Abstract Pterocladia capillacea, a red marine macroalgae, was tested for its ability to remove toxic
hexavalent chromium from aqueous solution. A new activated carbon obtained from P. capillacea
via acid dehydration was also investigated as an adsorbent for toxic chromium. The experiments
were conducted to study the effect of important parameters such as pH, chromium concentration
and adsorbent weight. Batch equilibrium tests at different pH conditions showed that at pH 1.0,
a maximum chromium uptake was observed for both inactivated dried red alga P. capillacea and
its activated carbon. The maximum sorption capacities for dried red alga and its activated carbon
were about 12 and 66 mg g1
, respectively, as calculated by Langmuir model. The ability of inactivated
red alga P. capillacea and developed activated carbon to remove chromium from synthetic sea
water, natural sea water and wastewater was investigated as well. Different isotherm models were
used to analyze the experimental data and the models parameters were evaluated. This study
showed that the activated carbon developed from red alga P. capillacea is a promising activated carbon
for removal of toxic chromium.