Application of a Low-Cost Cellulose-Based Bioadsorbent for the Effective Recovery of Terbium Ions from Aqueous Solutions

The preparation of a low-cost cellulose-based bioadsorbent from cellulosic material extracted from rose stems (CRS) was carried out; rose stems are considered agricultural waste. After the required pretreatment of this waste and further treatment with an acidic mixture of acetic and nitric acids, the CRS product was produced. The resulting bioadsorbent was characterized by several techniques, such as X-ray diffraction, which revealed diffraction maxima related to the cellulose structure, whose calculated crystallinity index (CrI) was 75%. In addition, Fourier Transform Infrared spectroscopy (FTIR), 13C Nuclear Magnetic Resonance (NMR), and X-ray Photoelectron Spectroscopy (XPS) showed signs of acetylation of the sample. The thermal properties of the solid were also evaluated through Thermogravimetric Analysis (TGA). Scanning Electron Microscopy (SEM) showed cellulose fibers before and after the adsorption process, and some particles with irregular shapes were also observed. The CRS bioadsorbent was used for the effective adsorption of valuable Tb(III) from an aqueous solution. The adsorption data showed a good fit to the Freundlich isotherm and pseudo-second-order kinetic models; however, chemisorption was not ruled out. Finally, desorption experiments revealed the recovery of terbium ions with an efficiency of 97% from the terbium-loaded bioadsorbent.