3,003 research outputs found
Current advances on the photocatalytic degradation of fluoroquinolones: photoreaction mechanism and environmental application
No full textHeterogeneous photocatalysis is one of the most studied and promising techniques for degradation of contaminants of emerging concern, especially pharmaceuticals, and it represents a potential application in wastewater treatment of recalcitrant pollutants, such as fluoroquinolones, which are almost not abated by standard WWTPs. Although photodegradation partially contributes to alleviate their accumulation into the aquatic systems, heterogeneous photocatalysis assures complete sequestration and mineralization of FQs and their photoproducts and offers many advantages with respect to the other advanced oxidation processes (AOPs). The present brief review summarizes the most recent studies regarding the development and application of novel photocatalytic materials to the removal of FQs from contaminated waters. The collected data are arranged relating the mechanistic aspects to specific catalysts' properties, such as adsorption capacity, easy recovery, and reusability, especially under actual conditions.[GRAPHICS]
Photoarylation/Alkylation of Bromo-Naphthols
No full textThe photochemistry of 6-bromo-2-naphthols has been studied in acetonitrile, aqueous acetonitrile, and isopropyl alcohol in the absence and in the presence of triethylamine by product distribution analysis, laser flash photolysis (LFP), fluorescence, phosphorescence, electrochemical measurements, and DFT calculations. Hydrobromic acid loss in the presence of Et3N occurs from the triplet state of 6-bromo-2-naphthol, generating an electrophilic carbene intermediate, which has been successfully trapped by oxygen, allyltrimethylsilane, 2,3-dimethylbut-2-ene, pyrrole, acrylonitrile, 1,4-dimethoxybenzene, and also pyridine.
The generation and the reactivity of a triplet carbene intermediate has been supported by LFP, with the
detection of 2,6-naphthoquinone-O-oxide (530-650 nm) in the presence of O2. The electrophilic diradical character of the carbene has been supported by DFT calculations, using the B3LYP, PBE0, and MPWB1K functionals, with the 6-31+G(d,p) basis set and PCM solvation model
Solid-Phase Extraction and HPLC determination of fluoroquinolones in surface waters
No full textAn investigation on filtration procedures and SPE sorbents used for the determination of traces of the most common veterinary fluoroquinolones (FQs), marbofloxacin (MAR) and enrofloxacin (ENR) used as antibacterial agents in cattle and swine farms in the province of Pavia (Italy), was performed in natural waters. The composition and the sorbent used in the SPE strongly influence the correct recovery,both in terms of total and issolved FQs concentration. An accurate comparison among different filters and SPE sorbents showed that a full determination of analytes was possible on nylon filters followed by anionic (WAX) and hydrophilic–lipophilic balance (HLB) resins as SPE. Quantitative analysis was done by chromatography with fluorescence detection (HPLC-FD). Fluoroquinolones recovery was between 90 and 116% with RSD not greater than 10% (sample volume 250 mL). The developed method allowed to determine both dissolved and NOM-absorbed fractions of FQs, therefore a full determination of the analytes was possible. Limits of detection (LOD) and quantification (LOQ) were, respectively, 0.7 and 2.2 ng/L for ENR and 2 and 6 ng/L for MAR. The kinetics of degradation under solar light was explored
Analytical Determination and Electrochemical Characterization ofthe Oxazolidinone Antibiotic Linezolid
No full textLinezolid belongs to a class of antibiotics known as oxazolidinones. It is receiving great attention due to its activity
toward multidrugs resistant bacteria, and simple and cheap methods for the analysis of this compound in pharmaceutical
preparations are required. In this work, the electrochemistry of the antibiotic linezolid was investigated and
a differential pulse voltammetric method based on the oxidation of the oxazolidinonic compound at a glassy carbon
electrode has been developed and optimized for its determination; LOD of 50 mgL1 and a linearity up to
200 mgL1 were reported. The electrochemical process was studied by using different electrochemical techniques
and confirmed by HPLC-MS/MS
Photochemistry of some non zwitterionic fluoroquinolones
No full textTwo non zwitterionic analogues of fluoroquinolone drugs, viz. 1-ethyl-7-piperidino-8-fluoroquinol-4-
one-3-carboxylic acid and 1-ethyl-7-piperidino-6,8-difluoroquinol-4-one-3-carboxylic acids have been
