Spectroscopic, mineralogical and photocatalytic characterization of bentonite clay: A jointed DFT and experimental approach

Abstract

Over the years, the research and development of different systems based on clay minerals as raw materials stand out due to their eco-friendly behavior, abundant world reserves, low cost, and high industry suitability. Although bentonite clays have been largely studied, the literature still lacks a careful mineralogical and spectroscopic characterization. In this work, sodium bentonite clay mineral found in Argentina was carefully characterized from different spectroscopic techniques and had their mineralogical properties evaluated. Photocatalytic studies aiming at the degradation of reactive blue dye and DFT quantum calculations were also performed. The results indicate the existence of cluster particles with irregular sizes and lamellae stacking typically found in montmorillonite clay minerals. It was also observed high amounts of SiO2 and Al2O3 as well as the presence of Al atoms within the tetrahedral sheet evidencing isomorphic substitutions of Si. The properties evaluation showed increased swelling and exchange cation capacities allied to a typical semiconductor band gap. The degradation essays performed indicate a decoloration efficiency of 40 % in the presence of H2O2. In addition, the theoretical investigation provides valuable insights into the influence of impurities and defects on the structural and electronic properties of bentonite mineral clays.