Navegando por Autor "Ferreira, Gabriel Max Dias"
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Item Adsorption of organic and inorganic arsenic from aqueous solutions using MgAl-LDH with incorporated nitroprusside.(2020) Borges, Gabriella Alexandre; Ferreira, Gabriel Max Dias; Siqueira, Kisla Prislen Félix; Dias, Anderson; Najera Navarro, Keirom Osmany; Silva, Sílvia Juliana Barros e; Rodrigues, Guilherme Dias; Mageste, Aparecida BarbosaAn evaluation was made of the use of MgAl-LDH with incorporated nitroprusside as an adsorbent to remove inorganic arsenic (As(III) and As(V)) and organic arsenic (DMA) from aqueous matrices. The material was synthesized by the co-precipitation method at constant pH and was characterized by Raman spectroscopy, infrared spectroscopy, thermogravimetry, X-ray diffraction, and high-resolution transmission electron microscopy, before and after use in the adsorption process. The effects on adsorption of contact time, initial metalloid concentration, and pH were investigated. For an initial concentration of 10 mg L1 and pH 2.00, the MgAl-LDH with incorporated nitroprusside was only able to adsorb the DMA and As (V) species, with removal percentages of 25.10 and 103.8%, respectively. At pH 6.02 and 12.00, only the inorganic species were adsorbed, with removal percentages of 22.93% and 60.07%, respectively, for As(III), and 89.81% and 71.64%, respectively, for As(V). Application of the Langmuir and Freundlich isotherm models indicated that the features of the adsorption process depended on the pH of the medium and the arsenic species. The results showed that the use of MgAl-LDH with incorporated nitroprusside has potential for the development of techniques for the speciation of arsenic species.Item Adsorption of red azo dyes on multi-walled carbon nanotubes and activated carbon : a thermodynamic study.(2017) Ferreira, Guilherme Max Dias; Ferreira, Gabriel Max Dias; Hespanhol, Maria C.; Rezende, Jaqueline de Paula; Pires, Ana Clarissa dos Santos; Gurgel, Leandro Vinícius Alves; Silva, Luis Henrique Mendes daCarbonaceous materials have been extensively studied as highly efficient adsorbents for the removal of dyes from wastewater. However, investigations of thermodynamic aspects of the interactions between these materials and dyes remain scarce. This paper describes the thermodynamics of the interactions between the Ponceau 4R (PR), Congo Red (CR), and Allura Red (AR) dyes and multi-walled carbon nanotubes (MWCNTs). The interactions between the dyes and activated carbon (AC) were also evaluated for comparison. The investigation used a combination of adsorption isotherms and isothermal titration nanocalorimetry (ITC) measurements, and a thermodynamic approach provided full characterization of the adsorption process. For both MWCNT and AC, the amount of adsorbed dye (ΓD) increased in the order ΓD (PR) < ΓD (AR) < ΓD (CR), and the adsorption capacity normalized by the adsorbent specific area was up to 5.6 times higher for MWCNT. The maximum amount adsorbed (ΓD,max) reached values of up to 2.00 μmol m−2 for CR adsorption on MWCNT. For both adsorbents, the process of dye adsorption was enthalpically driven and entropically unfavorable. All the thermodynamic parameters depended on the surface coverage and the structures of both dye and adsorbent. The adsorption enthalpy change (ΔadsH) and entropy change (TΔadsSref) values were higher than −137.0 kJ mol−1 and −114.2 kJ mol−1, respectively. In addition to the structural differences between MWCNT and AC, the ITC data suggested that the adsorption sites are heterogeneous and that the dyes preferentially adsorb on the more hydrophilic sites on the adsorbent surfaces.Item Aggregation of sodium dodecylbenzene sulfonate : weak molecular interactions modulated by imidazolium cation of short alkyl chain length.(2020) Patino Agudelo, Alvaro Javier; Ferreira, Guilherme Max Dias; Ferreira, Gabriel Max Dias; Coelho, Yara Luiza; Hudson, Eliara Acipreste; Pires, Ana Clarissa dos Santos; Silva, Luis Henrique Mendes daIonic liquids (ILs) can modify cooperative process in aqueous solutions to a large extent, including anionic surfactant aggregation. Here, the micellization of sodium dodecylbenzene sulfonate (SDBS) was evaluated in low concentrations of 1-alkyl-3-methylimidazolium chloride (CnmimCl, n = 0, 2, and 4) aqueous solutions through fluorescence spectroscopy, isothermal titration calorimetry, dynamic light scattering, and conductometry. The thermodynamic stability of SDBS aggregates strongly depended on the IL structure and concentration, following the order C4mim+ > C0mim+ ≈ C2mim+. At 1.0 mmol L−1 of the ILs, the increase of the hydrophobicity of the imidazolium cation decreased the enthalpic favorableness, changing from −3.75 ± 0.07 kJ mol−1, for C0mim+, to −2.69 ± 0.01 kJ mol−1, for C4mim+. On the other hand, the entropic feasibility showed an opposite trend, i.e., the higher hydrophobicity of C4mim+ overcame the kosmotropic effect of IL cations in the bulks. We suggested that the imidazolium cations interact with the SDBS monomers on the micellar surface, mainly through hydrophobic, π-π, and electrostatic interactions for C4mim+ and C2mim+, and through electrostatic interactions and hydrogen bonds for C0mim+.Item Aminated cellulose as a versatile adsorbent for batch removal of As(V) and Cu(II) from mono- and multicomponent aqueous solutions.