Confined growth of MOF in chitosan matrix for removal of trace Pb(Ⅱ) from reclaimed water

The removal of lead ions from water is a global concern due to the great damage to human health when they enter the human body through drinking water. Herein, metal-organic framework/chitosan composite beads for the adsorption of Pb(II) were prepared by the secondary growth method, which allowed the domain-limited growth of TIF-A1 (a tetrahedral imidazolate framework) in the porous matrix of chitosan. This material can remove trace Pb(II) from aqueous solution (100 ppb) with an efficiency of 99.95%, and the remaining Pb(II) content meets the international drinking water standards. Moreover, it exhibited good recoverability for at least five adsorption/desorption cycles. The adsorption mechanism can be ascribed to that Pb(II) ions chelate with the hydroxyl, carboxyl and amino groups in the adsorbent. This work offers a good adsorbent for the removal of trace Pb(II), which has potential applications in reclaimed water treatment.