In this work, we report the synthesis and characterization of new amorphous graphene-like TiO2/chitosan carbon microspheres and its performance as photocatalyst. Four different carbon chitosan microspheres materials were obtained based on the distinctive procedure to incorporate TiO2 and TiOSO4 to chitosan structure by pyrolysis at 600 °C. Detailed characterizations were carried out using many different techniques, as thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), scanning electron miscroscopy/energy dispersive X-ray spectroscopy (SEM/EDS), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), N2 adsorption-desorption, and the obtained materials show an amorphous and a graphene-like structure, which improve the photocatalytic activity. The synthesized materials promoted a fast degradation of three micropollutants under UV-A radiation and, in all cases the degradation rate was approximately 98% at 30 min of reaction, being superior to the P-25 TiO2 efficiency. Due to the amorphous graphene-like structure, all the materials present low adsorption capacity, the high photocatalytic efficiency can be attributed to the material structure that promotes the effective charge separation which reduces the recombination electron/hole, enhancing the photocatalytic efficiency.

Parabens are widely used as preservatives in the last decades. Others preservatives such as 2-phenoxyethanol, which in addition to his good antimicrobial activity, has low allergenic potential as well others properties of interest to the cosmetic industry. In this work was developed a method for determination of methylparaben (MP), propylparaben (PP) and 2-phenoxyethanol (FE) in cosmetic products by HPLC-DAD using QuEChERS as sample preparation. For application in cosmetic samples, the original QuEChERS method was modified and optimized by evaluate of different solvents for extraction and sorbents for clean up step. Increases at recoveries of analytes were obtained employing acetone as solvent and PSA for clean up step, showed recoveries between 83.7% and 88.6% for all analytes. The method was validated according to ANVISA (linear range: 0.1 to 2.5 µg mL-1 for MP and PP, and 1.5 to 6.0 µg mL-1 for FE). Precision was evaluated by repeatability and intermediate precision with coefficients of variation (%) lower than 10% in all concentrations analysed, and accuracy was evaluated, with values ranging from 93.77% to 108.13%. The QuEChERS-HPLC-DAD method was tested in real samples (moisturizing cream and lotion, cleansing gel), where the concentration values were found below the maximum limit established by ANVISA.

Many studies have reported significant improvements in the photocatalytic degradation capacity of TiO2 immobilized in carbonaceous materials, mainly due to a well-characterized synergistic effect. The photocatalytic degradation of the estrogens 17β-estradiol and 17α-ethynylestradiol was evaluated using 1 mg L-1 aqueous solutions, employing a nanocomposite containing TiO2 and activated carbon (TiO2-AC) prepared by sol-gel technique. The synthesized materials were characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM). These techniques allowed to estimate the carbon proportion (11.4 wt.%), the phase composition (anatase: 80.2%, brookite: 14.0%, and rutile: 5.8%) and the superficial morphology. Using UV-A radiation provided by a high pressure mercury vapor lamp (125 W) and the synthesized photocatalysts, it was observed the almost complete removal of both estrogens in times shorter than 10 minutes. Considering the similarity between the degradation percentage of nanocomposites (TiO2 and TiO2-AC), no synergistic effects between AC and TiO2 could be assumed.

In this work the sol-gel method was used to synthesize a nanocomposite containing TiO2 and graphene oxide (GO). The photocatalytic activity of the TiO2/GO nanocomposite was evaluated regarding the degradation of a reactive dye (reactive black 5) in aqueous solution using processes assisted by UV-A radiation. Under these conditions the nanocomposite showed higher degradation efficiency than the reference photocatalyst (Degussa P25 TiO2), mainly due to the high degradation capacity of the synthesized TiO2 nanoparticles. Although contradictory to several reports in the specialized literature, no synergistic effect was observed between the nanocomposite components.