(2020) Pereira, Amanda Raimundi; Soares, Liliane Catone; Teodoro, Filipe Simões; Carvalho, Megg Madonyk Cota Elias; Ferreira, Gabriel Max Dias; Savedra, Ranylson Marcello Leal; Savedra, Melissa Fabíola Siqueira; Martineau Corcos, Charlotte; Silva, Luis Henrique Mendes da; Prim, Damien; Gurgel, Leandro Vinícius AlvesA bioadsorbent (CEDA) capable of adsorbing As(V) and Cu(II) simultaneously was prepared by tosylation of microcrystalline cellulose (MC) and nucleophilic substitution of the tosyl group by ethylenediamine. MC, tosyl cellulose, and CEDA were characterized by elemental C, H, N, and S analysis, infrared spectroscopy, and 13C solid-state nuclear magnetic resonance spectroscopy. The adsorption of As(V) and Cu (II) on CEDA was evaluated as a function of solution pH, contact time, and initial solute concentration. The maximum adsorption capacities of CEDA for As(V) and Cu(II) were 1.62 and 1.09 mmol g1 , respectively. The interactions of As(V) and Cu(II) with CEDA were elucidated using thermodynamic parameters, molecular quantum mechanics calculations, and experiments with ion exchange of Cd(II) by Cu(II), and As(V) by SO4 2. Adsorption enthalpies were determined as a function of surface coverage of the CEDA, using isothermal titration calorimetry, with DadsH values of 32.24 ± 0.07 and 93 ± 2 kJ mol1 obtained for As(V) and Cu(II), respectively. The potential to reuse CEDA was evaluated and the interference of other ions in the adsorption of As(V) and Cu(II) was investigated. Multi-component experiments showed that Cd(II), Co(II), Ni(II), and Pb(II) did not interfere in the adsorption of Cu(II), while SO4 2 inhibited As(V) adsorption.Item Anthocyanin immobilization in carboxymethylcellulose/starch films : a sustainable sensor for the detection of Al(III) ions in aqueous matrices.(2020) Silva, Heriveltom Morais da; Mageste, Aparecida Barbosa; Silva, Sílvia Juliana Barros e; Ferreira, Guilherme Max Dias; Ferreira, Gabriel Max DiasA robust and sustainable sensor for the detection of Al(III) ions in water was developed by immobilization of anthocyanin (AN) from black rice in a film formed by carboxymethylcellulose (CMC) and starch. Characterization of the films was performed using solubility, thickness, FTIR, and mechanical analysis. The film exhibited an irreversible color change from red to purple in response to the presence of Al(III). The best colorimetric response of the sensor was observed at pH 4.5 and a time of 60 min, achieving the detection of 3 mg L−1 of Al(III). For concentrations higher than 5 mg L−1, the sensor response time decreased to 20 min. The minimum Al(III) concentration detected with the naked eye was lower than the maximum permissible concentrations in aqueous effluents according to different legislations, indicating the potential of this study to develop sensors for the detection of Al(III).Item Batch and continuous adsorption of Cd(II) and Pb(II) on polycarboxylated sugarcane bagasse.(2023) Carvalho, Megg Madonyk Cota Elias; Soares, Liliane Catone; Maia, Luisa Cardoso; Taylor, Jason Guy; Herrera Adarme, Oscar Fernando; Ferreira, Gabriel Max Dias; Azevedo, Eduardo Ribeiro de; Siervo, Abner de; Silva, Luis Henrique Mendes da; Gurgel, Leandro Vinícius AlvesA bioadsorbent composed of polycarboxylated sugarcane bagasse (PSB) was prepared in a one-step reaction by the esterification of sugarcane bagasse hydroxyl groups with butane-1,2,3,4-tetracarboxylic dianhydride. 13C SS NMR measurements showed that 0.3 butane-1,2,3,4-tetracarboxylic acid units were grafted per cellobiose unit. PSB was used in the batch adsorption of Cd(II) and Pb(II) from mono-, bi-, and multicomponent aqueous solutions. For upscaling of the technology aiming at practical applications, evaluation was made of 4 cycles of continuous adsorption of Cd(II) and Pb(II) on PSB in a fixed-bed column. The maximum adsorption capacities for Cd(II) and Pb(II) on PSB in batch and continuous modes were 0.55 and 1.164 mmol g− 1 (62 and 241.2 mg g− 1 ), and 0.58 and 0.71 mmol g− 1 (65 and 153 mg g− 1 ), respectively. The standard adsorption enthalpy change (ΔadsH◦) values for Cd(II) and Pb(II) were 8.6 ± 0.5 and − 0.28 ± 0.03 kJ mol− 1 , respectively. The interactions involved in the adsorption of Cd(II) and Pb(II) on PSB were investigated. Multicomponent studies showed that Pb (II) and Cd(II) acted to suppress the adsorption of each other. In the presence of Cu(II) and Zn(II), the adsorption capacity followed the order: Pb(II) > Cu(II) > Cd(II) > Zn(II). Batch and continuous adsorption-desorption studies showed that PSB could be reused in at least 4 successive cycles, with desorption efficiencies of 88–100 %, which is essential for minimizing waste generation and reducing process costs.Item Caracterização e avaliação do potencial adsortivo de biocarvões produzidos a partir de bagaço de malte cervejeiro.