Navegando por Autor "Nogueira, Cleitiane da Costa"

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Avaliação do uso de tensoativos nos pré-tratamentos ácido e alcalino diluídos da casca do coco verde e quantificação de água na pós-lavagem
(2017-02-07) Nogueira, Cleitiane da Costa; Santos, Everaldo Silvino dos; Macedo, Gorete Ribeiro de; ; http://lattes.cnpq.br/3324083094904117; ; http://lattes.cnpq.br/4330639792072559; ; http://lattes.cnpq.br/8630679962860994; Sousa Júnior, Francisco Canindé de; ; http://lattes.cnpq.br/3721560802857426; Nascimento, Ruthineia Jéssica Alves do; ; http://lattes.cnpq.br/9261029993364342
O Brasil é o quarto maior produtor de coco e aproximadamente 85 % em massa do fruto torna-se resíduo que pode ser usado como fonte renovável para produzir etanol. Entretanto, o pré-tratamento da biomassa é um passo importante para aumentar a acessibilidade e biodegradabilidade da celulose e hemicelulose, características necessárias na posterior etapa de sacarificação. Na maioria dos pré-tratamentos, são produzidos paralelamente agentes inibidores como compostos fenólicos e ácidos que devem ser removidos. Geralmente, utiliza-se água na etapa de lavagem, mas o seu uso deve ser reduzido para viabilizar o processo do ponto de vista econômico e ambiental. Além disso, estudos indicam que tensoativos podem ser usados como coadjuvantes no pré-tratamento, auxiliando em melhores rendimentos de açúcares fermentescíveis e, consequentemente, de produção de etanol. Nesse contexto, o presente trabalho visa avaliar a influência do tensoativo Tween 80 no processo de pré-tratamento da fibra de coco verde e analisar o uso de água na lavagem do material pré-tratado. Através de planejamentos experimentais e análises estatísticas, os pré-tratamentos com H2SO4 e NaOH foram avaliados investigando-se a influência da concentração do agente químico, do tensoativo e do tempo de pré-tratamento. Os materiais obtidos após lavagem foram submetidos à hidrólise enzimática (Celluclast® 1.5L, 50 oC, 150 rpm, 96 h, 20 FPU/g, 20 CBU/g, 10 FXU/g) avaliando-se a conversão em açúcares fermentescíveis produzidos. Para o pré-tratamento ácido diluído, verificou-se que a concentração do H2SO4 e o tempo foram significativos, tendo o primeiro efeito negativo e o segundo, positivo. O melhor resultado de hidrólise enzimática nesse planejamento foi de 6,86 g/L e 2,14 g/L para glicose e xilose, respectivamente, obtido no ensaio sem H2SO4 e Tween 80 e no tempo de 60 min. Com relação ao pré-tratamento alcalino diluído, as concentrações de NaOH e Tween 80 foram significativas, ao nível de 95 % de confiança, sendo que o melhor resultado de hidrólise produziu 13,83 g/L para glicose e 5,77 g/L para xilose obtido com 2,0% (m/v) de NaOH, 3,0 % (m/m) de Tween 80 em 10 min. Os materiais pré-tratados que permitiram as melhores concentrações de açúcares fermentescíveis foram avaliados morfológica e físico-quimicamente na presença e ausência de tensoativo. A avaliação da lavagem dos materiais pré-tratados na produção de açúcares fermentescíveis, durante a hidrólise enzimática, mostrou uma possibilidade de se reduzir em 75 % o volume de água inicialmente usada na lavagem sem prejudicar a produção final. O uso do Tween 80 no pré-tratamento alcalino diluído melhorou a conversão em glicose e xilose durante a hidrólise enzimática dos materiais pré-tratados. Entretanto, não apresentou influência nos materiais pré-tratados em condições ácidas. Além disso, verificou-se que a quantidade de água da lavagem pode ser consideravelmente reduzida, contribuindo para viabilidade da produção de etanol lignocelulósico.
