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The use of advanced modulation and control schemes for power converters, such as a Feedback Quantizer and Predictive Control, is widely studied in the literature. This work focuses on improving the closed-loop modulation scheme called Feedback Quantizer, which is applied to a three-phase voltage source inverter. This scheme has the natural behavior of mitigating harmonics at low frequencies, which are detrimental to electrical equipment such as transformers. This modulation scheme also provides good tracking for the voltage reference at the fundamental frequency. On the other hand, the disadvantage of this scheme is that it has a variable switching frequency, creating a harmonic spectrum in frequency dispersion, and it also needs a small sampling time to obtain good results. The proposed scheme to improve the modulation scheme is based on a Discrete Space Vector with virtual vectors to obtain a better approximation of the optimal vectors for use in the algorithm. The proposal improves the conventional scheme at a high sampling time (200 µs), obtaining a THD less than 2% in the load current, decreases the noise created by the conventional scheme, and provides a fixed switching frequency. Experimental tests demonstrate the correct operation of the proposed scheme.
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As a result of human population growth, the availability of residual lignocellulosic materials from agriculture, forestry, food- and wood-processing industries, and other waste streams is continuously increasing [...].
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Agricultura , Alimentos , Humanos , Biomassa , Agricultura FlorestalRESUMO
The use of controlled power converters has been extended for high power applications, stacking off-the-shelve semiconductors, and allowing the implementation of, among others, AC drives for medium voltages of 2.3 kV to 13.8 kV. For AC drives based on power cells assembled with three-phase diode rectifiers and cascaded H-bridge inverters, a sophisticated input multipulse transformer is required to reduce the grid voltage, provide isolation among the power cells, and compensate for low-frequency current harmonics generated by the diode-based rectifiers. However, this input multipulse transformer is bulky, heavy, and expensive and must be designed according to the number of power cells, not allowing total modularity of the AC drives based on cascade H-bridges. This study proposes and evaluates a control strategy based on a finite control set-model predictive control that emulates the harmonic cancellation performed by an input multipulse transformer in a cascade H-bridge topology. Hence, the proposed method requires conventional input transformers and replaces the three-phase diode rectifiers. As a result, greater modularity than the conventional multicell converter and improved AC overall input current with a THD as low as 2% with a unitary displacement power factor are achieved. In this case, each power cell manages its own DC voltage using a nonlinear control strategy, ensuring stable system operation for passive and regenerative loads. The experimental tests demonstrated the correct performance of the proposed scheme.
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The use of lignocellulosic biomass as potential raw material for fractionation and transformation into high value-added products or energy is gathering the attention of scientists worldwide in seeking to achieve a green transition in our production systems [...].
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Conservação dos Recursos Naturais/métodos , Conservação dos Recursos Naturais/tendências , Lignina/metabolismo , Biocombustíveis , Biomassa , Celulose/química , Fracionamento Químico , Lignina/química , PlantasRESUMO
Awareness on deforestation, forest degradation, and its impact on biodiversity and global warming, is giving rise to the use of alternative fiber sources in replacement of wood feedstock for some applications such as composite materials and energy production. In this category, barley straw is an important agricultural crop, due to its abundance and availability. In the current investigation, the residue was submitted to thermomechanical process for fiber extraction and individualization. The high content of holocellulose combined with their relatively high aspect ratio inspires the potential use of these fibers as reinforcement in plastic composites. Therefore, fully biobased composites were fabricated using barley fibers and a biobased polyethylene (BioPE) as polymer matrix. BioPE is completely biobased and 100% recyclable. As for material performance, the flexural properties of the materials were studied. A good dispersion of the reinforcement inside the plastic was achieved contributing to the elevate increments in the flexural strength. At a 45 wt.% of reinforcement, an increment in the flexural strength of about 147% was attained. The mean contribution of the fibers to the flexural strength was assessed by means of a fiber flexural strength factor, reaching a value of 91.4. The micromechanical analysis allowed the prediction of the intrinsic flexural strength of the fibers, arriving up to around 700 MPa, and coupling factors between 0.18 and 0.19, which are in line with other natural fiber composites. Overall, the investigation brightness on the potential use of barley straw residues as reinforcement in fully biobased polymer composites.
