Utilization and characterization of cellulose nanocrystals decorated with silver and zinc oxide nanoparticles for removal of lead ion from wastewater

Abstract

Several studies have been reported in order to utilize cellulosic based sorbents for lead decontamination from wastewater. However, the research still undergoes so that a highly efficient system is obtained. In the present study, cellulose nanocrystals (CNCs) were successfully decorated during the synthesis of silver (Ag) and zinc oxide (ZnO) nanoparticles, separately. The obtained nanocomposites, Ag/CNC and ZnO/CNC, have been intensively investigated with FTIR, XRD, XPS, and TEM to emphasize the workability of in-situ surface modification of CNCs with Ag and ZnO nanoparticles. The performance of these nanocomposites as effective adsorbents for lead ion Pb(II) has been evaluated under various conditions such as pH, temperature, concentration, and time. Generally, Ag/CNC nanocomposite improved Pb(II) uptake by ~ 22% while ZnO/CNC improved uptake by ~ 60% compared to CNCs. However, the results revealed that 60 min was sufficient time to reach adsorption equilibrium in all cases, which indicates a fast adsorption process. Moreover, ion uptake is enhanced by increasing pH, temperature, and concentration of Pb2+. The kinetic model is pseudo-second-order and the adsorption obeyed Langmuir isotherm (R2 ~ 0.997). The sorbents have revealed more than 94% removal efficiency for pb2+ from wastewater. Furthermore, the developed nanocomposites can be regenerated and reused for three cycles. No doubt, this work paves the way for next generation of functional biosorbants for water treatment applications.