Photocatalytic degradation of non-steroidal anti-inflammatory drugs with TiO2 and simulated solar irradiation

The aim of this work is to evaluate and compare the degradation achieved for three non-steroidal anti-inflammatory drugs (NSAIDs) by heterogeneous TiO2 photocatalytic means in aqueous solution at laboratory scale. The selected pharmaceutical compounds were diclofenac (DCF), naproxen (NPX) and ibuprofen (IBP). These compounds were used in their sodium salt chemical form. Previous experiments (adsorption, photolysis and thermodegradation) were developed to evaluate non-catalytic degradation for each NSAID. Photocatalytic experiments were carried out in a Xe-lamp reactor in order to study the influences of different operational conditions (catalyst load, temperature and dissolved oxygen concentration). These results showed that the optimum amount of TiO2, to achieve maximum degradation, of IBP was 1g/L. In contrast, the maximum degradation for DCF or NPX was observed at a TiO2 loading of 0.1g/L. Temperature had a significant effect only for NPX degradation, achieving almost 99% phototransformation. No significant differences were observed for DCF and IBP at 20, 30 and 40 degrees C. Dissolved oxygen concentration was an important parameter to increase the degradation for NPX and IBP. However, it was observed that its rate of mineralization did not increase. Intermediate metabolites were detected in all cases. Hydroxyl metabolites were the most important residual compounds after the photocatalytic treatment of IBP. The inhibition percentage of bioluminescence from Vibro fischeri--as a toxicity parameter--increased during the irradiation time due to the residual concentration of the hydroxyl metabolites generated. However, after 120 min, in experiments with 40 mg/L of dissolved oxygen, a decrease of the % inhibition was observed. Only photocatalytic treatment of IBP drives to a satisfactory biodegradability index BOD5/COD (between 0.16 and 0.42) and, only in this case, a post-biological treatment could be suggested.     

Factors determining the photovoltaic performance of a CdSe quantum dot sensitized solar cell: the role of the linker molecule and of the counter electrode

Colloidal CdSe quantum dots (QDs) of different sizes, prepared by a solvothermal route, have been employed as sensitizers of nanostructured TiO(2) electrode based solar cells. Three different bifunctional linker molecules have been used to attach colloidal QDs to the TiO(2) surface: mercaptopropionic acid (MPA), thioglycolic acid (TGA), and cysteine. The linker molecule plays a determinant role in the solar cell performance, as illustrated by the fact that the incident photon to charge carrier generation efficiency (IPCE) could be improved by a factor of 5-6 by using cysteine with respect to MPA. The photovoltaic properties of QD sensitized electrodes have been characterized for both three-electrode and closed two-electrode solar cell configurations. For three-electrode measurement a maximum power conversion efficiency near?1% can be deduced, but this efficiency is halved in the closed cell configuration mainly due?to?the decrease of the fill factor (FF).     

Interaction of uranium with in situ anoxically generated magnetite on steel

In the high level nuclear waste repository concept, spent nuclear fuel is designed to be encapsulated in steel canisters. Thus, it is necessary to study the influence of the steel and/or its corrosion products on the behaviour of the radionuclides released from the fuel. In this sense, the main objective of this work is to contribute to the knowledge of the influence of the steel and/or its corrosion products on the uranium(VI) retention. To this aim, magnetite (Fe(3)O(4)) has been generated by anaerobic steel corrosion in an autoclave reactor at an overpressure of 8atm of H(2)(g). After characterisation by X-ray diffraction (XRD), the obtained corroded steel coupons were contacted, at two different H(2)(g) pressures (1atm and 7.6atm), with a U(VI) solution. The evolution of the uranium concentration in solution is determined and a study of the composition of the coupons at the end of the experiments is carried out. The main conclusion obtained from this work is that magnetite generated on a steel coupon is able not only to retain uranium via sorption, but also to reduce hexavalent to tetravalent uranium in a higher extent than commercial magnetite, thus, providing an effective retardation path to the migration of uranium (and, potentially, other actinides) out of the repository.     

