Desenvolvimento de membranas com baixos custo e potencial de incrustação a partir de membranas de osmose inversa em final de vida, incorporando óxido de grafeno e prata

Abstract

Water scarcity, according to the National Water Agency (ANA), is characterized by the imbalance between the growing demand for water and the limited availability of this essential resource. This scarcity may not be directly related to the volume of water available, as a water body may have sufficient volume to supply a population, but its quality may render it unusable. One of the contaminants that can be highlighted in Brazilian territory is atrazine, which has been found in concentrations up to five times higher than the limit established by Ordinance GM/MS No. 888/2021. In this context, membrane separation processes stand out due to their robustness and ability to treat water of varying qualities depending on its intended use. The exponential increase in demand for membrane technologies in water treatment represents a significant advancement in the search for effective solutions to water scarcity, while also posing the growing challenge of proper disposal of these materials. Thus, methods to extend their lifespan, such as chemical recycling and coating with nanomaterials to enhance treatment performance, are being explored. In this context, the present study aims to use a low-cost methodology to reuse end-of-life reverse osmosis membranes by recycling and coating them with graphene oxide and silver nanoparticles. The project intends to evaluate the potential of these membranes for treating deionized water and river water contaminated with atrazine, ensuring compliance with the potability limits set by Ordinance GM/MS No. 888/2021 of the Ministry of Health. The membranes were analyzed using FTIR to assess changes in surface structure during recycling, demonstrating the removal of the polyamide layer with the proposed method. For nanoparticle synthesis, the samples were analyzed using TEM/EDS, revealing a most frequent size of 2 nm and a composition of crystalline silver. Regarding the coating, permeability and atrazine rejection were analyzed. Ultrafiltration membranes showed a decrease in permeability, while nanofiltration membranes exhibited an increase. In terms of rejection, the membranes demonstrated improved treatment of the herbicide, and in the case of river water, they were able to reduce the contaminant to within the potability limit. The antimicrobial activity of the membranes was analyzed using disk-diffusion and microdroplet tests, showing a complete absence of E. coli in samples in contact with the coated membranes. The methodology was evaluated for economic feasibility, demonstrating costs close to those of commercial modules and extending the lifespan of used modules by producing membranes with greater contaminant removal potential and enhanced resistance to microbial activity.