Effects of synthesis parameters on the properties and photocatalytic activity of the magnetic catalyst TiO2/CoFe2O4 applied to selenium photoreduction

intake to human health. Heterogeneous photocatalysis can be successfully applied to remove selenium ions from water, but the photocatalyst recovery in the end of the process still needs improvement. The application of a magnetic photocatalyst (TiO2/CoFe2O4) in the Se(IV) photoreduction was investigated, with emphasis in the catalyst magnetic separation. The photocatalyst was synthetized via a simple sol-gel method and a central composite design was considered to evaluate the effects of titanium isopropoxide mass ratio used in the synthesis, calcination temperature and pH on Se(IV) reduction. Calcination temperature showed a strong influence in the photocatalytic activity, and the catalyst calcined at 381 ◦C presented the best performance. In the bests test, at pH 2.61, it was possible to remove >99% selenium after 2 min of exposure to radiation. Photocatalysts containing great amounts of rutile phase produced the lowest removal results. The TiO2/CoFe2O4 photocatalyst was magnetically separable, however its saturation magnetization (2.7 emu g 1) was considerably smaller than pure CoFe2O4 (84.6 emu g 1) and the photocatalyst magnetic separation from the aqueous medium was about 11 times slower in comparison to pure cobalt ferrite. The synthetized photocatalyst was able to satisfactorily photoreduce Se(IV) (96.5%) even after five cycles of photocatalysis

Respiration of yellow bell pepper 'Zarco HS' under influence of the maturation stage and of the storage temperature

The respiratory rate of the yellow bell pepper 'Zarco HS' was determined under influence of the stadium of maturation at harvest and at storage temperature. The bell peppers were placed inside tightly closed flasks and conditioned in 4 BODs with different temperatures: 5; 10; 15 and 25ºC, for the products harvested at summer, and 5; 10; 15 and 20ºC, for harvested at winter. Five flasks were used with approximately 0.5 kg of product. The system of continuous air flow was used inside of the flasks with aid of a flow board. The readings of CO2 were made in gaseous chromatograph VARIAN 3400, being accomplished five readings for each temperature during a period of seven days, in the summer, and 8 days, in the winter. After the end of the winter experiment, the temperature of BODs was maintained at 10ºC for the conduction of the second study. In this second study, bell peppers with 25%; 50%; 75% and 100% of yellow coloration were stored for determination of the respiratory rate for six days. The experimental design was completely randomized, with five repetitions in both studies. The ripening of the yellow bell pepper was characterized by the increment of respiratory rate, and the temperature of 5ºC resulted in larger reduction of this process.Determinou-se a taxa respiratória do pimentão amarelo 'Zarco HS' sob influência do estádio de maturação na colheita e da temperatura de armazenamento. Os pimentões foram colocados em frascos hermeticamente fechados e acondicionados em 4 BODs com diferentes temperaturas: 5; 10; 15 e 25ºC, para os produtos colhidos no verão, e 5; 10; 15 e 20ºC, para os colhidos no inverno. Foram utilizados cinco frascos com aproximadamente 0,5 kg de produto por temperatura. Foi utilizado o sistema de fluxo contínuo de ar dentro dos frascos com auxílio de um fluxômetro (flow board). As leituras do CO2 foram feitas em cromatógrafo gasoso VARIAN 3400, sendo realizadas cinco leituras por temperatura durante um período de sete dias, no verão, e 8 dias, no inverno. Após o término do experimento de inverno, a temperatura das BODs foi mantida a 10ºC para a condução do segundo estudo. Neste, pimentões com 25%; 50%; 75% e 100% de coloração amarela foram armazenados para determinação da taxa respiratória durante seis dias. O delineamento experimental utilizado, em ambos os estudos, foi o inteiramente casualizado com cinco repetições. O amadurecimento do pimentão amarelo caracterizou-se por acréscimo na taxa respiratória, sendo que a temperatura de 5ºC resultou em maior redução deste processo, em frutos de pimentão amarelo.717

Physico-chemical characterization of 'Zarco HS' yellow bell pepper for different ripeness stages Caracterização físico-química de pimentão amarelo 'Zarco HS' em diferentes estádios de maturação

The bell pepper presents alterations in its composition and its properties with the process of senescence during ripening. These composition and textual factors are part of the quality of the fruit and therefore of the selection. This permits the correct knowledge of the factors necessary for post-harvest measures, so that they can be adequately applied. The aim of this study is to analyze the 'Zarco HS' yellow pepper at various levels of ripeness taking into account its physico-chemical properties (titratable acidity, pH, total soluble solids, water content, and ascorbic acid), in order to understand this behavior during the ripening process. Bell peppers were separated based on their yellow percentage, which varied from 0% to 100%, and for each percentage five fruits were chosen as replicates. They were compared to 0%, 25%, 50%, 75% and 100% levels of ripening, due to the difficulty of the methodology in identifying the smaller differences between coloring. The 'Zarco HS' yellow bell pepper presents greater levels of soluble solids and lower levels of malic acid as the percentage of external yellow coloring increases. The yellow bell peppers, especially when totally yellow, represent an important source of vitamin C.<br>O pimentão apresenta, durante seu amadurecimento, alterações com o processo de senescência. Estes fatores de composição e propriedades texturais fazem parte da qualidade de frutas e hortaliças e, portanto da seleção. Isto faz com que seja necessário o correto conhecimento destes fatores, para que, através de testes físico-químicos, as tecnologias de conservação após a colheita possam ser adequadamente aplicadas. Este trabalho teve por objetivo analisar o pimentão amarelo 'Zarco HS' com vários graus de maturação quanto às propriedades físico-químicas (acidez titulável, pH, sólidos solúveis totais, teor de umidade e ácido ascórbico), para conhecimento deste comportamento durante o processo de amadurecimento. Os pimentões foram separados pela porcentagem de amarelo, que variou de 0% a 100%, e para cada porcentagem foram escolhidos 5 frutos, sendo cada fruto uma repetição. Os frutos foram comparados por faixas de amadurecimento, 0%, 25%, 50%, 75% e 100% devido à dificuldade de metodologia para identificar diferenças menores entre as colorações. O pimentão amarelo 'Zarco HS' apresenta níveis maiores de sólidos solúveis e níveis menores de ácido málico conforme aumenta a porcentagem externa de coloração amarelo. Pimentões, principalmente os totalmente amarelos, representam importante fonte de vitamina C