Biosorption of nickel using filamentous fungi.

Nickel (Ni) uptake capability from aqueous solutions was studied in a filamentous fungi strains group of Rhizopus sp., Penicillium sp. Aspergillus sp., Trichoderma sp., Byschoclamyss sp., and Mucor sp. The metal uptake of a Rhizopus sp. strain, which has the highest uptake capacity, was corroborated by electron microscopy; no Ni deposits were observed on the cell wall, but rather a homogeneous accumulation was seen on the cell surface. The influence on the capacity of metal uptake by environmental parameters such as pH, temperature, time, and the interference of other ions in the solution, was also studied. Nickel accumulation by the selected strains is fast, occurring in less than 30 min, and does not require a microorganism's active metabolism to take place. The sorption isotherms were established for the selected fungi, in order to determine the maximum metal uptake capacity. The sorption isotherms were fixed to the mathematical models of Freundlich and Langmuir, obtaining better performance on the Langmuir model.