Abstract
AbstractChromium is one of the most toxic and carcinogenic heavy metals. Conventional techniques which are commonly applied for removal of chromium ions from aqueous matrices have several drawbacks whereas biosorption has a high performance for metal extraction. Three fungal strains, i.e., (1) Aspergillus ustus (Asp), (2) Fusarium verticillioides (Fus), and (3) Pencillium funiculosum (Pen), have been immobilized on nanosilica (NSi) surface to develop highly effective three biosorbents, i.e., (1) NSi-Asp, (2) NSi-Fus, and (3) NSi-Pen. They are used for solid phase extraction and selective removal of Cr(III) and Cr(VI) ions. Surface characterization and immobilization of fungal cells on nanosilica were examined and confirmed by using scanning electron imaging and Fourier-transform infrared analysis. Biosorption and removal of chromium ions were followed up via batch experiment under the influence of pH, contact time, biosorbent dosage, and initial metal ion concentration. The maximum biosorption capacity values of Cr(III) were 2,466.7, 2,666.7, and 1,866.7 μmol g−1 by using NSi-Asp, NSi-Fus, and NSi-Pen, respectively. These were observed at pH 7.0, while those for Cr(VI), 6,466.7, 6,400.0, and 3,800.0 μmol g−1, were observed at pH 2.0. Fast sorption equilibria were established at about 15 min and their data were well described by both Langmuir and Freundlich isotherms. Potential applications for speciation and selective extraction of chromium ions from real wastewater samples were successfully accomplished.