O método de regressão por mínimos quadrados parciais (PLSR) foi utilizado para a quantificação simultânea de dois tuberculostáticos rifampicina (RIF) e isoniazida (INH) por espectrofotometria na região do visível utilizando uma reação de derivatização simples. Na presença de neocuproína, íons cobre(II) foram facilmente reduzidos por INH para um complexo Cu(I)-neocuproína de absorção máxima a 455 nm. Sob essas mesmas condições, RIF mostrou uma absorção máxima a 449 nm. O conjunto de calibração foi estabelecido entre 8 e 57 mg L-1 de RIF e 1,5 e 7 mg L-1 de INH. O método foi aplicado para a determinação das drogas em amostras de urina (recuperações entre 92 e 119%) e em formulações farmacêuticas (erro relativo inferior a 5%).

Partial least squares regression (PLSR) was used for the simultaneous quantification of rifampicin (RIF)and isoniazid (INH) by visible spectrophotometry using a simple derivatization reaction. In the presence of neocuproine, copper(II) is easily reduced by INH to a Cu(I)-neocuproine complex that shows an absorption maximum at 455 nm. Under these conditions, RIF shows an absorption maximum at 449 nm. The calibration set was established between 8and 57 mg L-1 for RIFand 1.5and 7 mg L-1 for INH. The method was applied to the determination of the drugs in urine samples (recoveries between 92and 119%)and in pharmaceutical formulations (relative error lower than 5%).

Neste trabalho foi proposto um procedimento para a extração do herbicida atrazina (AT) e dos principais metabólitos desetil-atrazina (DEA) e desisopropil-atrazina (DIA) de uma amostra de latossolo vermelho proveniente da região sudoeste do estado do Paraná no Brasil, onde a AT está entre os herbicidas mais amplamente utilizados. Foi conduzida uma comparação usando extração por agitação e por ultrassom, sendo obtido um procedimento de extração simples e rápido, seguido pela quantificação por cromatografia em fase líquida de alta eficiência. Cabe ressaltar que foi utilizado um estudo por planejamento fatorial, o qual foi decisivo para determinar as melhores condições de extração por agitação. Foram obtidos percentuais de recuperação e desvios padrão relativos adequados, para amostras de solo de três diferentes profundidades, o que sugere a possibilidade de empregar o método de extração proposto para a quantificação de AT, DEA e DIA em amostras de latossolo vermelho.

An optimization procedure for the extraction of the herbicide atrazine (AT), and the main degradation products deethylatrazine (DEA) and deisopropylatrazine (DIA) from an oxisol soil sample was carried out, for a soil from the Southwest of Paraná State in Brazil, where AT is among the most largely employed herbicide. A comparison between shaking and ultrasound extraction was performed, to define a simple and fast extraction procedure, followed by the quantification using high performance liquid chromatography. It is important to inform that a factorial planning was employed, that was very important to define the best conditions of extraction by shaking. Appropriate recovery values were observed using soil samples from three different depths, as well as the relative standard deviation, suggesting the possibility to employ the proposed extraction method for quantification of AT, DEA and DIA in oxisol samples.

In this work the degradation capacity of a photo-electrocatalytic system was evaluated, mainly regarding the effect of the electrolyte solution on the degradation capacity toward a reactive textile dye. In the presence of NaCl the photo-electrochemical process shows high degradation efficiency, permitting almost total color removal in treatment of about 5 min. In view of the low degradation efficiency observed for the photocatalytic process it is possible to assume that the high degradation efficiency of the process is a function of electrochemical generation of oxidant active chlorine species, which are subsequently transformed to higher oxidant radical forms.

In this work the photocatalytic degradation of sulfametoxazole, trimethoprim and potassium diclofenac was evaluated by using TiO2 and ZnO photocatalysts. In optimized experimental conditions (pH 4, TiO2: 50 mg) the TiO2-photocatalysis allowed an almost total degradation of the studied drugs with mineralization of about 80% at reaction times of 120 min. Some mechanistic differences were observed between TiO2 and ZnO in the degradation study involving potassium diclofenac. At the first reaction times the use of ZnO leads to generation of transient species that strongly absorb in the UV spectral region, a fact not observed in studies involving TiO2.

