Occurrence and removal of pharmaceutical and personal care products using subsurface horizontal flow constructed wetlands.

A significant number of emerging pollutants resulting from point source and diffuse pollution are present in the aquatic environment. These are chemicals that are not commonly monitored, but have the potential to cause adverse effects on human and ecological health. One form of emerging pollutants, pharmaceutical and personal care products (PPCPs), are becoming a serious problem in the discharge of domestic wastewater.

Behavior of ionophore antibiotics in aquatic environments in Argentina: The distribution on different scales in water courses and the role of wetlands in depuration.

We studied for the first time three ionophore anticoccidial drugs: monensin (MON), lasalocid (LAS), and salinomycin (SAL) as emerging pollutants originating from animal and plant husbandry in surface waters (n = 89) in one of the most extensive hydrological basins in South América (Del Plata basin). The soluble fraction of ionophores was pretreated by solid-phase extraction and analyzed by LC-MS/MS at a limit of detection of 1.7 ng·L.

Pharmaceutical emerging pollutants removal from water using powdered activated carbon: Study of kinetics and adsorption equilibrium.

Pharmaceutical products and their byproducts which are present in wastewater and superficial water are becoming an environmental problem. A large effort has been made to introduce new and more efficient treatment processes for removing these emerging pollutants. Among them, activated carbon is currently being studied to be implemented in wastewater treatment plants.

Correlation between DAS-28 and neopterin as a biochemical marker of immune system activation in early rheumatoid arthritis.

Objective: The objective of this study was to evaluate neopterin plasma concentrations in patients with early Rheumatoid Arthritis (RA) and correlate them with disease activity.

Methods: This is a 28-month prospective study carried out on 65 individuals. There were 27 patients with early RA and 38 healthy volunteers as control group.

Intermediate distributions and primary yields of phenolic products in nitrobenzene degradation by Fenton's reagent.

Nitrobenzene thermal degradation was investigated using the Fenton reagent in different experimental conditions. Reaction products were analyzed by HPLC, GC-MS, LC-MS and IC. The products obtained at different nitrobenzene conversion degrees show that degradation mainly involves successive hydroxylation steps of the aromatic ring and its subsequent opening followed by oxidation of corresponding aliphatic compounds.

Oxidation of 2'-deoxyguanosine 5'-monophosphate photoinduced by pterin: type I versus type II mechanism.

UV-A radiation (320-400 nm) induces damage to the DNA molecule and its components through different photosensitized reactions. Among these processes, photosensitized oxidations may occur through electron transfer or hydrogen abstraction (type I) and/or the production of singlet molecular oxygen ((1)O2) (type II). Pterins, heterocyclic compounds widespread in biological systems, participate in relevant biological processes and are able to act as photosensitizers.

Photosensitization of 2'-deoxyadenosine-5'-monophosphate by pterin.

UV-A radiation (320-400 nm) induces damages to the DNA molecule and its components through photosensitized reactions. Pterins, heterocyclic compounds widespread in biological systems, participate in relevant biological processes and are able to act as photosensitizers. We have investigated the photosensitization of 2'-deoxyadenosine-5'-monophosphate (dAMP) by pterin (PT) in aqueous solution under UV-A radiation.

Photooxidation of pterin in aqueous solutions: biological and biomedical implications.

Studies of the photochemical reactivity of pterin (= 2-aminopteridin-4(3H)-one; PT) in acidic (pH 5.0-6.0) and alkaline (pH 10.

Reactivity of conjugated and unconjugated pterins with singlet oxygen (O2(1Deltag)): physical quenching and chemical reaction.

Pterins (PTs) belong to a class of heterocyclic compounds present in a wide range of living systems. They participate in relevant biological functions and are involved in different photobiological processes. We have investigated the reactivity of conjugated PTs (folic acid [FA], 10-methylfolic acid [MFA], pteroic acid [PA]) and unconjugated PTs (PT, 6-hydroxymethylpterin [HPT], 6-methylpterin [MPT], 6,7-dimethylpterin [DPT], rhamnopterin [RPT]) with singlet oxygen (1O2) in aqueous solutions, and compared the efficiencies of chemical reaction and physical quenching.

Substituent effects on the photophysical properties of pterin derivatives in acidic and alkaline aqueous solutions.

Pterins are heterocyclic compounds with important biological functions, and most of them may exist in two acid-base forms in the pH range between 3 and 13 in aqueous solution. In this work, the photophysical properties of acid and basic forms of six compounds of the pterin family (6-hydroxymethylpterin [HPT], 6-methylpterin [MPT], 6,7-dimethylpterin [DPT], rhamnopterin [RPT], N-methylfolic acid [MFA], and pteroic acid [PA]) have been studied. The effects of the chemical nature of the substituents at position 6 of the pterin moiety and the effects of the pH on the absorption and emission properties are analyzed.

Photochemical behavior of 6-methylpterin in aqueous solutions: generation of reactive oxygen species.

Pterins are a family of heterocyclic compounds present in a wide range of living systems that participate in relevant biological functions and are involved in different photobiological processes. 6-Methylpterin (MPT) was investigated for its efficiency of singlet-oxygen (1O2) production and quenching in aqueous solution. The quantum yields of 1O2 production (phi(delta)) was determined by measurements of the 1O2 luminescence in the near-infrared upon continuous excitation of the sensitizer.

