Activated carbons obtained from rice husk exhibit low specific surface areas when physical activation is applied due to its high silica content. The purpose of this work was to improve textural parameters of powdered activated carbons obtained from rice husk. To avoid the negative influence of the raw material ash content, a leaching step was included in the preparation process. Hydrofluoric acid, in two concentrations (25 and 50 wt %), was used as leaching agent and applied in different stages of the process. Physical activation using water vapor as activating agent was applied. Specific surface area and porosity were evaluated from nitrogen adsorption data. When a leaching step was included, specific surface area values between 700 and 1200 m2/g were obtained. These values are higher than that corresponding to the activated carbon prepared from rice husk not treated with acid (290 m2/g). Pore size distribution depends on the step sequence of the preparation process and on the HF concentration.
Textile industry is an important source of water contamination. Some of the organic contaminants cannot be eliminated by nature in a reasonable period. Heterogeneous catalytic wet air oxidation is one of the most effective methods to purify wastewater with organic contaminants. In this work, catalysts based on copper supported on activated carbon were synthesized. The activated carbons were obtained from industrial wastes (apricot core and grape stalk) of San Juan, Argentina. These were impregnated with a copper salt and thermically treated in an inert atmosphere.Analysis of specific surface, pore volume, p zc , acidity, basicity and XRD patterns were made in order to characterize the catalysts. The catalytic activity was tested in the oxidation of methylene blue (MB) and polyvinyl alcohol (PVA) in aqueous phase with pure oxygen. Reaction tests were carried out in a Parr batch reactor at different temperatures, with a 0.2 MPa partial pressure of oxygen. The amount of unconverted organics was measured by spectrophotometry.Higher temperatures were necessary for the degradation of PVA compared to those for methylene blue.
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