Crown ether modification of starch for adsorption of heavy metals from synthetic wastewater.

The adsorbent resin was prepared by grafting copolymerization of dibenzo‑18‑crown‑6 onto corn starch under microwave irradiation and was used to adsorb Cd2+, Zn2+, Ni2+ and Cu2+ from aqueous solution. Microwave assisted synthesis method, which uses only microwave radiation to generate free radical in the polymer backbone, is fast, and reliable. It can produce high-quality product as compared to the conventional method. The resultant microwave produced modified starch was characterized by FTIR, UV-Vis, XRD and SEM devices. Adsorption of heavy metal ions on adsorbent could be well fitted by the pseudo-second-order and Freundlich equations. The influences of pH, contact time, adsorbent dose, temperature and metal ion concentration were studied in batch method experiments. Grafted corn starch could be reused by HNO3 as eluting agent. All the results show that St:DB18C6 is a good adsorbent for the removal of heavy metal ions from wastewater.