(2023) Mendes, Débora Beatriz Teles; Ferreira, Gabriel Max Dias; Ferreira, Guilherme Max Dias; Ferreira, Gabriel Max Dias; Ferreira, Guilherme Max Dias; Soares, Jenaina Ribeiro; Gil, Laurent FrédéricA indústria têxtil possui um vasto uso de corantes e a remoção desses poluentes, especialmente de matrizes aquosas, tem sido cada vez mais estudada, uma vez que a presença desses em águas pode trazer riscos ao ambiente e à saúde humana. Nesse contexto, a adsorção utilizando biocarvões tem sido proposta como tecnologia sustentável e inovadora para a remoção desses contaminantes. Neste trabalho foram investigadas as propriedades de diferentes biocarvões (BC) produzidos a partir do resíduo de bagaço de malte, bem como seu potencial de adsorção frente ao corante azul de metileno. A geração de resíduo de bagaço do malte tem aumentado nos últimos anos, mostrando-se uma biomassa lignocelulósica interessante para produzir BC. Foram produzidos o biocarvão a partir da pirólise da biomassa in natura, bem como variações do biocarvão obtidas a partir de modificações, especificamente modificações pré-pirólise usando sais metálicos (MnCl2 ou CoCl2) ou surfactante catiônico (brometo de cetiltrimetilamônio) e modificações pós-pirólise usando ácido (H3PO4 ou ácido cítrico). Os biocarvões foram caracterizados por meio de análises de ponto de carga zero (PCZ), FTIR, MEV e número de grupos ácidos e básicos. O efeito do pH da solução sobre a capacidade de adsorção dos materiais com maior potencial de adsorção (pré-modificados com MnCl2 ou CoCl2) foi investigado. Estudos de cinética nos mesmos materiais foram realizados e os dados experimentais foram analisados usando os modelos de pseudo-primeira ordem, pseudo-segunda ordem, Elovich e difusão intrapartícula. Isotermas de adsorção foram também obtidas nesses materiais e os dados experimentais foram modelados pelas isotermas de Freundlich, Langmuir, Dubinin–Radushkevich, Temkin e Redlich-Peterson. Resultados de FTIR indicaram a presença de grupos hidroxila, fenólicos e carboxílicos na superfície da biomassa in natura, bem como uma perda desses grupos nos biocarvões após o processo de pirólise. Também foi observado a presença de grupos específicos relacionados à incorporação de metais na estrutura dos materiais obtidos a partir da pirólise da biomassa modificada com sais metálicos. O pH no ponto de carga zero (PCZ) para todos os materiais foi próximo da neutralidade. Os valores de PCZ foram correlacionados com o número de grupos ácidos e básicos na superfície dos biocarvões. O pH da solução afetou pouco a capacidade de adsorção dos biocarvões modificados com sais metálicos, sendo levemente mais alta em pH 5,0, sugerindo uma baixa contribuição de interações eletrostáticas no processo de adsorção. Os estudos de cinética revelaram uma taxa de adsorção lenta dos materiais, sendo o tempo de equilíbrio de 48 e 70 h para os materiais modificados com os sais CoCl2 e MnCl2, respectivamente. O modelo de Elovich foi o que se ajustou melhor aos dados experimentais de cinética, sugerindo que o processo envolveu quimissorção, com a formação de interações específicas entre o substrato e o adsorvato. Além disso, o modelo de isoterma que melhor descreveu a adsorção do azul de metileno sobre ambos os biocarvões modificados com sais metálicos foi o de Redlich-Peterson, apresentando parâmetros Krp, α e β iguais a 2,97 L mg–1 ; 0,759 L mg–1 e 0,940 para o BC contendo cobalto e iguais a 4,21 L mg–1 ; 0,452 L mg–1 e 0,963, para o BC contendo manganês, respectivamente, sugerindo que a adsorção ocorre em monocamada e o adsorvente possui um número definido de sítios com energias levemente distintas. Valores de qe,máx foram iguais a 5,14 e 11,43 mg g –1 para os biocarvões contendo cobalto e manganês, respectivamente. Diante do exposto, conclui-se que os biocarvões obtidos a partir de resíduos do bagaço de malte cervejeiro apresentam baixas capacidades de adsorção para o corante azul de metileno, embora tenha sido observado uma dependência desse valor com o tipo de sal metálico utilizado na pré-modificação da biomassa utilizada para produzir o BC. Esses resultados são importantes e revelam a necessidade do aprofundamento de estudos nessa perspectiva a fim de se viabilizar estratégicas mais eficientes na produção de biocarvões produzidos a partir da biomassa avaliada nesse trabalho.Item Comportamento de fase e aspectos interacionais de sistemas aquosos bifásicos formados por sais de tiocianato e surfactante não iônico triton X.