RESUMO
The global presence of pharmaceutical pollutants in water sources represents a burgeoning public health concern. Recent studies underscore the urgency of addressing this class of emerging contaminants. In this context, our work focuses on synthesizing a composite material, FexOy/MAF-32, through a streamlined one-pot reaction process, as an adsorbent for diclofenac, an emerging environmental contaminant frequently found in freshwater environments and linked to potential toxicity towards several organisms such as fish and mussels. A thorough characterization was performed to elucidate the structural composition of the composite. The material presents magnetic properties attributed to its superparamagnetic behavior, which facilitates the recovery efficiency of the composite post-diclofenac adsorption. Our study further involves a comparative analysis between the FexOy/MAF-32 and a non-magnetic counterpart, comprised solely of 2-ethylimidazolate zinc polymer. This comparison aims to discern the relative advantages and disadvantages of incorporating magnetic iron oxide nanoparticles in the contaminant removal process facilitated by a coordination polymer. Our findings reveal that even a minimal incorporation of iron oxide nanoparticles substantially enhanced the composite's overall performance in pollutant adsorption.
RESUMO
The photocatalytic decomposition of caffeine under UV-light irradiation was observed for the first time in a matrix of synthetic urine using granules of hydrogenated and iron-exchanged natural zeolite, coated with two loadings of TiO2. A natural clinoptilolite-mordenite blend was used to prepare photocatalytic adsorbents coated with TiO2 nanoparticles. The performance of the obtained materials was tested in the photodegradation of caffeine, a water contaminant of emerging concern. The photocatalytic activity was better in the urine matrix, due to the formation of surface complexes on the TiO2 coating, cation exchange performed by the zeolite support, and use of the carrier electrons in the reduction of ions, affecting recombination of the electrons and holes during photocatalysis. The composite granules maintained photocatalytic activity for at least four cycles, with more than 50% of caffeine removal in the synthetic urine matrix.
Assuntos
Cafeína , Zeolitas , Titânio , Raios Ultravioleta , CatáliseRESUMO
In this research, changes in several characteristics of partially reduced titania were studied. The reduction process used made it possible to gradually observe changes in the material depending on the amount of reducing agent used. We used NaBH4 to impregnate commercial TiO2 with isopropyl alcohol. Impregnated TiO2 nanoparticles were dried and thermally treated in a nitrogen flow to obtain blue titania samples. Thorough spectroscopic characterization showed that oxygen atoms from hydroxyl groups, as well as from the surface, and the lattice of TiO2 was consumed. This caused changes in the surface and even in the bulk of TiO2 when the amount of reducing agent used was increased. Structural, optical, superficial, and textural characteristics were studied using XRD, Raman, DRS UV-Vis-NIR, Mid-DRIFT, XPS, and nitrogen adsorption/desorption isotherms. A photocatalytic test of the degradation of methylene blue dye was performed. Among different effects on the mentioned characteristics, we found evidence of changes in the surface properties of the blue titania samples and their probable effect on the photocatalytic properties. The reduction process implied a preponderant decrease in the surface hydrophilicity of the reduced samples, an effect shown for the first time in this type of material.
RESUMO
Conotrachelus dimidiatus (Coleoptera: Curculionidae) interacts with immature guava fruits (Psidium guajava L.) for feed, sleep, mate and oviposit. Determination of the volatile organic compounds (VOCs) emitted by the insect and immature fruits can help improve understanding of plant-insect and intraspecific insect interactions between females and males of C. dimidiatus. Daytime fruit setting emissions of immature guava consist mainly of limonene, caryophyllene, and aromadendrene. In addition to the host's volatiles, the aim of this study was to assess the VOCs released by the insect. Static headspace-solid phase microextraction (SHS-SPME), combined with gas chromatography/quadrupole time of flight mass spectrometry (GC/Q-ToF-MS), allowed the identification of the C10 terpenoids: grandlure I, II, II, IV, grandisoic acid, papayanol and papayanal bioactive compounds released by female and male C. dimidiatus under laboratory conditions. These chemical compounds are candidates for the preparation of a lure formulation.
