Fibras de álcool polivinílico (PVA) e quitosana obtidas por eletrofiação para remoção do corante vermelho BF-4B

Abstract

The environmental concern in the face of environmental and often emerging contaminants is a problem that mainly interferes with human health. Among these contaminants, dyes have special attention due to the risks they can bring to microorganisms and human beings, which can trigger serious and even chronic consequences. In this context, this work aims to produce chitosan and polyvinyl alcohol (PVA) membranes by electrospinning technique and apply them in the treatment of BF- 4B red reactive dye solutions. A polymeric chitosan solution (3% m/v) and a PVA solution (8% m/v) with a determined concentration were subjected to electrospinning with a rotating collector. Parameters such as flow, distance from needle to collector and electrical potential were evaluated. The chitosan membranes were crosslinked with water vapor while the PVA membranes with citric acid, being characterized using infrared absorption spectroscopy (FTIR-ATR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), contact angle (AC), zero charge point (pHpcz), adsorption experiments, in addition to experiments on compaction and permeation of dye solution in a frontal filtration. All filtration tests were performed in a dead-end cell with hydrostatic pressure until a stabilized flow was obtained. Regarding the characterizations, it was observed the presence of characteristic bands of the constituent polymers and that after the use of the chitosan membrane there was no displacement of the bands (FTIR). Through SEM it was possible to obtain nanofibers

with diameters of 604.7 and 340.0 nm of PVA and chitosan, respectively. Through the pHpcz study, it was observed that at pH between 4 and 6, the adsorption of the dye on the chitosan membrane was favored, with 80.2% removal. The adsorption behavior of the dye followed a second order kinetics and in 23 hours it had an adsorption of 99%. For the filtration model, a sandwich system of chitosan and PVA membranes (PVA/QTS/PVA) was set up, which rejects around 39% of the dye, and these membranes are biodegradable and can be done in a continuous process. Thus, it was found that membranes produced by biopolymers can be an excellent alternative to filter and/or adsorb dyes (such as red BF- 4B) contained in water.