Síntese e caracterização de heteroestrutura de fosfato de prata e goethita para degradação de Rodamina B por fotocatálise induzida por luz na região do visível

Abstract

Due to the scarcity of water resources, there is currently a growing global demand for the development of new technologies for the treatment of wastewater and industrial effluents, as research has shown an increase in the toxicity levels of residues as well as persistent organic pollutants in the environment, further reducing the availability of potable water on the planet. One of the major sources of water pollution is the improper discharge of natural and synthetic dyes into the environment, which represents a serious threat to water resources. These dyes are widely used in painting, printing, paper, plastic, pharmaceutical, food processing, cosmetic industries, and especially in the textile industry, which is considered the second largest contributor to effluent-related pollution. An example of a widely used dye is Rhodamine B, which, in addition to its application in the textile industry, is also employed as an ink component in printing devices, among other uses. When improperly disposed of, Rhodamine B can cause significant adverse effects on both human health and the environment. Consequently, a wide range of wastewater treatment technologies has been developed or optimized to address this issue. Among the available treatment processes, photocatalysis has attracted significant attention, and silver phosphate (Ag3PO4) has emerged as a promising photocatalyst for wastewater treatment due to its relatively narrow band gap (2.45 eV), which enables absorption in the visible light region. However, owing to its poor structural stability, Ag3PO4 requires the incorporation of other materials to stabilize its structure. In this work, aiming to better exploit the photocatalytic properties of Ag3PO4, a heterostructure with an iron oxide was proposed. Iron oxides are abundant, low-cost materials and exhibit several advantageous properties, such as surface modifiability and high biocompatibility. Iron oxides occur in various forms in nature, with magnetite (Fe3O4), maghemite (γ-Fe2O3), hematite (α- Fe2O3), and goethite (α-FeOOH) being the most common. Goethite was selected for this study due to its stability and band gap in the range of 2.5–3.1 eV. The Ag₃PO₄/α-FeOOH heterostructure was synthesized and subsequently characterized using FTIR, XRD, SEM, TGA, XRF, and Rietveld refinement of XRD data. Its photocatalytic performance was evaluated using Rhodamine B as a model pollutant, achieving 100 % degradation within 120 minutes under visible-light irradiation.