Use of Spirulina platensis micro and nanoparticles for the removal synthetic dyes from aqueous solutions by biosorption

► Micro and nanoparticles of Spirulina platensis were used as dyes biosorbents. ► Nanoparticles presented biosorption capacities higher than microparticles. ► The maximum biosorption capacity was 1450 mg g−1. ► Biosorption onto microparticles occurred mainly by physical interactions. ► Chemisorption was dominant in the biosorption of food dyes onto nanoparticles.