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

Activated carbon is a porous material with several industrial applications. In this research, brazil nut shell was used to produce activated carbon, a promising raw material based on its low cost and high quality. Also, nut processing generates an extensive amount of waste, requiring proper disposal. The carbon was produced at temperatures of 600, 700, and 800 °C and activated by physical method using steam or CO2. Yield was calculated, and the activated carbon was analyzed according to the following physical-chemical parameters: water content, volatile material, fixed carbon, ash, apparent density, and pH. Infrared spectroscopy and BET adsorption isotherms were also performed. The fixed carbon contents of the carbons produced at 700 and 800 °C remained above 84%. The pH values characterized them as basic. The surface areas of the carbon obtained at 800 °C were 397 ± 8 m2 g–1 and 325 ± 7 m2 g–1 in those which were activated by steam and CO2, respectively

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