(2022) Gonçalves, Gessyca Rosa Silva; Ferreira, Gabriel Max Dias; Cardoso, Marcus Vinícius Cangussu; Ferreira, Gabriel Max Dias; Cardoso, Marcus Vinícius Cangussu; Patino Agudelo, Alvaro Javier; Virtuoso, Luciano SindraNeste trabalho foram obtidos dados de equilíbrio líquido-líquido para sistemas aquosos bifásicos (SABs) formados por surfactante não iônico triton X (triton X-165 ou triton X- 305) + sal (tiocianato de sódio (NaSCN), tiocianato de amônio (NH4SCN) ou tiocianato de potássio (KSCN) + água, em diferentes temperaturas (298,2, 313,2 e 328,2 K). Os diagramas de fase dos SABs investigados foram obtidos pelo método de quantificação das fases, sendo discutidos os efeitos da mudança de temperatura, do aumento da cadeia hidrofílica do surfactante e da mudança do cátion formador do sal sobre os dados de equilíbrio. Além disso, aspectos interacionais associados com as propriedades dos SABs foram discutidos a partir dos dados de equilíbrio e de análises de RMN. Para os SABs formados com NaSCN ou KSCN, constatou-se que a fase superior foi rica em surfactante (wTX ≥ 25,43% m/m), ao mesmo tempo em que apresentou elevada concentração de sal (wsal ≥ 26,50% m/m), enquanto a fase inferior foi rica em sal (wsal ≥ 35,45% m/m) e com concentrações de surfactante próximas de 0% m/m. Por outro lado, nos SABs formados com NH4SCN foi verificado uma inversão de fase, em que a fase superior passou a ser a fase rica em sal (wsal ≥ 47,59% m/m) e a fase inferior passou a ser a fase rica em surfactante (wTX ≥ 28,63% m/m), com esta última também contendo elevadas concentrações de sal. Foi observado que o tamanho da região bifásica dependeu do cátion formador do sal e aumentou na ordem: K+ > Na+ > NH4 + . Além disso, o aumento da temperatura promoveu um leve aumento da região bifásica dos SABs, sendo a magnitude desse efeito maior no sistema formado por NaSCN. Foi verificado que o surfactante TX– 305 foi mais eficiente para induzir a separação de fases que o surfactante TX–165, sendo este efeito atribuído à maior massa molar do TX–305. Além disso, verificou-se que para determinadas condições termodinâmicas, os SABs formados com NaSCN apresentaram a capacidade de formar sistemas com uma fase líquida em equilíbrio com uma fase de aspecto de gel. A partir dos resultados de RMN, pode-se inferir que a capacidade relativa de indução de fase foi associada ao efeito combinado do cátion com o ânion SCNsobre a estrutura da água, em que a combinação do cátion NH4 + com aqueles ânions é mais eficiente para diminuir a contribuição entrópica que induz o sistema a se separar em duas fases. Os resultados obtidos trazem avanços e perspectivas relevantes para estudos que visem à compreensão dos processos que regem a formação de SABs baseados em surfactantes não iônicos.Item Diagramas de fase de sistemas aquosos bifásicos compostos por PEO 400 + sais inorgânicos + água e estudo da extração de ácido monometilarsônico (MMA) utilizando sistema aquoso bifásico.(2017) Carvalho, Roberta de Almeida; Mageste, Aparecida Barbosa; Mageste, Aparecida Barbosa; Santos, Igor José Boggione; Ferreira, Gabriel Max DiasO Arsênio (As) é um semi-metal comumente encontrado no meio ambiente sob formas de compostos inorgânicos e orgânicos através de fontes naturais ou por fontes antropogênicas. Este elemento apresenta alta toxicidade e quando em contato com seres vivos, provoca uma série de doenças, que têm gerado grande preocupação a nível mundial e esforços para reduzir sua concentração em diferentes meios ambientais. Devido à necessidade de sua remoção do meio ambiente, este estudo avalia a utilização de Sistemas Aquosos bifásicos (SAB) na extração do ácido monometilarsônico (MMA). A fim de determinar os parâmetros ótimos para extração de As, o efeito do pH, da massa molar do polímero, do comprimento da linha de amarração (CLA), a natureza do eletrólito (cátion/ânion) e da concentração do metal presente no sistema foram avaliados. Ao avaliar o polímero, melhores resultados de extração de MMA foram obtidos com o Póli (óxido de etileno) 400 g.mol-1. Entretanto, existem muito poucos diagramas deste polímero com sais inorgânicos na literatura, sendo assim, novos diagramas de PEO 400 (PEO 400 + K2CO3 ou Na2CO3 ou KSCN + água) foram obtidos para aplicação nos estudos de extração de As. Avaliou-se o efeito da temperatura e a natureza do eletrólito na formação destes SAB, e os sistemas compostos por PEO 400 + sais de carbonato apresentaram aumento da região bifásica com o aumento da temperatura, indicando que o processo de separação de fases destes sistemas é entropicamente dirigido. Já o sistema composto por KSCN não apresentou modificação da região bifásica com o aumento da temperatura. A inclinação da linha de amarração (ILA) também apresentou pequena mudança, indicando que a composição das fases varia muito pouco com o aumento da temperatura. Os cátions e ânions testados apresentaram a seguinte ordem de formação de fases devido ao efeito Salting-out: Na+ > K+ e CO32- > SCN-. Após obtenção destes novos diagramas, avaliou-se o efeito do eletrólito na extração de MMA e com o sistema composto por PEO 400 + Na2SO4 + água em pH 1 através de duas extrações sequenciais foi possível atingir 100.0 % de extração do MMA, sem fazer uso de nenhum extratante/complexante. Em pH 1 o MMA está sob a forma neutra, realizando interações do tipo ligação de hidrogênio com os óxidos de etileno contidos no PEO, o que possibilita sua extração para a fase superior de forma espontânea. Não houve efeito do CLA na extração do MMA e maiores % E foram obtidas em menores concentrações do metal no sistema (5 mg.Kg-1). Este comportamento de extração do MMA em SAB é diferenciado e vantajoso quando comparado à maioria dos metais extraídos por SAB relatados na literatura, que necessitam da adição de um extratante/complexante para levar o metal da fase inferior para a fase superior.Item Estudo da adsorção de Cd(II) e Ni(II) em biocarvões produzidos a partir de casca de café.