Mechanisms of interactions and the significance of different colloidal structures in the vertical transport of glyphosate in soils with contrasting mineralogies.

Soil is regarded as a natural repository for strongly adsorbed pollutants since glyphosate (GLY) is preferentially adsorbed by the inorganic fraction of the soil, which may greatly limits its leaching. In this way, understanding how clay mineralogy influences the sorption and transport processes of glyphosate in soils with different mineralogical characteristics is highly relevant. In this work, two clay mineralogy contrasting soils were used to evaluate GLY retention: a Oxisol (OX) with high levels of iron oxides (amorphous and crystalline) and a Inceptisol (IN) with a predominance of kaolinite.

Photocatalytic degradation of bisphenol-A (BPA) over titanium dioxide, and determination of its by-products by HF-LPME/GC-MS.

In this work, analytical strategies were developed based on the technique of hollow fiber liquid-phase microextraction and chromatographic methods (LC-UV and GC/MS). These methods allowed the identification of the main Bisphenol-A by-products applying heterogeneous photocatalysis in water samples. BPA degradation in this study was in the order of 90%, and the conditions used in the HF-LPME were optimized through 2 factorial design (6 cm fiber length, stirring speed of 750 rpm, and an extraction time of 30 min).

Simultaneous multi-residue pesticide analysis in southern Brazilian soil based on chemometric tools and QuEChERS-LC-DAD/FLD method.

A simple and straightforward QuEChERS extraction method was proposed for the simultaneous determination of atrazine (ATZ), desethylatrazine (DEA), desisopropylatrazine (DIA), carbaryl (CBL), carbendazim (CBD), and diuron (DIU) in soil with high agricultural activity from southeastern Brazil, using high-performance liquid chromatography-diode-array detection/fluorescence detection. Screening studies carried out by 2 factorial design indicate better recoveries when less sample (1.0 g) and the volume of solvent (2.

Understanding the nature of Fenton processes in soil matrices: The role of iron forms and organic matter.

Understanding the processes of pollutants removal in soil remediation practices is crucial to apply the appropriate treatment method. Although widely employed in soil contamination events, the mechanisms of the Fenton reaction are still debatable. To investigate the catalytic performance of soils towards the degradation of p-xylene in Fenton reactions, we performed a series of experiments employing two soil samples with different physical-chemical properties, Oxisol and Alfisol.

Relationship of the physicochemical properties of novel ZnO/biochar composites to their efficiencies in the degradation of sulfamethoxazole and methyl orange.

Three different composites were produced, based on zinc oxide and biochar (ZnO/biochar), varying the type of biomass (Salvinia molesta: SM; exhausted husk of black wattle: EH; and sugarcane bagasse: SB), with pyrolysis under mild conditions at 350 and 450 °C. Evaluation was made of the capacities of the composites for photocatalytic degradation of sulfamethoxazole antibiotic (SMX) and methyl orange dye (MO). The properties of the prepared composites were influenced by the biomass source, with larger crystallite size (SB), lower band gap energy (SM), higher specific surface area (SB), and larger pore size (SM) resulting in higher photocatalytic efficiency.

Use of scavenger agents in heterogeneous photocatalysis: truths, half-truths, and misinterpretations.

Even though a gap exists in understanding the behavior of radical scavengers and interfering species, they have been extensively employed to elucidate degradation mechanisms or to improve the degradation efficiency in heterogeneous photocatalysis. Focusing on the influence of different species, such as scavengers (t-butanol, formic acid, methanol, p-benzoquinone, oxalate, superoxide dismutase, and azide), interfering species (sulfite, dichromate, bromate, carbonate, chloride, and iodide) and inorganic ions (nitrate, sulfate, and phosphate), this work investigated the production of hydroxyl radicals and singlet oxygen during TiO/UVA reactions. Electron paramagnetic resonance spectroscopy (EPR) was applied to investigate radicals formed in the presence of each interfering/scavenger species.

Visible-light reduced silver nanoparticles' toxicity in Allium cepa test system.

Silver nanoparticles (AgNPs) are widely used in consumer products due to their antibacterial property; however, their potential toxicity and release into the environment raises concern. Based on the limited understanding of AgNPs aggregation behavior, this study aimed to investigate the toxicity of uncoated (uc-AgNP) and coated with polyvinylpyrrolidone (PVP-AgNP), at low concentrations (0.5-100 ng/mL), under dark and visible-light exposure, using a plant test system.

Evaluation of the Fenton process effectiveness in the remediation of soils contaminated by gasoline: Effect of soil physicochemical properties.

