Due to the usual resistance of textile dyes to conventional biological treatment processes, the color removal of dyeing wastewaters remains a challenge for the textile industry. This work evaluates the capacity of advanced oxidation processes based on thermally-activated persulfate concerning textile dyes’ degradation in aqueous solution and the reuse of dyeing baths. Preliminary studies were carried out in a bench-scale jacketed reactor, using Reactive Black 5 (40 mg L−1) as a model dye. Almost complete dye degradation was observed in 60 min in this stage, using 300 mg L−1 of persulfate and activation temperatures of 80 ºC, basically due to the action of radical sulfate. The use of high concentrations of persulfate (1000 mg L−1) allowed efficient color removal of dyeing baths containing remazol dyes in processes activated at 80 and 90 ºC. However, the wastewaters treated under these conditions did not lead to high dyeing efficiency in reuse studies, probably due to residual persulfate presence. In contrast, low concentrations of persulfate (250 mg L−1) lead to partial color removal and a better dyeing quality. The results suggest a good potential for treating high-temperature dyeing baths, saving water and auxiliary agents used in textile dyeing processes.

ENVIRONMENTAL APPLICATIONS OF PERSULFATE: REMEDIATION OF CONTAMINATED GROUNDWATER AND SOILS. Environmental remediation represents a major technological challenge due to the complexity of the environmental matrices and the high treatment cost. In recent years, in situ chemical oxidation technologies (ISCO) have shown a good cost/benefit ratio, which has favored their use in the degradation of several relevant environmental pollutants. In this context, persulfate-mediated processes are of relevant importance once persulfate can be activated in situ, promoting the formation of highly oxidative radical species. Persulfate-based treatments have been frequently reported in environmental remediation studies because they guarantee the effective degradation of pollutants without producing significant changes in the remediated matrix. Given these statements, this study aims to discuss the main ways of activating persulfate and the relevant applications in the remediation of groundwater and soils contaminated with resistant organic pollutants.

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.

This work reports the remediation of a liquid residue derived from the thermal treatment of petrochemical residues by advanced oxidation processes. Firstly, degradation studies of phenol aqueous solutions by heterogeneous photocatalysis, Fenton, and photo-Fenton were conducted. Fenton processes showed a higher efficiency, mainly in the UVA photo-assisted mode (94% in 3 min), and henceforward it was chosen for the remediation of the residue. However, the high organic load of the raw residue (6,000 mg L-1 of chemical oxygen demand (COD)) limited the efficiency of the Fenton processes. Hence, the raw liquid residue was diluted with the scrubber residue, produced during the thermal treatment of the petrochemical residues, reducing the COD to values close to 2,000 mg L-1. The photo-Fenton treatment allowed the removal of approximately 95% of the COD load, decreasing the residual concentration of phenolic compounds from 213 to 0.5 mg L-1. At the same time, the concentration of BTEXs (benzene, toluene, ethylbenzene and xylene) were reduced to values lower than the limit of quantification (LOQ) of the chromatographic technique. Therefore, the photo-Fenton process is an efficient alternative to the remediation of residues with high complexity and with high COD values, like the ones obtained in the petrochemical industry.

A binary solvent dispersive liquid-liquid microextraction (BS-DLLME) technique was developed for simultaneous determination of diuron, teflubenzuron, atrazine, and two of its metabolites (desisopropylatrazine and desethylatrazine) in natural waters. The extraction was investigated using a three components mixture design to determine the best ratio between the extractors (dichloromethane and chloroform) and the disperser solvent (acetonitrile). According to the analysis of variance, empirical response surfaces were obtained for each analyte, correlating the absolute recovery and the mixture composition. The analysis of the overlapping surfaces allowed the detection of the best condition for the analytes extraction: 481 µL of chloroform, 56.6 µL of dichloromethane, 906 µL of acetonitrile, 5.00 mL of the aqueous sample, and 10% (m/v) of sodium chloride. The proposed method was validated and successfully applied in the analysis of surface waters, presenting suitable linearity (r > 0.9990), low limits of detection (0.015 to 0.36 µg L-1) and quantification (0.049 to 1.2 µg L-1), and relative recoveries between 84.8 and 106.1%.

Polyaniline is a conducting polymer that has recently been studied regarding its potential in the removal of contaminants by heterogeneous photocatalysis. Since it is a polymer with a high absorption capacity of photons in the visible region, it promotes the photosensitization of catalysts that are typically inactive in solar systems. The increasing number of publications applying photocatalysis and composite catalysts based on polyaniline highlights the importance of this subject. This review systematizes the most important and specific contributions of composite catalysts formed by polyaniline. The main mechanisms proposed for photosensitization, which show the synergism between the phases of the composite, are summarized. Moreover, the relevance of morphology and conductivity of the composite catalyst, operating parameters (eg. pH, and light source contaminant) are some of the aspects discussed, revealing how these differ from traditional catalysts. Future prospects for the continuation and improvement of this issue mainly involve a greater variety of contaminant removal tests and understanding of relations between the structure of the material and its photocatalytic property.

