Kinetic Modeling of Nonylphenol Biosorption and Desorption by Immobilized Non-living Fungal Mycelium grown in Chitosan Beads

Abstract

In this study, isotherm and kinetics models for nonylphenol (NP) biosorption and desorption by the fungal biomass using chitosan as a supporting material were investigated. Filamentous fungal biomass 

of Rhizopus arrhizus exhibited the most potential uptake of NP, an endocrine disrupting chemicals. Scanning electron microscopy (SEM) revealed the exuberant mycelia distributed inside and on the bead surface. Biosorption of NP using the immobilized fungal mycelium grown in chitosan beads was performed under batch conditions with initial NP concentrations ranging from 20.12 to 245.15 mg/L. The equilibrium adsorption data were best correlated with various adsorption isotherms in the order Redlich-Peterson, Langmuir, and Freundlich by using non-linear least-regression with the solver add-in in Microsoft Excel. The adsorption selectivity of the beads for NP was excellently higher than the two similar structure compounds, phenol and poly(ethylene glycol)4-nonylphenol-3-sulfopropyl ether, potassium salt (PSE). Desorption to recover the adsorbed NP from the beads was performed in methanol and was best described using a pseudo second-order kinetic model compared to pore diffusion model and pseudo first-order. The second-order desorption rate (KD2 constant was determined as 0.2243 g/mg min. The regeneration of used dead beads was effective for at least 3 batch consecutive cycles which almost NP uptake could still be eluted.