Effective removal of hexavalent chromium by novel modified alginate-based biocomposites: Characterization, kinetics and equilibrium studies

This study aims to synthesise novel biocomposites by combining fungal hyphae (Aspergillus oryzae or Penicillium roqueforti) and reduced graphene oxide to evaluate their adsorption potential for hexavalent chromium (Cr(VI)) from synthetic solutions and real wastewater. Fourier-transform infrared spectroscopy, scanning electron mi-croscopy, X-ray diffraction, and thermogravimetric analyses were used to characterize the effects of the carbon -based materials on microbial structure. In addition, independent variables including with a contact time (1-11 h), reduced graphene oxide concentration (0.1-1 g.L-1), and initial Cr(VI) concentration (10-50 mg L-1) were tested in batch-scale laboratory experiments by response surface methodology. Accordingly, maximum adsorp-tion was achieved at 11 h contact time, 1.0 g L-1 rGO, and 50 mg L-1 Cr(VI) with a removal rate of 98.9%. The pseudo-first-order and Freundlich isotherm models were well fitted. The results show that these biocomposites can serve as novel adsorbent for the removal of Cr(VI) from wastewater.