Comparison of delignified coconuts waste and cactus for fuel-ethanol production by the simultaneous and semi-simultaneous saccharification and fermentation strategies
(Elsevier, 2014-09-01) Santos, Everaldo Silvino dos; Gonçalves, Fabiano Avelino; Leza, Héctor Arturo Ruiz; Nogueira, Cleitiane da Costa; Teixeira, José António; Macedo, Gorete Ribeiro de
It is of the highest importance to study different alternatives/strategies as simultaneous (SSF) and semi-simultaneous (SSSF) saccharification and fermentation process, as well as the prospects of the utilization of lignocellulosic residues as raw materials for fuel-ethanol production. In the first part of this work, different raw materials (cactus (CAC), green coconut shell (GCS), mature coconut fibre (MCF) and mature coconut shell (MCS)) were pretreated by sequential alkaline hydrogen peroxide (Alk-H2O2)–sodium hydroxide (NaOH) process. The characterization of the obtained solids by FTIR, SEM, X-ray and crystallinity indexes confirmed the higher susceptibility of these pretreated materials to enzymatic action. These results were further confirmed by the corresponding glucose conversion yields – 68.44%, 70.20%, 76.21% and 74.50% for CAC, GCS, MCF and MCS, respectively. Subsequently, the comparison between SSF and SSSF using Saccharomyces cerevisiae, Pichia stipitis, Zymomonas mobilis and pretreated MCF (selected in the enzymatic hydrolysis step) was done, being shown that a short presaccharification step at 50 C for 8 h in the SSSF had a positive effect on the overall ethanol yield, with an increase from 79.27–84.64% to 85.04–89.15%. In all the cases, the SSSF strategy allowed the obtention of higher ethanol concentrations than SSF
Enhancing enzymatic hydrolysis of green coconut fiber—Pretreatment assisted by tween 80 and water effect on the post-washing
(Elsevier, 2018-02) Santos, Everaldo Silvino dos; Nogueira, Cleitiane da Costa; Padilha, Carlos Eduardo de Araújo; Leitão, Ana Laura de Sá; Rocha, Patrícia Maria; Macedo, Gorete Ribeiro de
This study evaluated the hydrothermal, alkaline (NaOH) and acid (H2SO4) pretreatment all combined with Tween 80 of the green coconut fiber aiming to improve the fermentable sugars production during the enzymatic hydrolysis. In addition, the water use during the post-washing of the pretreated materials was also assayed, seeking to ration its use without compromising the enzymatic hydrolysis and the removal of inhibitors. Untreated and pretreated biomass were assayed in terms of total solids, extractables, polysaccharides, lignin and total ashes according to the protocols proposed by NREL. Enzymatic hydrolysis was carried out using the preparation of cellulases from Trichoderma reesei ATCC 26921 and β-glucosidases (NS-22118 DCN00218) and xylanases (NS-22036 CDN01015). Additionally, the mass loss during pretreatment and washing was estimated. Results showed that the use of 3.0% (w/w) Tween 80 in the dilute alkaline pretreatment (2.0% (w/v) NaOH, 121 °C, 10 min) increased the conversion into glucose during the enzymatic hydrolysis of the pretreated materials from 48.7% to 56.1%. However, it did not show any influence on the pretreated materials in acid and hydrothermal conditions. The evaluation of the washing of the pretreated materials reduced the volume of water initially used in up to 75%, without affecting the final sugar production and the reduction of inhibitory compounds in the residual water, contributing to the viability of the production of cellulosic ethanol from green coconut fiber
Fabrication of hollow polymer microcapsules and removal of emulsified oil from aqueous environment using soda lignin nanoparticles
(Elsevier, 2020-10) Souza, Domingos Fabiano de Santana; Padilha, Carlos Eduardo de Araújo; Nogueira, Cleitiane da Costa; Matias, Stephanie Caroline Bivar; Costa Filho, José Daladiê Barreto da; Oliveira, Jackson Araújo de; Santos, Everaldo Silvino dos
