Perlita como adsorvente: avaliação da remoção de óleo de efluente gerado em área de lavagem de veículos

Abstract

The vehicle washing activity generates large volumes of effluent containing mostly oils and greases, MBAS and solids. The usual treatment system generates system purge effluents from filter backwashing, which makes it costly. Adsorption is an alternative to minimize these costs. Compounds that have aluminum silicate in their composition, such as perlite, are generally good adsorbents. Perlite is a very porous, low cost, easy to obtain, thermally and chemically inert aluminosilicate, with sustainable mining and transportation. This mineral becomes a residue after being removed from cryogenic tanks. The objective of this work was to reuse the perlite as adsorbent in the adsorption process as an alternative for the treatment of vehicle wash effluents. The methodology of the work consisted in the characterization of the adsorbent by the methods BET, Thermogravimetry; in the preparation of synthetic effluent by means of motor oil, hydrochloric acid, NaCl and detergent; and in the realization of a finite bath according to ASTM D 3860/98, where different masses of perlite were placed in contact with the synthetic effluent of known concentration. To evaluate the final concentration of the oil in the synthetic effluent, a calibration curve was made and finally the final concentration spectrophotometer reading. Thus it was possible to obtain the parameters of the experimental model. Frendluich's model best fit the experimental data. Based on the equation of this model, the amount of perlite to be used to meet the requirements of the wash water treatment process has been estimated for a company that performs 80 vehicle washes per day. The amount of perlite to be used to treat about 21 m³ / day will be approximately 319 kg perlite per day. According to the results obtained in the BET method, it was possible to estimate the surface area of the perlite at 2.47m².g-1, its pore size at 776.36 Å and pore volume at 1.892.10-3 cm³.g-1. , with the adsorption rate being 0,06459g.g-1. By the thermogravimetry method it was possible to estimate the thermal decomposition phases of the perlite at 90 ° C to 190 ° C due to water loss and at 310 ° C to 355 ° C due to phase transformation of any of the elements of perlite or dehydroxylation. structures.