Physicochemical and toxicological studies on 4-chloro-3,5-dinitrobenzoic acid in aqueous solutions.

Physicochemical characterization of hazardous compounds often is required for the development of structure-reactivity correlations. Physical, chemical, and toxicological properties of target pollutants require determination for an efficient application of wastewater treatments. In the present work, we chose a chloro-nitro-aromatic derivative (4-chloro-3,5-dinitrobenzoic acid [CDNBA]), as a model compound on which to perform physicochemical and toxicological studies.

Temperature effects on the quenching of the 5D0-->7F2 emission of Eu(6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionate)3 by a Cu(II) macrocycle.

Luminescence quenching of Eu(fod)3(fod = 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionate) by a Cu(II) macrocycle was studied at 25, 35 and 45 degrees C by steady-state and flash luminescence techniques, varying the Cu(II) concentration between 0.2 and 20 mM. Experimental variation of the observed rate constant with the quencher concentration is rationalized in terms of a mechanism involving the quenching of two unequilibrated species by the Cu(II) macrocycle.

Quenching of the fluorescence of pterin derivatives by anions.

Steady-state and time-resolved studies of the fluorescence of pterins in aqueous solutions in the presence of different anions have been performed using the single-photon counting technique. In the pH range between 3 and 13, most pterins exist in a protonated and a deprotonated form. Results obtained for both acid and basic forms of five compounds belonging to the pterin family (pterin, 6-carboxypterin, 6-formylpterin, biopterin and neopterin) show that the fluorescence of the acid forms is dynamically quenched by phosphate and acetate, and the corresponding bimolecular rate constants of fluorescence quenching (k(q)) are reported.

Competition kinetics using the UV/H2O2 process: a structure reactivity correlation for the rate constants of hydroxyl radicals toward nitroaromatic compounds.

The rate constants for hydroxyl radical reaction toward a set of nitroaromatic substrates kS, have been measured at 25 degrees C using competition experiments in the UV/H2O2 process. For a given pair of substrates S1 and S2, the relative reactivity beta (defined as kS1/kS2) was calculated from the slope of the corresponding double logarithmic plot, i.e.

Fluorescence of pterin, 6-formylpterin, 6-carboxypterin and folic acid in aqueous solution: pH effects.

Steady-state and time-resolved studies have been performed on four compounds of the pterin family (pterin, 6-carboxypterin, 6-formylpterin and folic acid) in aqueous solution, using the single photon counting technique. The fluorescence characteristics (spectra, quantum yields, lifetimes) of these compounds and their dependence on the pH have been investigated. Most pterins can exist in two acid-base forms over the pH range between 3 and 13.

Singlet oxygen (1deltag) production by pterin derivatives in aqueous solutions.

Six compounds of the pterin family (pterin, 6-carboxypterin, 6-formylpterin, folic acid, biopterin and neopterin) have been investigated for their efficiencies of singlet oxygen (O2(1deltag)) production and quenching in aqueous solutions. The quantum yields of 1O2 production (phidelta) have been determined by measurements of the 1O2 luminescence in the near-infrared (1270 nm) upon continuous excitation of the sensitizer. Under our experimental conditions, all studied compounds (except folic acid) are relatively efficient 1O2 sensitizers with phidelta values of up to 0.

Degradation of nitroaromatic compounds by the UV-H2O2 process using polychromatic radiation sources.

The UV-H2O2 process, a standard advanced oxidation process (AOP) for water treatment, has been applied to the degradation of a series of nitroaromatic compounds (nitrobenzene, 1-chloro-2,4-dinitrobenzene, 2,4-dinitrophenol, 3-nitrophenol, 4-nitrophenol and 4-chloro-3,5-dinitrobenzoic acid) using polychromatic radiation sources. The optimal concentration of hydrogen peroxide ([H2O2]OPT) leading to the fastest degradation rate of a given substrate (S) was determined experimentally and estimated using a simplified kinetic model based on the main reactions involved in the first stages of the oxidation. We have shown that, under conditions of monochromatic irradiation, the ratio ROPT (= [H2O2]OPT/[S]0) is given by a simple mathematical expression containing only a few parameters, whereas, under conditions of polychromatic irradiation, ROPT is expressed by a complex mathematical equation (involving the spectral distribution of the lamp emission and the absorption spectra of H2O2 and the substrate).

Evaluation of the efficiency of photodegradation of nitroaromatics applying the UV/H2O2 technique.

Photolysis of nitroaromatic compounds in aqueous solution is a very slow and inefficient process. As already observed for a variety of organic pollutants, considerably faster degradation rates of nitrobenzene (NBE), 1-chloro-2,4-dinitrobenzene (CDNB), 2,4-dinitrophenol (DNP), and 4-nitrophenol (PNP) could be achieved, when the oxidative degradation of these compounds was initiated by hydroxyl radicals produced by UV-C photolysis of H2O2. Analysis of intermediate products formed during irradiation by HPLC and IC showed that cleavage of the aromatic ring should occur at an early stage of the oxidation process and that organic nitrogen was almost completely converted to nitrate.