Lignin-based materials have been explored as a way to minimize dependence on petroleum products and consolidate valorization schemes of lignocellulosic biomass. Soda lignins have peculiar properties and can generate lignin nanoparticles (LNP) with the potential ability to solve emulsification/demulsification problems. The present study focuses on the use of soda LNPs for fabrication of polymer microcapsules via Pickering emulsion template and for removing emulsified oil from aqueous environment. Structural characteristics of lignins recovered from corn cob (CC) and green coconut fibre (GCF) were evaluated after analyses of chemical composition, thermal degradation and infrared spectroscopy. Both LNPs were obtained by pH-shifting method and showed low absolute values of zeta potential. LNPs provided good emulsification capacity (emulsification index > 40 % at 5.00 g/L LNP) and micrometer-scale droplets in oil-water Pickering emulsions. LNPs have been successful as a stabilizing agent in the preparation of microcapsules of poly(methyl methacrylate) (PMMA) and polycaprolactone (PCL), in which size was strongly dependent on the LNP concentration. Hollow PCL microcapsules were manufactured by stabilization with GCF-LNP, but did not show to be stable in experiments involving CC-LNP. In addition, the tendency of soda LNPs to form aggregates was used as a mechanism to remove emulsified oil, which made it possible to remove up to 90.6 % for CC-LNP and 94.4 % for GCF-LNP experiments
Fractionation of green coconut fiber using sequential hydrothermal/alkaline pretreatments and amberlite XAD-7HP resin
(Elsevier, 2019-12) Souza, Domingos Fabiano de Santana; Padilha, Carlos Eduardo de Araújo; Nogueira, Cleitiane da Costa; Oliveira Filho, Marcos Antônio; Sousa Júnior, Francisco Canindé de; Assis, Cristiane Fernandes de; Oliveira, Jackson Araújo de; Santos, Everaldo Silvino dos
The fractionation of agroindustrial and forest residues is a premise of the biorefinery concept. Thus, the present study focuses on pretreatments (hydrothermal and alkaline) and detoxification processes in order to transform green coconut fiber (GCF) into cellulose-rich material, dye biosorbent, bioactive phenolic compounds, lignin and arabinoxylan. The adsorption onto Amberlite XAD-7HP resin allowed the best recovery of phenolic compounds from hydrothermal pretreatment liquor, which presented potent antioxidant activities such as inhibition of hydroxyl and superoxide radicals of 77.05% and 76.88%, respectively. Acid precipitation was effective to recover 41.23% of the initial lignin content from alkaline pretreatment liquor. The detoxified hydrothermal pretreatment liquor was used as an additional source of glucose, increasing the final concentration of ethanol by 79.6% in simultaneous saccharification and fermentation of delignified GCF. Using delignified GCF as biosorbent, made it possible to obtain a static adsorption capacity of 200 mg of methylene blue dye per gram of biosorbent and good recyclability in dynamic experiments. Therefore, the proposed methodology guarantees a practical way of manufacturing value-added products from lignocellulosic materials
Optimization of separation of bioactive compounds in daily foods by aqueous two-phase flotation coupled with HPLC-DAD
(Gavin Publishers, 2017-06-10) Santos, Everaldo Silvino dos; Padilha, Carlos Eduardo de Araújo; Nogueira, Cleitiane da Costa; Leitão, Ana Laura de Sá; Rocha, Patrícia Maria; Almeida, Hanna Nóbrega; Souza, Domingos Fabiano Santana; Oliveira, Jackson Araújo de; Macedo, Gorete Ribeiro de
In this study, we have used Aqueous Two-Phase Flotation (ATPF) in order to recovery and concentrate bioactive phenolic compounds found in foods. Firstly, the effects of the operational conditions on the ATPF performance have been investigated using a model solution of Gallic Acid (GA). The optimal conditions were: [ammonium sulfate] = 450 g/L, pH = 3.8, air flowrate = 37.5 mL/min, time flotation = 120 min, initial organic phase volume = 10.0 mL and polyethylene glycol 400 as solvent. Next, experiments were carried out with aqueous extracts of daily foods and the ATPF phases were analyzed by HPLC-DAD. In terms of total phenolic compounds content, the highest percentage of separation was obtained for clove extract with 38.80% due to transfer of gallic acid and eugenol to PEG rich-phase. The results showed that ATPF is a promising technique for be applied for separation and purification of phenolic compounds mainly in natural extracts
