Novel polyethyleneimine functionalized chitosan–lignin composite sponge with nanowall-network structures for fast and efficient removal of Hg(<scp>ii</scp>) ions from aqueous solution

An environmental-friendly polyethyleneimine functionalized chitosan–lignin composite sponge with interconnected nanowall-network structures is feasibly fabricated for rapidly and selectively removing Hg(<sc>ii</sc>) ions from aqueous solution.