This work evaluated the photocatalytic activity of suspended TiO2, and TiO2-coated glass Raschig rings with respect to degradation of estrogens estrone (E1), 17β-estradiol (E2), and 17α-ethinylestradiol (EE2) in aqueous solutions and wastewater effluent samples. Gas chromatography/tandem mass spectrometry (GC-MS/MS) studies were carried out to identify degradation products for EE2. TiO2 suspensions allowed degradation rates higher than 90% for all studied estrogens in 30 min for an artificial (ultraviolet A) UVA-assisted process and aqueous solution. Immobilized TiO2 showed less favorable degradation kinetics, requiring ca. 60 min to achieve almost complete estrogen degradation. Some derivatized degradation products were identified for the first time by GC-MS/MS applying ultraviolet C (UVC) photolysis and TiO2/UVA photocatalysis. A degradation route was suggested for EE2 in UVC photolysis and TiO2/UVA processes. In the degradation of pretreated sewage samples, the immobilized TiO2 was more efficient than free TiO2, allowing ca. 85% removal of E2 and EE2 in 60 min.

Resumo Este trabalho teve como objetivo determinar duas drogas psicotrópicas mais dispensadas pelos Centros de Atenção Psicossocial (CAPS) nas águas de um rio urbano (sub-bacia do rio Belém, Curitiba - PR, Brasil). Foi desenvolvido e validado um método analítico SPE seguido de HPLC-DAD. Os cartuchos Strata-X® foram utilizados para extrair carbamezepina (CZ) e diazepam (DZ) das águas e as condições de SPE foram otimizadas por um planejamento fatorial 23. O método validado foi específico para compostos alvo. Os coeficientes de correlação foram superiores a 0,9998, a recuperação entre 85,8 e 98,4% e a precisão abaixo de 6,60% (RSD, n = 3). Este método foi aplicado com sucesso para analisar amostras de rios e pontos críticos de poluição foram reconhecidos. A CZ e DZ foram encontradas em concentrações variando de 0,670 a 0,856 μg L-1 e de LOQ a 0,763 μg L-1, respectivamente, confirmam que o consumo de drogas está diretamente relacionado à poluição do rio na região estudada.

Abstract This work sought to determine the two psychotropic drugs most commonly released by Psychosocial Care Centers (CAPS) into urban river waters (Belém sub-basin, Curitiba, PR, Brazil). A simple analytical method using SPE followed by a HPLC-DAD was developed and validated. Strata-X® cartridges were used to extract (carbamazepine) CZ and diazepam (DZ) from water and SPE conditions were optimized by 23 factorial design. The validated method was specific for target compounds; correlation coefficients were above 0.9998, recovery between 85.8 and 98.4% and precision below 6.60% (RSD, n=3). This method was successfully applied to analyze river samples and pollution hotspots were identified. The CZ and DZ concentrations found ranged from 0.670 to 0.856 µg L-1 and from LOQ to 0.763 µg L-1, respectively, and confirmed that drug consumption is directly related to river pollution in the studied region.

A sensitive high-performance liquid chromatography-fluorescence detection method (HPLC-FLD) was developed and validated for 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) determination in wastewater samples. Sample preparation was performed by solid-phase extraction (SPE) on Hypersep C18 cartridges. Conditioning and elution solvents and sample volume were investigated by a 23 factorial design for both analytes. The pre-concentration factor was 2500 times, allowing to quantify 5.0 ng L-1 for both hormones. The SPE-HPLC-FLD method was successfully applied to detect and quantify trace amount of target compounds in raw and treated wastewater samples. E2 was found below limit of quantification in influent and effluent samples. Nevertheless, the recoveries of E2 in standard addition experiments were between 41 and 72%, with relative standard deviations between 4 and 16%. An important matrix effect was observed in the determination of EE2, with fluorescence signal suppression.

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.

The remediation of contaminated soils is probably one of the biggest environmental challenges, mainly due to the complex dynamics of the pollutants in this medium. Among a variety of treatment alternatives proposed for the in-situ remediation of contaminated soils, Fenton processes appear as the most cost-effective, particularly when catalyzed by native iron oxides. However, both the efficiency of the Fenton process and its effect on the treated soil, are largely dependent of the treatment conditions and the main characteristics of the soil, which implies the nonexistence of universal procedures. In this work, the use of Fenton processes in soil remediation routines is critically evaluated, emphasizing aspects related to the degradation efficiency, the influence of the soil properties, the degradation mechanisms and the impacts on the treated soil.

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.

Two simple and efficient procedures have been developed for the rapid simultaneous determination of compounds with mutual spectral interference (rifampicin (RIF) and isoniazid (INH)). The first method was based on the UV–Vis spectral signal (190–600 nm) of synthetic RIF and INH aqueous solutions, whereas the second method involved the visible spectral signal registered between 350 and 800 nm after the reaction of INH with a Cu2+/neocuproine complex. Both multivariate spectrophotometric methods show excellent prevision capacity, providing results that are statistically equivalent with those provided by the standard chromatographic procedure. The methods were validated according to criteria established by ANVISA, showing precision, accuracy and robustness compatible with the requirements for new analytical methods, additionally allowing the reduction of waste generation.

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%).