Quality Attributes and Shelf Life of High-Pressure Preserved Beef as Affected by Pre-treatment Conditions

This study analyzed the effects of high hydrostatic pressure (HHP) and composition of the pre-treatment immersion step, on quality attributes (color and lipid oxidation) and shelf life based on microbial counts of a beef product, during cold storage at 0 °C. Meat slices were immersed in a preservative solution containing sodium nitrite, ascorbic acid, and two different concentrations of NaCl (30 and 60 g/L); HHP of 400 and 600 MPa were applied. Results were compared with those of an untreated beef control. Color parameters of the HHP-treated beef were visually acceptable (a* > 14) in all tested cases, although they were affected by NaCl concentration and the applied pressure. HHP increased TBARS index, observing higher values at 600 than at 400 MPa; samples immersed in the solution containing 30 g/L NaCl presented higher TBARS values. However, in all cases, they remained below the detection limit of rancid meat products (<1 mg MDA/kg). Beef samples immersed in the solution with the highest concentration of NaCl (60 g/L) and subjected to 400 or 600 MPa maintained their microbial stability over 5 and 6 weeks, respectively, at 0 °C; these shelf life values were higher than those observed in the samples treated with 30 g/L NaCl.     

Nylon fibers coated with diclofenac: adsorption properties

Dried gauzes properly coated with anti-inflammatory drugs could be helpful in providing topical treatment in inflammatory process. Therefore, thermodynamic of adsorption of Diclofenac Sodium, over Nylon fibers, as a function of concentration, temperature, and pH of the medium, have been studied. Maximum amount adsorbed in the best conditions tested, pH 5.6, 323 K and initial concentration of 150 mg/L has been 2.6 mg/g. Isotherm adsorption data were well fitted to the Langmuir and Freundlich model; therefore, multilayer formation must be considered. Negative and low values of free-energy change, ?17.9 kJ/mol and ?15.9 kJ/mol, in addition to moderate value of activation energy 13.14 kJ/mol point to physical interactions governing the process that, besides, is exothermic with negative enthalpy-change, ?43.44 kJ/mol, and also follows pseudo-first order kinetic model that is typical of this interaction. Desorption experiments carried out under physiological conditions confirm that the proposed procedure for DCF administration could be achieved.     

A transportation model approach for constructing the cost effective central hydrogen supply system in Korea

One of the major tasks in transition to a hydrogen economy is to build a cost-effective infrastructure of hydrogen supply. Building an infrastructure of hydrogen supply includes a series of logistical steps from production through delivery and storage to utilization of the hydrogen. This paper attempts to build the cost-effective central hydrogen supply system using a transportation model. As a case study, a hydrogen delivery plan for 2040 was established by dividing the Korean peninsula into two regions, northern and southern regions. Average hydrogen delivery distances for 2040 in the northern and the southern regions are estimated as 69.8 km and 85.2 km. The subsequently derived hydrogen supply network of centrally produced hydrogen in 2040 is expected to be similar to the liquefied natural gas pipeline network in 2005. The derived hydrogen supply network, delivery distances, and delivery costs are expected to provide a set of basic and indispensable information in building a cost-effective infrastructure of hydrogen supply in the Korean peninsula.     

Integrating software and hardware hierarchies in an autotuning method for parallel routines in heterogeneous clusters

The Journal of Supercomputing - A hierarchical approach for autotuning linear algebra routines on heterogeneous platforms is presented. Hierarchy helps to alleviate the difficulties of tuning...     

Direct Management or Inter-Municipal Cooperation in Smaller Municipalities? Exploring Cost Efficiency and Installed Capacity in Drinking Water Supply

Water Resources Management - The aim of this study is to determine whether, in small municipalities, drinking water services are supplied more efficiently under direct public provision or through...