Enzymatic Hydrolysis of Cassava Starch Using Barley Malt Amylases

Barley malt was used as a source of amylases for the hydrolysis of cassava starch to produce reducing sugars for the alcoholic fermentation. Two routes of hydrolysis were evaluated in this work. One using milled barley malt and the other using the enzyme extract of this grain. The first one evaluated three concentrations of milled barley malt: 5, 10 and 15% (w/w) and there was no significant difference between the values of reducing sugars obtained as a function of the three concentrations. Three concentrations were also tested for barley malt extract: 0.5, 1.0 and 1.5 mL of extract. The higher content of reducing sugars was found for the 0.5 mL concentration of extract. The barley malt extract was more efficient in the enzymatic hydrolysis of cassava starch due to a better contact of the enzymes with substrate. The alcoholic fermentation of the wort obtained with 0.5 mL yielded an ethanol content of 7.74 ± 3.19 g/L with an efficiency of 88.6%. DOI: http://dx.doi.org/10.17807/orbital.v13i3.152

Uma alternativa sustentável: aplicação do resíduo do ácido 3,5 dinitro salícilico em células solares / An sustainable alternative: application of 3,5 dinitrosalicylic acid residue in solar cells

Células solares sensibilizadas por corante (CSSC) são dispositivos promissores para conversão de energia. Os corantes empregados nas CSSCs, geralmente baseados em rutênio, são sintéticos e, apresentam um custo elevado, conduzindo ao estudo de novos materiais fotossensibilizadores para serem aplicados. Uma alternativa sustentável é a utilização do ácido 3,5 dinitrosalícilio (DNS) e do seu resíduo após a análise de açúcares redutores, o 3-amino 5–nitrosalícilio (ANS), que é tóxico ao meio ambiente e não têm valor comercial após utilização. Este trabalho teve como objetivo produzir e analisar um sistema fotovoltaico contendo DNS e ANS, com fins de se agregar valor e incentivar a aplicação sustentável de descartes poluentes. As técnicas empregadas foram Espectroscopia na região do Ultravioleta – visível (Vis), fotocronoamperometria (j-t) e curvas de densidade de corrente em função do potencial (j- E). Os corantes empregados apresentaram bandas de absorção na região do visível e foram capazes de produzir um dispositivo fotovoltaico como verificado pelas análises foto-eletroquímicas, com uma foto-corrente de 55 µA cm-2 para o DNS e 20 µA cm-2 para o resíduo

Persea pyrifolia Peel Extract as a Carbon Steel Corrosion Inhibitor

Carbon steel is one of the most widely used alloys in industrial applications. However, the use of this metal may be limited because of corrosion tendency. Thus, it is necessary to develop methods that inhibit its degradation. One way to inhibit corrosion is to use organic inhibitors. Some organic compounds with heteroatoms inhibit corrosion by forming a protective film. In this study, the corrosion inhibition of carbon steel 1020 in 0.1 mol L-1 hydrochloric acid medium was evaluated. The natural inhibitor used was an aqueous extract of the bark of Persea pyrifolia (PP) plant at concentrations of 2.5, 5 and 10% V / V. The electrochemical response was determined by open circuit potential measurements, electrochemical impedance spectroscopy, and anodic potentiodynamic polarization. Therefore, mass loss was measured, and inhibitory efficiency was evaluated. The best results were observed for the concentration of 2.5% V / V of Persea pyrifolia extract, presenting and inhibition efficiency of 82.5% on the 1020 carbon steel. The electrochemical results indicates that PP extract can be used as green corrosion inhibitor in acidic medium. DOI: http://dx.doi.org/10.17807/orbital.v13i2.146