Preparation and characterization of steam and CO2 activated carbon from Brazil nut shell

Comprehension of the bean responses of beans common under to water deficit is an important tool in agricultural planning, like sowing time, and deficit irrigation management strategies. The study aimed to understand the morpho-physiological responses and yield attributes of two common bean genotypes submitted to water stress at different phenological stages. The study was carried out in a greenhouse, in randomized block scheme with five repetitions. To achieve the objectives deficit irrigation of 25% of crop evapotranspiration was practiced during vegetative (DI-V), flowering (DI-F), and pod filling (DI-PF) stages. A non-deficit irrigated (NDI) and deficit irrigated through vegetative to pod filling stages (DI-VP) treatments were added for comparison. The following morphophysiological responses and yield attributes were evaluated: net assimilation of CO2, stomatal conductance, and leaf transpiration, chlorophyll index, number of trifoliate leaves, chlorophyll index, leaf area, number of grains per plant, number of grains per pod, number of pods per plant, the mass of thousand grains, harvest index, and water use efficiency. The beans genotype under DI-V exhibited acclimation, observed by the relative increment with NDI of 195%, 759%, and 231% of net assimilation of CO2, stomatal conductance, and leaf transpiration, respectively. Plants under treatment DI-PF experienced dis-stress and plastic responses as leaf losses and exhaustion of gas exchanges. Treatment DI-V received 11% less water than NDI and exhibited equal yield, resulting in higher water use efficiency. Yield attributes correlations indicated that yield penalty might be related to pods abortion, which not occurred to plants under DI-V.

New alternative for adsorption of 2, 4-dichlorophenoxyacetic acid herbicide (2, 4-D)

The adsorptive capacity of charcoal from the husk of the brazil nut fruit, called "ouriço" (the hard ball with nuts inside) for the herbicide dichlorophenoxyacetic acid (2,4-D) was evaluated. Activated carbons were produced from the brazil nut in a tubular oven at 800 °C and activated with CO2 or water steam. The specific surface area was determined by the Brunauer, Emmett and Teller (BET) method, demonstrating the mean density of micropores. Analysis of N2 adsorption/desorption isotherms was undertaken and the morphology of activated carbons was visualized by Scanning Microscopy (SEM). The activated carbons were successfully obtained and had a specific surface area of 395 m2.g-1 and 401 m2.g-1 after activation with either CO2 or water steam, respectively. The highest pore mean density occurred with a diameter of 1.17 nm for carbons activated in both atmospheres. The graph of the adsorption/desorption isotherms of N2 showed Type I isotherms, regardless of the activation atmosphere. The SEM analysis showed that, for both activation atmospheres, pore formation occurred in the shape of uniform honeycomb craters. Adsorption kinetics followed the pseudo-second order model, indicating chemisorption. Regardless of the activation atmosphere, the activated carbon from the brazil nut "ouriço", was highly efficient for 2,4-D adsorption.