Pontos quânticos de TiO2: um inovativo nanomaterial para funcionalização de materiais têxteis

Abstract

The UN 2030 agenda aims to achieve sustainability through 17 objectives, including: industry, innovation and infrastructure; clean water and sanitation. In this sense, it is necessary to search for sustainable materials, especially to treat water in the textile industry, which generates a high load of polluting effluents. As a result, nanomaterials are studied and used for applications that minimize this problem. One of the applications is for photocatalysis processes, due to the high efficiency of these nanostructures due to their surface area, such as: TiO2, ZnO and other semiconductors. Other emerging nanomaterials are nanoparticles with reduced size (1-10 nanometers), which, due to their size, undergo quantum confinement and are therefore called quantum dots. The main problem involving TiO2 quantum dots is the agglomeration of particles in the medium, which makes their use in photocatalysis complex. In this study, the objective was to evaluate the applicability of TiO2 quantum dots (PQs TiO2) immobilized on textile fibers for potential application in photocatalysis. The synthesis of PQs TiO2 was carried out via sol gel and immobilized on regenerated soy fibers using the layer-by-layer method. The photocatalytic evaluation was carried out using a variation of rhodamine B concentration. In the second study, a Box-Behken type factorial design was used where the variables: TiO2/Au ratio (%), temperature, time and pH of the solution immobilization, with the photodegradation of the reactive dye black 5 as the response variable. The soybean and polyamide fabric samples were characterized by XRD, XPS, HRTEM-SAED, SEM-FEG as well as colorimetric analyses. The results prove that the quantum dots obtained have a tetragonal crystalline structure, corresponding to the anatase phase, with a size of approximately 6 nm. The results of photocatalysis of functionalized soy fiber showed excellent photocatalytic efficiency, degrading 2 ppm of rhodamine B in 120 minutes, with durability of up to 5 reuse cycles. The polyamide fabric nanocoated with PQs TiO2/Au showed an efficiency of approximately 100% photodegradation of 20 ppm of the RB5 dye, in 240 minutes and with reuse stability in 5 consecutive cycles. Therefore, the application of quantum dots to textile fibers as functionalization agents is a promising way to obtain flexible surfaces with excellent photocatalytic properties.