Design of magnetic nanotechnological devices for the removal of fluoride from groundwater

Abstract

The problem associated with water availability embodies a great challenge for scientists and the industrial sector. Groundwater appears as an interesting option to contribute to solving this problem. The natural occurrence of fluoride, among other contaminants, may restrict the widespread use of groundwater. Increasing efforts are dedicated to finding out novel, efficient, green, and low-cost technologies that can solve this inconvenience, being those based on adsorption the preferred ones. In this work, nanocomposites based on natural zeolite and magnetite were synthesized and subsequently superficially modified with aluminum and calcium cations. Themain objective is to get surface specificity and functionality for fluoride removal from a real groundwater environment. The raw and modified materials were characterized, aiming to determine their physicochemical as well as stability properties. The crystalline pattern was analyzed by XRD; and the composition by atomic absorption spectroscopy. Besides, FTIR and zeta potential were assayed to identify the functional groups and the surface charge, respectively. Data suggested that surface modification did not affect the crystalline structure of constituent materials. Composition data and FTIR analysis allowed to verify only the aluminum incorporation.Zeta potential evidenced critical changes in modified materials. The adsorption performance of both raw materials and nanocomposites, were tested through batch assays using fluoride model solutions. The first did not show adsorption capacity. As a difference, the surface-modified nanocomposites demonstrated high efficiency, reaching around 90% of fluoride removal. Besides, adsorption assays were replicated employing real groundwater samples from Bahía Blanca (Buenos Aires, Argentina) rural region, achieving greatly satisfactory results when the surfacemodifiednanocomposites were tested.