Assuntos
Psidium/química , Terpenos/química , Gorgulhos/fisiologia , Animais , Feminino , Frutas/química , Frutas/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Herbivoria , Masculino , Feromônios/química , Feromônios/isolamento & purificação , Feromônios/farmacologia , Psidium/metabolismo , Comportamento Sexual Animal/efeitos dos fármacos , Microextração em Fase Sólida , Terpenos/análise , Terpenos/isolamento & purificação , Terpenos/farmacologia , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/química , Compostos Orgânicos Voláteis/isolamento & purificação , Gorgulhos/químicaRESUMO
Immature guava fruits (Psidium guajava L.) of commercial orchards in Mexico are affected by adults of Conotrachelus dimidiatus (Champion) causing economic losses to producers. The aim of this study was to assess the behavioral and electrophysiological responses of the weevil to selected semiochemicals emitted by the host plant fruit and to conspecifics. Volatile organic compounds isolated from host plant as ß-caryophyllene, (S)-(-)-limonene, hexanal, and nonanal significantly attracted adults of both sexes in behavioral bioassays. Electroantennogram recordings showed largest responses to papayanal and grandlure III + IV released by C. dimidiatus and C. nenuphar, respectively. Our results indicate that behavioral and electroantennographic assays using synthetic compounds from host plant volatiles and insect volatile pheromones produce olfactometry and electroantennographic responses in C. dimidiatus. This is the first report of intraspecific chemical communication in this weevil. We discuss the significance of these responses for the natural behavior in guava orchards and their potential use in a pest management strategy.
Assuntos
Besouros , Psidium , Compostos Orgânicos Voláteis , Gorgulhos , Animais , Feminino , Masculino , MéxicoRESUMO
The mature larva and pupa of Conotrachelus dimidiatus Champion, 1904 (Curculionidae: Molytinae) are morphologically re-described, keyed and, for the first time, compared with known larvae and pupae of other Conotrachelus species. The chaetotaxy of the larval and pupal body in the genus Conotrachelus is probably strictly uniform. The immature stages of described species are also compared with available data on the immature stages of genera from several tribes in the subfamily Molytinae. All larvae of Conotrachelus have a distinct endocranial line of a different size and a frons with only three setae. The states of these two distinct characteristics in larvae of the eight known Conotrachelus species are constant and unique compared to other tribes in the subfamily Molytinae. In Central Mexico, overwintering Conotrachelus beetles emerge in July and then feed and mate on host plants. Larvae are endophagous within the fruits. In September and October, the larvae pupate in the soil. This new information will be very useful in the application of pesticides to the fight against this well-known pest in Mexico.
Assuntos
Besouros , Gorgulhos , Animais , Larva , México , PupaRESUMO
INTRODUCTION: Determination of the volatile organic compounds (VOCs) emitted by immature fruits furthers our understanding of plant-pest interactions and by fruits in a ripe state concerns food quality. OBJECTIVES: To apply headspace solid-phase microextraction gas chromatography quadrupole time-of-flight mass spectrometry (HS-SPME-GC-QTOF/MS) to compare the volatiles emitted by different parts of guava (Psidium guajava L. cv. "Media China") at different maturation stages. METHODOLOGY: HS-SPME combined with GC-QTOF/MS was used to characterise the VOCs of entire guavas in the orchard and under laboratory conditions. For chemical analysis X-ray fluorescence spectroscopy, refractometry, titration, complexometry, diode array detector high-performance liquid chromatography (DAD-HPLC) and refractive index detector (RI)-HPLC were used. RESULTS: The guava variety was rich in potassium and poor in sodium. A total of 44 VOCs were identified in different phenological stages and parts of the fruits. Release of VOCs was influenced by the temperature in the plantation, and transformation of innate fruit VOCs started immediately after cutting. CONCLUSION: The most abundant VOC released by the immature fruit in the plantation overnight was (S)-limonene, and it concentrated in the outer skin (pericarp). The esters ethyl benzoate, ethyl octanoate, butyl-2-methylbutanoate, ethyl hexanoate, cis-3-hexenyl acetate, and ethyl butanoate were emitted by ripe whole fruits. During ripening ethyl benzoate reached a maximum production after three to five days, while the formation of the aldehydes benzaldehyde, hexanal and trans-2-hexen-1-al started thereafter.
