Similar result has been reported bySinganan and Peters (2013) suggesting that the saturation of a sys-tem occurred at certain amount of sorbent applied where the metalbonded to sorbent and free metal ions in aqueous solution remainconstant. The predominant sorption mechanism is ion exchange aswell as surface absorption on the hydrogel. The optimum amountof CMSS-acid hydrogel for Pb ions was 0.050 g, while for Cu and Cdions were 0.150 g and 0.200 g with the amount of metal uptake was94.0%, 87.8% and 84.4%, respectively.3.4.3. Effect of contact time and kinetic study