In this work, the efficiency of some homogeneous advanced oxidation processes (UVC/H2O2, Fe2+/H2O2, UVC/Fe2+/H2O2, UVA/Fe2+/H2O2, solar/Fe2+/H2O2) was investigated toward the degradation of geosmin and 2-methylisoborneol (2-MIB). The effect of relevant experimental parameters (ie. pH, Fe2+ and H2O2 concentration) was first investigated by factorial design, using camphor as a model substrate. In the geosmin and 2-MIB degradation studies the Fenton processes assisted by solar and UVA radiation offered the most promising results, mainly on account of high degradation capacity (higher than 80% at a reaction time of 60 min), high operational simplicity and low cost.

The chemical and microbiological decomposition of the garbage deposited in landfills leads to the generation of a dark and malodorous liquid residue that shows a chemical composition of extreme variability and complexity. When matured, the leachates show low biodegradability, which makes it difficult to treat by conventional biological processes. In this work a new strategy for the treatment of landfill leachates is proposed, involving a preliminary treatment by heterogeneous photocatalysis followed by an activated sludge system. The results demonstrate that photochemical treatments of 60 and 90 min significantly enhance the leachates' biodegradability favoring subsequent biological treatment. The biodegradability rate (BOD/COD) was also greatly enhanced.

Neste trabalho está sendo proposto um processo integrado para a remediação de chorume, consistente na separação preliminar das substâncias húmicas, por precipitação em meio ácido, e o tratamento subseqüente do sobrenadante por meio de processos oxidativos avançados. Em geral, a precipitação preliminar permite remover uma pequena parcela da DQO (14%) e grande parte da cor, o que permite significativas melhoras no tratamento fotoquímico posterior. Quando aplicado na forma de um sistema de múltiplas adições de peróxido de hidrogênio, o sistema UV/H2O2 permite descolorações da ordem de 95% e reduções de DQO de 75%, em tempos de reação de 120 min. Trata-se de um resultado bastante promissor, principalmente levando-se em consideração a elevada resistência da matriz em estudo.

In this work, we propose the integration of processes for remediation of landfill leachate, where humic substances are preliminary precipited and separated in acidic conditions and an advanced oxidative process further treats the soluble fraction. Typically, the precipitation of humic substances reduces 14% of the COD content and a great part of the intrinsic color, fact that significantly improves the efficiency of the photochemical treatment. When applied as a successive H2O2 additions system the UV/H2O2 process induce color and COD reductions of 95 and 75% respectively, in reaction times of 120 min. This results are very promissory, principally because the recalcitrant character of the leachate matrix.

The efficiency of a new procedure for the digestion of natural waters, based on a microwave-activated photochemical reactor was evaluated in this work. Fluorescence spectra showed a 99% reduction in the emission of a 40 mg L-1 humic acid solution after 15 min of UV irradiation. In the presence of H2O2, only 3 min were necessary to accomplish a reduction of almost 100% in the emission and 6 min to reduce the concentration of dissolved organic carbon by 95%. The copper recovery from synthetic samples containing commercial humic acid, from soil suspensions, as well as from natural waters varied between 91.5 and 106.6%. The digestion of dissolved and unfiltered samples was successfully accomplished in 6 and 12 min, respectively. No contaminations or sample losses were observed. Results of copper speciation in natural waters showed that this metal is predominantly bound to natural ligands. Only 3-6% of the total recoverable copper is present in the labile form.

One of the main problems in quantitative analysis of complex samples by x-ray fluorescence is related to interelemental (or matrix) effects. These effects appear as a result of interactions among sample elements, affecting the x-ray emission intensity in a non-linear manner. Basically, two main effects occur; intensity absorption and enhancement. The combination of these effects can lead to serious problems. Many studies have been carried out proposing mathematical methods to correct for these effects. Basic concepts and the main correction methods are discussed here.