Facile fabrication of crown ether functionalized lignin-based biosorbent for the selective removal of Pb(II)

A novel 1-Aza-18-crown-6 functionalized lignin-based adsorbent (AFL) is facilely prepared through Mannich reaction in a one-step process. Structure characterization by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, elemental analysis and X-ray photoelectron spectroscopy confirmed the successful fabrication of AFL. AFL was observed to display enhanced adsorption capacity (Qmax = 91.4 mg/g) and superior selectivity toward Pb(II) ions, due to a display of crown ether units and their interaction with metal ions. The adsorption equilibrium results from a kinetic study indicated that the Pb(II) adsorption by AFL was a chemisorption process. Additionally, the obtained thermodynamic parameters showed the adsorption mechanism to be an exothermic and spontaneous process at room temperature. The AFL could be regenerated by desorption of Pb(II) ions and remained at over 80 % adsorption efficiency after four adsorption-desorption cycles. Therefore, the AFL displays acceptable adsorption performance and can serve as a bioresource-based and recyclable adsorbent material, portending a new expectation in the application for water purification engineering.