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Resinas Compostas/química , Resistência à Flexão , Hordeum/química , Plásticos/química , Polietileno/química , Celulose/química , Resinas Compostas/análise , Estudos de Viabilidade , Lignina/química , Manufaturas/normas , Teste de Materiais , Polissacarídeos/química , Estresse Mecânico , Propriedades de SuperfícieRESUMO
Horticultural plant residues (tomato, pepper, and eggplant) were identified as new sources for lignocellulose nanofibers (LCNF). Cellulosic pulp was obtained from the different plant residues using an environmentally friendly process, energy-sustainable, simple, and with low-chemical reagent consumption. The chemical composition of the obtained pulps was analyzed in order to study its influence in the nanofibrillation process. Cellulosic fibers were subjected to two different pretreatments, mechanical and TEMPO(2,2,6,6-Tetramethyl-piperidin-1-oxyl)-mediated oxidation, followed by high-pressure homogenization to produce different lignocellulose nanofibers. Then, LCNF were deeply characterized in terms of nanofibrillation yield, cationic demand, carboxyl content, morphology, crystallinity, and thermal stability. The suitability of each raw material to produce lignocellulose nanofibers was analyzed from the point of view of each pretreatment. TEMPO-mediated oxidation was identified as a more effective pretreatment to produce LCNF, however, it produces a decrease in the thermal stability of the LCNF. The different LCNF were added as reinforcing agent on recycled paperboard and compared with the improving produced by the industrial mechanical beating. The analysis of the papersheets' mechanical properties shows that the addition of LCNF as a reinforcing agent in the paperboard recycling process is a viable alternative to mechanical beating, achieving greater reinforcing effect and increasing the products' life cycles.
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Lignina/química , Lignina/isolamento & purificação , Nanofibras/química , Papel , Extratos Vegetais/química , Capsicum/química , Solanum lycopersicum/química , Reciclagem , Solanum melongena/químicaRESUMO
EVICT project has noted the increase in cannabis use in the Spanish youth population, and has studied its association with tobacco, concluding that: It has an influence in the learning to smoke process: The beginning can be combined and with bi-directional influence. It has an influence on dependence the development of dependence Their interaction is relevant in the development of dependence. It has an influence on toxicity: Smoking tobacco and cannabis generates greater problems than smoking tobacco alone. And, therefore, the EVICT team issues some considerations: Prevention considerations. Differentiate between therapeutic and recreational use. Smoking cannabis is not therapeutic nor innocuous, and can affect the development of nicotine dependence, or, less frequently, cannabis dependence. Approach and treatment considerations. In A first option of cessation of both must be proposed in people who consume tobacco and cannabis Harm Reduction. To those that only consume tobacco/cannabis: Harm Reduction programs should be more applicable to those in whom consumption is considered more problematic.
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Fumar Maconha , Fumar Tabaco , Adolescente , Adulto , Idoso , Assistência Ambulatorial , Feminino , Humanos , Masculino , Fumar Maconha/efeitos adversos , Fumar Maconha/prevenção & controle , Pessoa de Meia-Idade , Espanha , Fumar Tabaco/efeitos adversos , Fumar Tabaco/prevenção & controleRESUMO
Some agricultural residues such as wheat or barley straw, as well as certain fast-growing plants like Leucaena leucocephala and Chamaecytisus proliferus, could be used as raw materials for the paper industry as an alternative to traditional plants (eucalyptus, pine, etc.). In the present study, four types of lignin obtained from the spent liquors produced by the pulping processes using the abovementioned feedstocks were isolated and characterized. Lignin samples were acquired through an acid precipitation from these spent liquors. The characterization of the precipitated lignin samples were performed using a Fourier transform infrared spectroscopy (FT-IR) and both liquid- and solid-state nuclear magnetic resonance spectroscopy (NMR) to analyse the chemical structure, and thermogravimetric analysis (TGA) for determining the thermal properties. Additionally, chemical composition of lignin fractions was also measured. Even though they were of different botanical origin, all the studied samples except for wheat straw lignin had a similar chemical composition and thermal behaviour, and identical chemical structure. Wheat straw lignin showed a greater amount of Klason lignin and lower carbohydrate content. Furthermore, this lignin sample showed a higher thermal stability and significantly different cross-peak patterns in the 2D-NMR experiments. The molecular structures corresponding to p-coumarate (PCA), ferulate (FA) and cinnamyl aldehyde end-groups (J) were only detected in wheat isolated lignin.
