Novel Applications of Micro/Nanostructured Volcanic Ash for Water Purification and Surface-Enhanced Raman Spectroscopy

Volcanic ash is frequently referenced as natural particles, yet few applications for wastewater purification and surface-enhanced Raman scattering (SERS) have been reported. Here, a unique micro/nanostructured nozzle-shaped volcanic ash was characterized. The natural volcanic ash had an ordered porous structure with an average diameter of 20 µm. Macropores with 200-nm pore size and 3–5-nm mesopores were homogeneously distributed on the surface of the volcanic ash. The volcanic ash provided an efficient water purification for simulated dye and livestock wastewater. The volcanic ash/silver nanoparticle hybrid also exhibited strong SERS. Moreover, the differing adsorption sequence of silver nanoparticles and probes on the surface of volcanic ash created distinctive enhancements. The micro/nanostructured volcanic ash was shown to be a promising water purifying agent and platform for SERS in environmental monitoring.