Organosolv lignin/Fe3O4 nanoparticles applied as a β-glucosidase immobilization support and adsorbent for textile dye removal
(Elsevier, 2020-04) Souza, Domingos Fabiano de Santana; Padilha, Carlos Eduardo de Araújo; Nogueira, Cleitiane da Costa; Oliveira, Jackson Araújo de; Santos, Everaldo Silvino dos
In this paper, the liquor obtained from organosolv pretreatment of green coconut fiber (GCF) was used for the synthesis of lignin/Fe3O4 nanoparticles. The coating of Fe3O4 nanoparticles was evaluated by X-ray and dynamic light scattering analysis. β-glucosidase immobilized on lignin/Fe3O4 nanoparticles by covalent bonding exhibited better stability than free enzyme. Compared to the free enzyme, β-glucosidase immobilized on lignin/Fe3O4 nanoparticles achieved good digestibility performance of crystalline cellulose (∼ 21.9 g/L reducing sugars) and delignified GCF (∼ 6.4 g/L reducing sugars). In adsorption experiments, lignin/Fe3O4 nanoparticles exhibited low equilibration time and high adsorption capacity of Methylene blue (203.66 mg/g), Cibacron blue (112.36 mg/g) and Remazol red (96.46 mg/g) dyes. After four cycles, the adsorption of the Methylene blue dye on lignin/Fe3O4 nanoparticles reduced 43.68 % using 0.1 M HCl as eluent
Pressurized pretreatment and simultaneous saccharification and fermentation with in situ detoxification to increase bioethanol production from green coconut fibers
(Elsevier, 2019-04) Souza, Domingos Fabiano de Santana; Nogueira, Cleitiane da Costa; Padilha, Carlos Eduardo de Araújo; Jesus, Anderson Alles de; Assis, Cristiane Fernandes de; Sousa Junior, Francisco Canindé de; Santos, Everaldo Silvino dos
In this study, we investigated four conventional pretreatments under pressurized conditions, as well as in situ detoxification using polyethylene glycol (PEG 400), for the simultaneous saccharification and fermentation (SSF) of green coconut fibers. The highest fermentable sugar production (22.05% g/g untreated fiber) was reached with pressurized dilute alkaline pretreatment. In the SSF, the addition of PEG favored ethanol production compared to that in experiments without the polymer, reaching a maximum value of 7.87 g/L at a liquor content of 50% v/v for the pressurized water pretreatment. After lignin recovery by acid precipitation, the liquors had interesting antioxidant properties, similar to those of fruit extracts. The proposed pressurized water pretreatment could be an advantageous choice because it can be performed at mild temperatures (70 °C) and high solid loadings (26.67% w/v) and achieves a high mass yield (72.84% w/w) without the addition of a chemical agent. Furthermore, the liquor can be used in the SSF, reducing the water consumption and number of steps in the cellulosic ethanol process
Pressurized water pretreatment to increase sugar production from green coconut
(Universidade Federal do Paraná, 2019-03-28) Souza, Domingos Fabiano de Santana; Nogueira, Cleitiane da Costa; Padilha, Carlos Eduardo de Araújo; Jesus, Anderson Alles de; Santos, Everaldo SIlvino dos
Pretreatment of lignocellulosic industrial waste is necessary to promote the cellulose accessibility. Thus, this study evaluated the production of green coconut sugars during pressurized hydrothermal pre-treatment and enzymatic hydrolysis of the pretreated biomass. Pretreatment of the green coconut shell was carried out at 70 °C, 150 bar and water flow rate of 1 mL/min for 4 h. Samples from the system output stream were analyzed by HPLC and Folin Ciocalteu method. The solid fraction was characterized (chemical composition, XRD and FTIR) and subjected to enzymatic hydrolysis. The liquid fractions of pretreatment provided a defined profile of released glucose, xylose, phenolic components and acetic acid over time. After 40 min, most of fermentable sugars were released, forming a liquor with a sugar content above 10 g/L. Post-treated biomass showed a reduction of cellulose (26 % to 17 %) and hemicellulose (23 % to 18 %) and an increase in lignin content (32 % to 44 %). Despite this new chemical composition of the biomass, the pretreated material had lower crystallinity indexes and modifications in its chemical groups. This favored cellulosic conversion from 15 % to 55 %, producing 63.5 % more glucose than the untreated green coconut shell during enzymatic hydrolysis. Thus, the pressurized pre-treatment favored the fermentable sugar production from the green coconut shell, and there is also the possibility of utilizing the sugars present in the pre-treatment liquor
