Leachate from a composting plant was characterized and applied as a biofertilizer in lettuce crops. Characteristics of untreated (UE) and anaerobically treated (TE) leachate samples were compared. The pH of TE (8.2) increased in relation to the UE (5.2) due to an increase in ammonia nitrogen in TE (1197 mg L-1) compared to UE (859 mg L-1). Anaerobic treatment was efficient in the removal of organic matter from the leachate, evaluated by the decrease of dissolved organic carbon, biochemical oxygen demand, total organic carbon and total solids. K presented the highest concentration (1743 mg L-1) in TE, followed by Mg (135 mg L-1). Cd, Pb and Cr were present at low concentrations in the samples, 0.047, 0.206 and 0.081 mg L-1, respectively. Salmonella, thermotolerant coliforms and viable helminth eggs were not present in TE, which was applied as a biofertilizer in a lettuce crop and compared to mineral fertilization based on fresh matter and dry matter production. Lettuce production using TE was statistically equivalent to mineral fertilization. Toxic metals were not detected in the lettuce shoots. It was concluded that the anaerobically treated leachate from the composting company has the potential to be used as a biofertilizer.

Essential oils (EO) have diverse applications, such as antibacterial and antifungal activity. However, they are susceptible to oxidation in the presence of air, light, and moisture. In addition, they are thermally unstable. In this sense, it is necessary to develop techniques to increase the lifespan of EO. In this work, EO was obtained from cloves and characterized by different techniques. The major compounds found were eugenol (83%), eugenol acetate (9%), and β-caryophyllene (8%). The EO was encapsulated by extrusion using a microfluidic device. The sodium alginate was used as wall material, and the CaCl2 solution was used as a crosslinking agent. The microcapsule presented sizes of 164.7 ± 0.3 μm, with an encapsulation yield of 64 ± 14%. Functional characteristic groups of EO were observed in the microcapsule by infrared and Raman spectroscopies. The microcapsule increased the thermal decomposition of the EO from 162 to 230 °C. Release kinetics of the capsule was performed, with an equilibrium time of 72 h and release of 54% of the EO. Finally, the pure EO and encapsulated EO-microcapsules were applied in the Aedes aegypti larvae control, showing mean lethal concentration necessary to eliminate 50% (LC50) values of 74.4 and 96.9 μg mL-1 and lethal concentration necessary to eliminate 90% (LC90) of 106.2 and 133.3 μg mL-1 for pure EO and encapsulated EO, respectively. Therefore, it was concluded that these microcapsules have the potential for application in the Aedes aegypti larvae control.

In this work, cellulose-based composite biofilms doped with silver nanoparticles (AgNPs) have been produced by eco-friendly process. The AgNPs were synthesized from Ilex paraguariensis with an average size of 45 nm, a characteristic plasmon band at 450 nm and zeta potential of -23 mV. The biofilm has been synthesized by casting method, using different volumes of AgNPs suspension with glycerol plasticizing agent (T6-T10) or not (T1-T5). The AgNPs were successfully incorporated into the biofilms, which was confirmed by scanning electron microscopy. The mechanical and optical structural and the antimicrobial properties of the biofilms have been determined. In the presence of AgNPs, the mechanical properties, thermal stability and water vapor barrier of the biofilms have not been altered. However, the addition of glycerol decreased the tensile strength and the modulus of elasticity, in addition to increasing the elongation of the biofilms and the water vapor barrier. The biofilm T10 showed a transmittance of ca. 10%, with high potential to be used as a UV light blocker. Finally, the biofilms doped with AgNPs showed activity against the bacterium Pseudomonas fluorescens. Given the above, this work presented a new biofilm with activity against the bacterium Pseudomonus fluorescens obtained by eco-friendly process.