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Fabaceae/química , Lignina/química , Lignina/isolamento & purificação , Poaceae/química , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Compostos Fitoquímicos/química , Compostos Fitoquímicos/isolamento & purificação , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Espectroscopia de Infravermelho com Transformada de Fourier , TermogravimetriaRESUMO
We do have very effective and efficient interventions to help our patients to stop smoking. The strategy that has more evidence and consensus in primary care is the 5 A's, that is, ask, advise, assess willingness to try to quit smoking, helping those who want to try and make follow-up visits. However, we intervene lot less than we should. The available protocols oversized interventions, and propose elements without scientific evidence or therapeutic effect. It is therefore necessary to develop more simple, useful and evidence-based interventions to assist us in carrying out our work interventions, and stop doing those that dont contribute. In this article we will use as an example a critical review of Smoker Care Service Portfolio of Madrid Health Service, and we will propose a number of alternatives to allow a simple, effective and evidence-based intervention.
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Atenção Primária à Saúde , Abandono do Hábito de Fumar , Humanos , Fumar , NicotianaRESUMO
In recent years, antimony sulfide (Sb2S3) has been investigated as a photovoltaic absorber material due to its suitable absorber coefficient, direct band gap, extinction coefficient, earth-abundant, and environmentally friendly constituents. Therefore, this work proposes Sb2S3 film preparation by an effective two-step process using a new graphite box design and sulfur distribution, which has a high repeatability level and can be scalable. First, an Sb thin film was deposited using the RF-Sputtering technique, and after that, the samples were annealed with elemental sulfur into a graphite box, varying the sulfurization time from 20 to 50 min. The structural, optical, morphological, and chemical characteristics of the resulting thin films were analyzed. Results reveal the method's effectivity and the best properties were obtained for the sample sulfurized during 40 min. This Sb2S3 thin film presents an orthorhombic crystalline structure, elongated grains, a band gap of 1.69 eV, a crystallite size of 15.25 Å, and a nearly stoichiometric composition. In addition, the formation of a p-n junction was achieved by depositing silver back contact on the Glass/FTO/CdS/Sb2S3 structure. Therefore, the graphite box design has been demonstrated to be functional to obtain Sb2S3 by a two-step process.
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INTRODUCTION: Whether men find it easier to quit smoking than women is still controversial. Different studies have reported that the efficacy of pharmacological treatments could be different between men and women. This study conducted a secondary analysis of 'Subsidized pharmacological treatment for smoking cessation by the Spanish public health system' (FTFT-AP study) to evaluate the effectiveness of a drug-funded intervention for smoking cessation by gender. METHODS: A pragmatic randomized clinical trial by clusters was used. The population included smokers aged ≥18 years, smoking >10 cigarettes per day, randomly assigned to an intervention group receiving regular practice and financed pharmacological treatment, or to a control group receiving only regular practice. The main outcome was continued abstinence at 12 months, self-reported and validated with CO-oximetry. The percentage, with 95% confidence intervals, of continued abstinence was compared between both groups at 12 months post-intervention, by gender and the pharmacological treatment used. Multilevel logistic regression analysis was performed. RESULTS: A total of 1154 patients from 29 healthcare centers were included. The average age was 46 years (SD=11.78) and 51.7% were men. Overall, the self-reported abstinence at 12 months was 11.1% (62) in women and 15.7% (93) in men (AOR=1.4; 95% CI: 1.0-2.0), and abstinence validated by CO-oximetry was 4.6% (26) and 5.9% (35) in women and men, respectively (OR=1.3; 95% CI: 0.7-2.2). In the group of smokers receiving nicotine replacement treatment, self-reported abstinence was higher in men compared to women (29.5% vs 13.5%, OR=2.7; 95% CI: 1.3-5.8). CONCLUSIONS: The effectiveness of a drug-financed intervention for smoking cessation was greater in men, who also showed better results in self-reported abstinence with nicotine replacement treatment.
