Synthesis, characterization, and application of micro- and nanomaterials for the removal of organic contaminants from groundwater and wastewater

Abstract

The increasing presence of chemicals and pharmaceuticals in the aquatic environment represents a latent threat both to ecosystems and to human health. Conventional treatment methods for water hardly eliminate these pollutants, which are usually dissolved in low concentrations (μgL-1 or ngL-1). Because of their physicochemical characteristics, the use of micro- and nanomaterials in advanced treatment processes represents a feasible alternative to eliminate this kind of persistent pollutants. In this study, different methods were applied to enhance the performance of micro- and nanomaterials for water treatment applications. Specifically, titanate nanotubes were synthesized, characterized, and successfully used for the adsorption of six organic pollutants of interest. First and second order kinetic models as well as, adsorption isotherms of Freundlich and Langmuir were investigated. Also, the photocatalytic activity of different bismuth-based materials was investigated. For instance, the photocatalytic efficiency of BiVO4 was enhanced through rare-earth doping (Gd3+) and a series of Bi2O3/rGO/MonO3n-1 all-solid-state ternary Z-scheme were synthesized as well. The synthesized photocatalysts were studied through photocatalytic degradation of selected contaminants and the photocatalytic experiments were carried out in different water matrices such as pure water, groundwater, or urban wastewater effluent. Also, different light sources were applied during photocatalytic processes to evaluate and compare the performance using conventional and LED light sources. To better understand the properties of the synthesized materials, scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and diffuse reflectance spectroscopy (DRS) among other techniques, were applied. All the synthesized materials, after being modified in their physical or chemical form, showed a better performance than the pristine materials during adsorption or photocatalysis treatments for the removal of persistent organic contaminants in the water.