higher stability constant). Therefore, these results contribute more knowledge about the mechanism of HS and metal ion interaction, as well as showing that HTC can be an interesting option for HLS production, to be used as humic based materials.

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Both the catalytic production of 5-hydroxymethylfurfural (5-HMF) from carbohydrates and the use of a catalyst obtained from residues stand out for adding value to by-products and wastes. These processes contribute to the circular economy. In this work it was evaluated optimized conditions for 5-HMF production from fructose with high yield and selectivity. The reaction was catalyzed by an acidic carbon obtained from glycerol, a byproduct of the biodiesel industry. Special attention has been given to the use of dimethyl sulfoxide (DMSO) as a solvent and its influence on system activity, both in the presence and absence of O2. Glycerol's carbon with acidic properties can be effectively used as catalyst in fructose dehydration, allowed achieving conversions close to 100% with 5-HMF selectivities higher than 90%. The catalyst can be reused in consecutive batch runs. The influence of DMSO in the presence of O2 should be considered in the catalytic activity, as the stabilization of a reaction intermediate by the [O2:DMSO] complex is favored and, both fructose conversion and 5-HMF yield increase.

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Acetaminophen has shown a gradual increase in detection in surface waters. Although present in low concentrations, it should be removed to prevent deleterious effects. Thus, adsorption onto activated carbon is emphasized. Adsorbents may be produced by hydrothermal carbonization (HTC), an environmental-friendly process. Therefore, this work aimed to investigate the use of HTC, verifying its application in acetaminophen removal. Brewer's spent grain (BSG), its hydrochar (HC-BSG) and its activated hydrochar (AHC-BSG) were characterized. HTC provided material with high carbon content. Lignocellulosic breakdown has been demonstrated in HC-BSG and AHC-BSG, but in the latter it was more intense as a result of activation with KOH. Also, a high surface area was found in AHC-BSG (1512.83 m2 g-1), resulting in an adsorption of 318.00 mg g-1. The pseudo-second-order and Langmuir models were fitted to the experimental data. Therefore, HTC was effective as a pretreatment for AHC-BSG, resulting in significant acetaminophen removals.

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Highly acidic lignin-derived sulfonated carbons (LDSCs) were produced from hardwood and softwood kraft lignins under mild conditions by applying fractionation and/or pre-carbonization treatments combined with acid-assisted hydrothermal carbonization. The use of lignin fraction with higher amount oxygen, obtained from the fractionation process, resulted in carbon with the highest density of surface acid groups and improved catalytic activity. The LDSCs were successful tested in the dehydration reaction of fructose to obtain 5-hydroxymethylfurfural, and the best catalyst can be recycled without loss in its catalytic activity after perform a simple regeneration process. In contrast, the pre-carbonization step, commonly performed in several works, resulted in LDSCs with low acidity. A simple and optimized methodology for obtaining LDSCs under mild conditions was developed, and the correlations between the preparation method and the physicochemical and catalytic properties established in this work may be extendible to other starting materials for rational sulfonated carbons production.

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O objetivo deste trabalho foi avaliar a qualidade do carvão vegetal da espécie Cecropia glaziovii, produzido em pequenas propriedades rurais, no município de Biguaçu, estado de Santa Catarina, e em laboratório e comparar suas propriedades ao carvão vegetal de outras espécies. Foram analisadas amostras de carvão de três fontes: amostras de carvão de Cecropia glaziovii coletadas dos fornos de alvenaria (1), amostras de carvão produzido nestes mesmos fornos, porém a partir de várias espécies diferentes (2) e amostras obtidas a partir da carbonização em laboratório da madeira de três árvores de Cecropia glaziovii coletada nas mesmas propriedades rurais (3). Determinou-se o poder calorífico superior, porcentagem de voláteis e carbono fixo e teor de cinzas. Analisando as amostras de carvão vegetal, as médias para análise energética mostraram que o carvão vegetal da amostra 2 apresentou melhores características comparadas às amostras 1 e 3. A amostra 2 apresentou maior poder calorífico superior (PCS 7.281 Kcal/Kg a 7.336 Kcal/Kg), menor teor de voláteis (TV 26,26%), menor teor de cinzas (TC 2,05 a 2,46%) e maior teor de carbono fixo (66,02%). As médias das propriedades da amostra 3 também foram comparadas com outras espécies de importância comercial para produção de carvão. O poder calorífico superior (6.573 Kcal/Kg) e porcentagem de carbono fixo (61,32%) foram respectivamente...