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INTRODUCTION: Advice can have a small but clinically important effect in promoting smoking cessation. Where studied, the rate of delivery has been found to be low. Training has been found to increases this rates, but there is little research on effectiveness in terms of smoking cessation rates. This study aimed to assess the effectiveness and cost-effectiveness of an health professionals educational program to increase long-term rates of nicotine abstinence in smoking outpatients. METHODS: We conducted a pragmatic cluster-randomized, controlled trial in 35 primary health care centers in Spain. Participants were all 830 health professionals who attended 5,970 smokers during recruiting period. After that we measured continuous abstinence 6 months after the intervention and biochemically validated (saliva cotinine test) 1 year following intervention. Cost-effectiveness was measured in terms of cost per life year gained. RESULTS: After 6 months, the rate of continuous abstinence was significantly higher in the intervention group (2.1% vs. 0.3%, p > .0001) with an odds ratio of 6.5 (95% CI = 3.3-12.7). After 1 year, biochemical validation was performed on 31 of the 67 patients previously registered as abstinent. All of them were abstinent and belonged to intervention group. The incremental cost per life year gained after 6 months was 969. CONCLUSIONS: A primary care training program on smoking cessation based on scientific evidence, behavioral theory, and active learning methods increases long-term continuous nicotine abstinence rate among outpatients in a significant way. These may be relevant for planning training of professionals, clinical assistance, and public health programs.
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Abandono do Hábito de Fumar/métodos , Tabagismo/terapia , Adulto , Análise Custo-Benefício , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Abandono do Hábito de Fumar/economia , Inquéritos e QuestionáriosRESUMO
As a transition strategy towards sustainability, food packaging plays a crucial role in the current era. This, carried out in a biorefinery context of agricultural residues, involves not only obtaining desirable products but a comprehensive utilization of biomass that contributes to the circular bioeconomy. The present work proposes the preparation of bioactive absorbent food pads through a multi-product biorefinery approach from bay tree pruning waste (BTPW). In a first step, chitosan aerogels reinforced with lignocellulose and cellulose micro/nanofibers from BTPW were prepared, studying the effect of residual lignin on the material's properties. The presence of micro/nanofibers improved the mechanical performance (up to 60%) in addition to increasing the water uptake (42%) when lignin was present. The second step was to make them bioactive by incorporating bay leaf extract. The residual lignin in the micro/nanofibers was decisive, since when present, the release profiles of the extract were faster, reaching an antioxidant power of more than 85% after only 30 min. Finally, these bioactive aerogels were used as absorbent pads for fresh meat. With the use of the bioactive aerogels (with ≥2% extract), the meat remained fresh for 10 days as a result of delayed oxidation of the food during storage (20% metmyoglobin proportion).
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(1) Background: Nanostructured cellulose has emerged as an efficient bio-adsorbent aerogel material, offering biocompatibility and renewable sourcing advantages. This study focuses on isolating (ligno)cellulose nanofibers ((L)CNFs) from barley straw and producing aerogels to develop sustainable and highly efficient decontamination systems. (2) Methods: (Ligno)cellulose pulp has been isolated from barley straw through a pulping process, and was subsequently deconstructed into nanofibers employing various pre-treatment methods (TEMPO-mediated oxidation process or PFI beater mechanical treatment) followed by the high-pressure homogenization (HPH) process. (3) Results: The aerogels made by (L)CNFs, with a higher crystallinity degree, larger aspect ratio, lower shrinkage rate, and higher Young's modulus than cellulose aerogels, successfully adsorb and remove organic dye pollutants from wastewater. (L)CNF-based aerogels, with a quality index (determined using four characterization parameters) above 70%, exhibited outstanding contaminant removal capacity over 80%. The high specific surface area of nanocellulose isolated using the TEMPO oxidation process significantly enhanced the affinity and interactions between hydroxyl and carboxyl groups of nanofibers and cationic groups of contaminants. The efficacy in adsorbing cationic dyes in wastewater onto the aerogels was verified by the Langmuir adsorption isotherm model. (4) Conclusions: This study offers insights into designing and applying advanced (L)CNF-based aerogels as efficient wastewater decontamination and environmental remediation platforms.