Produção de etanol celulósico sob elevadas concentrações de polímeros à base de óxido de etileno
(Universidade Federal do Rio Grande do Norte, 2021-04-12) Nogueira, Cleitiane da Costa; Santos, Everaldo Silvino dos; Padilha, Carlos Eduardo de Araújo; ; http://lattes.cnpq.br/1186888955341616; ; http://lattes.cnpq.br/4330639792072559; ; http://lattes.cnpq.br/8630679962860994; Dutra, Emmanuel Damilano; ; http://lattes.cnpq.br/0359600775598226; Silva, Francinaldo Leite da; ; http://lattes.cnpq.br/1239745530214820; Souza Filho, Pedro Ferreira de; ; http://lattes.cnpq.br/3140602874903609; Franco, Telma Teixeira;
A conversão de resíduos agroindustriais como a casca de coco verde (CCV) e o sabugo de milho (SM) em etanol é uma alternativa promissora para o Brasil superar impasses industriais, econômicos e ambientais. Entretanto, a produção de etanol celulósico requer um aperfeiçoamento de suas principais etapas: o pré-tratamento, a hidrólise enzimática e a fermentação. Para isso, as pesquisas têm mostrado muitas possibilidades. Dentre elas, destacase o uso de polímeros como o polietileno glicol (PEG) e seus derivados como coadjuvantes nessas etapas, visto que, além de auxiliar beneficamente o pré-tratamento da biomassa, eles têm favorecido a atividade enzimática e aumentado a viabilidade e tolerância celular em meio fermentativo com inibidores. Assim, este trabalho avaliou como os tipos de polímeros e suas concentrações podem influenciar o desempenho de cada etapa. Para isso, utilizaram-se as biomassas CCV e SM (não tratada e pré-tratada em condições hidrotérmica, ácida e alcalina) e SigmaCell celulose, leveduras (Saccharomyces cerevisiae CAT-1 e Kluyveromyces marxianus) e polímeros (Triton X-100, Tween 80, PEG 400 a 4000 e EOPO 5800) em diferentes concentrações durante as etapas estudadas. Ainda, foram propostas estratégias fermentativas para integrar essas etapas com uso dos polímeros. Nas fermentações em meio inibitório, os polímeros polietilenoglicol (PEG) e etileno óxido-propileno óxido (EOPO) agiram como desintoxicantes, mantendo a viabilidade celular e a produção de etanol semelhante ao controle sem inibidor e polímero. Esse comportamento foi diretamente relacionado com a concentração do polímero até os valores 175 e 100 g.L-1 para o PEG 4000 e EOPO 5800, respectivamente. Na hidrólise enzimática simulada, o PEG e o EOPO aumentaram a atividade celulolítica e a liberação de açúcares fermentescíveis em ambiente rico em lignina. O PEG 400 permitiu utilizar os açúcares presentes no licor do pré-tratamento hidrotérmico pressurizado na sacarificação e fermentação simultâneas (SFS) com sucesso, aumentando o título etanólico de 6,43 g.L-1 (controle sem PEG) para 7,87 g.L-1. Em ambiente ácido, o PEG aumentou a deslignificação do sabugo durante o pré-tratamento. Entretanto, o efeito dos polímeros foi mais pronunciado com a CCV nas etapas subsequentes de hidrólise e fermentação, provavelmente devido ao alto teor de lignina dessa biomassa. Os resultados de SFS com licor e PEG 4000 para a CCV pré-tratada ácida e hidrotérmica foram respectivamente 8,8±0,8 g.L-1 e 9,3±1,2 g.L-1 de etanol, mas esses valores foram superados quando utilizado o coco não tratado (9,7±0,5 g.L-1). A SFS em batelada da CCV não tratada atingiu 89,8% de rendimento mássico de etanol, utilizando 175 g.L-1 de PEG 4000, 20 FPU.g-1 e 108 celúlas.mL-1 de S. cerevisiae CAT-1. A adição de PEG possibilitou operar a SFS em batelada alimentada utilizando até 30% (m/m) de carga de sólidos, 13,3 FPU.g-1 de carga enzimática e 1x108 celúlas.mL-1 de S. cerevisiae CAT-1, produzindo 35,1 g.L-1 de etanol em 48 h. Portanto, os resultados indicaram que o PEG em elevadas concentrações é uma alternativa para facilitar o processamento da CCV na indústria do etanol celulósico.
