Sonophotocatalytic Degradation of Poly (Vinyl Pyrrolidone) in the Presence of Fe (III)/H2O2
N. S. Orang,
R. Abdollahi
Issue:
Volume 3, Issue 3, June 2014
Pages:
26-32
Received:
1 March 2014
Accepted:
12 April 2014
Published:
30 June 2014
Abstract: The degradation of poly (vinyl pyrrolidone) (PVP) by means of ultrasound irradiation and its combination with homogeneous photocatalysis (photo-Fenton) was investigated. Emphasis was given on the effect of additive on degradation rate constants. 24 kHz of ultrasound irradiation was provided by a sonicator, while an ultraviolet source of 16 W was used for UV irradiation. To increase the efficiency of degradation process, degradation system was combined with Fe (III) (2.510-4mol/L) and H2O2 (0.020 - 0.118 mol/L) in the presence of UV irradiation and the rate of degradation process change from 4.07x10-5 to 8.24x10-5 mol15 l-1.5 min-1. Photo-Fenton process led to complete PVP degradation in 150 min with the rate increasing with increasing catalyst loading. Sonophotocatalysis in the presence of Fe (III)/H2O2 was always faster than the respective individual processes. A negative order for the dependence of the reaction rate on total molar concentration of PVP solution within the degradation process was suggested. Results of this study indicate that the presence of catalyst in the reaction medium can be utilized to reduce molecular weight of PVP while maintaining the power of irradiated ultrasound.
Abstract: The degradation of poly (vinyl pyrrolidone) (PVP) by means of ultrasound irradiation and its combination with homogeneous photocatalysis (photo-Fenton) was investigated. Emphasis was given on the effect of additive on degradation rate constants. 24 kHz of ultrasound irradiation was provided by a sonicator, while an ultraviolet source of 16 W was us...
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Controlling the Passive Oxide Film Formation on Indium Electrode in Na2B4O7 Solutions
Ahmed Diab,
Salah Abd El Wanees
Issue:
Volume 3, Issue 3, June 2014
Pages:
33-40
Received:
8 July 2014
Accepted:
18 July 2014
Published:
20 August 2014
Abstract: The oxide film formation and growth on indium electrode in Na2B4O7 solutions have been studied using polarization technique. The effects of concentration of Na2B4O7, pH and temperature of electrolyte solution are investigated based on the formation of oxide film. It was found that lowering the concentrations of Na2B4O7 solutions, pH or decreasing of temperature of the solution assist the formation of a passive oxide film on indium electrode. The corrosion current density, icorr, increased with increasing the concentrations of Na2B4O7 solutions, pH and the rising of solution temperature. The free activation energy of oxide film growth process is determined to be 15.7kJ/mole. The above studies indicate that the oxide film growth process is diffusion-controlled. The effect of addition of NaCl, NaBr, and NaI with different amounts was also investigated. Higher concentrations of these salts lead to the dissolution of the passive oxide film due to the increasing of corrosion current density, icorr, and the shift of corrosion potential, Ecorr, to more active potentials.
Abstract: The oxide film formation and growth on indium electrode in Na2B4O7 solutions have been studied using polarization technique. The effects of concentration of Na2B4O7, pH and temperature of electrolyte solution are investigated based on the formation of oxide film. It was found that lowering the concentrations of Na2B4O7 solutions, pH or decreasing o...
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