Navegando por Autor "Almeida, Hanna Nóbrega"
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Artigo Characterization and pyrolysis of Chlorella vulgaris and Arthrospira platensis: potential of bio-oil and chemical production by Py-GC/MS analysis(Springer Nature, 2017-04-17) Melo, Marcus Antônio de Freitas; Almeida, Hanna Nóbrega; Calixto, Guilherme Quintela; Chagas, Bruna M. E.; Melo, Dulce Maria de Araújo; Resende, Fabio M.; Braga, Renata MartinsBiofuels have been seen as potential sources to meet future energy demand as a renewable and sustainable energy source. Despite the fact that the production technology of first-generation biofuels is consolidated, these biofuels are produced from foods crops such as grains, sugar cane, and vegetable oils competing with food for crop use and agricultural land. In recent years, it was found that microalgae have the potential to provide a viable alternative to fossil fuels as source of biofuels without compromising food supplies or arable land. On this scenario, this paper aims to demonstrate the energetic potential to produce bio-oil and chemicals from microalgae Chlorella vulgaris and Arthrospira platensis. The potential of these biomasses was evaluated in terms of physical-chemical characterization, thermogravimetric analysis, and analytical pyrolysis interfaced with gas chromatograph (Py-GC/MS). The results show that C. vulgaris and A. platensis are biomasses with a high heating value (24.60 and 22.43 MJ/kg) and low ash content, showing a high percentage of volatile matter (72.49 and 79.42%). These characteristics confirm their energetic potential for conversion process through pyrolysis, whereby some important aromatic compounds such as toluene, styrene, and phenol were identified as pyrolysis products, which could turn these microalgae a potential for biofuels and bioproduct production through the pyrolysisTCC Extração e purificação parcial de antocianinas do mirtilo com remoção simultânea dos açúcares redutores usando o Sistema de duas fases aquosas etanol/sulfato de amônio(Universidade Federal do Rio Grande do Norte, 2016-12-02) Almeida, Hanna Nóbrega; Santos, Everaldo Silvino dos; Padilha, Carlos Eduardo de Araújo; Nogueira, Cleitiane CostaO Sistema de Duas Fases Aquosas (SDFA) etanol/ sulfato de amônio ((NH4)2SO4) foi empregado a fim de extrair e, preliminarmente, purificar antocianinas obtidas a partir do Vaccinium uliginosum, conhecido popularmente como mirtilo. Vários fatores que influenciam a formação do SDFA foram investigados tais como a concentração de sal e álcool, quantidade de extrato de mirtilo, e o pH do sistema, a fim de melhorar desempenho da extração. Para o sistema, determinaram-se as condições ótimas de 30% (m/m) de etanol, 20%(m/m) de (NH4)2SO4, com a adição de 10% de extrato, sob pH 5,0. Essas condições permitiram obter índices de recuperação e coeficiente de partição de antocianina iguais a 95,5 % e 15,6, respectivamente; embora tenha-se obtido baixo desempenho na remoção de açúcares redutores. Apesar disto, o uso da Extração em Duas Fases Aquosas (EDFA) para a recuperação de biomoléculas é uma tecnologia viável, sendo possível utilizá-la na extração de antocianinas obtidas do mirtilo.Artigo 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 deIn 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 extractsArtigo The energetic characterization of pineapple crown leaves(Springer Nature, 2015-08-02) Melo, Marcus Antônio de Freitas; Braga, Renata Martins; Queiroga, T. S.; Calixto, Guilherme Quintela; Almeida, Hanna Nóbrega; Melo, Dulce Maria de Araújo; Freitas, Júlio César de Oliveira; Curbelo, Fabiola Dias da SilvaEnergetic characterization of biomass allows for assessing its energy potential for application in different conversion processes into energy. The objective of this study is to physicochemically characterize pineapple crown leaves (PC) for their application in energy conversion processes. PC was characterized according to ASTM E871-82, E1755-01, and E873-82 for determination of moisture, ash, and volatile matter, respectively; the fixed carbon was calculated by difference. Higher heating value was determined by ASTM E711- 87 and ash chemical composition was determined by XRF. The thermogravimetric and FTIR analyses were performed to evaluate the thermal decomposition and identify the main functional groups of biomass. PC has potential for application in thermochemical processes, showing high volatile matter (89.5 %), bulk density (420.8 kg/m3), and higher heating value (18.9 MJ/kg). The results show its energy potential justifying application of this agricultural waste into energy conversion processes, implementing sustainability in the production, and reducing the environmental liabilities caused by its disposal