The remediation of four different soils contaminated by gasoline was performed using Fenton processes. Herein, the effect of the main physicochemical characteristics of the soils in the Fenton performance is emphasized. Fenton processes were applied in a column system, with and without addition of soluble iron (II), using undisturbed soil samples collected in four regions of the Paraná State (Brazil).

Evaluation of a Hollow-Fiber Liquid-Phase Microextraction Technique for the Simultaneous Determination of PPI Drugs in Human Plasma by LC-DAD.

This study involved the development, validation and application of a three-phase hollow-fiber liquid-phase microextraction (HF-LPME) and liquid chromatography with diode array detection (LC-DAD) method for the simultaneous determination of the proton pump inhibitor (PPI) drugs omeprazole, pantoprazole and lansoprazole in human plasma. The evaluation of the HF-LPME parameters was crucial for the determination of the drugs and the conditions selected were: 1-octanol as solvent; phosphate buffer at pH 5 as donor phase; borate buffer at pH 10 as acceptor phase; extraction time of 15 min; stirring at 750 rpm and NaCl was added at 5% (w/v). Validation of the method according to US-FDA recommendations showed a good linear range (0.

Statistical analysis of wheat under different seed treatments: development of a discriminative model based on physicochemical and rheological properties.

Background: Quality control in the wheat industry comprises numerous analyses that are time-consuming and demand numerous procedures and specific apparatus. The application of multivariate calibration techniques contributes to the interpretation of the data generated during these analyses. The present study aimed to correlate a representative number of wheat properties with the treatment applied to the wheat seeds using multivariate calibration techniques.

New insight into monitoring degradation products during the TiO-photocatalysis process by multivariate molecular spectroscopy.

This study focuses on the feasibility of a spectroscopic multivariate method for monitoring the concentration of phenol and its main degradation products during heterogeneous photocatalysis. Phenolic compounds were chosen as model to evaluate the degradation process due to their toxicity and persistence in the environment and also their well-known degradation pathway. The predictive capability of the multivariate method developed by partial least squares regression (PLSR) over the spectral range of 200-350 nm was satisfactory, allowing mean predicted errors below 5.

Microcystin-LR degradation by solar photo-Fenton, UV-A/photo-Fenton and UV-C/H2O2: a comparative study.

This work assessed the effectiveness of several methods on degradation of microcystin-LR (MC-LR) by different Advanced Oxidation Processes, like solar photo-Fenton, UV-A/photo-Fenton and UV-C/H2O2. UV-C/H2O2 and UV-A/photo-Fenton processes were carried out in a bench scale photochemical apparatus and the solar photo-Fenton treatment was performed in a CPC photoreactor. MC-LR degradation was monitored by LC-ESI-MS/MS and kinetic parameters were calculated for all systems evaluated.

Photocatalytic degradation of microcystin-LR in aqueous solutions.

In this work, the photocatalytic degradation of aqueous microcystin-LR was studied using TiO(2) and ZnO as photocatalysts. The process was optimised and characterised at the bench scale (200 mL); both semiconductors exhibited a high degradation capacity at reaction times of 1 min (degradation greater than 95%). The transient species that were observed indicate that the degradation occurs via the multiple hydroxylation and elimination of the labile peptide residues of the molecule.

TiO2 and ZnO mediated photocatalytic degradation of E2 and EE2 estrogens.

In this work, the photocatalytic degradation of selected estrogens (E2 and EE2) was evaluated, using bench-scale and continuous treatment systems assisted by artificial UV-A and solar radiation. Processes based on the use of TiO2 permit an efficient degradation of E2 and EE2 estrogens, usually at reaction times lower than 15 min. Especially remarkable is the high degradation efficiency shown by sunlight-assisted processes, which are extremely favored by the high efficiency of compound parabolic collectors.

Multivariate optimization of mercury determination by flow injection-cold vapor generation-inductively coupled plasma optical emission spectrometry.

In this work a procedure for mercury determination by Flow Injection-Cold Vapor Generation-Inductively Coupled Plasma Optical Emission Spectrometry (FI-CVG-ICP OES) has been developed. The system uses a small homemade glass separator constructed to drive the Hg vapor to the plasma. An evolutionary operation factorial design was used to evaluate the optimal experimental conditions for mercury vapor generation, aiming at the low consumption of reagents, the improvement of the analytical signal and consequently greater sensitivity.