The objective of this work was to assess the quality of the charcoal of the species Cecropia glaziovii, produced in small rural properties, in the municipality of Biguaçu, in the state of Santa Catarina, and in the laboratory and to compare its properties with charcoal from other species. We analyzed charcoal samples from three sources: charcoal samples collected from Cecropia glaziovii kilns Biguaçu, SC (1), charcoal samples produced in these same kilns, but from several different species (2) and samples obtained from the laboratory carbonization of woods from three Cecropia glaziovii trees collected in the same rural properties (3). It was determined the gross calorific value, percentage of volatile, percentage of ash, and fixed carbon. Analyzing the samples of charcoal, the averages for the energy analysis showed that the charcoal from sample 2 presents better characteristics compared to the samples 1 and 3. Sample 2 had a gross calorific value (GCV - 7,281 Kcal/Kg to 7,336 Kcal/Kg), lowest volatiles content (TV - 26.26%), lower ash content (TC - 2.05 to 2.46%) and higher fixed carbon content (66.02%). The average of the properties of Sample 3 was also compared to other species of commercial importance to produce charcoal. The gross calorific value (6,573 Kcal/Kg) and percentage of fixed carbon (61.32%) were respectively lower when compared to other carbon species: Mimosa...

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O objetivo deste trabalho foi avaliar a qualidade do carvão vegetal da espécie Cecropia glaziovii, produzido em pequenas propriedades rurais, no município de Biguaçu, estado de Santa Catarina, e em laboratório e comparar suas propriedades ao carvão vegetal de outras espécies. Foram analisadas amostras de carvão de três fontes: amostras de carvão de Cecropia glaziovii coletadas dos fornos de alvenaria (1), amostras de carvão produzido nestes mesmos fornos, porém a partir de várias espécies diferentes (2) e amostras obtidas a partir da carbonização em laboratório da madeira de três árvores de Cecropia glaziovii coletada nas mesmas propriedades rurais (3). Determinou-se o poder calorífico superior, porcentagem de voláteis e carbono fixo e teor de cinzas. Analisando as amostras de carvão vegetal, as médias para análise energética mostraram que o carvão vegetal da amostra 2 apresentou melhores características comparadas às amostras 1 e 3. A amostra 2 apresentou maior poder calorífico superior (PCS 7.281 Kcal/Kg a 7.336 Kcal/Kg), menor teor de voláteis (TV 26,26%), menor teor de cinzas (TC 2,05 a 2,46%) e maior teor de carbono fixo (66,02%). As médias das propriedades da amostra 3 também foram comparadas com outras espécies de importância comercial para produção de carvão. O poder calorífico superior (6.573 Kcal/Kg) e porcentagem de carbono fixo (61,32%) foram respectivamente...(AU)

The objective of this work was to assess the quality of the charcoal of the species Cecropia glaziovii, produced in small rural properties, in the municipality of Biguaçu, in the state of Santa Catarina, and in the laboratory and to compare its properties with charcoal from other species. We analyzed charcoal samples from three sources: charcoal samples collected from Cecropia glaziovii kilns Biguaçu, SC (1), charcoal samples produced in these same kilns, but from several different species (2) and samples obtained from the laboratory carbonization of woods from three Cecropia glaziovii trees collected in the same rural properties (3). It was determined the gross calorific value, percentage of volatile, percentage of ash, and fixed carbon. Analyzing the samples of charcoal, the averages for the energy analysis showed that the charcoal from sample 2 presents better characteristics compared to the samples 1 and 3. Sample 2 had a gross calorific value (GCV - 7,281 Kcal/Kg to 7,336 Kcal/Kg), lowest volatiles content (TV - 26.26%), lower ash content (TC - 2.05 to 2.46%) and higher fixed carbon content (66.02%). The average of the properties of Sample 3 was also compared to other species of commercial importance to produce charcoal. The gross calorific value (6,573 Kcal/Kg) and percentage of fixed carbon (61.32%) were respectively lower when compared to other carbon species: Mimosa...(AU)

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In this work, lemon and onion biomasses commonly found in street markets are for the first time used to develop a facile, fast and low-cost one-step microwave-assisted carbonization method for synthesis of highly fluorescent carbon dots (CDs). The structure and optical properties of CDs were investigated by TEM, XRD, XRF, UV-Vis, FTIR, and fluorescence spectroscopy. CDs displayed satisfactory optical proprieties, a high quantum yield of 23.6%, and excellent water solubility, and the particle size was 4.23-8.22 nm with an average diameter of 6.15 nm. An efficient fluorescent resonance energy transfer (FRET) between the CDs and riboflavin was achieved with CDs acting as donor and riboflavin as acceptor. A linear relationship between FRET and the riboflavin concentration from 0.10 to 3.0 µg/mL was observed, allowing the development of an accurate and fast analytical method to determine this vitamin in multivitamin/mineral supplements. Despite the potential interferences in these supplements, CDs were selective for riboflavin under optimized conditions. A paired t-test at a 95% confidence level indicated no statistically significant difference between the proposed and the reference methods. Recovery test presented values ranged from 96.0% to 101.4%. The limit of detection and relative standard deviation were estimated at 1.0 ng/mL and <2.6% (n = 3), respectively. CDs were successfully synthesized in a domestic microwave oven (1450 W, 6 min), presenting satisfactory parameters when compared with results of other studies reported in the literature, suggesting that the proposed method is a potentially useful method for the synthesis of CDs and determination of riboflavin.