Removal of Pb(II) and malachite green from aqueous solution by modified cellulose

A low-cost, highly efficient and eco-friendly cellulose-based adsorbent (CMGT) was synthesized and used to uptake Pb(II) and malachite green (MG) from aqueous solutions. The CMGT was characterized by FTIR, SEM, TGA and XRD. Different experimental parameters were evaluated in batch adsorption experiments to determine the optimal adsorption conditions. The optimal pHs for Pb(II) and MG were 5.5 and 7.0, respectively; the optimal contact times for Pb(II) and MG were 60 and 180 min, respectively. Among the Langmuir, Freundlich and Temkin isotherm models, the Langmuir model fitted the adsorption data best for both Pb(II) and MG adsorption. In theory, the maximum adsorption capacities of Pb(II) and MG were 584.80 and 131.93 mg g⁻¹, respectively. The pseudo-second-order model fitted the experimental data very well, and the thermodynamics were also used to discuss the mechanism in depth. Additionally, desorption tests showed that CMGT could be effectively regenerated by 0.2 mol L⁻¹ HCl solution and could be reused for at least six cycles successively with a stable sorption ability in the dynamic adsorption process.