Harnessing the fungal biomass of Purpureocillium lilacinum for adsorptive removal of Cr(VI) from aqueous solution: investigation on the effect of Pre-treatment

In this study, the dead fungal biomass of Purpureocillium lilacinum was explored as an efficient and sustainable biosorbent for the removal of Cr(VI) ions from aqueous solutions, with a special focus on the optimization of pre-treatment strategies. Unlike the majority of biosorption studies that target well-established fungal genera, this work focused systematical investigation on P. lilacinum an underexplored species for Cr(VI) remediation. The effects of various pre-treatment agents, their concentrations, and drying methods were evaluated to enhance the biosorptive performance. One-variable-at-a-time and Plackett-Burman statistical design (PBD) approaches were employed to optimize the key biosorption parameters, revealing that initial Cr(VI) concentration was the most influential factor, followed by adsorbent dose, pH, and contact time. Mechanistic characterization by FTIR, SEM, and XRD provided molecular-level insights into the role of functional groups and surface morphology in chromium binding. Notably, P. lilacinum biomass pre-treated with 0.5 N HCl and oven-dried at 105 °C demonstrated superior Cr(VI) removal efficiency (up to 96.6%) compared to many commonly studied fungal biosorbents. This research not only establishes a novel and cost-effective biosorbent protocol but also provides comprehensive mechanistic understanding and optimization, laying a scientific foundation for industrial application of P. lilacinum in chromium remediation.