Spectroscopic Approach on Bulk and Surface Properties of Fungal Biomass-Clay Adsorbents: Effect of Temperature and Amount of Clay during Synthesis

Abstract

The physicochemical properties of an enhanced adsorbent material generated by clays and fungal biomass can be modified systematically. We used spectroscopic techniques to investigate the interaction mechanisms between biomass and clay and how surface properties change with synthesis temperature and clay amounts. Biomass-clay complexes were synthesized and either shock-frozen and freeze-dried or dried at 60 °C in the oven. Surface and bulk properties were analyzed by scanning electron microscopy, attenuated total reflectance-Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and by wettability and surface charge measurements. Interactions of specific biomass-related molecules with clay and changes in physicochemical properties were observed. Higher amounts of clay caused a decrease in particle aggregation while the biomass arranged more evenly. XPS proved interactions due to exchange reactions between Na from the clay and biomass external organic compounds. FTIR, wettability, surface charge, and XPS indicated a less ordered arrangement of the biomass on the clay when drying was performed at 60 °C. The properties of these types of materials define their potential use in future applications. These results indicate the possibility of the selective creation of bioclays: more hydrophobic, with a higher content of organic matter or more specific functional groups on the surface.