(2021) Najera Navarro, Keirom Osmany; Ferreira, Gabriel Max Dias; Ferreira, Guilherme Max Dias; Ferreira, Gabriel Max Dias; Moreira, Renata Pereira Lopes; Gil, Laurent FrédéricAs intensas atividades antropogênicas, especialmente aquelas associadas aos processos de mineração, têm intensificado os problemas com relação à presença de metais tóxicos no ambiente. Nesse contexto, a adsorção utilizando biocarvões tem sido proposta como tecnologia inovadora para a remoção desses contaminantes de diferentes matrizes ambientais. Neste trabalho foi estudada a adsorção de íons Cd(II) e Ni(II) em biocarvões produzidos a partir de casca de café em temperaturas finais de pirólise de 400, 500, 750 e 900 °C, designados BC400, BC500, BC750 e BC900, respectivamente. Os biocarvões foram caracterizados por meio de análises de ponto de carga zero (PCZ), FTIR, área superficial específica e número de grupos ácidos e básicos. As propriedades dos biocarvões foram relacionadas com suas capacidades de adsorção para os íons avaliados. Os efeitos da temperatura de pirólise, do pH da solução e da concentração inicial de adsorvato sobre a quantidade de íons metálicos adsorvida foram investigados. Isotermas de adsorção foram analisadas usando os modelos de Langmuir, Freundlich e Dubinin-Radushkevich. O aumento da temperatura de pirólise do biocarvão levou a um aumento na sua área superficial específica e promoveu a perda de grupos funcionais ácidos e básicos na sua superfície. Análise de FTIR indicou a presença de grupos –OH, –COOH e –SO3H na superfície da casca de café in natura, bem como uma perda crescente desses grupos nos biocarvões com o aumento da temperatura de pirólise. Biocarvões com temperaturas de pirólise menores e pH da solução mais elevado promoveram maiores quantidades adsorvidas dos metais, associado principalmente à interações eletrostáticas atrativas entre sítios de carga negativa na superfície do biocarvão e os metais de carga positiva. As quantidades máximas de adsorção foram obtidas para o BC400 em pH 5,0, com quantidades adsorvidas de 33,03 e 25,48 mg/g para Cd(II) e Ni(II), respectivamente. O modelo de Freundlich se ajustou melhor à maioria das isotermas, sugerindo quem os sítios de adsorção na superfície dos biocarvões são distintos. Além de enfatizar o potencial de biocarvões de casca de café como potenciais adsorventes para a remoção de metais de matrizes aquosas, nossos resultados alimentam uma base de dados importantes para compreensão do VI comportamento de adsorção de solutos diversos sobre biocarvões, os quais fundamentam a aplicação destes materiais em diferentes áreas.Item Extraction of anthocyanins from the byproduct and wastes of black rice production by ecofriendly method.(2022) Fernandes, Tayrine Silva; Ferreira, Gabriel Max Dias; Silva, Gilmare Antônia da; Santos, Igor José Boggione; Mageste, Aparecida BarbosaA green and sustainable method has been developed to extract anthocyanins from broken black rice (BBR) using aqueous solutions of poly(ethylene glycol) (PEG). The effects of time, PEG concentration, temperature, BBR mass, and PEG molar mass were investigated using multivariate experimental designs. Time and temperature were not significant in the studied range and PEG 1500 was the most suitable. Under the optimized conditions, the anthocyanin concentration was 130.7 mg 100 g−1. The stability of the extract was higher at 25 °C and pH 5.0, with a reduction in absorbance (λmax = 455 nm) of only 7.14% after 60 days. The extract was applied in a colorless soap, and the color remained stable for 60 days (greater reduction in absorbance of 15.5% at 40 °C, λmax = 497 nm), indicating its potential for direct application in products of industrial interest. The method was also effective to extract anthocyanins from the husk and bran of black rice, with concentrations of 148.1 and 883.2 mg 100 g−1, respectively. In comparison with conventional methods for extracting anthocyanins, the proposed new technique offers the advantages of efficiency, simplicity and low cost, with the difference in extract concentration being obtained with methanol acidified with HCl of only 11%.Item Extraction of anthocyanins from the byproduct and wastes of black rice production by ecofriendly method.