Feasibility of iron-based sorbents for arsenic removal from groundwater

BACKGROUND Arsenic is one of the most serious drinking water contaminants around the world. The development of iron oxide materials, including nanoparticles, as sorbents for arsenic remediation has shown promising results in recent years. Some of these materials are already used as commercial-grade arsenic sorbents. However, the use of iron-oxide nanoparticles (IONPs) has barely been used in real-world conditions. This work compares commercial IONPs with three proven arsenic sorbents. RESULTS The full chemical characterization includes electron microscopy, X-ray diffraction and X-ray photon spectroscopy to determine morphology, crystalline structure and elemental analysis, respectively. Arsenic remediation studies also were conducted in both batch and column set-ups with real water samples from Salamanca, Mexico. The conditions (pH 8, high concentration of silica and presence of other interferences) found in this site are outside the recommended parameters of operations for most of the arsenic sorbents. All of the materials observed a negative effect because of silica presence. However, the effects observed in batch did not correlate directly to the column tests. This is important when evaluating the viability of using sorbents in specific conditions. CONCLUSIONS A feasibility analysis revealed that some commercial sorbents can treat water with the conditions presented in the selected site, but the cost of treatment is not viable for developing countries. In addition, the generated waste by using these sorbents would be substantial. These challenges could be diminished by using nanoparticles, yet the commercially-available IONPs do not fill this gap. Better designed nanomaterials are still needed for arsenic removal. (c) 2022 Society of Chemical Industry (SCI).