Utilização de resíduo industrial de poliamida para obtenção de membranas aplicadas no tratamento de emulsões oleosas

Abstract

The need to apply cleaner technologies for the treatment of effluents is essential to minimize the impacts caused to the environment and the recovery of water resources. Among these technologies, membrane technology stands out for presenting advantages such as energy savings, ease of operation, replacement of conventional processes, and flexibility in system design and in the development of hybrid processes. Microporous membranes were obtained from pure polyamide 66 (PA66) waste dissolved in formic acid (FA) and hybrids with the addition of 1, 3 and 5% by weight of zinc oxide (ZnO), both by introducing potassium chloride salt (KCl) through the phase inversion technique by the immersion-precipitation method. The membranes were characterized by atomic force microscopy (AFM), water absorption, porosity, mean pore radius (MPR), contact angle (CA), optical microscopy (OM), water vapor permeation, water flow measurements, oil emulsion separation test, color, turbidity, and yield. The MFA results indicated that all roughness parameters of the hybrid membranes were higher than those of the pure membrane. The water vapor permeation of the hybrid membranes was lower than that of the pure PA66, due to ZnO acting as physical barriers, acting as a nucleating agent, preventing vapor passage. The addition of ZnO increased the flow and permeability properties of the hybrid membranes, as well as showed significant results for the removal of oil droplets present in oil emulsions, justified by the positive results of contact angle, porosity, water absorption, decrease in the average pore radii, highlighting that the PA66/3%ZnO membrane showed the best results. The physicochemical analysis of color and turbidity of the oil emulsions showed results above 95%. The membranes tested for separation of oil from emulsions, at concentrations (50, 100 and 200 mg.L-1), obtained a significant reduction of oil in the permeate, especially the hybrid membranes with removals above 95%, meeting the maximum limit of 20 mg.L-1 allowed by law. Furthermore, it is important to emphasize that due to the excellent results obtained using an industrial waste, the importance of using this waste to obtain membranes for microfiltration, confirming that it is a viable and sustainable technology when compared with other wastewater treatment processes.