RESUMO
This work proposes the use of tree termite nest as an adsorbent for the reduction/removal of Cr(VI) present in aqueous solution. In laboratory experiments, adsorption of Cr(VI) was sensitive to pH in the range investigated (2-5), with maximum adsorption capacity achieved at pH 2 (3.70 ± 0.04 mg g(-1), representing 93.2% removal of Cr). The termite nest was characterized by off-line pyrolysis GC/MS (py-GC/MS), infrared spectroscopy (FTIR), and electron paramagnetic resonance spectroscopy (EPR). Pyrolysis of the adsorbent produced a complex mixture of aromatic compounds, including the guaiacyl and syringilic derivatives that are characteristic of lignocellulosic materials. Infrared spectroscopy revealed deprotonation of the carboxylic acid group of the biomass with increasing pH, which was associated with a decrease in the capacity for adsorption of Cr(VI). The EPR g-factor for the termite nest samples varied between 2.0037 and 2.0038, indicating the presence of organic free radicals that were responsible for the redox reaction. A second line with g-factor values of 1.9790, only observed for the samples after contact with Cr(VI) solutions at different pH values, was assigned to Cr(III)-Cr(III) exchange coupled pairs, which explained the capacity of the adsorbent to retain a large portion of the Cr(III) ions produced after reduction of Cr(VI) to Cr(III). Fixed-bed column experiments showed that the termite nest had a maximum adsorption capacity of 18.60 mg Cr g(-1), an adsorption efficiency varying between 60.8 and 97.4%, and a desorption efficiency varying between 54.5 and 91.4%, for three successive cycles. The adsorbent presented excellent performance in the removal of chromium under acidic conditions, with the advantage that it could be regenerated and reused.
Assuntos
Cromo/química , Recuperação e Remediação Ambiental/métodos , Isópteros , Poluentes Químicos da Água/química , Poluição Química da Água/prevenção & controle , Adsorção , Animais , Espectroscopia de Ressonância de Spin Eletrônica , Cromatografia Gasosa-Espectrometria de Massas , Comportamento de Nidação , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
This work investigates the potentials of peat and angico hardwood sawdust to remove BTEX (benzene, toluene, ethylbenzene, and isomers of xylene) from the produced water discharged into aquatic systems during petroleum extraction. Peat and angico sawdust samples were pyrolyzed at 500°C, and found to contain n-alkenes, n-alkanes and pentacyclic triterpenes (peat), and 4-methoxyphenol, 1,4-dimethoxyphenol and 1,3,4-trimethoxyphenol (angico sawdust). In batch experiments, the removal capacities using peat were 32.4%, 50.0%, 63.0%, 67.8%, and 61.8% for benzene, toluene, ethylbenzene, m,p-xylenes and o-xylene, respectively. This compared with removal capacities using angico sawdust of 20.2%, 36.4%, 52.8%, 57.8%, and 53.7% for these compounds respectively, demonstrating the superior performance of the peat.
Assuntos
Biodegradação Ambiental , Biomassa , Biotecnologia/métodos , Petróleo , Purificação da Água/métodos , Adsorção , Benzeno/química , Derivados de Benzeno/química , Cromatografia Gasosa/métodos , Indústrias , Espectroscopia de Ressonância Magnética/métodos , Solo , Solventes/química , Temperatura , Tolueno/química , Xilenos/químicaRESUMO
CONTEXT: Essential oils (EOs) have been reported to possess pharmacological properties, of which those related to the central nervous system have been especially attributed to mono- and sesquiterpenes. Baccharis uncinella DC. (Asteraceae) is used by the Laklaño Indians (Santa Catarina, Brazil) for sedative purposes. Interestingly, the species does not seem to be used medicinally elsewhere in Brazil. OBJECTIVE: This study was designed to compare the composition and sedative properties of B. uncinella EOs obtained closer (BU-SC) and farther (BU-PR) to the Laklaño Indian Reserve. MATERIALS AND METHODS: BU-SC and BU-PR obtained by hydrodistillation were analyzed by CG-MS. Mice treated with BU-SC and BU-PR (50 and 100 mg/kg) were evaluated regarding pentobarbital-induced sleeping time, body temperature, and locomotion. RESULTS: BU-SC presents a higher monoterpene/sesquitherpene ratio (0.31); α-pinene (6.42%), limonene (7.21%), caryophyllene (26.13%), spathulenol (13.39%) and caryophyllene oxide (13.26%) were identified as major components. BU-PR presents a low monoterpene/sesquitepene ratio (0.004); spathulenol (32.93%), caryophyllene oxide (27.78%), viridiflorol (5.29%) and α-cadinol (2.42%) were identified as the main components. Both samples significantly (p < 0.05, ANOVA) decreased locomotion and body temperature, as well as increased sleeping time. The hypnotic activity was sensitive to the differences in monoterpene composition. CONCLUSIONS: In comparison with a sample collected in Paraná State, B. uncinella EO collected closer to the Laklaño Indians possess a composition that better justifies the claimed sedative properties. The study confirms the value of traditional information to guide bioactivity assessment in medicinal plants, and gives notice to the ecological factors that can interfere with the conclusions of such assessments.
Assuntos
Baccharis/química , Hipnóticos e Sedativos/farmacologia , Óleos Voláteis/farmacologia , Sono/efeitos dos fármacos , Animais , Temperatura Corporal/efeitos dos fármacos , Brasil , Relação Dose-Resposta a Droga , Cromatografia Gasosa-Espectrometria de Massas , Hipnóticos e Sedativos/administração & dosagem , Hipnóticos e Sedativos/isolamento & purificação , Locomoção/efeitos dos fármacos , Masculino , Camundongos , Monoterpenos/isolamento & purificação , Monoterpenos/farmacologia , Óleos Voláteis/administração & dosagem , Óleos Voláteis/isolamento & purificação , Fatores de TempoRESUMO
The continuous fast pyrolysis of soybean oil in a pilot plant was investigated. The experimental runs were carried out according to an experimental design alternating the temperature (from 450 to 600 degrees C) and the concentration of water (from 0% to 10%). The liquid products were analyzed by gas chromatography and by true boiling point (TPB) distillation. A simple distillation was used to obtain purified products such as gasoline and diesel. Physical-chemical analysis showed that these biofuels are similar to fossil fuels. Mass and energy balances were carried out in order to determine the vaporization enthalpy and the reaction enthalpy for each experiment. The thermal analysis showed that it is possible to use the products as an energy source for the process.