This research demonstrates the production of mesoporous activated carbon from sargassum fusiforme via physical activation with carbon dioxide. Central composite design was applied to conduct the experiments at different levels by altering three operating parameters. Activation temperature (766-934 ℃)

CO

2

flow rate (0.8-2.8 L·min

-1

) and activation time (5-55 min) were the variables examined in this study. The effect of parameters on the specific surface area

total pore volume and burn-out rate of activated carbon was studied

and the influential parameters of methylene blue adsorption value were identified employing analysis of variance. The optimum conditions for maximum methylene blue adsorption value were: activation temperature = 900 ℃

activation time = 29.05 min and CO

2

flow rate = 1.8 L·min

-1

. The activated carbon produced under optimum conditions was characterized by BET

FTIR and SEM. The adsorption behavior on congo red was studied. The effect of parameters on the adsorbent dosage

temperature

PH and initial congo red concentration was investigated. The adsorption properties of the activated carbon were investigated by kinetics. The

equilibrium removal rate and maximum adsorption capacity reaches up to 94.72%

234 mg·g

-1

respectively when initial congo red concentration is 200 mg·L

-1

under adsorbent dosage (0.8 g·L

-1

)

temperature (30 ℃)

PH7.