(2021) Fernandes, Tayrine Silva; Ferreira, Gabriel Max Dias; Silva, Gilmare Antônia da; Santos, Igor José Boggione; Mageste, Aparecida BarbosaA green and sustainable method has been developed to extract anthocyanins from broken black rice (BBR) using aqueous solutions of poly(ethylene glycol) (PEG). The effects of time, PEG concen-tration, temperature, BBR mass, and PEG molar mass were investigated using multivariate experi-mental designs. Time and temperature were not significant in the studied range and PEG 1500 was the most suitable. Under the optimized conditions, the anthocyanin concentration was 130.7 mg 100 g−1. The stability of the extract was higher at 25 °C and pH 5.0, with a reduction in absorbance (λmax = 455 nm) of only 7.14% after 60 days. The extract was applied in a colorless soap, and the color remained stable for 60 days (greater reduction in absorbance of 15.5% at 40 °C, λmax = 497 nm), indicating its potential for direct application in products of industrial interest. The method was also effective to extract anthocyanins from the husk and bran of black rice, with concentrations of 148.1 and 883.2 mg 100 g−1, respectively. In comparison with conventional methods for extracting anthocyanins, the proposed new technique offers the advantages of efficiency, simplicity and low cost, with the difference in extract concentration being obtained with methanol acidified with HCl of only 11%.Item Filme polimérico contendo antocianina como sensor colorimétrico de cobre em cachaça.(2021) Figueiredo, Matheus Torres Duarte; Mageste, Aparecida Barbosa; Ferreira, Gabriel Max Dias; Mageste, Aparecida Barbosa; Stefani, Ricardo; Cunha, Luciana Rodrigues daA cachaça é um produto genuinamente brasileiro, sendo o primeiro destilado mais consumido no Brasil e quarto em nível mundial. Quando produzida em alambiques de cobre, este metal pode ser lixiviado, contaminando a bebida. Em vista disso, é necessário o desenvolvimento de técnicas simples, de baixo custo e rápidas para detecção e quantificação daquele metal em cachaça. Neste trabalho, filmes poliméricos de amido e polivinil álcool (PVA), enriquecidos ou não com amilopectina, foram produzidos e utilizados como suporte para a imobilização de antocianina (AN) visando à obtenção de um sensor para detecção de Cu(II) em cachaça. Análises de FTIR mostraram que a incorporação da AN nos filmes ocorreu de forma não covalente. O aumento do teor de amilopectina alterou as propriedades morfológicas dos materiais, como indicado pelas medidas de MEV. O filme mais homogêneo e com baixa solubilidade em cachaça no tempo de análise foi aplicado como sensor na detecção de Cu(II) em amostra real de cachaça contendo o metal. A detecção do metal ocorreu em concentrações a partir de 2,0 mg/L por meio da mudança de cor do sensor de vermelho para verde. A presença do Cu(II) na matriz do filme foi confirmada por XEDS, tendo o metal se distribuído homogeneamente sobre o filme. A resposta do filme à presença do íon metálico dependeu da sua concentração e do pH da amostra. Em pH 7,00 e para concentrações de 5,0 mg/L (concentração máxima de cobre permitido em cachaça pela legislação brasileira) o tempo de resposta foi de 3,16 h, sendo o sensor seletivo para detecção de Cu(II). Diante das características do sensor, evidencia-se a capacidade de aplicação comercial do filme obtido como sensor colorimétrico para identificação de cobre em cachaça de forma simples, de baixo custo e seletiva.Item Immobilization of anthocyanin in polymeric film to obtain a colorimetric sensor for detection of copper in cachaça.(2022) Figueiredo, Matheus Torres Duarte; Ferreira, Gabriel Max Dias; Ruiz Lopez, Melany Alejandra; Cardoso, Maria das Graças; Oliveira, Juliano Elvis de; Bianchi, Rodrigo Fernando; Ferreira, Guilherme Max Dias; Mageste, Aparecida BarbosaCachaça is a uniquely Brazilian product, being the most popular distilled spirit in Brazil and the fourth most consumed world- wide. Its production using copper stills can result in the leaching of the metal, contaminating the product. Then, techniques that are simple, inexpensive, and fast are required for the quantifcation of copper in cachaça. Here, flms composed of starch, with or without enrichment of amylopectin, and polyvinyl alcohol were produced for use as supports to immobilize anthocya- nin, with the aim of obtaining a sensor for detection of Cu2+ in cachaça. FTIR showed that the incorporation of anthocyanin in the flms was according to a non-covalent mechanism. An increase in the amylopectin content altered the morphology of the material, as shown by MEV. The most homogeneous flm, with low solubilization in cachaça, was applied as a sensor to detect Cu2+. The Cu2+ presence in the flm, after its contact with cachaça samples containing Cu2+ at pH 7.0, was confrmed by XEDS, with the metal being homogeneously distributed over the flm. Detection of Cu2+ in the cachaça was achieved by a change of the sensor color from red to green. The LOD and LOQ of the method were 1.39 and 2.00 mg/L, respectively. The method was accurate to determine Cu2+ in real samples of cachaça, with percentual relative error, in modulus, in the range of 3.02–9.54% in comparison with the standard spectrophotometric method using 2,2′-diquinolyn. At pH 7.00 and 5.0 mg/L Cu2+ (the maximum concentration permitted according to Brazilian legislation), the response time of the sensor was 3.16 h, with the sensor being selective towards Cu2+. The characteristics of the sensor evidenced the commercial applicability of the flm as a colorimetric sensor for the simple, inexpensive, and selective identifcation of copper in cachaça.Item Immobilization of anthocyanin in polymeric film to obtain a colorimetric sensor for detection of copper in cachaça.