Assuntos
Frutas/química , Espectrometria de Massas/métodos , Psidium/química , Compostos Orgânicos Voláteis/químicaRESUMO
Carbofuran is a toxic carbamate pesticide, and its use has increased in recent years. While marketing information indicates stability in different chemical media, carbofuran exhibits relative photolability. The aim of this research was to decompose carbofuran and to identify the photoproducts achieved when two different doped titania photocatalysts were employed under UV irradiation. The iron-doped TiO2 materials were obtained (a) via a hydrothermal method and (b) by an ultrasound-assisted sol-gel method. The precursors were TiOSO4â xH2O and Fe3(NO3)·9H2O. X-ray studies confirmed that the anatase phase of the iron-doped TiO2 resulted from the two preparation methods. The photocatalytic performance of the prepared materials was monitored by LC/ESI-QTOF-MS, enabling the identification of photoproducts: oxo-carbamates, hydroxylated benzofuranes, a carboxamide, and one amine. By using the iron-doped TiO2 materials, 2,2-dimethyl-2,3-dihydrobenzofuran-3,7-diol was the most abundant photoproduct, and N,2,2-trimethyl-2,3-dihydrobenzofuran-7-amine was the only compound that had not been previously reported in the photolysis and photocatalysis of carbofuran. The product 3-hydroxy carbofuran, a cholinesterase inhibitor, was quantified and was found to be transformed into compounds that lack this inhibitive property.
Assuntos
Carbofurano/química , Ferro/química , Titânio/química , Carbofurano/análogos & derivados , Catálise , Colinesterases , Fotólise , Raios UltravioletaRESUMO
Three carbon samples were employed in this work, including commercial (1690 m2 g-1), activated carbon prepared from guava seeds (637 m2 g-1), and activated carbon prepared from avocado kernel (1068 m2 g-1), to study the adsorption of the following gadolinium-based contrast agents (GBCAs): gadoterate meglumine Dotarem®, gadopentetate dimeglumine Magnevist®, and gadoxetate disodium Primovist®. The activation conditions with H3PO4 were optimized using a Taguchi methodology to obtain mesoporous materials. The best removal efficiency by square meter in a batch system in aqueous solution and model urine was achieved by avocado kernel carbon, in which mesoporosity prevails over microporosity. The kinetic adsorption curves were described by a pseudo-second-order equation, and the adsorption isotherms in the concentration range 0.5-6 mM fit the Freundlich equation. The chemical characterization of the surfaces shows that materials with a greater amount of phenolic functional groups adsorb the GBCA better. Adsorption strongly depends on the pH due to the combination of the following factors: contrast agent protonated forms and carbon surface charge. The tested carbon samples were able to adsorb 70-90% of GBCA in aqueous solution and less in model urine. This research proposes a method for the elimination of GBCA from patient urine before its discharge into wastewater.
