Comparative study of Cd(II) biosorption on cultivated Agaricus bisporus and wild Lactarius piperatus based biocomposites. Linear and nonlinear equilibrium modelling and kinetics

Abstract Biosorption of Cd(II) ions from aqueous solutions onto immobilized fruit bodies of cultivated Agaricus bisporus and wild Lactarius piperatus was investigated in batch system. The biosorbent was characterized using FTIR analysis. Cd(II) removal process was studied using as biosorbent A. bisporus and L. piperatus immobilized in calcium alginate (biocomposite). The influences of stirring rate, biomass quantity, initial metal ion concentration, contact time and pH were studied. The equilibrium adsorption data were fitted to Langmuir and Freundlich isotherm models (linear regression) and the model parameters were evaluated. A nonlinear optimization algorithm (CMA-ES) applied on ten isotherm models was also used to describe the biosorption process. The optimization algorithm tested showed that nonlinear regression analysis has better performances, with Sips model describing biosorption process the best. Experimental data were also used to study biosorption kinetics using pseudo-first-, pseudo-second-order, intra-particle and film diffusion models. The results showed that the biosorption process of both macrofungus studied, followed well pseudo second-order kinetics. From the experimental data we can concluded that wild L. piperatus showed higher removal efficiency on Cd(II) ions compared to the cultivated A. bisporus.