Adsorptive performance and mechanism exploration of l-lysine functionalized celluloses for enhanced removal of Pb(II) from aqueous medium

In this study, two novel biosorbents of l-lysine grafted cellulose (L-PCM, L-TCF) were prepared for Pb(II) removal from aqueous solutions. Various adsorption parameters were surveyed, such as adsorbent dosages, initial concentration of Pb(II), temperature and pH, using adsorption techniques. At normal temperature, less adsorbent can achieve better adsorption capacity (89.71 ± 0.27 mg g−1 with 0.5 g L−1 of L-PCM, 16.84 ± 0.02 mg g−1 with 3.0 g L−1 of L-TCF). The pH range of application for L-PCM was 4–12 and that of L-TCF was 4–13. The adsorption of Pb(II) by biosorbents went through the boundary layer diffusion stage and void diffusion stage. The adsorption mechanism was chemisorption based on multilayer heterogeneous adsorption. The pseudo-second-order model fitted the adsorption kinetics perfectly. The Freundlich isotherm model adequately described Multimolecular equilibrium relationship between Pb(II) and biosorbents; the predicted maximum adsorption capacities of the two adsorbents were 904.12 and 46.74 mg g−1, respectively. The results showed that the adsorption mechanism was the electrostatic attraction between Pb(II) and -COOH and the complexation between Pb(II) and -NH2. This work demonstrated that l-lysine modified cellulose-based biosorbents have great potential in the field of Pb(II) removal from aqueous solutions.