Desenvolvimento de uma membrana verde à base de poli(vinil álcool) para a remoção de diclofenaco de sódio de matrizes aquosas

Abstract

Membrane separation processes are efficient to reduce water pollution by emerging contaminants, such as pharmaceuticals. In Brazil, as well as worldwide, the production of membranes still faces challenges concerning the use and later disposal of organic solvents, thus making the process harmful to the environment. A more sustainable alternative is water-soluble polymers, such as poly(vinyl alcohol) (PVA). However, controlling the PVA solubility with crosslinking reactions is necessary when applied in water treatment. In this sense, this work aimed to develop a PVA-based membrane using citric acid as a crosslinker, striving the removal of sodium diclofenac (DCF) from aqueous matrices. The experimental design methodology associated to statistical analysis was used to determine the optimal conditions of crosslinking time and temperature, aiming at the best balance between permeate flux and DCF removal during a filtration process. Furthermore, the filtration parameters were adjusted to maximize the efficiency of the process. The morphologic, chemical, thermal, and physical characterization results demonstrated that the crosslinking conditions affected the membrane properties, modifying its performance regarding permeate flux and DCF removal. The optimal conditions of time and temperature of crosslinking were at 110 min and 110 °C, respectively. The operational parameters of the filtration process also affected the membrane behavior. Under optimized conditions (5 bar, feed containing 0.008 g L-1 of DCF at 25 °C, natural pH ~5.75), the developed membrane produced 0.12 L m-2 h-1 of permeate with about 80% DCF removal. Under these conditions, the green membrane was comparable to commercial nanofiltration membranes. Finally, this study culminated in the development of a membrane with "green" characteristics, in other words, with promising qualities to sustainably remove any contaminants resistant to conventional water treatments, as is the case with DCF. [resumo fornecido pelo autor]