Assuntos
Carbono/química , Meios de Contraste/química , Gadolínio DTPA/química , Meglumina/química , Compostos Organometálicos/química , Poluentes Químicos da Água/química , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Urina/química , Poluição da Água/prevenção & controleRESUMO
Applications of carbon-TiO2 materials have attracted attention in nanotechnology due to their synergic effects. We report the immobilization of TiO2 on carbon prepared from residues of the plant Manihot, commercial TiO2 and glycerol. The objective was to obtain a moderate loading of the anatase phase by preserving the carbonaceous external surface and micropores of the composite. Two preparation methods were compared, including mixing dry precursors and immobilization using a glycerol slurry. The evaluation of the micropore blocking was performed using nitrogen adsorption isotherms. The results indicated that it was possible to use Manihot residues and glycerol to prepare an anatase-containing material with a basic surface and a significant SBET value. The activities of the prepared materials were tested in a decomposition assay of indigo carmine. The TiO2/carbon eliminated nearly 100% of the dye under UV irradiation using the optimal conditions found by a Taguchi L4 orthogonal array considering the specific surface, temperature and initial concentration. The reaction was monitored by UV-Vis spectrophotometry and LC-ESI-(Qq)-TOF-MS, enabling the identification of some intermediates. No isatin-5-sulfonic acid was detected after a 60 min photocatalytic reaction, and three sulfonated aromatic amines, including 4-amino-3-hydroxybenzenesulfonic acid, 2-(2-amino-5-sulfophenyl)-2-oxoacetic acid and 2-amino-5-sulfobenzoic acid, were present in the reaction mixture.
Assuntos
Carbono/química , Corantes/isolamento & purificação , Índigo Carmim/isolamento & purificação , Manihot/química , Fotólise , Titânio/química , Corantes/química , Índigo Carmim/química , Raios UltravioletaRESUMO
Carbon-TiO2 composites were obtained from carbonised Manihot dulcis waste and TiO2 using glycerol as an additive and thermally treating the composites at 800 °C. Furthermore, carbon was obtained from manihot to study the adsorption, desorption and photocatalysis of carminic acid on these materials. Carminic acid, a natural dye extracted from cochineal insects, is a pollutant produced by the food industry and handicrafts. Its photocatalysis was observed under different atmospheres, and kinetic curves were measured by both UV-Vis and HPLC for comparison, yielding interesting differences. The composite was capable of decomposing approximately 50% of the carminic acid under various conditions. The reaction was monitored by UV-Vis spectroscopy and LC-ESI-(Qq)-TOF-MS-DAD, enabling the identification of some intermediate species. The deleterious compound anthracene-9,10-dione was detected both in N2 and air atmospheres.
Assuntos
Carmim/química , Corantes de Alimentos/química , Manihot/química , Nanopartículas/química , Carbono/química , Cromatografia Líquida de Alta Pressão , Espectrometria de Massas , Fotólise , Titânio/químicaRESUMO
Five sulfonyl aromatic alcohols, namely 4-((2-hydroxyethyl)sulfonyl)phenol, 4-((2-(2-((4-hydroxyphenyl)sulfonyl)ethoxy)vinyl)sulfonyl)phenol, 4-(ethylsulfonyl)phenol, 4-(vinylsulfonyl)phenol and 5-((4-aminophenyl)sulfonyl)-2-penten-1-ol were identified by LC-ESI-Qq-TOF-MS as products formed by electrolysis of the bisazo reactive dye Reactive Black 5 (RB5). Since electrolyses were performed in an undivided cell equipped with Ni electrodes in alkaline medium, amines like 4-(2-methoxyethylsulfonyl)benzene-amine (MEBA) with m/z 216 were also suspected to be formed due to the plausible chemical reaction in the bulk or the cathodic reduction of RB5 and its oxidation by-products. Aiming to check this hypothesis, a method was used for the preparation of MEBA with 98% purity, via chemical reduction also of the dye RB5. The logP of the synthesized sulfonyl aromatic compounds was calculated and their logkw values were determined chromatographically. These data were discussed in regard to the relationship between hydrophobicity/lipophilicity and toxicity.