synthesized and their photochemistry has been investigated. Both compound undergo photoheterolysis
of the C8 F bond generating a triplet cation that either inserts into the 1-alkyl chain or is trapped or
reduced by external nucleophiles. The reaction is analogous to that observed with the corresponding
(zwitterionic) 7-piperazino derivatives, but the quantum yield is ca five times lower. This supports the
rationalization that in the latter case assistance to defluorination by the N+ H bond has a determining
role
Photoarylation of Alkenes and Heteroaromatics by Dibromo-BINOLs in Aqueous Solution
No full textThe photochemistry of 6,6’-dibromo-BINOLs (BINOL=2,2’-dihydroxy-1,1’-binaphthyl) under mild conditions has been investigated in neat and aqueous acetonitrile through product distribution analysis and laser flash photolysis. Arylation and alkylation have been successfully achieved in the presence of allyltrimethylsilane, ethyl vinyl ether, pyrrole, pyridine, thiophene, benzene, and indole. Such a photoreactivity offers a metal and protecting group free synthetic protocol toward mono- and disubstituted 6-aryl/alkyl BINOLs, since the BINOL chirality is preserved in the photoactivation process
Detailed analytical study of radiolysis products of simple organic compounds as a methodological approach to investigate prebiotic chemistry—Part 1
No full textAqueous solutions of simple organic C1 compounds(methanol and acetonitrile) and ammonia, presumably present on primordial Earth, were subjected to 60Co gamma irradiation(total dose 800kGy).The irradiation gave a complex mixture of organic compounds leading interestingly to a positive balance of synthesis vs. degradation reactions. Inparticular, if acetonitrile was used, nucleobase analogues could be detected among
products. Highly sensitive and powerful analytical techniques(e.g.GC–MS,HPLC-MS) made this investigation feasible at areas on able cost in terms of time and results. Plausible reaction pathways leading to major compounds were proposed, supported by literature dat
Botanical and biological pesticides elicit a similar Induced Systemic Response in tomato (Solanum lycopersicum) secondary metabolism
No full textNatural pesticides have attracted substantial interest due to the increase in organic agriculture and enhanced attention to environmental pollution. Plant Growth Promoting Bacteria (PGPB) are applied for both disease control and growth enhancement; PGPBs are known to elicit Induced Systemic Response (ISR) in plants. However, less is known about the effect of botanical pesticides, such as the azadirachtincontaining neem extracts, on plant metabolism. This study aimed to investigate the effects of foliar application of the above-mentioned natural pesticides on the metabolic profiling of tomato. Leaf application of Bacillus subtilis fostered Induced Systemic Resistance (ISR) in treated plants via the Jasmonic acid pathway, and enhanced production of secondary metabolites such as flavonoids, phytoalexins and auxins. Changes in sterols and terpenes, as well as an increase in glucosinolates were also observed. Interestingly, azadirachtin-treated tomatoes also showed an increase in ISR and our results revealed that most of the enriched metabolites are shared with a B. subtilis treatment, suggesting conserved biochemical responses. These (un)expected findings indicate that plants are not insensitive to application of natural pesticide and while Azadirachtin is applied as a direct pesticide, it also stimulates a defense response in tomatoes very similar to B. subtilis induced ISR
An assessment of the impact of possible CAP reform scenarios on Romanian agriculture
No full textUsing a simplified model, with key-variable the prices of two different possible scenarios of CAP reform after 2013 (moderate and radical), this paper present a comparison between the price effects of implementation of each reform scenario at 2015 horizon on Romanian agriculture. This short analysis shows that, under the presented hypotheses, the net welfare effect, due to the price changes, for the selected products, is positive in both reform scenarios, yet greater in the case of the radical reform. Integrated in the large context of Romanian development, it seems that the influence of CAP reform upon agriculture and rural areas will be most likely a gradual one: an interpenetration between the two scenarios is foreseeable, starting with the moderate reform that will dominate the period around 2013, the reform measures acquiring a more radical character afterwards.CAP reform, Romania, welfare effects, Agricultural and Food Policy,
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