Antonio Neves | Universidade Federal de Viçosa (original) (raw)
Papers by Antonio Neves
Eclética Química Journal, 2018
The salting-out assisted liquid-liquid extraction (SALLE) was developed for the analysis of four ... more The salting-out assisted liquid-liquid extraction (SALLE) was developed for the analysis of four pesticides (cypermethrin, chlorpyrifos, deltamethrin, and thiamethoxam) in water samples. For its optimization, a 2³ factorial design was used to evaluate the simultaneous behavior of three factors: sample and extraction solvent ratio, saline concentration, and stirring mode. A 1.0 mL saline solution (NaCl) was added to the single-phase mixture of water and extraction solvent to separate the phases. The mixture was stirred, allowed to stand and the top organic phase containing the pesticides of interest was analyzed by gas chromatography coupled with electron capture detector (GC/ECD). The optimized method was validated for some merit figures. The limit of detection of the method ranged from 0.15 to 5.5 µg L-1 and the limit of quantification from 5.5 to 18.2 µg L-1. The method showed satisfactory results for the linearity (R2 ≥ 0,990), precision (CV < 9 %) and accuracy (72 % ≤ recover...
Journal of the Brazilian Chemical Society, 2015
Due to uncontrolled use of pesticides and disregard for harvest intervals, some pesticide residue... more Due to uncontrolled use of pesticides and disregard for harvest intervals, some pesticide residue is present in various foods. Treatments using ozone as an alternative for food decontamination have been studied in recent years due to ozone's high oxidation potential even at low concentrations. The present work aimed to evaluate chlorothalonil removal from table grapes by the immersion of fruit in distilled water continuously bubbled with ozone gas. This strategy allowed the removal of 60% of chlorothalonil from table grapes (pulp and skin), regardless of ozone concentration. Ozone treatment of table grapes at a gas concentration of 3 mg L −1 changed most of the quality parameters evaluated. Treatment at 2 mg L −1 maintained the fruit quality for a longer storage period compared to the untreated control table grapes.
Journal of Seed Science, 2016
Sarcotesta, a mucilaginous layer found in papaya seeds, negatively affects the germination of pap... more Sarcotesta, a mucilaginous layer found in papaya seeds, negatively affects the germination of papaya seeds and its removal has been manually performed. The use of sodium hypochlorite can be an alternative to manual removal of sarcotesta in papaya seeds. The objective of this study was to evaluate the effect of different active chlorine concentrations (0, 2, 4, 6 and 8%)
Journal of the Brazilian Chemical Society
Diethylene glycol is an extremely toxic substance to humans. Recently, cases of beer contaminatio... more Diethylene glycol is an extremely toxic substance to humans. Recently, cases of beer contamination in Brazil have raised awareness of the need for developing simple screening methods to evaluate this type of compound. This research developed a liquid-liquid extraction with low-temperature partitioning technique to determine diethylene glycol in beer via gas chromatography. Employing a flame-ionization detector simplifies the method, lowers its cost and therefore, it can be used as screening step to assess the possibility of contamination. A gas chromatograph coupled to a mass spectrometer would be used only for a confirmatory analysis. The optimized method was validated for the main figures of merit, and it proved to be adequate, with good values of recovery rate (94-106%), limit of detection (3.0 mg L-1), and quantification (10.0 mg L-1). Accuracy, in terms of repeatability and intermediate accuracy, showed variation coefficients lower than or equal to 20%. This method was applied ...
Journal of the Brazilian Chemical Society, 2019
Clomazone exhibits high water solubility, low sorption in soil colloids, and therefore can leach ... more Clomazone exhibits high water solubility, low sorption in soil colloids, and therefore can leach and contaminate deep layers of soil profile and groundwater. In this work, the effect of the incorporation of sugarcane bagasse biochar in leaching and bioavailability of clomazone in red latosol was evaluated. Soil samples amended with 1% (m/m) biochar were placed in different depths (0-1, 0-2.5 and 0-5 cm) on the top of polyvinyl chloride (PVC) columns filled with soil. Clomazone-based herbicide was applied, and rainfall was simulated on top of the columns. A validated chromatographic method, together with a greenhouse bioassay, were used to quantify and to evaluate the mobility and availability of clomazone along the columns. The incorporation of sugarcane bagasse biochar in the superficial layers at the column tops increased herbicide sorption, reduced its leaching and bioavailability in soil and scaled down the environmental risk of clomazone avoiding contamination of underground aquifer reservoirs.