Assuntos
Álcoois/química , Corantes/química , Eletrólise/métodos , Álcoois/análise , Aminas/química , Compostos de Anilina/síntese química , Biodegradação Ambiental , Eletrodos , Naftalenossulfonatos/análise , Naftalenossulfonatos/química , Fenóis/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/químicaRESUMO
Sorption of phenylarsenicals including 4-hydroxy-3-nitrophenylarsonic acid (roxarsone), an animal feed additive widely used for growth stimulation, on soils was investigated in batch systems. Phenylarsonic acid, o-arsanilic acid and roxarsone were retained differently by unpolluted, non-sterilized soils. Sorption isotherms were analyzed by the Henry, Tóth and Langmuir-Freundlich equations. The saturation capacity of the Acrisol soil was 3.4 for o-arsanilic acid, 10.9 for phenylarsonic acid and 1.9 g(As) kg(soil)(-1) (dry mass) for roxarsone. The iron content in the soil was not the only factor determining retention of the studied phenylarsenicals. The order of retention on the three soils after 24 h was: roxarsone>o-arsanilic acid>phenylarsonic acid. Besides arsenite and arsenate, new arsenic-containing compounds were detected.
Assuntos
Arsenicais/química , Poluentes do Solo/análise , Erupções Vulcânicas/análise , Adsorção , Algoritmos , Ácido Arsanílico/química , Arsênio/química , Cromatografia Líquida de Alta Pressão , Dessecação , Umidade , Cinética , Espectrometria de Massas , Roxarsona/química , Solo/análise , Espectrofotometria Ultravioleta , TermodinâmicaRESUMO
Arsenic is a metalloid well known to be potentially toxic depending of its species. Lipid-soluble arsenicals (arsenolipids) are present in a wide range of biological samples in which they could play a role in the biosynthesis of organoarsenic compounds from inorganic arsenic compounds. Arsenolipids have recently attracted considerable interest. In order to gain deeper insights into the impact of arsenolipids new analytical approaches for reliable determination of this class of arsenic-containing hydrocarbons in various matrices are needed. High concentrations of arsenolipids were found in seafood which served as sample material in this study. We report the investigation of three arsenolipids found in canned cod liver from which they were extracted and purified by solid phase extraction (SPE) using a silica gel column and ethyl acetate/methanol as eluent. Analytical studies were conducted by means of gas chromatography coupled with ICP-MS, MIP-AES and EI-qMS and by TOF-MS. The results obtained by GC-ICP-MS and GC-MIP-AES showed the existence of numerous arsenic compounds in the SPE fractions collected. Three major peaks were found within a retention time window between 10 and 25 min. The presence of arsenic compounds in the fish tissue could be confirmed using GC-EI-qMS analysis. Corresponding information of the molecular weights of the major arsenic species were provided by TOF-MS which allows highly accurate mass determinations. The results showed the presence of the arsenic-containing hydrocarbons with the following molecular formulas: C(17)H(37)AsO (calculated for [M+H](+) 333.2133; found 333.2136; Deltam=0.90 ppm); C(19)H(41)AsO (calculated for [M+H](+) 361.2446; found 361.2446; Deltam=0.00 ppm); C(23)H(37)AsO (calculated for [M+H](+) 405.2133; found 405.2145; Deltam=2.96 ppm). Suggestions for the corresponding structures are discussed.
Assuntos
Arsênio/análise , Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Alimentos em Conserva/análise , Gadus morhua , Hidrocarbonetos/química , Fígado/citologia , Animais , Arsênio/química , Cromatografia Gasosa-Espectrometria de Massas , Lipídeos/química , SolubilidadeRESUMO
In this study the husk of mango seed and two carbonaceous adsorbents prepared from it were used to study the adsorption behavior of eight acid dyes. The adsorbed amount in mmol m(-2) decayed asymptotically as the molecular volume and area increased. The interaction between the studied dyes and the mesoporous carbon was governed by the ionic species in solution and the acidic/basic groups on the surface. Less than 50% of the external surface of the microporous carbon became covered with the dyes molecules, though monolayer formation demonstrating specific interactions only with active sites on the surface and the adsorption magnitudes correlated with the shape parameter of the molecule within a particular dye group. The adsorption behavior in mixtures was determined by the molecular volume of the constituents; the greater the molecular volume difference, the greater the effect on the adsorbed amount. We also demonstrated that the raw husk of the mango seed can be used to remove up to 50% from model 50 mg l(-1) solutions of the studied acid dyes.
