Biosorption Potential of Ganoderma lucidum Biomass for Cd(II) Remediation: Adsorption Kinetics and Isotherm Studies

Heavy metals release in the environment represents a growing threat to human health and nature, particularly due to industrial activities contributing to soil and water contamination. In this study, Ganoderma lucidum heteropolysaccharides (GLHP) were evaluated as a biosorbent for cadmium removal. The biomass was acquired following the production of Ganoderma lucidum fruiting bodies and consisted of remnants from the fungus and cultivation substrate. Cd(II) and elemental analysis were carried out by atomic adsorption spectrometry (AAS) and inductively coupled plasma mass spectroscopy (ICP-MS), respectively. The biosorption efficiency was critically evaluated, optimizing physical adsorption parameters for batch, column, and percolation configuration, as well as application in real environmental water. Utilizing a simple pre-rinsing step, completely omitting any chemical pretreatment, the Cd(II) removal efficiency was improved from 41.2% to 78.4% in a batch system and up to 98.4% in a fixed-bed column, making it suitable not only for wastewater treatment but also for drinking water purification. The adsorption kinetics were described by a pseudo-second-order (PSO) model and further analyzed using a revised PSO (rPSO) model, which explicitly accounts for adsorbate and adsorbent concentrations. A global fit to the PSO model demonstrated that the rate constant was independent of the adsorbent concentration, supporting its application as a robust descriptor of the adsorption process. GLHP showed good adsorption performance, following the Sips adsorption isotherm and Thomas model for batch and column setup, respectively, demonstrating the potential as a scalable, low-cost biosorbent for fast and efficient Cd(II) removal from contaminated waters.