Microchemical Journal, 2017
Abstract The aim of this work is to develop a method for determining trihalomethanes (THMs) in fi... more Abstract The aim of this work is to develop a method for determining trihalomethanes (THMs) in fish samples. The proposed method uses solid phase microextraction and gas chromatography with an electron capture detector. Factors such as temperature, extraction time and type of fiber were assessed to maximize the performance of the extraction technique. The performance of the method was evaluated using selectivity, linearity, precision, accuracy and limits of detection (LOD) and quantification (LOQ). The new method allows analysis of THMs with appropriate selectivity and linearity, with coefficient of correlation > 0.98. The LOD and LOQ of the analytes of interest are from 0.11 to 0.35 μg kg − 1 and 0.35 to 1.18 μg kg − 1 , respectively. In addition, the relative standard deviation (RSD) was between 1.6 and 8%, and the relative recovery was between 76 and 113%. The optimized and validated method was applied to fish samples purchased from the Vicosa (MG) local market. At least three of the THMs of interest were detected in most of the analyzed fish samples with maximum values for the concentration of chloroform, bromodichloromethane and bromoform at 8.33, 0.42 and 2.41 μg kg − 1 , respectively.
Journal of the Brazilian Chemical Society, 2017
A new method has been developed to determine trace levels of organophosphorus pesticide parathion... more A new method has been developed to determine trace levels of organophosphorus pesticide parathion-methyl in water samples by using dispersive liquid-liquid microextraction (DLLME), followed by gas chromatograph coupled with electron capture detector (GC/ECD) analysis. The optimized and validated method showed high extraction recovery (101.1%), high enrichment factor (57.3), low limits of detection and quantification, 0.083 and 0.250 μg L-1 , respectively. The established DLLME-GC/ECD method has been successfully applied for the evaluation of the photodegradation of the parathion-methyl by UV 254nm radiation in different conditions of pH and temperature. The parathion-methyl photodegradation at pH 3 and 35 °C achieved > 99.5% after 120 min of exposition. For this condition, it was observed the kinetic rate of 0.0515 min-1 , the quantum yield of 1.22 × 10-5 mol Einstein-1 and a half-life time of 13.46 min. All experimental conditions tested proved to be strongly influenced by pH and temperature. The application of the optimized process in distilled and drinking water spiked with parathion-methyl provided residues of this pesticide at levels below the maximum permitted by Brazilian legislation, which is 9.0 μg L-1 .
Journal of the Brazilian Chemical Society, 2015
A new method for the extraction of pesticide residues from soil was developed, optimized, validat... more A new method for the extraction of pesticide residues from soil was developed, optimized, validated and applied to real samples. The technique consisted of combining single-drop microextraction and solid-liquid extraction with low temperature partitioning (SLE/LTP-SDME) followed by analysis using gas chromatography with electron capture detection (GC/ECD). This method was used to determine the presence of alachlor, methyl parathion, trifluralin, endrin, lindane, dieldrin and dichloro-diphenyl-trichloroethane (4,4'-DDT) in soil samples. Recoveries ranging from 67.2 to 122.5% were achieved, coefficients of variation (repeatability) were lower than 22.4% and limits of detection ranged from 0.18 to 0.59 µg kg-1. Recovery from soils fortified with different concentrations of the pesticides ranged from 61.5 to 123.5%. The new method combines the primary advantages of the two techniques: purification of the sample using SLE/LTP and preconcentration using SDME. The new method also enables the determination of low volatility compounds without requiring the sample to be heated.
Journal of the Brazilian Chemical Society, 2018
Effluents from pulp mills have a high organic load and can still contain high organic biorecalcit... more Effluents from pulp mills have a high organic load and can still contain high organic biorecalcitrant material that is harmful to the aquatic environment, even after undergoing biological treatment in effluent treatment plants. This study presents a novel treatment method tested on effluents (prior to and after biotreatment) from a Brazilian kraft pulp mill, based on hydroxyl radical production and hydrogen peroxide obtained by plasma generated by high-voltage electrolysis. These species present significant oxidation potential that could enable the complete breakdown of the organic matter. From the application of plasma to treat pulp mill effluent for a 7-hour period, it was obtained a chemical oxygen demand (COD) removal between 88.2 and 99.7%, total organic carbon (TOC) removal of 90.3 to 95.6%, and a color removal of 95.0 to 98.0%. The final pH of the treated effluent was 11.6 to 11.9. The results obtained in this study showed that the high-tension plasma treatment, applied on effluent from kraft pulp mills before and after biological treatment, can be an attractive alternative.
Research, Society and Development, 2021
This study evaluated the mobility and persistence of aldicarb and its degradation products in red... more This study evaluated the mobility and persistence of aldicarb and its degradation products in red-yellow oxisol (LVA) using soil columns, after the application of Temik 150. Leaching experiments were performed using polyvinyl chloride (PVC) columns filled with soil contaminated with aldicarb and rain simulation of 6.05 mm day-1, at 10 day intervals, for 90 days. Aldicarb, aldicarb sulfoxide and aldicarb sulfone residues were extracted from soil (solid-liquid) and percolated water (liquid-liquid) samples with quantification by CG-FID. The results showed that aldicarb was rapidly oxidized to aldicarb sulfoxide and aldicarb sulfone in 10 days after the application. Aldicarb sulfoxide percolated through 15 cm of the soil column and could not be detected in the soil after 40 days incubation. From the 60 days since application, residues were no longer detected in the samples of percolated water and soil fractions, indicating rapid degradation and low potential for groundwater contamination.