Assuntos
Antraquinonas/isolamento & purificação , Compostos Azo/isolamento & purificação , Corantes/isolamento & purificação , Mangifera/metabolismo , Sementes/metabolismo , Ácidos , Adsorção , Antraquinonas/química , Compostos Azo/química , Biodegradação Ambiental , Carbono , Corantes/química , Nitrogênio/química , Soluções , Espectroscopia de Infravermelho com Transformada de Fourier , TemperaturaRESUMO
The preparation of carbon from waste materials is a recent and economic alternative for the removal of dyes. In this study four samples of carbon were obtained by thermal treatment at 1000 degrees C using as precursor the guava seed with different particle sizes. The Taguchi method was applied as an experimental design to establish the optimum conditions for the removal of acid orange 7 in batch experiments. The chosen experimental factors and their ranges were: pH (2-12), temperature (15-35 degrees C), specific surface area (50-600 m(2)g(-1)) and adsorbent dosage (16-50 mg ml(-1)). The orthogonal array L(9) and the larger the better response category were selected to determine the optimum removal conditions: pH 2, temperature 15 degrees C, S(esp) 600 m(2)g(-1) and dosage 30 mg ml(-1). Under these conditions a total removal of acid orange 7 was achieved. Moreover, the most significant factors were the carbon specific surface area and the pH. The influence of the different factors on the adsorption of acid orange 7 from solution is explained in terms of electrostatic interactions by considering the dye species and the character of the surface.
Assuntos
Compostos Azo/isolamento & purificação , Benzenossulfonatos/isolamento & purificação , Psidium , Carbono , Corantes/isolamento & purificação , Concentração de Íons de Hidrogênio , Resíduos Industriais/prevenção & controle , Modelos Teóricos , Sementes , TemperaturaRESUMO
The guava seed (SEGUVE) was characterized by ultimate and proximate analysis. In SEGUVE the principal thermal effect occurred at 363 degrees C and this can be attributed to the cellulose degradation, which was the main component ( approximately 61%). The guava seed has an acidic character with a high content of bulk functional groups (CO) and these characteristics were affected by carbonization. Two samples of carbon were prepared from the seeds at 600 and 1000 degrees C without chemical activation. Adsorption of eight acid dyes belonging to the monoazo and anthraquinone class was studied at 25 degrees C. The non-carbonized SEGUVE adsorbed the acid dyes more efficiently than SEGUVE-C600 and SEGUVE-C1000 although the specific surface of the raw material SEGUVE was low.
Assuntos
Carbono/metabolismo , Corantes/isolamento & purificação , Psidium/metabolismo , Sementes/metabolismo , Ácidos , Adsorção , Biodegradação Ambiental , Corantes/química , Análise Diferencial Térmica , Modelos Químicos , Nitrogênio , Sementes/citologia , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície , Temperatura , TermogravimetriaRESUMO
The surface chemistry of maize naturasorbent was altered in this work by the modifying agents: phosphoric acid and different amines (triethanolamine, diethylenetriamine and 1,4-diaminobutane). Removal of methyl orange (25 mg l(-1)) was <50% by maize corn cobs modified by phosphorylation and higher by the quaternized samples: 68% with the 1,4-diaminobutane and 73% with the diethylenetriamine modificators. Adsorption of arsenite by the samples modified with phosphoric acid/ammonia was 11 microg g(-1), which corresponds to 98% removal from a 550 microg As l(-1) solution for an adsorbent dose of 50 mg ml(-1). The samples modified by phosphoric acid/urea removed 0.4 microg g(-1) arsenate from a 300 mug As l(-1) solution. Adsorption of methyl orange, arsenite and arsenate was superior by the chemically modified maize cobs judged against the initial naturasorbent. For comparison, removal by the commercial anion exchanger was 100% for methyl orange, 45% (5 microg g(-1)) for arsenite and 99% (5 microg g(-1)) for arsenate.