A novel core–shell structured biosorbent derived from chemi-mechanical pulp for heavy metal ion removal

Carboxymethylated cellulose fiber (CMF), a cellulose-based biosorbent, was prepared from chemi-mechanical pulp. The CMF biosorbent showed a high stability/recovery and an excellent adsorption capacity during the metal ion removal due to its unique core–shell structure: (1) the CMF maintained a good fiber formwork even at a high carboxyl content level (175.40 mmol/100 g) due to the protection of carboxymethyl-free lignin shell on the fiber surface, thus facilitating the follow up separation/recovery of CMF; (2) the high carboxyl content in the core of CMF cellulose enabled its strong adsorption capacity towards metal ions. The results showed that the adsorption behavior fitted well to the pseudo-second-order kinetic and the CMF had high selective adsorption towards Pb(II). The CMF also exhibited an excellent recycling performance. Therefore, the as-prepared CMF with high adsorption capacity, good solid–liquid separation and high regeneration performance indicates that the novel core–shell CMF biosorbent can provide a method to remove metal ion in practical wastewater treatment.