Water
Studies show that agricultural activities around the world still present a strong dependence on a... more Studies show that agricultural activities around the world still present a strong dependence on agrochemicals that can leach into the soil profile, causing its contamination, as well as that of water resources. In this context, the present study evaluates the potential risk of pesticide leaching in areas of edaphoclimatic suitability for coffee cultivation in Espírito Santo state, Brazil. As a methodology, the areas of edaphoclimatic suitability for conilon and arabica coffee were defined, and subsequently, the risk of leaching of active agrochemical ingredients in these areas was evaluated using the Groundwater Ubiquity Score (GUS), Leaching Index (LIX) and Attenuation Factor/Retardation Factor (AF/RF) methods. Of the ten active ingredients evaluated, sulfentrazone and thiamethoxam present a potential risk of leaching into the groundwater level. The study allowed us to evaluate the potential risk of agrochemical leaching in tropical soils cultivated with coffee using geographic inf...
Various greener microextraction procedures have been proposed with low limits of detection to con... more Various greener microextraction procedures have been proposed with low limits of detection to control of pesticides present in the environment, including the low-density solvent dispersive liquid-liquid microextraction (LDS/DLLME) technique. The addition of electrolytes is important in order to induce the salting-out effect. Thus, it is possible to use the Hofmeister series and the Voet lyotropic number to study the effect of different ions on pesticide extraction in LDS/DLLME technique. Different anions were tested and a strong correlation was observed between the lyotropic number of the anion and the recovered volume of extraction solvent. The lyotropic numbers of the anions were successfully compared with the chromatographic peak areas normalized by the recovered solvent volumes, and similar empirical cubic relationships were obtained for all the pyrethroids evaluated. In the extraction of the organophosphorous pesticides, chlorpyrifos presented similarity with the pyrethroids, w...
Journal of the Brazilian Chemical Society
Two types of manganese oxide were investigated for the removal/degradation of Orange G (OG) dye i... more Two types of manganese oxide were investigated for the removal/degradation of Orange G (OG) dye in aqueous solution. One manganese oxide (pyrolusite) was obtained commercially and the other (birnessite) was prepared according to the polyol method by means of the oxidation of Mn II hydroxide by H 2 O 2. Both materials were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), and nitrogen adsorption/desorption at 77 K. The effects of agitation time, pH, and MnO 2 dose on the degradation of OG by the birnessite and pyrolusite were evaluated. Approximately 90 and 99% decoloration of OG (10 mg L-1) was obtained after 30 min of stirring with 0.20 g L-1 of birnessite or pyrolusite, respectively. The decoloration and increased intensity of absorbance bands in the UV-visible spectrum were indicative of a degradation process that followed pseudo-first order kinetics. The findings demonstrated the high efficiency of different types of manganese oxides for removal of this organic pollutant from waters.
Journal of the Brazilian Chemical Society
Birnessite type manganese oxide (δ-MnO 2) was synthesized for use in degradation of the cationic ... more Birnessite type manganese oxide (δ-MnO 2) was synthesized for use in degradation of the cationic dye methylene blue in aqueous solution. The material was characterized using infrared spectroscopy, X-ray diffraction, and Brunauer-Emmett-Teller (BET) surface area calculations. The removal of the dye from aqueous solutions was evaluated considering the effects of the following variables: pH, manganese oxide concentration, contact time, and temperature. UV-Vis spectroscopy analyses indicated achievement of 99 and 95% removal of methylene blue (7 mg L −1) at pH 2.0 and 4.0, respectively, after 120 min of contact with the birnessite (100 mg L −1). At higher pH of 6.0 and 8.0, removals of around 99 and 80%, respectively, were obtained after a longer time of 1860 min. Analyses of total organic carbon (TOC) revealed that 80% reduction of organic matter was obtained at pH 4.0. The method of multivariate curve resolution-alternating least squares (MCR-ALS) was used together with UV-Vis spectroscopy to evaluate the removal process, confirming the degradation of methylene blue. Thionine (λ max = 601 nm) was identified as one of the byproducts of N-demethylation of methylene blue. The results indicated that the degradation process started with N-demethylations of the methylene blue molecule.
