A novel solution blending method for using olive oil and corn oil as plasticizers in chitosan based organoclay nanocomposites.

In the current study a novel reflux-solution blending method is being followed with the introduction of small ethanol volumes into chitosan acetic acid aquatic solution in order to incorporate olive oil and corn oil in chitosan and its organoclay nanocomposites. Ethanol enables the direct interaction of chitosan with oils and results in effective plasticization of chitosan/oil films with remarkable increase of the strain at break from 8% of chitosan and chitosan/oil aquatic samples to app. 22% for chitosan/oil ethanol samples. Compared with olive oil, corn oil is less effective as plasticizer (max strain at break app. 14%). Addition of oils is beneficial for water sorption, water vapor permeability and oxygen permeability response of the obtained films. Barrier properties are further improved after the use of OrgMMT, however OrgMMT results in significant reduction of strain at break of all oil containing samples (app. 8%) acting as stress concentrator upon deformation.

Photocatalytical removal of fluorouracil using TiO2-P25 and N/S doped TiO2 catalysts: A kinetic and mechanistic study.

In the present study, the photocatalytic activity of TiO2-based photocatalysts toward degradation and mineralization of the anti-cancer drug 5-fluorouracil (5-FU) in aqueous phase was investigated under simulated solar and visible irradiation. Commercial TiO2 (P25) and N/S-doped TiO2 catalysts synthesized by a simple sol-gel method were used as photocatalysts. TiO2 P-25 was found to be the most photoactive catalyst for the removal of 5-FU, under simulated solar irradiation. Among N/S-doped TiO2 catalysts, the one with molar Ti:N/S ratio equal to 0.5 was the most efficient under simulated solar irradiation. In contrast, under visible irradiation the catalyst with equimolar Ti:N/S ratio showed the highest performance for the removal of 5-FU. Scavenging experiments revealed that HO radicals and h+ were the major reactive species mediating photocatalytic degradation of 5-FU using TiO2 P-25 and N/S-doped TiO2 catalysts, under simulated solar irradiation. On the other hand, the essential contribution of 1O2 and O2- in the degradation of 5-FU under visible light was proved. The transformation products (TPs) of 5-FU, were identified by LC-MS-TOF suggesting that defluorination followed by hydroxylation and oxidation are the main transformation pathways, under all the studied photocatalytic systems.

Photocatalytic reduction of Cr(VI) by char/TiO2 composite photocatalyst: optimization and modeling using the response surface methodology (RSM).

The photocatalytic reduction of Cr(VI) using pyrolytic char/TiO2 (PC/TiO2) composite catalyst under simulated solar irradiation was studied. Response surface methodology (RSM) and experimental design were used for modeling the removal kinetics and for the optimization of operational parameters. RSM was developed by considering a central composite design with four input variable, i.e. catalyst concentration, initial concentration of Cr(VI), pH, and % (v/v) methanol concentration for assessing individual and interactive effects. A quadratic model was established as a functional relationship between four independent variables and the removal efficiency of Cr(VI). It was found that all selected variables have significant effect on Cr(VI) removal efficiency; however, the pH, the % concentration of methanol, and their interaction exhibited the major effects. Within the studied experimental ranges, the optimum conditions for maximum Cr(VI) removal efficiency (72.1 %) after 60 min of photocatalytic treatment were: catalyst concentration 55 mg L-1, Cr(VI) concentration 20 mg L-1, pH 4, and 5 % (v/v) methanol concentration. Under optimum conditions, Cr(VI) reductive removal followed pseudo-first-order kinetics, and nearly complete removal took place within 90 min. The results revealed the feasibility and the effectiveness of PC/TiO2 as photocatalyst in reduction reactions due to their ability of e--h+ pair separation increasing the transfer of the photogenerated e- to the catalyst's surface and thus the reduction of Cr(VI).

Variation of surface properties and textural features of spinel ZnAl2O4 and perovskite LaMnO3 nanoparticles prepared via CTAB-butanol-octane-nitrate salt microemulsions in the reverse and bicontinuous states.

Two binary oxides, a spinel, ZnAl2O4, and a typical perovskite, LaMnO3, have been prepared via CTAB-1-butanol-n-octane-nitrate salt microemulsion in the reverse and bicontinuous states. The exact point of the reverse and bicontinuous states of the microemulsion used in the synthesis was determined by conductivity experiments. The materials obtained after heating at 800 degrees C were characterized by XRD analysis for their crystal structure, N2 porosimetry for their surface area and porosity, and SEM and TEM photography for their texture. The ZnAl2O4 spinel obtained via the reverse microemulsion appears in SEM in a more fragmented form and with a higher specific surface area (143.7 m(2)g(-1)), compared to the corresponding solid prepared via the bicontinuous microemulsion, which appears more robust with lower surface area (126.7 m(2)g(-1)). Nevertheless both materials reveal in TEM a sponge-like structure. The perovskite materials LaMnO3 prepared via the reverse microemulsion showed in SEM a peculiar doughnut-like texture, each doughnut-like secondary particle having a diameter of 2 microm. The corresponding sample developed via the bicontinuous microemulsion showed in SEM uniform secondary particles of size approximately 0.2 microm. Both perovskite samples LaMnO3 appear well crystallized with relative low surface areas, 23.7 m(2)g(-1) for the reverse sample and 10.9 m(2)g(-1) for the bicontinuous one. The TEM photographs reveal that both of them, of reversed and bicontinuous origin, are made up of primary nanoparticles in the size range 40-100 nm. In SEM those materials showed a different secondary structure.