Characterization of cadmium removal by Rhodotorula sp. Y11

Experiments were conducted studying the removal of Cd²⁺ from water via biosorption using Rhodotorula sp. Y11. The effects of temperature and initial pH of the solution on biosorption were studied. Caustic and heat treatments showed different influences on the biosorption capacity, and the highest metal uptake value (19.38 mg g⁻¹) was obtained by boiling treated yeast cells. The presence of competing cations, such as Ag⁺, Cu²⁺, and Mg²⁺, except Na⁺ ions, significantly interfered with the metal uptake. Results indicate that the Langmuir model gave a better fit to the experimental data than the Freundlich equation. The q ₁₀ value was 11.38 mg g⁻¹ for Cd²⁺ uptake by Y11. Chemical modifications of the biomass demonstrated that carboxyl and amide groups play an important role in Cd²⁺ biosorption.