Journal of the Brazilian Chemical Society
The method is based on the adsorptive accumulation of complex molybdenum(VI) with 8-hydroxyquinol... more The method is based on the adsorptive accumulation of complex molybdenum(VI) with 8-hydroxyquinoline, using voltammetric square wave cathodic stripping voltammetry. The composition and concentration of the supporting electrolyte, frequency (Hz), amplitude (mV) and deposition time (s), were optimized by factorial design in relation to current reduction of molybdenum(VI). The optimum methodology provided the following values for the process variables: scan increase (0.5 mV), pulse amplitude (127 mV), frequency (96 Hz), adsorption time (80 s) and drop size (0.60 mm 2), the concentration of KNO 3 (2.0 mol L-1), acetate buffer (0.5 mol L-1) and 8-hydroxyquinoline (0.01 mol L-1). The results obtained after optimization showed a linear response in the range from 1.0 to 6.0 mg L-1 and limits of detection and quantification, respectively equal to 0.02 and 0.08 mg L-1. The molybdenum contained in the samples were determined using the optimized methodology, with values consistent with the values determined by atomic emission spectrometry with inductively coupled plasma (ICP-AES).
Anais da Academia Brasileira de Ciências
Biochar is a carbonaceous material that has excellent potential as a fertilizer and soil conditio... more Biochar is a carbonaceous material that has excellent potential as a fertilizer and soil conditioner. However, there is a lack of information concerning the effects of the amount and particle size of this pyrogenic material on the soil sorption capacity. In this work, evaluation was made of changes in clomazone (CMZ) sorption in a Red Latosol following soil conditioning using different percentages (0.25, 0.5, and 1% w/w) of sugarcane biochar in three particle sizes (<106, 106-508, and 508-610 µm). The conditioned soils presented apparent sorption coefficients (K d) up to 1300 times higher than that of pure soil, besides changes in the behavior of CMZ sorption. The biochar particle size and percentage influenced sorption of the herbicide as well as its retention in the amended soil during desorption processes. Both sorption and desorption Freundlich constants were linearly correlated with the external surface area of the biochar present in the soil.
Chemosphere, Jan 14, 2018
The Fundão dam collapsed releasing 60 million tons of mining waste into the environment. The mini... more The Fundão dam collapsed releasing 60 million tons of mining waste into the environment. The mining wastes should be better studied, since some of them are deposited on the alluvial plains soil and at the bottom of the rivers, like sediments, of the region affected. Thus, this work aims to perform the chemical, physical and adsorptive characterization of the samples colleted in region de Paracatu de Baixo. The mining waste has uneven surface, with sizes ranging from 2 to 200 μm, pHPCZ in 6.0. Are composed predominantly by kaolinite, goethite, hematite, gibbsite and quartz. It has been classified as non-hazardous residues. The adsorption studies showed the mining waste have a low Cationic Exchange Capacity. The sorption process was occurs by ion exchange and the kinetics follows the pseudo second order model (R > 0.78). The process is endothermic (ΔH in 29.33 kJ mol) and spontaneous (ΔG in -24.7 kJ mol at 25 °C). The Langmuir model presented a better fit (R > 0.995) to the expe...
Journal of environmental science and health. Part. B, Pesticides, food contaminants, and agricultural wastes, Jan 28, 2017
This study was undertaken to evaluate the effectiveness of several household practices (washing w... more This study was undertaken to evaluate the effectiveness of several household practices (washing with water or acidic, alkaline, and oxidizing solutions, and peeling) in minimizing pesticide residue contamination of tomatoes, as well as the impact on the quality of the treated fruit. Tests were performed using two systemic fungicides (azoxystrobin and difenoconazole) and one contact fungicide (chlorothalonil). Solid-liquid extraction with low temperature partition (SLE/LTP) and liquid-liquid extraction with low temperature partition (LLE/LTP) were used to prepare the samples for pesticides determination by gas chromatography. Washing the tomatoes with water removed approximately 44% of chlorothalonil, 26% of difenoconazole, and 17% of azoxystrobin. Sodium bicarbonate (5%) and acetic acid (5%) solutions were more efficient, removing between 32 and 83% of the residues, while peeling removed from 68 to 88% of the pesticides. The washing solutions altered some fruit quality parameters, i...
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, Jan 5, 2016
EDTA is an important ligand used in many industrial products as well as in agriculture, where it ... more EDTA is an important ligand used in many industrial products as well as in agriculture, where it is employed to assist in phytoextraction procedures and the absorption of nutrients by plants. Due to its intensive use and recalcitrance, it is now considered an emerging pollutant in water, so there is great interest in techniques suitable for its monitoring. This work proposes a method based on formation of the Mn(III)-EDTA complex after oxidation of the Mn(II)-EDTA complex by PbO2 immobilized on cyanoacrylate spheres. A design of experiments (DOE) based on the Doehlert matrix was used to determine the optimum conditions of the method, and the influence of the variables was evaluated using a multiple linear regression (MLR) model. The optimized method presented a linear response in the range from 0.77 to 100.0μmolL(-1), with analytical sensitivity of 7.7×10(3)Lmol(-1), a coefficient of determination of 0.999, and a limit of detection of 0.23μmolL(-1). The method was applied using samp...
