Preparation of amidoxime modified biomass and subsequent investigation of their lead ion adsorption properties

Amidoximated biosorbent (oximated MT) was successfully synthesized from manna tree (Alhagi Graecorum) residue and subsequently applied for the adsorption of aqueous lead ions. The oximated MT was obtained from tri-synthesis steps of dried residue pulverization, polymerization and nitrile amidoximation. The synthesized adsorbent was effectively characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy dispersion x-ray (EDX) measurements. An optimum adsorptive uptake was established at a contact time of 45 min, pH 6.0, and 0.03 g/L adsorbent dosage. The experimental isotherm and kinetic data were best fitted to the Temkin and Elovich models, respectively. Furthermore, the "approaching equilibrium factor" (RE) value of the Elovich model suggests the occurrence of a mildly rising curve, since 0.1 < RE< 0.3. The mechanistic investigation reveals the predominance of pore and intraparticle diffusion mechanism at low (200 mg/L initial adsorbate concentration) and high (400 & 600 mg/L initial adsorbate concentrations), respectively. Furthermore, the thermodynamic study suggests a prevailing endothermic process.