Researchers develop materials to remove pharmaceuticals from wastewater
Researchers of the Jaume I University of Castellón (UJI), in collaboration with the Centre for the Development of Functional Materials (CDMF) of the Universidad Federal de São Carlos (UFSCar) have published an article titled "Selective Synthesis of α-, β-, and γ-Ag2WO4 Polymorphs: Promising Platforms for Photocatalytic and Antibacterial Materials" in Inorganic Chemistry, which reports new photocatalytic and antibacterial materials to remove medicines from wastewater.
The study reveals a simple method for the selective synthesis of silver tungstate polymorphs (Ag2WO4), known as α-, β-, and γ, at ambient temperature and without using surfactants; these benefits make it easier to manufacture these materials on an industrial level. Furthermore, the report discusses the possible photocatalytic and antimicrobial mechanisms of the polymorphs, as well as the processes of formation and growth.
Initially, the silver tungsten polymorphs (phases α, β, and γ) were synthesized selectively by precipitation, controlling the volumetric relations of the two dissolution precursors: silver nitrate and sodium tungsten. After surpassing these phases, the structural, microstructural and electronic properties of the material was studied using a combination of experimental techniques.
Then, the structure-activity relations between the morphology and photocatalytic activities were analyzed under ultraviolet light, putting special emphasis on the degradation of the amiloride medicine, a diuretic that prevents the body from absorbing too much salt and helps control sodium levels, and antibacterial properties for the removal of penicillin-resistant Staphylococcus aureus.
Several analysis and characterisation methods were used in the research, such as X-ray diffraction and Rietveld refinement, X-ray absorption spectroscopy, field emission scanning electron microscopy and photoluminescence images, among others. First principal calculations were also made on the functional theory of density.
The research team will carry out theoretical and computational studies to supplement and rationalize the experimental results, which have enabled a detailed understanding of the atomic level, morphology and external surfaces of silver tungsten polymorphs.
The results suggest that even though α-Ag2WO4 was the most stable and most researched phase, β-Ag2WO4 had the best results for the explored uses. "Now, we want to research other behaviors and uses of the β- and γ-Ag2WO4 phases, the least stables ones, and therefore, the ones that have least been studied until now," says lecturer Juan Andrés, director of the QTC laboratory of the UJI and head researcher of this project.