Eclética Química Journal, 2018
The salting-out assisted liquid-liquid extraction (SALLE) was developed for the analysis of four ... more The salting-out assisted liquid-liquid extraction (SALLE) was developed for the analysis of four pesticides (cypermethrin, chlorpyrifos, deltamethrin, and thiamethoxam) in water samples. For its optimization, a 2³ factorial design was used to evaluate the simultaneous behavior of three factors: sample and extraction solvent ratio, saline concentration, and stirring mode. A 1.0 mL saline solution (NaCl) was added to the single-phase mixture of water and extraction solvent to separate the phases. The mixture was stirred, allowed to stand and the top organic phase containing the pesticides of interest was analyzed by gas chromatography coupled with electron capture detector (GC/ECD). The optimized method was validated for some merit figures. The limit of detection of the method ranged from 0.15 to 5.5 µg L-1 and the limit of quantification from 5.5 to 18.2 µg L-1. The method showed satisfactory results for the linearity (R2 ≥ 0,990), precision (CV < 9 %) and accuracy (72 % ≤ recover...
Journal of the Brazilian Chemical Society, 2015
Due to uncontrolled use of pesticides and disregard for harvest intervals, some pesticide residue... more Due to uncontrolled use of pesticides and disregard for harvest intervals, some pesticide residue is present in various foods. Treatments using ozone as an alternative for food decontamination have been studied in recent years due to ozone's high oxidation potential even at low concentrations. The present work aimed to evaluate chlorothalonil removal from table grapes by the immersion of fruit in distilled water continuously bubbled with ozone gas. This strategy allowed the removal of 60% of chlorothalonil from table grapes (pulp and skin), regardless of ozone concentration. Ozone treatment of table grapes at a gas concentration of 3 mg L −1 changed most of the quality parameters evaluated. Treatment at 2 mg L −1 maintained the fruit quality for a longer storage period compared to the untreated control table grapes.
Journal of Seed Science, 2016
Sarcotesta, a mucilaginous layer found in papaya seeds, negatively affects the germination of pap... more Sarcotesta, a mucilaginous layer found in papaya seeds, negatively affects the germination of papaya seeds and its removal has been manually performed. The use of sodium hypochlorite can be an alternative to manual removal of sarcotesta in papaya seeds. The objective of this study was to evaluate the effect of different active chlorine concentrations (0, 2, 4, 6 and 8%)
Journal of the Brazilian Chemical Society
Diethylene glycol is an extremely toxic substance to humans. Recently, cases of beer contaminatio... more Diethylene glycol is an extremely toxic substance to humans. Recently, cases of beer contamination in Brazil have raised awareness of the need for developing simple screening methods to evaluate this type of compound. This research developed a liquid-liquid extraction with low-temperature partitioning technique to determine diethylene glycol in beer via gas chromatography. Employing a flame-ionization detector simplifies the method, lowers its cost and therefore, it can be used as screening step to assess the possibility of contamination. A gas chromatograph coupled to a mass spectrometer would be used only for a confirmatory analysis. The optimized method was validated for the main figures of merit, and it proved to be adequate, with good values of recovery rate (94-106%), limit of detection (3.0 mg L-1), and quantification (10.0 mg L-1). Accuracy, in terms of repeatability and intermediate accuracy, showed variation coefficients lower than or equal to 20%. This method was applied ...
Journal of the Brazilian Chemical Society, 2019
Clomazone exhibits high water solubility, low sorption in soil colloids, and therefore can leach ... more Clomazone exhibits high water solubility, low sorption in soil colloids, and therefore can leach and contaminate deep layers of soil profile and groundwater. In this work, the effect of the incorporation of sugarcane bagasse biochar in leaching and bioavailability of clomazone in red latosol was evaluated. Soil samples amended with 1% (m/m) biochar were placed in different depths (0-1, 0-2.5 and 0-5 cm) on the top of polyvinyl chloride (PVC) columns filled with soil. Clomazone-based herbicide was applied, and rainfall was simulated on top of the columns. A validated chromatographic method, together with a greenhouse bioassay, were used to quantify and to evaluate the mobility and availability of clomazone along the columns. The incorporation of sugarcane bagasse biochar in the superficial layers at the column tops increased herbicide sorption, reduced its leaching and bioavailability in soil and scaled down the environmental risk of clomazone avoiding contamination of underground aquifer reservoirs.
