Viviane da Silva Lobo

Degradação fotocalítica de bentazona com TiO2

This study evaluated the oxidative degradation of the post-emerging herbicide Basagran(r) 600 by photolysis and photocatalysis using TiO2 as catalyst, and both processes were compared in their efficiency. The experiments were done irradiating aqueous solutions of the herbicide in a slurry type reactor. The treatments were accompanied by spectrophotometry in the UV-visible range observing the band centered in 335 nm. The first process showed rather ineffective, being observed minimal reduction of the absorbance values. On the other hand, the second process was much more efficient, being observed, after 270 min of irradiation, 100% absorbance reduction of the band in the choose wavelength. This process followed pseudo-first-order kinetic and the estimated rate constant (k) was 0.0116 min-1.

Chemical Composition of the Essential Oil Obtained from Ocimum basilicum (Basil) Cultivated in Two Regions from South Brazil

Abstract A comparative study of the chemical composition of essential oils of basil (Ocimum basilicum L.) grown in different localities in southern Brazil was conducted. This plant is seen as a promising source of linalool, a substance widely used in cosmetics and fragrances. The main objective of this study was to determine whether the procedures of drying plant and geographic origin of material plant (municipalities of Toledo (PR) and Jardinópolis (SC), south Brazil) provide significant changes in the chemical composition of essential oil. As a result, there were no significant differences in chemical composition of the oil from different regions, while the drying procedure has profoundly altered the chemical profile of the oil. Plant drying under sun reduced the concentration of linalool in the essential oil. These results can support future projects of essential oil production in these regions, characterized by the presence of small farms with a high incidence of family labor, which may represent a new source of income with a product with high added value.

Larvicidal activity against Aedes aegypti of essential oil of Laurus nobilis leaves obtained at different seasons

Abstract Aedes aegypti is a mosquito and vector of dengue, chikungunya and Zika virus making it a serious global health problem. We aimed to evaluate the chemical composition of the essential oil (EO) of Laurus nobilis leaves obtained at different seasons and its A. aegypti larvicidal activity. The EO was obtained from fresh leaves by hydrodistillation. Larvicidal activity was determined by the larval immersion test. It was identified 37 EO chemical compounds and the major ones were 1,8-cineole and linalool. Seasonal variations affected EO larvicidal activity: spring LC50 was 0.41 mg/mL and LC99 0.77 mg/mL, autumn LC50 was 0.60 mg/mL and LC99 1.37 mg/mL, winter LC50 was 0.66 mg/mL and LC99 3.19 mg/mL and summer LC50 was 0.91 mg/mL and LC99 2.50 mg/mL. The EO extracted during spring showed the highest larvicidal activity on A. aegypti larvae. Our results present a new perspective of L. nobilis EO use as a larvicidal agent.

Adsorption of Methylene Blue in Potato Peel Using Batch and Fixed-bed Column Systems

The search for an efficient and low cost adsorbent for the treatment of wastewaters containing dyes motivated this work. The efficiency of the adsorbent from agro-waste, potato peel (Solanum tuberosum L.), was tested using the cationic dye methylene blue as adsorbate. Adsorption studies were conducted in batch and fixed-bed column systems. The parameters evaluated in batch system were: point of zero charge (PZC), kinetics and adsorption isotherm, applying the theoretical models of Langmuir and Freundlich. With fixed-bed column it was possible to obtain saturation and reuse curves of the adsorbent and recovery of the dye. The Langmuir isotherm model was the best fit to the experimental data, with a maximum amount adsorbed (qmax) of 48.7 mg g 1. The maximum adsorption capacity of the column was 35.83 mg g1. It was also verified the possibility of recovery the dye using HCl solution and reusing the adsorbent after this process.

Synthesis and Application of Acetil-β-cyclodexitrin on Essential Oil

Abstract This work presents the structural modification of the β-cyclodextrin through acetylation reaction, the spectroscopic characterization of the product (acetyl-β-cyclodextrin) in the mid infrared region, NMR of 1H, 13C and DEPT135, and the use of these compounds on essential oil of clove as photoprotectors and reducers of evaporation loss. The photodegradation experiments were done in alcoholic solutions and both compounds showed good photoprotective properties, although β-cyclodextrin has presented a better performance. In the presence of 5x10-4mol L-1 of β-cyclodextrin was observed a reduction of 72 % in the degradation rate while for the acetyl derivative, in the same concentration, this rate was lowered in 38 %. On the other hand, acetyl-β-cyclodextrin showed very good results in the evaporation assays, lowering the mass loss in 52 % when compared with the oil without this derivative in the same experimental conditions. So, the results presented here point out acetyl-β-cyclodextrin applicability for the complexation of essential oil of clove, reducing its volatility and increasing its photochemical stability.