It was observed that the amount of Cd2+ ions adsorbed varied
with varying algae amounts (Fig. 2). The results recorded
removal percentages of 86.6%, 99.2%, and 98.7% and
98.1% at weights of 0.05, 0.1, 0.2 and 0.4 g, respectively. It
seems that the highest biosorption uptake was found at the
biomass weight of 0.1 g. High biosorbent amounts are known
to cause cell agglomeration and a consequent reduction in
intercellular distance and produce ‘screen effect’ among a
dense layer of cells, leading to the ‘protection’ of binding sites
from metal ions (Pons and Fuste, 1993). The obtained data
were in agreement with those of Esposito et al. (2001) and
El-Sikaily et al. (2011), who reported lower biosorbed metal
percentage (q) at high adsorbent concentrations.