Comparison of Spirulina platensis microalgae and commercial activated carbon as adsorbents for the removal of Reactive Red 120 dye from aqueous effluents

► Spirulina platensis (SP) and activated carbon (AC) were used to remove RR-120 dye. ► The maximum adsorption capacities were found at pH 2 and 298 K. ► The values were 482.2 and 267.2 mg g−1 for SP and AC, respectively. ► Adsorption was exothermic, spontaneous and favorable. ► SP and AC were effective to treat a simulated dye-house effluent.