Distribution and origin of polycyclic aromatic hydrocarbons in surface sediments from an urban river basin at the Metropolitan region of Curitiba, Brazil.

The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) were determined in surface sediment samples from nine sites located at the Iguaçu River Basin in the Metropolitan Region of Curitiba, Brazil to evaluate their distribution and sources. The total concentration of the PAHs was greater for sediments from highly urbanized areas, while the sediments from the Iraí Environmental Protection Area (Iraí EPA) showed significantly low concentrations. The sediments from the Iguaçu and Barigui rivers were classified as highly contaminated, while those from the Cercado and Curralinho rivers were classified as moderately contaminated.

Production of rhamnolipids in solid-state cultivation: Characterization, downstream processing and application in the cleaning of contaminated soils.

Pseudomonas aeruginosa UFPEDA 614 produced a rhamnolipid biosurfactant when grown on sugarcane bagasse impregnated with a solution containing glycerol. Biosurfactant levels reached 40 g of rhamnolipid per kilogram of dry initial substrate after 12 days. On the basis of the volume of liquid used, the biosurfactant levels were similar to those obtained in submerged liquid culture of a medium identical to the impregnating solution.

Multivariate monitoring of soybean oil ethanolysis by FTIR.

In this work, an analytical procedure was developed to monitor the ethanolysis of degummed soybean oil (DSO) using Fourier-transformed mid-infrared spectroscopy (FTIR) and methods of multivariate analysis such as principal component analysis (PCA) and partial least squares regression (PLS). The triglycerides (reagents) and ethyl esters (products) involved in ethanolysis were shown to have similar FTIR spectra. However, when the FTIR spectra derived from seven standard mixtures of triolein and ethyl oleate were treated by PCA at the region that represents the CO stretching vibration of ester groups (1700-1800cm(-1)), only two principal components (PC) were shown to capture 99.

Multifactorial optimization approach for the determination of polycyclic aromatic hydrocarbons in river sediments by gas chromatography-quadrupole ion trap selected ion storage mass spectrometry.

A procedure for the determination of very low polycyclic aromatic hydrocarbons (PAHs) concentrations in sediment samples has been developed by gas chromatography-quadrupole ion trap mass spectrometry (GC-QIT MS) after extraction with dichloromethane and purification by using silica gel cleanup. Identification and quantification of analytes were based on the selected ion storage (SIS) strategy using deuterated PAHs as internal standards. In order to search out the main factors affecting the SIS mass spectrometry efficiency, four MS parameters, including target total ion count (TTIC), waveform amplitude (WA), transfer line (XLT) and ion trap temperatures (ITT) were subjected to a complete multifactorial design.

Photochemically-assisted electrochemical degradation of landfill leachate.

In this work, the treatment of landfill leachates by a photoelectrochemical procedure is reported. When applied to untreated leachates the photochemical system was significantly hindered on account of the characteristic dark coloration of the samples. At this condition the degradation process was essentially electrochemical permitting typical color and COD removal of about 50% and 20%, respectively.

Degradation of aqueous solutions of camphor by heterogeneous photocatalysis.

In this study the photocatalytic degradation of aqueous solutions of camphor was investigated by using TiO2 and ZnO photocatalysts. In the presence of artificial UV-light the highly photosensitive camphor was almost totally degraded after reaction times of 60 min. However, under these conditions the mineralization degree was lower than 25%.

Treatment of gasoline-contaminated waters by advanced oxidation processes.

In this study, the efficiency of advanced oxidative processes (AOPs) was investigated toward the degradation of aqueous solutions containing benzene, toluene and xylenes (BTX) and gasoline-contaminated waters. The results indicated that BTX can be effectively oxidized by near UV-assisted photo-Fenton process. The treatment permits almost total degradation of BTX and removal of more than 80% of the phenolic intermediates at reaction times of about 30 min.

Use of advanced oxidation processes to improve the biodegradability of mature landfill leachates.

Two advanced oxidative processes (Fe2+/H2O2/UV and H2O2/UV systems) were used for the pre-treatment of mature landfill leachate with the objective of improving its overall biodegradability, evaluated in terms of BOD5/COD ratio, up to a value compatible with biological treatment. At optimized experimental conditions (2000 mgL(-1) of H2O2 and 10 mgL(-1) of Fe2+ for the photo-Fenton system, and 3000 mgL(-1) of H2O2 for the H2O2/UV system), both methods showed suitability for partial removal of chemical oxygen demand (COD), total organic carbon (TOC) and color. The biodegradability was significantly improved (BOD5/COD from 0.