We report the performance of the seaweed
(Caulerpa serrulata) before and after modification with ethylenediamine (EDA), on adsorption of copper,
lead and cadmium in aqueous solution. The adsorption capacities for Cu, Cd and Pb were 5.27 mg g1,
2.12 mg g1 and 2.16 mg g1, respectively, with the EDA-modified seaweed, and 3.29 mg g1, 4.57 mg g1
and 1.06 mg g1, with the unmodified weed, respectively. The pH for maximum adsorption was found to
be within the range of pH 4–pH 6. In a separate investigation, it was found that 0.1 g of dried seaweed
leached 20 mg of dissolved organic carbon (DOC) using 100 ml of distilled-deionised water. The resulting
solution was green. The leaching phenomenon contributes to secondary pollution. Modification of the
seaweed with EDA reduced the DOC content by half (50%) and also removed the green colouration.
Kinetic studies showed that the adsorbent was able to take up to 95% of the metals (in synthetic standard
solutions) in less than 10 min. The adsorbed metals were then stripped using a solution of 0.5 M HNO3
indicating that the adsorbent can be regenerated. In addition, the study revealed that modification
improved the thermal stability of the adsorbent such that even when the temperature was raised to
1000 C, more than 80% (compared to