In this work, an iron/biochar composite was evaluated as a catalyst for 3,6-dichloro-2-methoxybenzoic acid (dicamba) herbicide degradation by heterogeneous Fenton-like process. The biochar was produced from pyrolysis of coffee husks. After FeII adsorption by biochar, the material was submitted to chemical reduction, via borohydride, producing zero-valent iron nanoparticles (BIO-Fe0). The material was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy and energy dispersive X-ray spectroscopy, Raman scattering spectroscopy, nitrogen adsorption/desorption analysis, among other techniques. The BIO-Fe0 is a heterogeneous material, and the main constituent elements are carbon (C), oxygen (O), silicon (Si), sulfur (S) and iron (Fe). The dicamba degradation was monitored by high-performance liquid chromatography and biological assays using beans (Phaseolus vulgaris) as indicator species. The commercial dicamba (500 mL; 250 mg L 1) was submitted to Fenton-like process (initial pH 3.20; BIO-Fe0: 3 or 5 g; 1.00 mL H2O2 at 3.00 mmol L 1; 1.00 mL Al2(SO4)3 at 1.00 mol L 1; 25 ºC and 5 h of reaction), presenting ca. 100% of degradation. These treated solutions were used in a biological assay. The intoxication levels were less 30%. These results show that BIO-Fe0 has the potential to be used in the dicamba degradation by Fenton-like processes.

In this work, a method for food dyes determination in fibrous fruit pulps was developed. The analytes Tartrazine, Twilight Yellow FCF, Erythrosine, Orange G and Allura Red were analyzed by reverse phase chromatography with diode array (DAD) detection. The sample preparation consisted of a simple procedure, based on initial pH adjustment of the sample (pH = 10.0), followed by an extraction with acetonitrile (5.0 mL and agitation for 30 s), ultrasonic (5 min) and centrifugation (4000 rpm, 20 ºC, for 20 min). The supernatant had its pH adjusted to 3.0, followed by filtration. The method was validated, with the analytical curves prepared in a matrix, in the range of 50to150mg kg-1 for all the analytes studied (determination coefficients (R2) > 0.99). The method veracity was evaluated in terms of recovery, obtaining recoveries of 93-110%. The repeatability was less than 13.7%, while the intermediate precision was less than 19.0%. The limits of detection and quantification were determined, being 15 and 30 mg kg-1, respectively. The combined relative uncertainties were less than 13.8%. Therefore, it can be concluded that a simple method was developed, suitable for monitoring the presence of dyes in fruit pulps in routine analyzes.

The biomass use is of considerable ecological and economical interest and here, biochar, a by-product of biomass carbonization, is magnetized with Fe3O4 for its use as gold nanoparticle (NP) support towards catalysis of p-nitrophenol (4-NP) reduction. Biochar was synthesized from coffee straw biomass via pyrolysis, while magnetite functionalization was obtained using the precipitation method. The magnetite was identified by X-ray diffraction (XRD). The material had a specific surface area of 30 m2 g-1 and a zero point charge of 7.5. The gold NPs were deposited via reduction with NaBH4, which yielded Au and Fe3O4 NP of 4.61 and 10.9 nm, respectively. The materials were applied in the 4-NP reduction, Fe3O4Fe 3 O 4 NPs was observed. Remarkably, comparison with graphene oxide to which biochar resembles showed similar behavior, and the material was reused in several catalytic cycles.

Silver nanoparticles (AgNPs) stabilized with glutathione (GSH) were used as nanosensors for the determination of fluoroquinolones such as ciprofloxacin (CIP), norfloxacin (NOR) and enrofloxacin (ENRO) in aqueous systems. The AgNPs were stabilized with GSH (Ag-GSH NPs), whereas the decrease of the surface plasmon resonance (SPR) band at 400 nm and the bathochromic shift of the absorption band were monitored. The method was validated and the analytical performance was verified. The results were satisfactory, with recoveries between 83.7 and 110% in almost all the experimental conditions and the repeatability and intermediate accuracy of less than 20%. The limits of detection were 0.397, 0.437 and 0.398 µmol L-1, and the limits of quantification were 1.203, 1.323 and 1.205 µmol L-1 for ciprofloxacin, norfloxacin and enrofloxacin, respectively. The method was selective in a group of drugs and applied in the determination of fluoroquinolones in potable water samples.

