Navegando por Autor "Luna, Airton José de"

Agora exibindo 1 - 3 de 3

Photo-Fenton degradation of phenol, 2,4-dichlorophenoxyacetic acid and 2,4- dichlorophenol mixture in saline solution using a falling-film solar reactor
(Taylor and Francis, 2014) Chiavone Filho, Osvaldo; Luna, Airton José de; Nascimento, Cláudio Augusto Oller do; Foletto, Edson Luiz; Moraes, José Ermírio Ferreira de
In this work, a saline aqueous solution of phenol, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-dichlorophenol (2,4-DCP) was treated by the photo-Fenton process in a falling-film solar reactor. The influence of the parameters such as initial pH (5–7), initial concentration of Fe2+ (1–2.5 mM) and rate of H2O2 addition (1.87–3.74 mmol min−1) was investigated. The efficiency of photodegradation was determined from the removal of dissolved organic carbon (DOC), described by the species degradation of phenol, 2,4-D and 2,4-DCP. Response surface methodology was employed to assess the effects of the variables investigated, i.e. [Fe2+], [H2O2] and pH, in the photo-Fenton process with solar irradiation. The results reveal that the variables’ initial concentration of Fe2+ and H2O2 presents predominant effect on pollutants’ degradation in terms of DOC removal, while pH showed no influence. Under the most adequate experimental conditions, about 85% DOC removal was obtained in 180 min by using a reaction system employed here, and total removal of phenol, 2,4- and 2,4-DCP mixture in about 30 min
Photo-Fenton oxidation of phenol and organochlorides (2,4-DCP and 2,4-D) in aqueous alkaline medium with high chloride concentration
(Elsevier, 2012-11-30) Chiavone Filho, Osvaldo; Luna, Airton José de; Machulek Júnior, Amilcar; Nascimento, Cláudio Augusto Oller do; Moraes, José Ermírio Ferreira de
A highly concentrated aqueous saline-containing solution of phenol, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-dichlorophenol (2,4-DCP) was treated by the photo-Fenton process in a system composed of an annular reactor with a quartz immersion well and a medium-pressure mercury lamp (450 W). The study was conducted under special conditions to minimize the costs of acidification and neutralization, which are usual steps in this type of process. Photochemical reactions were carried out to investigate the influence of some process variables such as the initial concentration of Fe2+ ([Fe2+]0) from 1.0 up to 2.5 mM, the rate in mmol of H2O2 fed into the system () from 3.67 up to 7.33 mmol of H2O2/min during 120 min of reaction time, and the initial pH (pH0) from 3.0 up to 9.0 in the presence and absence of NaCl (60.0 g/L). Although the optimum pH for the photo-Fenton process is about 3.0, this particular system performed well in experimental conditions starting at alkaline and neutral pH. The results obtained here are promising for industrial applications, particularly in view of the high concentration of chloride, a known hydroxyl radical scavenger and the main oxidant present in photo-Fenton processes
Photodecomposition of hydrogen peroxide in highly saline aqueous medium
(Brazilian Society of Chemical Engineering, 2006-09) Chiavone Filho, Osvaldo; Luna, Airton José de; Nascimento, Cláudio Augusto Oller do
The photodecomposition of hydrogen peroxide was performed in highly saline aqueous medium (60 g.L-1 of NaCl). The Fe3+/H2O2/NaCl/UV system was tested at temperatures from 20 to 50 o C, while the intervals of concentration of Fe3+ and H2O2 were 1 to 2.5 mM and 230 to 630 mM, respectively. It is known from the literature that chloride is an inhibitor of the oxidation of organic compound in aqueous medium, but this effect has not been observed to be expressive for hydrogen peroxide. Despite this result, experiments were conducted in presence of high concentration of salt (60 g.L-1), emulating the agrochemical process condition. The series of measurements has been evaluated and correlated. Thermal and photochemical dependencies were described satisfactorily by a simplified kinetic model. The apparent activation energy was estimated to be 27.6 kJ.mol-1

SIGAA

Navegando por Autor "Luna, Airton José de"