Estudo da adsorção de óleo mineral isolante em meio aquoso usando algas arribadas do litoral da Paraíba

Abstract

This research work aimed to study the adsorption mechanism of insulating mineral oil, dispersed in an aqueous medium, by biomass made up of algae found on the coast of Paraíba. Initially, the biomass was characterized by analyzing its particle size distribution and texture, using the B.E.T. method. and its ash content. Next, the adsorption capacity, adsorption kinetics and adsorption dynamics in a fixed bed column were studied. To study the adsorption capacity, an experimental design of type 23 was used, with three experiments at the central point and three input variables which, in this case, were the concentration of the oil/water dispersion, the rotation of the agitator and the amount of biomass. The minimum and maximum values, in grams of oil adsorbed per gram of biomass, for the adsorption capacity were, respectively, 1.16 and 2.75. The average adsorption capacity was 1.76 grams of oil per gram of biomass. For the kinetic curves, the experiments were carried out with a ratio between the masses of oil and biomass equal to 10, except one in which this ratio was equal to 20, and the initial concentrations, in grams of oil per liter of water, were 100, 150 and 200, with the shaker agitation being constant and equal to 300 rpm. The times, in minutes, used in the adsorption kinetic studies were 2, 6, 10, 20, 30 and 40. The kinetic curves showed fast kinetics, and, in some curves, sections suggesting the occurrence of a desorption process, possibly due to water co-adsorption. For fixed bed experiments, a type 22 experimental design was used, with three experiments at the central point, with input variables being the initial concentration in the fluid phase and the height of the bed. For these experiments, the flow rate used was 82mL/s, kept constant. The rupture curves were obtained for initial concentrations of the fluid phase at the column inlet, in percentage, of 10, 3, 14, 7 and 18.7, fixed bed heights, in centimeters, of 25, 30 and 35, with the Sample collections were carried out every 20 s, from the moment the oil/water dispersion reached the top of the column. The curves were the result of empirical modeling using sigmoidal Boltzman functions. For all experiments, these curves presented R2 values greater than 0.95, for a confidence level of 95%. The results obtained in this research suggest that the biomass used can be considered as an insulating smooth mineral oil adsorbent material dispersed in an aqueous medium.