The cobalt nanoparticles (NPs-Co) were synthesized and applied in the removal of Cr(VI). The obtained nanomaterials presented magnetic properties and were characterized by the techniques of Transmission Electron Microscopy and X-ray diffraction. The NPs-Co, with a diameter of less than 50 nm, had a composition based on metallic cobalt and cobalt oxide. The NPs-Co were applied in the removal of Cr(VI) being evaluated different parameters such as time of equilibrium, initial pH, dose of NPs-Co, concentration of Cr(VI), and system temperature. The removal of Cr(VI) was favored at lower pH values, being about 100% at pH 2.0. With the increase of Cr(VI) concentration from 40.0 to 300.0 mg L-1 the removal decreased from 80 to 15%. The NPs-Co dose promoted an increase in removal reaching 90% at a dose of 1.0 g L-1. The removal process was spontaneous and endothermic, and the Langmuir isotherm model fit better to experimental data. The maximum removal capacity was approximately 70.0 mg g-1. The removal kinetics followed the pseudo-second order model. The mechanism of Cr(VI) removal occurred through adsorption by electrostatic interactions between CrO42- anion and Co-NPs, followed by reduction of Cr(VI) to Cr(III) and, lastly, co-precipitation of Cr(III) as Cr(OH)3 on the NPs-Co.

ABSTRACT Kinetic studies of sulfentrazone herbicide dechlorination by Fe/Ni nanoparticles were performed in the presence of different electrolytes such as: Cl-, SO42-, NO3-, Cu2+, Na+ and Zn2+. In the presence of Cl- and SO42- the reaction occurred efficiently, reaching approximately 100% of dechlorination after 30 minutes of reaction. In the presence of NO3- and Cu2+ ions the sulfentrazone dechlorination was significantly inhibited, because these ions tend to compete with the substrate for the electrons donated by Fe0. In the presence of Na+ ions, the dechlorination efficiency remained approximately 100%, however, this electrolyte provided an increase on the reaction rate, due to the increase of the ionic strength in the system. The Zn2+ ions has no influence on the dechlorination efficiency, but the reaction rate was reduced due to the formation of a protective layer formed by the sorption of Zn2+ ions on the surface of the nanoparticles.

The removal of the beta-lactam antibiotics (ceftriaxone and cefadroxil) through zero-valent copper nanoparticle (nZVC) was studied in this work. Excellent removal degrees (> 85%) were obtained for both analytes in only 20 min of reaction. Studies were performed in both oxic and anoxic conditions, and in the presence of t-butyl alcohol (TBA), an inhibitor of radicals. The results did not show significant changes. Therefore, the hydroxyl radicals are not the main species responsible for the removal. Total organic carbon cefadroxil analysis indicated a removal of 57% after 180 min of reaction. Studies involving Cu+ indicated that probably these are the principal species responsible for the removal of antibiotics. Kinetic studies have shown that two-phase reaction occurred in the antibiotics removal process and both phases followed pseudo-first order kinetic model. The first mechanism is related to the antibiotics degradation by Cu+ species and the second mechanism is related to the antibiotics adsorption by hydroxides/oxides of Cu2+ species.

This study investigated the reductive degradation of acetamiprid (5 mg L-1) in aqueous medium (at pH 2.0) induced by zero-valent iron (50 mg). The process was monitored using high-performance liquid chromatography (HPLC) to determine the degradation rate as a function of reaction time, and direct infusion electrospray ionization mass spectrometry (DI-ESI-MS) to search for (and potentially characterize) any possible byproducts formed during degradation. The results obtained via HPLC showed that after 60 min, the degradation of the substrate reached nearly 100% in an acidic medium, whereas the mineralization rate (as determined by total organic carbon measurements) was as low as 3%. Data obtained by DI-ESI-MS showed that byproducts were formed mainly by insertions of hydrogen atoms into the nitrile, imine, and pyridine ring moieties, in addition to the observation of chlorine substitution by hydrogen replacement (hydrodechlorination) reactions.

This paper describes the optimization of a multiresidue chromatographic analysis for the identification and quantification of 20 pesticides in bovine milk, including three carbamates, a carbamate oxime, six organophosphates, two strobilurins, a pyrethroid, an oxazolidinedione, an aryloxyphenoxypropionate acid/ester, a neonicotinoid, a dicarboximide, and three triazoles. The influences of different chromatographic columns and gradients were evaluated. Furthermore, four different extraction methods were evaluated; each utilized both different solvents, including ethyl acetate, methanol, and acetonitrile, and different workup steps. The best results were obtained by a modified QuEChERS method that lacked a workup step, and that included freezing the sample for 2 hours at -20 ºC. The results were satisfactory, yielding coefficients of variation of less than 20%, with the exception of the 50 µg L-1 sample of famoxadone, and recoveries between 70 and 120%, with the exception of acephate and bifenthrin; however, both analytes exhibited coefficients of variation of less than 20%.