Water: From pollution to purification.

International audienc

Development and validation of a high-performance thin layer chromatography method for the determination of cholesterol concentration

An accurate, sensitive, precise, reliable, and quick method for the determination of cholesterol content by high-performance thin layer chromatography is developed. In this method, aluminum-backed precoated silica gel 60 F254 plates were used as the stationary phase and the samples were sprayed with the help of CAMAG sample applicator Linomat 5. The chromatogram was developed with the mobile phase consisting of chloroform:methanol (9.5:0.5, v/v). The samples were detected using CAMAG Scanner 4 and evaluated using the method developed on winCATS software. Densitometric analysis of cholesterol was performed in absorbance mode at 200 nm. In this solvent system, cholesterol gave a compact spot with an Rf value of 0.63 ± 0.03. The linear regression analysis of data for the calibration curve showed good linearity over a concentration range of 2–7 μg/spot with a regression value of 0.99933 and standard deviation of 1.44%. The limit of detection and limit of quantification were found to be 100 ng/spot and 500 ng/spot, respectively. Using the developed method, the concentration of cholesterol in the saponified and unsaponified egg yolk sample was determined. This method was found to be reproducible and can even be used for samples containing complex matrices

Electro-Fenton degradation of 4-aminosalicylic acid: Mineralization pathway using Pt/carbon-felt and BDD/carbon-felt cells.

International audienc

Oxidative degradation of benzoic acid using Fe0- and sulfidized Fe0-activated persulfate: A comparative study

Implications of sulfidized Fe-0(nFe/FeS) for the abatement of pollutants of various categories are widely established. In this study, degradation of one of the major organic pollutants, benzoic acid (BA), has been performed using persulfate activated with nFe/FeS. Complete degradation of BA and its transformed product, hydroxybenzoic acid, was observed within 6 min. When the degradation was performed at alkaline pH, the degradation decreased to 8% in the case of Fe-0, but nFe/FeS still showed 100% degradation after 60 min. Iron dissolution and persulfate decomposition in the presence of scavengers showed that both sulfate and hydroxyl radicals were involved in the Fe-0-persulfate system and that the hydroxyl radicals were the major species in the nFe/FeS-persulfate system. The major degradation pathway of benzoic acid was hydroxylation followed by complete mineralization, as supported by the practical removal of total organic carbons (more than 75% within 15 min). The observed results are promising in using perstlfate activated by nFe/FeS for the remediation of various micro-pollutants from a multitude of water sources. (C) 2017 Elsevier B.V. All rights reserved.1195sciescopu

Electro-Fenton oxidation of para-aminosalicylic acid: Degradation kinetics and mineralization pathway using Pt/carbon-felt and BDD/carbon-felt cells.

International audienc

Electro-oxidation of the Dye Azure B: Kinetics, mechanism and by-products

International audienc

Oxidative degradation study on antimicrobial agent Ciprofloxacin by electro-Fenton process: Kinetics and oxidation products

International audienc

Analysis of uranium and other water quality parameters in drinking water sources of 5 districts of Kerala in southern India and potability estimation using water quality indexing method

An analysis on the presence of uranium in drinking water sources of five districts in Kerala, Southern India has been carried out. 830 Samples from different sources during pre and post-monsoon seasons were subjected to the analysis for uranium and 11 other water quality parameters. The concentration of uranium was found to be varying from <0.5–12.54 μg/L in pre-monsoon and <0.5–5.93 μg/L in post-monsoon which is well within the standard limit i.e. 30 μg/L. Water Quality Indexing analysis shows that only less than 10% of the samples are unsuitable for drinking purpose. From the present study, it is clear that the current drinking water sources used by the public in the study area contain no or very low concentration of U and the overall water quality is satisfying the potability requirements and it is suitable for drinking water purpose

Ultrafast transient-absorption and steady-state fluorescence measurements on 2-aminopurine substituted dinucleotides and 2-aminopurine substituted DNA duplexes

Ultrafast transient-absorption and steady-state fluorescence measurements have been performed on dinucleotides comprising the fluorescent adenine analogue 2-aminopurine and guanine, adenine, cytosine, thymine or hypoxanthine, respectively. Two oligodeoxyribonucleotide duplexes that were site-selectively substituted with a single 2-aminopurine moiety were also studied. A strong quenching of the steady-state fluorescence was observed in all samples. The transient-absorption spectra were remarkably similar to those of the isolated 2-aminopurine (Larsen et al.; O. F. A. Larsen, I. H. M. van Stokkum, M.-L. Groot, J. T. M. Kennis, R. van Grondelle and H. van Amerongen, Chem. Phys. Lett., 2003, 371, 157-163), exhibiting both a fluorescent and a non-fluorescent excited state. There was no evidence for significant amounts of charge-separated states in the transient-absorption spectra. The probability that an excitation of 2AP leads to stable charge transfer products was estimated to be very low (0.1%). In the systems we studied, the observed fluorescence quenching can largely be explained by a shift of the equilibrium between the two excited states in 2AP, in which the non-fluorescent state is favore

Ultrafast transient-absorption and steady-state fluorescence measurements on 2-aminopurine substituted dinucleotides and 2-aminopurine substituted DNA duplexes

Ultrafast transient-absorption and steady-state fluorescence measurements have been performed on dinucleotides comprising the fluorescent adenine analogue 2-aminopurine and guanine, adenine, cytosine, thymine or hypoxanthine, respectively. Two oligodeoxyribonucleotide duplexes that were site-selectively substituted with a single 2-aminopurine moiety were also studied. A strong quenching of the steady-state fluorescence was observed in all samples. The transient-absorption spectra were remarkably similar to those of the isolated 2-aminopurine (Larsen et al.; O. F. A. Larsen, I. H. M. van Stokkum, M.-L. Groot, J. T. M. Kennis, R. van Grondelle and H. van Amerongen, Chem. Phys. Lett., 2003, 371, 157-163), exhibiting both a fluorescent and a non-fluorescent excited state. There was no evidence for significant amounts of charge-separated states in the transient-absorption spectra. The probability that an excitation of 2AP leads to stable charge transfer products was estimated to be very low (0.1%). In the systems we studied, the observed fluorescence quenching can largely be explained by a shift of the equilibrium between the two excited states in 2AP, in which the non-fluorescent state is favore