(2022) Figueiredo, Matheus Torres Duarte; Ferreira, Gabriel Max Dias; Ruiz Lopez, Melany Alejandra; Cardoso, Maria das Graças; Oliveira, Juliano Elvis de; Bianchi, Rodrigo Fernando; Ferreira, Guilherme Max Dias; Mageste, Aparecida BarbosaCachaça is a uniquely Brazilian product, being the most popular distilled spirit in Brazil and the fourth most consumed worldwide. Its production using copper stills can result in the leaching of the metal, contaminating the product. Then, techniques that are simple, inexpensive, and fast are required for the quantifcation of copper in cachaça. Here, flms composed of starch, with or without enrichment of amylopectin, and polyvinyl alcohol were produced for use as supports to immobilize anthocyanin, with the aim of obtaining a sensor for detection of Cu2+ in cachaça. FTIR showed that the incorporation of anthocyanin in the flms was according to a non-covalent mechanism. An increase in the amylopectin content altered the morphology of the material, as shown by MEV. The most homogeneous flm, with low solubilization in cachaça, was applied as a sensor to detect Cu2+. The Cu2+ presence in the flm, after its contact with cachaça samples containing Cu2+ at pH 7.0, was confrmed by XEDS, with the metal being homogeneously distributed over the flm. Detection of Cu2+ in the cachaça was achieved by a change of the sensor color from red to green. The LOD and LOQ of the method were 1.39 and 2.00 mg/L, respectively. The method was accurate to determine Cu2+ in real samples of cachaça, with percentual relative error, in modulus, in the range of 3.02–9.54% in comparison with the standard spectrophotometric method using 2,2′-diquinolyn. At pH 7.00 and 5.0 mg/L Cu2+ (the maximum concentration permitted according to Brazilian legislation), the response time of the sensor was 3.16 h, with the sensor being selective towards Cu2+. The characteristics of the sensor evidenced the commercial applicability of the flm as a colorimetric sensor for the simple, inexpensive, and selective identifcation of copper in cachaça.Item Influence of methyl groups in triphenylmethane dyes on their adsorption on biochars from cofee husks.(2022) Castro, Amanda Eugênio de; Martinho, Felipe da Silva; Barbosa, Mylene Lourdes; Franca, José Romão; Soares, Jenaina Ribeiro; Ferreira, Gabriel Max Dias; Ferreira, Guilherme Max DiasBiochars (BC), whose properties are highly dependent on the pyrolysis temperature used, have been proposed for the efcient removal of a vari- ety of contaminants from wastewater. In this work, pristine biochars were produced by the pyrolysis of cofee husks at temperatures of 400, 500, 750, and 900 °C, for use in the adsorption of pararosaniline (PRA) and methyl violet 10B (MV10B), which are triphenylmethane dyes with similar structures, but dif- ferent numbers of methyl groups. The biochars were characterized and the dye adsorption kinetics and equi- libria were investigated. FTIR and Raman spectros- copy analyses indicated that a higher pyrolysis temper- ature increased the aromaticity of the biochar surface structure, while decreasing the number of oxygenate functional groups. Higher adsorption capacities were generally observed at pH 7.5, with the maximum adsorption amounts increasing in the order BC900 ≈ BC750Item Lactoferrin denaturation induced by anionic surfactants : the role of the ferric ion in the protein stabilization.(2018) Ferreira, Gabriel Max Dias; Ferreira, Guilherme Max Dias; Patino Agudelo, Alvaro Javier; Hudson, Eliara Acipreste; Pires, Ana Clarissa dos Santos; Silva, Luis Henrique Mendes daHere, investigation was made of the interaction between lactoferrin (Lf) and the anionic surfactants sodium dodecyl sulfate (SDS), sodium dodecylbenzene sulfonate (SDBS), and sodium decyl sulfate (DSS), using isothermal titration calorimetry, Nano differential scanning calorimetry (NanoDSC), and fluorescence spectroscopy. The Lf-surfactant interaction was enthalpically favorable (the integral enthalpy change ranged from −5.99 kJ mol−1, for SDS at pH 3.0, to −0.61 kJ mol−1, for DSS at pH 12.0) and promoted denaturation of the protein. The Lf denaturation efficiency followed the order DSS < SDS < SDBS. The adsorption capacity of the protein with respect to surfactant strongly depended on pH and the surfactant structure, reaching a maximum value of 505 SDBS molecules per gram of Lf at pH 3.0. The different efficiencies of the surfactants in denaturing Lf were attributed to the balance of hydrophobic and electrostatic interactions, which also depended on pH and the surfactant structure, highlighting the SDBS-tryptophan residue specific interaction, where SDBS acted as a quencher of fluorescence. Interestingly, the NanoDSC and fluorescence measurements showed that the ferric ion bound to Lf increased its stability against denaturation induced by the surfactants. The results have important implications for understanding the influence of surfactants on structural changes in metalloproteins.Item Liquid-liquid extraction of rare earth elements using systems that are more environmentally friendly : advances, challenges and perspectives.