Remoção de ureia em soluções aquosas por adsorção e de composição catalítica na presença de carvões

Abstract

Urea is widely used in agriculture as a fertilizer because of its high nitrogen content. Nitrogen, macronutrient for plants, is able to cause many environmental problems by contamination of hydric bodies or volatization. Charcoals are materials very known by its high porosity, big superficial area, ionic exchange capacity. These characteristics make them excellent candidates to adsorb many species. Besidesthat, they are good suppliers of organic matter, justifying their usage in agriculture. In this work, the adsorption and decomposition of urea aqueous solutions were investigated in the presence of: commercial active carbon, before and after the insertion of oxygenated speciesin its surface; biocharcoal originated from the farming of thermic treated sugar cane; vegetal charcoal produced from the endocarp of macauba seeds at different temperatures. All the materials were successful in the urea removal from aqueous solution. The experimental findings prove that the adsorptions are not the solely responsible for the urea remove from solutions. During the charcoal contact with the solutions there is also the urea hydrolysis from the media, suggesting that catalytic mechanisms close to that of urease are happening. The commercial activated carbon that did not passed the acid treatment was the most efficient when compared to the treated ones. The biocharcoals had removals from even 57% of urea, with removal capacities of 863mg g-1,for solutions with 2,3 g L-1. The charcoals from macauba removed urea in aqueous solutions by adsorption and degradations.