Recovery and concentration of ortho-phenylphenol from biodesulfurization of 4-methyl dibenzothiophene by aqueous two-phase flotation
(Elsevier, 2017-04) Souza, Domingos Fabiano de Santana; Padilha, Carlos Eduardo de Araújo; Dantas, Paulo Victor Fortunato; Sousa Júnior, Francisco Canindé; Oliveira Júnior, Sérgio Dantas; Nogueira, Cleitiane da Costa; Oliveira, Jackson Araújo de; Macedo, Gorete Ribeiro de; Santos, Everaldo Silvino dos
In this study we focus on recovery and concentration of ortho-phenylphenol (OPP) from fermentation broth by aqueous two-phase flotation (ATPF). The effects of pH, ammonium sulfate concentration, OPP concentration, air flow-rate, flotation time and initial volume of organic phase were evaluated on process performance using multivariate statistical methodology. Under optimal conditions, the separation efficiency (E%), the concentration coefficient (a) and the distribution coefficient (D) for ATPF reached 57.55%, 4.23 and 9.86, respectively. When compared to others conventional techniques also used in this work, such as aqueous two-phase extraction, solvent sublation and liquid-liquid extraction, the ATPF showed better performance in terms of E%, a and D. Additionally, experiments carried out with fermentation broth derived from the biodesulfurization of 4-MDBT have shown promise in the recovery and concentration of OPP. In summary, the results indicated that the ATPF is an effective separation technique in the pretreatment of the OPP from bona fide mixtures
Separation and concentration of bioactive phenolic compounds by solvent sublation using three-liquid-phase system
(Elsevier, 2020-03) Santos, Everaldo Silvino dos; Padilha, Carlos Eduardo de Araújo; Nogueira, Cleitiane da Costa; Hanna Nóbrega Almeida, Hanna Nóbrega; Medeiros, Waleska Rayane Dantas Bezerra de; Oliveira Filho, Marcos Antônio; Araújo, Jaciara Silva de
The present work investigated the SS performance with focus on the addition of second collecting phase to intensify the separation of vanillin and eugenol. First, experiments were performed with only n-octanol as the only collecting phase and the effects of solutes concentration and pH of the bottom phase were evaluated on the separation efficiency (E%). Then,the SS process was performed in a three-liquid-phase system formed by n-octanol/PEG 400/(NH4)2SO4 and the results were evaluated based on E%, distribution coefficient (D) and vanillin selectivity (RVAN/EUG) values. When compared to single component experiments, the presence of another solute had little effect on the E% values of vanillin and eugenol, regardless of the range of the initial concentration. Moreover, in SS with n-octanol/acetate buffer it was possible to reach the highest values of E% for vanillin (53.83%) and eugenol (85.37%) in experiments with pH equal to 4.5. On the other hand, the three-liquid-phase system achieved selectivity at least twice as high as two-liquid-phase systems and D values higher than 25 for vanillin in the PEG 400-rich phase. Thus, SS using three-liquid-phase system appears as an alternative to solve multicomponent separation problems involving bioactive compounds
Síntese e caracterização de bioaditivo com lignina para cimentação de poços
(Universidade Federal do Rio Grande do Norte, 2024-10-11) Azevedo, Heitor Bruno Barbosa de; Braga, Renata Martins; Padilha, Carlos Eduardo de Araújo; https://orcid.org/0000-0002-6232-0945; http://lattes.cnpq.br/4603529162393328; http://lattes.cnpq.br/4430413701521111; Freire, Ageu da Silva Monteiro; Nogueira, Cleitiane da Costa; Silva, Elania Maria Fernandes
A gestão inadequada de resíduos agroindustriais é um desafio crescente, especialmente no Brasil. A indústria de taninos é bem consolidada no país e faz uso de resíduos florestais como matéria-prima, porém, após a extração, o material sólido não tem destino definido. No sentido de melhorar a cadeia de produção de taninos, o presente estudo teve por objetivo desenvolver um bioaditivo para cimentos a partir do resíduo de Anadenanthera colubrina (angico vermelho). Inicialmente, a composição química do subproduto lignocelulósico foi determinada por análise química e análise termogravimétrica (TGA/DTG). Em seguida, a lignina foi isolada por extração alcalina seguida de precipitação ácida. A partir dessa lignina, sintetizou-se o bioaditivo, visando propriedades específicas para aplicação em cimento. A eficácia do bioaditivo foi confirmada em pastas de cimento por ensaios reológicos e de consistometria, analisando seu efeito retardante e concentração. Observou-se que o bioaditivo reduz a interação entre as partículas de cimento, prolongando o tempo de pega e melhorando o controle de endurecimento, o que contribui para a qualidade e resistência do cimento em operações de cimentação.
