COMMITTEE CHAIR: Dr. Gina Chiarella Mansilla

TITLE: EVALUATION OF FOUR IRON OXIDE-OXYHYDROXIDE SORBENTS FOR ARSENIC REMOVAL IN FERTILIZER AND SOIL AMENDMENT SYSTEMSSYNTHESIS AND CHARACTERIZATION OF MIXED GREEN NANO CATALYSTS FOR AMMONIA SYNTHESIS

ABSTRACT: Arsenic contamination in agricultural fertilizers and soil amendments has become a significant environmental concern due to the persistence, mobility, and toxicity of arsenic species, as well as their potential transfer into soils, groundwater, crops, and ultimately, the food chain. Iron-based materials have been widely recognized as effective adsorbents for arsenic remediation; however, their performance in complex environments derived from fertilizers has not been systematically evaluated. This study investigates the adsorption of arsenate [As(V)] using four iron-based sorbents: natural goethite, goethite nanoparticles, ferrihydrite, and magnetite nanoparticles synthesized via a sol-gel method. Six commercially available fertilizers and soil amendment products were selected to represent a range of agricultural matrices differing in nutrient composition, phosphorus content, and organic matter levels. Initial experiments examined the effect of solution pH on arsenic adsorption, followed by batch adsorption studies designed to evaluate the influence of fertilizer composition, sorbent type, and arsenic concentration under controlled laboratory conditions. Adsorption experiments were conducted using a 100 ppm As(V) stock solution and a series of working concentrations to assess adsorption efficiency and sorbent performance across environmentally relevant conditions. The physicochemical properties of the iron-based materials were characterized before and after arsenic adsorption using Fourier Transform Infrared Spectroscopy (FTIR), Powder X-ray Diffraction (PXRD), Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA), and X-ray Photoelectron Spectroscopy (XPS). Quantitative determination of arsenic removal was performed using Atomic Absorption Spectroscopy (AAS) and Inductively Coupled Plasma (ICP) analysis. The combined use of these techniques provides detailed insight into adsorption mechanisms, surface interactions, and structural changes associated with arsenic uptake in fertilizer-containing systems. The results of this study are expected to advance the understanding of arsenic interactions with iron-based sorbents in agriculturally relevant environments and support the development of effective remediation strategies aimed at reducing arsenic contamination in fertilizers, soils, and agricultural production systems.

Keywords: Arsenic, Fourier Transform Infrared Spectroscopy, Inductively Coupled Plasma, Powder X-ray Diffraction

Room Location: E.E. O’Banion Science Building, Room 203