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An innovative colloidal approach is proposed here to carry out the customized functionalization of TEMPO-Oxidized Cellulose Nanofibers (CNF) incorporating non-noble inorganic nanoparticles. A heterocoagulation process is applied between the delignified CNF and as-synthetized CuO nanoparticles (CuO NPs) to formulate mixtures which are used in the preparation of aerogels with antibacterial effect, which could be used to manufacture membranes, filters, foams, etc. The involved components of formulated blending, CNF and CuO NPs, were individually obtained by using a biorefinery strategy for agricultural waste valorization, together with an optimized chemical precipitation, assisted by ultrasounds. The optimization of synthesis parameters for CuO NPs has avoided the presence of undesirable species, which usually requires later thermal treatment with associated costs. The aerogels-based structure, obtained by conventional freeze-drying, acted as 3D support for CuO NPs, providing a good dispersion within the cross-linked structure of the nanocellulose and facilitating direct contact of the antibacterial phase against undesirable microorganisms. All samples showed a positive response against Escherichia coli and Staphylococcus aureus. An increase of the antibacterial response of the aerogels, measured by agar disk diffusion test, has been observed with the increase of CuO NPs incorporated, obtaining the width of the antimicrobial "halo" (nwhalo) from 0 to 0.6 and 0.35 for S. aureus and E. coli, respectively. Furthermore, the aerogels have been able to deactivate S. aureus and E. coli in less than 5 h when the antibacterial assays have been analyzed by a broth dilution method. From CNF-50CuO samples, an overlap in the nanoparticle effect produced a decrease of the antimicrobial kinetic.
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The search for packaging alternatives that reduce the presence of non-biodegradable plastics in water is a focus of much research today. This fact, together with the increasing demand for active packaging capable of prolonging the shelf life of foodstuffs and the rise in the use of natural biopolymers such as cellulose, motivate the present work. This work evaluates CMC films loaded with gallic acid reinforced with (ligno)cellulose nanofibres from various agricultural residues as candidates for use in active food packaging. The first stage of the study involved the evaluation of different nanofibres as the reinforcing agent in CMC films. Increasing proportions of nanofibres (1, 3, 5 and 10% w/w) from horticultural residues (H) and nanofibres from vine shoots (V), containing residual lignin (LCNF) and without it (CNF), and obtained by mechanical (M) or chemical (T) pretreatment, were studied. The results of this first stage showed that the optimum reinforcement effect was obtained with 3% H-MCNF or 3% V-MCNF, where up to 391% and 286% improvement in tensile strength was achieved, respectively. These films offered slightly improved UV-light blocking ability (40-55% UV-barrier) and water vapor permeability (20-30% improvement) over CMC. Next, bioactive films were prepared by incorporating 5 and 10% wt of gallic acid (GA) over the optimised formulations. It was found that the joint addition of cellulose nanofibres and GA enhanced all functional properties of the films. Mechanical properties improved to 70%, WVP to 50% and UV light blocking ability to 70% due to the synergistic effect of nanofibres and GA. Finally, the bioactive films exhibited potent antioxidant activity, 60-70% in the DPPH assay and >99% in the ABTS assay and high antimicrobial capacity against S. aureus.
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Simulation and analysis of solar cells based on the heterojunction of zinc oxide doped with aluminum (AZO) and cadmium telluride (CdTe) with the structure (Al/AZO/CdTe/NiO/Ni) using the Simulator of the capacitance of solar cells - 1 dimension (SCAPS-1D) has been presented in this paper. AZO is used as a window layer and Nickel oxide (NiO) has been introduced as a hole transport layer (HTL). Through the software, the effect of thickness, absorber (CdTe), and window (AZO) layers carrier concentration, operating temperature, and resistances (series and shunt) have been studied. Simulation results show that the solar cell performance can be greatly improved by adjusting the layer's thickness and carrier concentration, obtaining optimal values of 10 nm and 10 18 c m - 3 for the AZO layer, while for the CdTe layer they were 2 µm and 10 15 c m - 3 . The optimum series and shunt resistances are in the range of 1-3 Ω c m 2 and 1800-2200 Ω c m 2 respectively. A maximum power conversion efficiency (PCE) of 14.2% is achieved with an open circuit voltage (Voc) of 0.74 V, short circuit current density (Jsc) of 26.15 m A / c m 2 and a fill factor (FF) of 72.83%, this shows AZO potential to be considered as an interesting material to replace CdS window layer.
