Síntese e caracterização de membranas compostas de película finas funcionalizadas com nanomateriais para aplicação em sistemas de dessalinização

Abstract

The accelerated population and industrial growth have put Earth’s water security at risk. The seawater and brackish water desalination using membranes has been considered a promising strategy for the global supply of potable water. In this work, the performance of thin film composites membranes functionalized with cellulose nanocrystals (NCC), carbon nanotubes (NTC), and graphene oxide (GO) was evaluated. The porous layer of the membrane was prepared by the phase inversion method using a polysulfone (PSU) solution, and the dense polyamide (PA) layer was prepared by the interfacial polymerization (IP) technique. During the PI process, NCC, NCC+NTC, and NCC+OG were incorporated into the aqueous solution containing the PA monomer. The membranes were characterized by Fourier transforms infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermogravimetric analysis (TG), and contact angle. Water flux and salt rejection tests in a dead-end filtration system were also performed. The permeation tests showed that, after incorporating the nanomaterials, the membranes with NCC and NCC+NTC exhibited a 26% increase in permeated water flux compared to the control membrane. Furthermore, the membrane with NCC+OG demonstrated nearly double the water flux of the control membrane. The results of the NaCl rejection performance test showed that the membrane functionalized with NCC rejected 39% of salt, and the membrane functionalized with NCC+NTC rejected 33%, values comparable to nanofiltration membranes. Na2SO4 rejection tests were performed, the results showed that membranes functionalized with NCC+NTC and NCC achieved a Na2SO4 rejection equal to 66% and 59%, respectively. The membrane functionalized with NCC+OG showed a reduction in salt rejection to values around 20% for both salts. Based on the results, it can be stated that when added to the PA layer, the nanomaterials influence the performance of the membranes, being able to modify the properties of permeability and selectivity.