BACKGROUND: In this study, the capability of low-cost, renewable and abundant marine biomass Posidonia oceanica (L.) for adsorptive removal of anionic and non-ionic surfactants from aqueous solutions have been carried out in batch mode. Several experimental key parameters were investigated including exposure time, pH, temperature and initial surfactant concentration. RESULTS: It was found that the highest surfactant adsorption capacities reached at 30 degrees C were determined as 2.77 mg g(-1) for anionic NaDBS and as 1.81 mg g(-1) for non-ionic TX-100, both at pH 2. The biosorption process was revealed as a thermo-dependent phenomenon. Equilibrium data were well described by the Langmuir isotherm model, suggesting therefore a homogeneous sorption surface with active sites of similar affinities. The thermodynamic constants of the adsorption process (i.e. Delta G degrees, Delta H degrees and Delta S degrees) were respectively evaluated as -8.28 kJ mol(-1), 48.07 kJ mol(-1) and -42.38 J mol(-1) K-1 for NaDBS and -9.67 kK mol(-1), 95.13 kJ mol(-1) and -174.09 J mol(-1) K-1 for TX-100. CONCLUSION: Based on this research, valorization of highly available Posidonia oceanica biomass, as biological adsorbent to remove anionic and non-ionic surfactants, seems to be a promising technique, since the sorption systems studied were found to be favourable, endothermic and spontaneous. (c) 2007 Society of Chemical Industry.