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The efficient and selective detection of volatile organic compounds (VOCs) provides key information for various purposes ranging from the toxicological analysis of indoor/outdoor environments to the diagnosis of diseases or to the investigation of biological processes. In the last decade, different sensors and biosensors providing reliable, rapid, and economic responses in the detection of VOCs have been successfully conceived and applied in numerous practical cases; however, the global necessity of a sustainable development, has driven the design of devices for the detection of VOCs to greener methods. In this review, the most recent and innovative VOC sensors and biosensors with sustainable features are presented. The sensors are grouped into three of the main industrial sectors of daily life, including environmental analysis, highly important for toxicity issues, food packaging tools, especially aimed at avoiding the spoilage of meat and fish, and the diagnosis of diseases, crucial for the early detection of relevant pathological conditions such as cancer and diabetes. The research outcomes presented in the review underly the necessity of preparing sensors with higher efficiency, lower detection limits, improved selectivity, and enhanced sustainable characteristics to fully address the sustainable manufacturing of VOC sensors and biosensors.
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Técnicas Biossensoriais , Compostos Orgânicos Voláteis , Animais , Detecção Precoce de Câncer , Monitoramento Ambiental , Compostos Orgânicos Voláteis/análiseRESUMO
Water pollution is one of the most serious problems worldwide. Nanocellulose-based aerogels usually show excellent adsorption capacities due to their high aspect ratio, specific surface area and surface charge, making them ideal for water purification. In this work, (ligno)cellulose nanofibers (LCNFs/CNFs) from wheat straw residues were obtained using two types of pre-treatments: mechanical (Mec) and TEMPO-mediated oxidization (TO), to obtain different consistency (0.2, 0.4, 0.6 and 0.8) bioaerogels, and their adsorption capacities as dye removers were further studied. The materials were characterized in terms of density, porosity and mechanical properties. An inversely proportional relationship was observed between the consistencies of the aerogels and their achieved densities. Despite the increase in density, all samples showed porosities above 99%. In terms of mechanical properties, the best results were obtained for the 0.8% consistency LCNF and CNF-Mec aerogels, reaching 67.87 kPa and 64.6 kPa for tensile strength and Young's modulus, respectively. In contrast, the adsorption capacity of the aerogels was better for TEMPO-oxidized aerogels, reaching removal rates of almost 100% for the CNF-TO5 samples. Furthermore, the residual lignin content in LCNF-Mec aerogels showed a great improvement in the removal capacity, reaching rates higher than 80%, further improving the cost efficiency of the samples due to the reduction in chemical treatments.
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Celulose , Nanofibras , Adsorção , Celulose/química , Lignina/química , Nanofibras/química , TriticumRESUMO
The hornification processes undergone by the fibers in the paper industry recycling processes lead to the loss of properties of the final products, which exhibit poor mechanical properties. Among the most promising solutions is the reinforcement of secondary fibers with cellulose nanofibers. The present work addresses two important issues: the efficient production of cellulose nanofibers from scarcely exploited agricultural wastes such as horticultural residues and vine shoots, and their application as a reinforcement agent in recycled linerboard recycling processes. The effect of the chemical composition and the pretreatment used on the nanofibrillation efficiency of the fibers was analyzed. Chemical pretreatment allowed a significantly higher nanofibrillated fraction (45−63%) than that produced by mechanical (18−38%), as well as higher specific surface areas (>430 m2/g). The application of the nanofibers as a reinforcing agent in the recycled linerboard considerably improved the mechanical properties (improvements of 15% for breaking length, 220−240% for Young's modulus and 27% for tear index), counteracting the loss of mechanical properties suffered during recycling when using chemically pretreated cellulose nanofibers from horticultural residues and vine shoots. It was concluded that this technology surpasses the mechanical reinforcement produced by conventional mechanical refining used in the industry and extends the number of recycling cycles of the products due to the non-physical modification of the fibers.