Microchemical Journal, 2017
Abstract The aim of this work is to develop a method for determining trihalomethanes (THMs) in fi... more Abstract The aim of this work is to develop a method for determining trihalomethanes (THMs) in fish samples. The proposed method uses solid phase microextraction and gas chromatography with an electron capture detector. Factors such as temperature, extraction time and type of fiber were assessed to maximize the performance of the extraction technique. The performance of the method was evaluated using selectivity, linearity, precision, accuracy and limits of detection (LOD) and quantification (LOQ). The new method allows analysis of THMs with appropriate selectivity and linearity, with coefficient of correlation > 0.98. The LOD and LOQ of the analytes of interest are from 0.11 to 0.35 μg kg − 1 and 0.35 to 1.18 μg kg − 1 , respectively. In addition, the relative standard deviation (RSD) was between 1.6 and 8%, and the relative recovery was between 76 and 113%. The optimized and validated method was applied to fish samples purchased from the Vicosa (MG) local market. At least three of the THMs of interest were detected in most of the analyzed fish samples with maximum values for the concentration of chloroform, bromodichloromethane and bromoform at 8.33, 0.42 and 2.41 μg kg − 1 , respectively.
Journal of the Brazilian Chemical Society, 2017
A new method has been developed to determine trace levels of organophosphorus pesticide parathion... more A new method has been developed to determine trace levels of organophosphorus pesticide parathion-methyl in water samples by using dispersive liquid-liquid microextraction (DLLME), followed by gas chromatograph coupled with electron capture detector (GC/ECD) analysis. The optimized and validated method showed high extraction recovery (101.1%), high enrichment factor (57.3), low limits of detection and quantification, 0.083 and 0.250 μg L-1 , respectively. The established DLLME-GC/ECD method has been successfully applied for the evaluation of the photodegradation of the parathion-methyl by UV 254nm radiation in different conditions of pH and temperature. The parathion-methyl photodegradation at pH 3 and 35 °C achieved > 99.5% after 120 min of exposition. For this condition, it was observed the kinetic rate of 0.0515 min-1 , the quantum yield of 1.22 × 10-5 mol Einstein-1 and a half-life time of 13.46 min. All experimental conditions tested proved to be strongly influenced by pH and temperature. The application of the optimized process in distilled and drinking water spiked with parathion-methyl provided residues of this pesticide at levels below the maximum permitted by Brazilian legislation, which is 9.0 μg L-1 .
Journal of the Brazilian Chemical Society, 2015
A new method for the extraction of pesticide residues from soil was developed, optimized, validat... more A new method for the extraction of pesticide residues from soil was developed, optimized, validated and applied to real samples. The technique consisted of combining single-drop microextraction and solid-liquid extraction with low temperature partitioning (SLE/LTP-SDME) followed by analysis using gas chromatography with electron capture detection (GC/ECD). This method was used to determine the presence of alachlor, methyl parathion, trifluralin, endrin, lindane, dieldrin and dichloro-diphenyl-trichloroethane (4,4'-DDT) in soil samples. Recoveries ranging from 67.2 to 122.5% were achieved, coefficients of variation (repeatability) were lower than 22.4% and limits of detection ranged from 0.18 to 0.59 µg kg-1. Recovery from soils fortified with different concentrations of the pesticides ranged from 61.5 to 123.5%. The new method combines the primary advantages of the two techniques: purification of the sample using SLE/LTP and preconcentration using SDME. The new method also enables the determination of low volatility compounds without requiring the sample to be heated.
Journal of the Brazilian Chemical Society, 2018
Effluents from pulp mills have a high organic load and can still contain high organic biorecalcit... more Effluents from pulp mills have a high organic load and can still contain high organic biorecalcitrant material that is harmful to the aquatic environment, even after undergoing biological treatment in effluent treatment plants. This study presents a novel treatment method tested on effluents (prior to and after biotreatment) from a Brazilian kraft pulp mill, based on hydroxyl radical production and hydrogen peroxide obtained by plasma generated by high-voltage electrolysis. These species present significant oxidation potential that could enable the complete breakdown of the organic matter. From the application of plasma to treat pulp mill effluent for a 7-hour period, it was obtained a chemical oxygen demand (COD) removal between 88.2 and 99.7%, total organic carbon (TOC) removal of 90.3 to 95.6%, and a color removal of 95.0 to 98.0%. The final pH of the treated effluent was 11.6 to 11.9. The results obtained in this study showed that the high-tension plasma treatment, applied on effluent from kraft pulp mills before and after biological treatment, can be an attractive alternative.
Research, Society and Development, 2021
This study evaluated the mobility and persistence of aldicarb and its degradation products in red... more This study evaluated the mobility and persistence of aldicarb and its degradation products in red-yellow oxisol (LVA) using soil columns, after the application of Temik 150. Leaching experiments were performed using polyvinyl chloride (PVC) columns filled with soil contaminated with aldicarb and rain simulation of 6.05 mm day-1, at 10 day intervals, for 90 days. Aldicarb, aldicarb sulfoxide and aldicarb sulfone residues were extracted from soil (solid-liquid) and percolated water (liquid-liquid) samples with quantification by CG-FID. The results showed that aldicarb was rapidly oxidized to aldicarb sulfoxide and aldicarb sulfone in 10 days after the application. Aldicarb sulfoxide percolated through 15 cm of the soil column and could not be detected in the soil after 40 days incubation. From the 60 days since application, residues were no longer detected in the samples of percolated water and soil fractions, indicating rapid degradation and low potential for groundwater contamination.
