The metal uptakereduced from 94.9 to 93.5%, 96.8 to 85.9% and 95.2 to 79.8% for Pb,Cu and Cd ions, respectively. It means that there were few activesites available on the CMSS-acid hydrogel while more ions are com-peting to be bonded. Thus, in the higher concentration of metal ions,the less amount of metal ions being uptake by the hydrogel