Cu(II) Ions Removal on Functionalized Cellulose Beads from Tunisian Almond (Prunus Dulcis) Shell

The aim of the present study is to prepare the eco-friendly and effective adsorbents for the removal of Cu(II) ions in wastewaters through the trisodium trimetaphosphate (STMP) functionalization of cellulose (CBBAS) and cellulose nanofibers (CBCNFs) beads obtained from the almond shell. The structure and properties of the STMP-functionalized cellulose beads were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermal gravimetric (TGA/DTG), and N₂ adsorption–desorption. Cu(II) ions were adsorbed at a great extent within the first 2 h, at 30 °C, and pH 6. The experimental isotherms were successfully fitted to the Redlich–Peterson model for the CBBAS/STMP adsorbent and Sips model for the CBCNFs/STMP one, yielding adsorption capacities of 141 mg g⁻¹ and 147 mg g⁻¹, respectively. The adsorption process onto both biosorbents followed a pseudo-second-order kinetic model, suggesting that chemisorption is the dominant mechanism of the metal ions onto the modified beads. CBBAS/STMP and CBCNFs/STMP biosorbents are easily regenerated using HCl (0.1 M) solution.