A Comparative Study on the Biosorption of Cd(2+) onto Paecilomyces lilacinus XLA and Mucoromycote sp. XLC

The filamentous fungi XLA and XLC isolated from Cd-contaminated soil were identified morphologically and phylogenetically as Paecilomyces lilacinus and Mucoromycote sp., respectively. The minimum inhibitory concentrations (MICs) of Cd(2+), Co(2+), Cu(2+), Zn(2+), Cr(3+) and Cr(6+) in minimum mineral (MM) medium agar plates were 29,786, 2945, 9425, 5080, 1785 and 204 mg·L(−1) for XLA and 11,240, 884, 9100, 2540, 3060 and 51 mg·L(−1) for XLC, respectively. Favorable biosorption conditions for adsorption of Cd(2+) by the tested fungi were investigated. Efficient performances of the biosorbents were described using Langmuir isotherm model, and the predicted maximum biosorption capacities for Cd(2+) were 77.61 mg·g(−1) of XLA and 79.67 mg·g(−1)of XLC. Experiments on desorption potential of biosorbents validated their efficacy at a large scale. Results showed that XLA obtained a desorption rate of 84.7% by 2% EDTA and XLC gained a desorption rate of 78.9% by 0.1 M HCl. Analysis by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) and X-ray photoelectron spectroscopy (XPS) suggested that groups of C–N, COO– for XLA and C–N, CH(2) and phosphate for XLC were the dominant binding sites for Cd(2+) biosorption. Our results indicated that the fungus XLA, rather than XLC, could potentially be used as an inexpensive, eco-friendly and effective bioremediation agent for the removal of Cd(2+) from wastewater.