Photoassisted Degradation of a Herbicide Derivative, Dinoseb, in Aqueous Suspension of Titania

The titanium dioxide (TiO2) photoassisted degradation of herbicide dinoseb has been examined in aqueous suspensions under UV light irradiation. The degradation kinetics were studied under various conditions such as substrate concentration, type of catalyst, catalyst dosage, pH, and light intensity as well as in presence of electron acceptors such as hydrogen peroxide, potassium bromate, and potassium persulphate under continuous air purging, and the degradation rates were found to be strongly influenced by these parameters. The Degussa P25 was found to be more efficient photocatalyst as compared to other photocatalysts tested. Dinoseb was found to degrade efficiently in acidic pH and all the electron acceptors studied enhanced the degradation rate. The results manifested that the photocatalysis of dinoseb followed pseudo-first-order kinetics. A qualitative study of the degradation products generated during the process was performed by GC-MS, and a degradation mechanism was proposed

Titanium Dioxide-Mediated Photcatalysed Degradation of Two Herbicide Derivatives Chloridazon and Metribuzin in Aqueous Suspensions

The aim of this paper is to find out the optimal degradation condition for two potential environmental pollutants, chloridazon and metribuzin (herbicide derivatives), employing advanced oxidation process using TiO2 photocatalyst in aqueous suspensions. The degradation/mineralization of the herbicide was monitored by measuring the change in pollutant concentration and depletion in TOC content as a function of time. A detailed degradation kinetics was studied under different conditions such as types of TiO2 (anatase/anatase-rutile mixture), catalyst concentration, herbicide concentration, initial reaction pH, and in the presence of electron acceptors (hydrogen peroxide, ammonium persulphate, potassium persulphate) in addition to atmospheric oxygen. The photocatalyst, Degussa P25, was found to be more efficient catalyst for the degradation of both herbicides as compared with two other commercially available TiO2 powders like Hombikat UV100 and PC500. Chloridazon (CHL) was found to degrade more efficiently under acidic condition, whereas metribuzin (MET) degraded faster under alkaline medium. All three electron acceptors tested in this study were found to enhance the degradation rate of both herbicides

Dynamic Patterns of Circulating Seasonal and Pandemic A(H1N1)pdm09 Influenza Viruses From 2007–2010 in and around Delhi, India

Influenza surveillance was carried out in a subset of patients with influenza-like illness (ILI) presenting at an Employee Health Clinic (EHS) at All India Institute of Medical Sciences (AIIMS), New Delhi (urban) and pediatric out patients department of civil hospital at Ballabhgarh (peri-urban), under the Comprehensive Rural Health Services Project (CRHSP) of AIIMS, in Delhi region from January 2007 to December 2010. Of the 3264 samples tested, 541 (17%) were positive for influenza viruses, of which 221 (41%) were pandemic Influenza A(H1N1)pdm09, 168 (31%) were seasonal influenza A, and 152 (28%) were influenza B. While the Influenza viruses were detected year-round, their types/subtypes varied remarkably. While there was an equal distribution of seasonal A(H1N1) and influenza B in 2007, predominance of influenza B was observed in 2008. At the beginning of 2009, circulation of influenza A(H3N2) viruses was observed, followed later by emergence of Influenza A(H1N1)pdm09 with co-circulation of influenza B viruses. Influenza B was dominant subtype in early 2010, with second wave of Influenza A(H1N1)pdm09 in August-September, 2010. With the exception of pandemic H1N1 emergence in 2009, the peaks of influenza activity coincided primarily with monsoon season, followed by minor peak in winter at both urban and rural sites. Age group analysis of influenza positivity revealed that the percent positivity of Influenza A(H1N1)pdm09 influenza virus was highest in >5–18 years age groups (OR 2.5; CI = 1.2–5.0; p = 0.009) when compared to seasonal influenza. Phylogenetic analysis of Influenza A(H1N1)pdm09 from urban and rural sites did not reveal any major divergence from other Indian strains or viruses circulating worldwide. Continued surveillance globally will help define regional differences in influenza seasonality, as well as, to determine optimal periods to implement influenza vaccination programs among priority populations

Photocatalytic degradation of a widely used insecticide Thiamethoxam in aqueous suspension of TiO2: Adsorption, kinetics, product analysis and toxicity assessment

This paper deals with the study of photocatalyzed degradation of an insecticide, Thiamethoxam in aqueous suspension of TiO2. The adsorption of Thiamethoxam on TiO2 surface under dark conditions was also investigated in order to find out equilibrium adsorption constant The degradation kinetics was studied using spectrophotometric method under various conditions such as substrate concentration, type of catalyst, catalyst dosage, pH, and in the presence of electron acceptors such as hydrogen peroxide, potassium bromate, and ammonium persulphate under continuous purging of atmospheric oxygen, and the degradation rates were found to be strongly influenced by these parameters. The results manifested that the photocatalysis of Thiamethoxam follows pseudo-first-order kinetics. The toxicity assessments of the irradiated samples were carried out using human erythrocytes as a model system under in vitro conditions. GC MS study showed the formation of several intermediate products which were characterised based on their molecular mass and mass fragmentation pattern. A probable mechanism for the formation of various products formed during the photocatalytic process of Thiamethoxam was also proposed. (C) 2013 Elsevier B.V. All rights reserved

Photocatalytic degradation of herbicide Bentazone in aqueous suspension of TiO2: mineralization, identification of intermediates and reaction pathways

