A promising natural material for pollutants removal

Natural resources have multiple advantages, including being eco-friendly, inexpensive, non-toxic, and widely available, as well as having good activity in pollutant removal. This study explores the performance of Romanian volcanic tuff tested on two persistent dyes, Reactive Black 5 (RB5) and Methylene Blue (MB), via photo-Fenton-like oxidation. Different approaches, including Scanning electron microscopy (SEM), X-ray diffraction (XRD), surface-enhanced Raman scattering (SERS), Fourier transformed infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and N₂ adsorption-desorption measurements, were used to investigate the structural, mineralogical, and textural properties of natural and modified volcanic tuff. The clinoptilolite phase in volcanic tuff is up to 85%. Furthermore, the structural investigation of volcanic tuff using SERS provides an original feature of this study. In real wastewater effluents, modified volcanic tuff proved to be highly effective at removing RB5 and MB by more than 90%, k = 0.0242-0.0309 min^- 1. After five cycles, RB5 decolorization is still greater than 60%. The obtained findings demonstrate that Romanian volcanic tuff can be successfully exploited as a green resource in wastewater treatment.