Dye adsorption on magnetically modified chlorella vulgaris cells

Abstract

Dried Chiorelia vulgaris ceIls were magnetically modified by contact with water-based magnetic fluid stabilized with perchloric acid in order to prepare a new type of magnetically responsive biocomposite material. This procedure enabled a simple separation of modified ceIls by means of strong permanent magnets. The prepared material was used as a new inexpensive magnetic adsorbent for the removal of water-soluble dyes. MagneticalIy modified cells were characterized by means of magnetic and microscopic methods. Both isolated magnetic nanoparticles and aggregates of particles were present on the ceIl surlace. The prepared material displayed a super-paramagnetic behavior at room temperature, with a transition to a blocked state at Tв ~ 200 K for the applied magnetic field H =50 Oe. Six dyes (aniline blue, Bismarck brown, congo red, crystal violeI, safranin O and Saturn blue LBRR) were used to study the adsorption processo The dyes' adsorption reached equilibrium in approximately 30-120 mino Langmuir isotherms were successfulIy used to fit lhe experimental data. The maximum adsorption capacities ranged between 24.2 (Saturn blue LBRR) and 257.9 (aniline blue) mg of dye per g of dried magneticalIy modified cells. Change of pH can significantly increase lhe adsorption of some dyes. Ferrofluid-modified Chio relia vulgaris ceIls represent an interesting material for furlher study and potential applications.