Semiconductor-mediated hydrogen peroxide-assisted photocatalytic degradation of a selected herbicide, Bentazone (1) has been investigated in aqueous suspensions of TiO2 under a variety of conditions. The degradation was studied by monitoring the depletion in total organic carbon content as a function of irradiation time. The degradation kinetics was investigated under different conditions such as type of TiO2 (Anatase/Anatase-Rutile mixture), reaction pH, catalyst dosage and hydrogen peroxide (H2O2) concentration. The degradation rates were found to be strongly influenced by all the above parameters. Titanium dioxide Degussa P25 was found to be more efficient as compared with other two commercially available TiO2 powders like Hombikat UV100 and PC500 from Millennium Inorganic Chemicals. Gas Chromatography-Mass Spectrometry (GC-MS) analysis of the irradiated mixture of Bentazone (1) indicates the formation of several intermediate products which have been characterized on the basis of molecular ion/mass fragmentation pattern and also on comparison with the National Institute of Standards and Technology (NIST) library. Plausible mechanism for the formation of different products during photocatalytic treatment of Bentazone in the presence of TiO2 has been proposed. The use of H2O2 substantially increased the efficiency of TiO2 photocatalytic degradation

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Not AvailableSaffron is an important spice derived from the stigmas of Crocus sativus, a species belonging to the family Iridaceae. Due to its triploid nature it is sterile and is not able to set seeds, so it is propagated only by corms. The natural propagation rate of most geophytes including saffron is relatively low. Anin vitro multiplication technique like micropropagation has been used for the propagation of saffron. In the present study, various explants were cultured on different nutrient media supplemented with various concentrations of plant growth regulators to standardize the best media combination for obtaining optimum response with respect to corm production and development of Stigma Like Structures (SLS). Highest response (60%) was observed with half ovaries on G-5 media supplemented with 27μM NAA and 44.4μM BA followed by 55% on LS media with 27μM NAA and 44.4μM BA. Maximum size (1.3 g) of microcorms were obtained from apical buds on the LS media supplemented with 21.6μM NAA and 22.2μM. Stigma Like Structures were developed from half ovary explants both directly and indirectly. Maximum number (120 indirectly and 20 directly) and size (5.2 cm) of SLS were obtained in G-5 medium supplemented with 27μM NAA and 44.4μM BA followed by 100 indirectly and 20 directly and 4.5 cm long on LS medium supplemented with 27μM NAA and 44.4μM BA.Not Availabl

Heterogeneous photocatalysed degradation of an insecticide derivative acetamiprid in aqueous suspensions of semiconductor

The photocatalytic degradation of an insecticide derivative, acetamiprid has been investigated in aqueous suspensions of titanium dioxide (TiO2) as a function of irradiation time under a variety of conditions using UV-Vis and HPLC analysis techniques. The degradation kinetics were studied under different conditions such as types of TiO2, catalyst and substrate concentration, reaction pH and in the presence of electron acceptors like hydrogen peroxide (H2O2), potassium bromate (KBrO3), and potassium persulphate (K2S2O8) besides molecular oxygen (O-2). The degradation rates were found to be strongly influenced by all the above parameters. The photocatalyst, Degussa P25 was found to be more efficient as compared to other TiO2 powders used under these studies. The model compound was found to degrade more efficiently in alkaline pH and all electron acceptors enhanced the degradation rate. GC/MS analysis of the irradiated samples indicated the formation of several by-products. A probable mechanism for the formation of by-products has been proposed. (C) 2010 Elsevier B.V. All rights reserved

Solar Photocatalytic Decolorization of Two Azo Dye Derivatives, Acid Red 17 and Reactive Red 241 in Aqueous Suspension

The photocatalytic decolorization approach using sunlight has potential applications in the treatment of effluents from textile dye industries. With this aim, the decolorization of two representative commercially used textile azo dye derivatives such as AR17 and RR241 have been investigated under sunlight and atmospheric oxygen in aqueous suspension of titanium dioxide by monitoring the change in concentration using UV-Vis. Spectrophotometry. A detailed decolorization kinetics of both dye derivatives have been investigated under variety of conditions such as type of TiO2 powders (Anatase/Anatase-rutile mixture), catalyst dose, substrate concentration, pH and electron acceptors (H2O2 and KBrO3). The highest decolorization rate for dye derivative AR17 and RR241 were observed at pH 7.5 and 6.0, respectively. The photocatalyst Degussa P25 having 80:20 anatase:rutile mixture was found to be better for the decolorization of both the dyes as compared to two other photocatalysts tested. The decolorization rate was enhanced in the presence of electron acceptors such as H2O2 and KBrO3. Results demonstrated that the decolorization of dyes under sunlight is strongly influenced by different parameters investigated in this paper

Semiconductor Mediated Photocatalysed Reaction of Two Selected Organic Compounds in Aqueous Suspensions of Titanium Dioxide

Semiconductor mediated hydrogen peroxide-assisted photocatalytic degradation of two selected pesticide compounds, chloramben (1) and cyanazine (2) has been investigated in aqueous suspensions under a variety of conditions. The degradation was studied by monitoring the depletion in total organic carbon (TOC) content and decrease in substrate concentration as a function of irradiation time. The degradation kinetics of pesticide compounds 1 and 2 were investigated under different conditions such as type of TiO2 (Anatase/Anatase-Rutile mixture), reaction pH, catalyst dosage and hydrogen peroxide (H2O2) concentration. The degradation rates were found to be strongly influenced by all the above parameters. Titanium dioxide Degussa P25 was found to be more efficient as compared with other two commercially available TiO2 powders like Hombikat UV100 and PC500 from Millennium Inorganic Chemicals. GC-MS analysis of the irradiated mixture of pesticide compounds 1 and 2 indicate the formation of several intermediate products which have been characterized on the basis of molecular ion/mass fragmentation pattern and also on comparison with the NIST library. Plausible mechanism for the formation of different products involving the reaction of hydroxyl and super oxide radical anions with 1 and 2 has been proposed