Water
Studies show that agricultural activities around the world still present a strong dependence on a... more Studies show that agricultural activities around the world still present a strong dependence on agrochemicals that can leach into the soil profile, causing its contamination, as well as that of water resources. In this context, the present study evaluates the potential risk of pesticide leaching in areas of edaphoclimatic suitability for coffee cultivation in Espírito Santo state, Brazil. As a methodology, the areas of edaphoclimatic suitability for conilon and arabica coffee were defined, and subsequently, the risk of leaching of active agrochemical ingredients in these areas was evaluated using the Groundwater Ubiquity Score (GUS), Leaching Index (LIX) and Attenuation Factor/Retardation Factor (AF/RF) methods. Of the ten active ingredients evaluated, sulfentrazone and thiamethoxam present a potential risk of leaching into the groundwater level. The study allowed us to evaluate the potential risk of agrochemical leaching in tropical soils cultivated with coffee using geographic inf...
Various greener microextraction procedures have been proposed with low limits of detection to con... more Various greener microextraction procedures have been proposed with low limits of detection to control of pesticides present in the environment, including the low-density solvent dispersive liquid-liquid microextraction (LDS/DLLME) technique. The addition of electrolytes is important in order to induce the salting-out effect. Thus, it is possible to use the Hofmeister series and the Voet lyotropic number to study the effect of different ions on pesticide extraction in LDS/DLLME technique. Different anions were tested and a strong correlation was observed between the lyotropic number of the anion and the recovered volume of extraction solvent. The lyotropic numbers of the anions were successfully compared with the chromatographic peak areas normalized by the recovered solvent volumes, and similar empirical cubic relationships were obtained for all the pyrethroids evaluated. In the extraction of the organophosphorous pesticides, chlorpyrifos presented similarity with the pyrethroids, w...
Journal of the Brazilian Chemical Society
Two types of manganese oxide were investigated for the removal/degradation of Orange G (OG) dye i... more Two types of manganese oxide were investigated for the removal/degradation of Orange G (OG) dye in aqueous solution. One manganese oxide (pyrolusite) was obtained commercially and the other (birnessite) was prepared according to the polyol method by means of the oxidation of Mn II hydroxide by H 2 O 2. Both materials were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), and nitrogen adsorption/desorption at 77 K. The effects of agitation time, pH, and MnO 2 dose on the degradation of OG by the birnessite and pyrolusite were evaluated. Approximately 90 and 99% decoloration of OG (10 mg L-1) was obtained after 30 min of stirring with 0.20 g L-1 of birnessite or pyrolusite, respectively. The decoloration and increased intensity of absorbance bands in the UV-visible spectrum were indicative of a degradation process that followed pseudo-first order kinetics. The findings demonstrated the high efficiency of different types of manganese oxides for removal of this organic pollutant from waters.
Journal of the Brazilian Chemical Society
Birnessite type manganese oxide (δ-MnO 2) was synthesized for use in degradation of the cationic ... more Birnessite type manganese oxide (δ-MnO 2) was synthesized for use in degradation of the cationic dye methylene blue in aqueous solution. The material was characterized using infrared spectroscopy, X-ray diffraction, and Brunauer-Emmett-Teller (BET) surface area calculations. The removal of the dye from aqueous solutions was evaluated considering the effects of the following variables: pH, manganese oxide concentration, contact time, and temperature. UV-Vis spectroscopy analyses indicated achievement of 99 and 95% removal of methylene blue (7 mg L −1) at pH 2.0 and 4.0, respectively, after 120 min of contact with the birnessite (100 mg L −1). At higher pH of 6.0 and 8.0, removals of around 99 and 80%, respectively, were obtained after a longer time of 1860 min. Analyses of total organic carbon (TOC) revealed that 80% reduction of organic matter was obtained at pH 4.0. The method of multivariate curve resolution-alternating least squares (MCR-ALS) was used together with UV-Vis spectroscopy to evaluate the removal process, confirming the degradation of methylene blue. Thionine (λ max = 601 nm) was identified as one of the byproducts of N-demethylation of methylene blue. The results indicated that the degradation process started with N-demethylations of the methylene blue molecule.
