Nanoadsorbents preparing from oligoethylene glycol dendron and citric acid: Enhanced adsorption effect for the removal of heavy metal ions

Poly(methacrylate oligoethylene glycol dendron-co-citric acid) (PGCA) that is based on citric acid and oligoethylene glycol (OEG) dendrons is utilized as a nanomaterial for the removal of heavy metal ions from aqueous solution. PGCA shows excellent solubility in aqueous solution and realizes satisfactory removal efficacy for Pb2+ ions; the removal rate exceeds 95 %. In addition, PGCA can be utilized in Chinese herbal decoctions; the removal rate of Pb2+ ions in the ligusticum wallichii decoction exceeds 90 %, meanwhile the concentration of the active ingredient, namely, ferulic acid, is maintained. In this nanoadsorbent, citric acid provides the active site for the chelation of heavy metal ions, and OEG dendron serves as a protective layer that reduces the opportunity for carboxyl groups to be occupied by other ingredients. In summary, nanomaterial PGCA is designed and synthesized successfully that can be applied as a nanoadsorbent for the removal of Pb2+ ions from aqueous solution, especially in Chinese herbal decoctions that have acidic compounds as active ingredients.