Valorization of cashew apple bagasse using acetic acid pretreatment: production of cellulosic ethanol and lignin for their use as sunscreen ingredients
(Elsevier, 2020-04) Souza, Domingos Fabiano de Santana; Padilha, Carlos Eduardo de Araújo; Nogueira, Cleitiane da Costa; Oliveira Filho, Marcos Antônio; Oliveira, Jackson Araújo de; Santos, Everaldo Silvino dos
The present study focuses on the fractionation of cashew apple bagasse via a pretreatment using acetic acid as a delignifying agent and sulfuric acid as an external catalyst. As expected, the concentrations of both acids and the incubation time dramatically affected delignification and hemicellulose solubilization. Under the optimal pretreatment conditions, recycling of the spent liquor had no apparent impact on the chemical composition of the pretreated material, yield of sugar produced via enzymatic hydrolysis (∼37 g/L reducing sugars at 7.5% (w/v) solid loading), or yield of ethanol obtained via fermentation with Saccharomyces cerevisiae (∼16 g/L at 10% (w/ v) solid loading). The lignin recovered from the spent liquor showed a good ultraviolet protective effect; the addition of 5% (w/w) of the biopolymer increased the sun protection factor of a commercial sunscreen lotion from 21.62 to 40.71. The combined use of hydrogen peroxide and ultraviolet radiation reduced the organosolv lignin color (absorbance at 450 nm was four times lower) owing to aromatic ring cleavage, but cosmetics containing whitened organosolv lignin had low sun protection factor values. In summary, the results obtained in this study demonstrate the utility of organic acid pretreatment in the valorization of lignocellulosic materials
Valorization of green coconut fibre: use of the black liquor of organolsolv pretreatment for ethanol production and the washing water for production of rhamnolipids by pseudomonas aeruginosa ATCC 27583
(Elsevier, 2019-11) Souza, Domingos Fabiano de Santana; Padilha, Carlos Eduardo de Araújo; Nogueira, Cleitiane da Costa; Oliveira, Jackson Araújo de; Santos, Everaldo Silvino dos
The present study proposes the production of ethanol, lignin and rhamnolipids from the valorization scheme of green coconut fibre (GCF) and glycerol. As expected, all pretreatments using 80% (w/w) glycerol and 1% (w/w) sulfuric acid promoted high delignification (> 60%) and good cellulose enrichment (> 50% w/w). The reuse of black liquor in the pretreatments apparently did not affect the glucose release (48.36–49.96 g/L) or the fermentability (22.62–29.64 g/L) of pretreated GCF at 20% (w/v) solid loading. Structural differences between recovered lignin from glycerol-based organosolv pretreatment and alkaline lignin were observed after spectroscopy and thermal stability analyses. In addition, the lignin precipitation water and washing water from the glycerol-based pretreatments of GCF were used in culture media preparation for Pseudomonas aeruginosa ATCC 27583. The production of rhamnolipids varied in the range of 0.57–1.25 g/L and presented greater emulsifying capacity than the rhamnolipids obtained from pure glycerol. Therefore, the methodology described in this study provides an unusual method for obtaining value-added products from organosolv pretreatment of lignocellulosic biomasses

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Navegando por Autor "Nogueira, Cleitiane da Costa"