Journal of the Brazilian Chemical Society
The method is based on the adsorptive accumulation of complex molybdenum(VI) with 8-hydroxyquinol... more The method is based on the adsorptive accumulation of complex molybdenum(VI) with 8-hydroxyquinoline, using voltammetric square wave cathodic stripping voltammetry. The composition and concentration of the supporting electrolyte, frequency (Hz), amplitude (mV) and deposition time (s), were optimized by factorial design in relation to current reduction of molybdenum(VI). The optimum methodology provided the following values for the process variables: scan increase (0.5 mV), pulse amplitude (127 mV), frequency (96 Hz), adsorption time (80 s) and drop size (0.60 mm 2), the concentration of KNO 3 (2.0 mol L-1), acetate buffer (0.5 mol L-1) and 8-hydroxyquinoline (0.01 mol L-1). The results obtained after optimization showed a linear response in the range from 1.0 to 6.0 mg L-1 and limits of detection and quantification, respectively equal to 0.02 and 0.08 mg L-1. The molybdenum contained in the samples were determined using the optimized methodology, with values consistent with the values determined by atomic emission spectrometry with inductively coupled plasma (ICP-AES).
Anais da Academia Brasileira de Ciências
Biochar is a carbonaceous material that has excellent potential as a fertilizer and soil conditio... more Biochar is a carbonaceous material that has excellent potential as a fertilizer and soil conditioner. However, there is a lack of information concerning the effects of the amount and particle size of this pyrogenic material on the soil sorption capacity. In this work, evaluation was made of changes in clomazone (CMZ) sorption in a Red Latosol following soil conditioning using different percentages (0.25, 0.5, and 1% w/w) of sugarcane biochar in three particle sizes (<106, 106-508, and 508-610 µm). The conditioned soils presented apparent sorption coefficients (K d) up to 1300 times higher than that of pure soil, besides changes in the behavior of CMZ sorption. The biochar particle size and percentage influenced sorption of the herbicide as well as its retention in the amended soil during desorption processes. Both sorption and desorption Freundlich constants were linearly correlated with the external surface area of the biochar present in the soil.
Chemosphere, Jan 14, 2018
The Fundão dam collapsed releasing 60 million tons of mining waste into the environment. The mini... more The Fundão dam collapsed releasing 60 million tons of mining waste into the environment. The mining wastes should be better studied, since some of them are deposited on the alluvial plains soil and at the bottom of the rivers, like sediments, of the region affected. Thus, this work aims to perform the chemical, physical and adsorptive characterization of the samples colleted in region de Paracatu de Baixo. The mining waste has uneven surface, with sizes ranging from 2 to 200 μm, pHPCZ in 6.0. Are composed predominantly by kaolinite, goethite, hematite, gibbsite and quartz. It has been classified as non-hazardous residues. The adsorption studies showed the mining waste have a low Cationic Exchange Capacity. The sorption process was occurs by ion exchange and the kinetics follows the pseudo second order model (R > 0.78). The process is endothermic (ΔH in 29.33 kJ mol) and spontaneous (ΔG in -24.7 kJ mol at 25 °C). The Langmuir model presented a better fit (R > 0.995) to the expe...
Journal of environmental science and health. Part. B, Pesticides, food contaminants, and agricultural wastes, Jan 28, 2017
This study was undertaken to evaluate the effectiveness of several household practices (washing w... more This study was undertaken to evaluate the effectiveness of several household practices (washing with water or acidic, alkaline, and oxidizing solutions, and peeling) in minimizing pesticide residue contamination of tomatoes, as well as the impact on the quality of the treated fruit. Tests were performed using two systemic fungicides (azoxystrobin and difenoconazole) and one contact fungicide (chlorothalonil). Solid-liquid extraction with low temperature partition (SLE/LTP) and liquid-liquid extraction with low temperature partition (LLE/LTP) were used to prepare the samples for pesticides determination by gas chromatography. Washing the tomatoes with water removed approximately 44% of chlorothalonil, 26% of difenoconazole, and 17% of azoxystrobin. Sodium bicarbonate (5%) and acetic acid (5%) solutions were more efficient, removing between 32 and 83% of the residues, while peeling removed from 68 to 88% of the pesticides. The washing solutions altered some fruit quality parameters, i...
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, Jan 5, 2016
EDTA is an important ligand used in many industrial products as well as in agriculture, where it ... more EDTA is an important ligand used in many industrial products as well as in agriculture, where it is employed to assist in phytoextraction procedures and the absorption of nutrients by plants. Due to its intensive use and recalcitrance, it is now considered an emerging pollutant in water, so there is great interest in techniques suitable for its monitoring. This work proposes a method based on formation of the Mn(III)-EDTA complex after oxidation of the Mn(II)-EDTA complex by PbO2 immobilized on cyanoacrylate spheres. A design of experiments (DOE) based on the Doehlert matrix was used to determine the optimum conditions of the method, and the influence of the variables was evaluated using a multiple linear regression (MLR) model. The optimized method presented a linear response in the range from 0.77 to 100.0μmolL(-1), with analytical sensitivity of 7.7×10(3)Lmol(-1), a coefficient of determination of 0.999, and a limit of detection of 0.23μmolL(-1). The method was applied using samp...