Facile and Effective Preparation of the Lotus Leaf-based Adsorbent by Exposing Cellulose Nanocrystal for Waste Water Treatment and Air Purification

One substantial plant waste, lotus leave was fabricated into lotus leave powder with different diameters by ball milling. The surface morphology, chemical composition, particle size, porosity parameters, crystal structure, and wettability of lotus leaf powders (LLPs) were analyzed by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), Fourier-transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), laser particle size analysis, N2 adsorption/desorption, X-ray diffraction (XRD) analysis, and water contact angle (WCA) analysis, respectively. The results showed that the micro- and nanoscale waxy papilla structures on the surface of the lotus leaf were gradually destroyed by mechanical forces along with extended balling time. Accompanied re-exposing of -OH affluent cellulose nanocrystals (CNCs) was proved by HR-TEM, XRD, and FTIR. FTIR also revealed a hydroxyl to carboxyl transition on the surface of CNCs. Both the re-exposure of CNCs and thereof chemical structure transition after ball milling made the LLP a good candidate for pollutant adsorbent for dye, formaldehyde, and heavy metal ions.