(2022) Neves, Heyder Pereira; Ferreira, Gabriel Max Dias; Ferreira, Guilherme Max Dias; Lemos, Leandro Rodrigues de; Rodrigues, Guilherme Dias; Leão, Versiane Albis; Mageste, Aparecida BarbosaThe rare earth elements, a group of metals consisting of the lanthanide series, together with yttrium and scan- dium, are increasingly important in high technology industries worldwide. Given the need to expand production of these elements, there is a search for processes to obtain them that are less environmentally damaging, since the rare earths production chain is associated with several environmental problems and concerns. Solvent extraction, one of the important steps involved in the obtaining of rare earth elements, is receiving much attention in the scientific and industrial community, with a renewed search for approaches that avoid the use of organic solvents. Among the various options, cloud point extraction and the use of aqueous two-phase systems are alternatives to the use of traditional organic solvents. This review considers these two more environmentally friendly techniques and their use for the extraction and/or separation of rare earth elements. The issues addressed include their potential to replace traditional liquid–liquid extraction, in terms of the efficiency, toxicity, and biodegradability of the components forming the systems, as well as their potential applications and future perspectives.Item Liquid−liquid equilibrium of aqueous two-phase systems composed of nonionic surfactant (Triton X‑100, Triton X‑165, or Triton X‑305) and choline chloride.(2019) Silva, Sílvia Juliana Barros e; Ferreira, Gabriel Max Dias; Lemos, Leandro Rodrigues de; Rodrigues, Guilherme Dias; Mageste, Aparecida BarbosaThe study of aqueous two-phase systems (ATPSs) formed by ionic liquids based on the choline cation and nonionic surfactants has received attention in recent years because of the biodegradability and nontoxicity of their components. In this work, liquid–liquid equilibrium data were obtained for ATPSs composed of Triton X (Triton X-100, Triton X-165, and Triton X-305), choline chloride, and water, at 298.15, 313.15, and 328.15 K. In general, these systems presented a top phase rich in choline chloride and a bottom phase rich in surfactant, although the phenomenon of phase inversion was observed for a specific thermodynamic condition of the system formed by Triton X-165. It was observed that increase of the temperature led to an increase of the biphasic region, indicating an endothermic phase separation process. In addition, higher hydrophobicity of the surfactant increased its ability to promote phase segregation (the biphasic region increased in the following order: Triton X-100 > Triton X-165 > Triton X-305). The reliability of the equilibrium data was confirmed using the Othmer–Tobias and Bancroft correlations.Item Modeling adsorption of copper(II), cobalt(II) and nickel(II) metal ions from aqueous solution onto a new carboxylated sugarcane bagasse. Part II : Optimization of monocomponent fixed-bed column adsorption.(2018) Xavier, Amália Luísa Pedrosa; Herrera Adarme, Oscar Fernando; Furtado, Laís Milagres; Ferreira, Gabriel Max Dias; Silva, Luis Henrique Mendes da; Gil, Laurent Frédéric; Gurgel, Leandro Vinícius AlvesIn the second part of this series of studies, the monocomponent adsorption of Cu2+, Co2+ and Ni2+ onto STA adsorbent in a fixed-bed column was investigated and optimized using a 22 central composite design. The process variables studied were: initial metal ion concentration and spatial time, and the optimized responses were: adsorption capacity of the bed (Qmax), efficiency of the adsorption process (EAP), and effective use of the bed (H). The higher Qmax for Cu2+, Co2+ and Ni2+ were 1.060, 0.800 and 1.029 mmol/g, respectively. The breakthrough curves were modeled by the original Thomas and Bohart- Adams models. The changes in enthalpy (DadsH ) of adsorption of the metal ions onto STA were determined by isothermal titration calorimetry (ITC). The values of DadsH were in the range of 3.0–6.8 kJ/mol, suggesting that the adsorption process involved physisorption. Desorption (Edes) and readsorption (Ere-ads) of metal ions from the STA adsorbent were also investigated in batch mode, and the optimum conditions were applied for three cycles of adsorption/desorption in a fixed bed column. For these cycles, the lowest values of Edes and Ere-ads were 95 and 92.3%, respectively, showing that STA is a promising candidate for real applications on a large scale.