Dual responsive copolymers-grafted microfibrillated cellulose composites for removing lead ions from aqueous solution

The work presented herein focuses on developing the environmentally friendly and microfibrillated cellulose-based composite beads (MCPA) for efficient removal of Pb2+ from aqueous solution. MCPAs were prepared through concurrent copolymerization and the crosslinking between microfibrillated cellulose and the monomers; and the resulting adsorbents are pH and thermo-responsive. The adsorption characteristics were systematically studied by varying the influencing factors such as pH, temperature, and contact time. The optimal pH of the adsorption of Pb2+ was found to be 6.0; and under this pH the adsorption/desorption kinetics and isotherms of Pb2+ on MCPA were investigated at 30 degrees C and 45 degrees C, respectively. The equilibrium data for Pb2+ fitted Langmuir model well with the maximum adsorption capacity of 171.2 mg/g at 45 degrees C; whereas the pseudo-second order kinetic better described the adsorption process. Meanwhile, the desorption process followed the Korsmeyer-Peppas kinetic model. The column study indicated that the adsorption capacity of Pb2+ (Qads) reached 187.3 mg/g, demonstrating the excellent adsorption performance in continuous system. Overall, MCPA is an environmental-friendly, renewable, and dual-responsive bioadsorbent which is not only highly effective in Pb2+ removal, but might also be promising for removing hazardous dyes and other types of heavy metal ions from sewage. (C) 2020 Elsevier Ltd. All rights reserved.