Entrapment of fungal hyphae in structural fibrous network of papaya wood to produce a unique biosorbent for the removal of heavy metals

A unique biosorbent was developed by entrapping fungal hyphae in structural fibrous network of papaya wood (SFNPW) and successfully used for the removal of Zn(II) from aqueous solution. The SFNPW-immobilized fungal biosorbent removed Zn(II) rapidly and efficiently with maximum metal removal capacity of 66.17 mg/g dry biomass at equilibrium, 41.93% higher than the amount of Zn(II) removed by free biomass (46.62 mg/g) under the identical conditions. Equilibrium was established in 1 h and biosorption was well defined by Langmuir isotherm model. SFNPW-immobilized fungal biosorbent was regenerated by washing with 50 mM HCl, with upto 99% recovery of the sorbed metal ions and the regenerated system was reused in five adsorption–desorption cycles without any significant loss in its biosorption capacity. The efficient metal removing ability of this unique biosorbent system, low cost of SFNPW and simplicity of the immobilization technique used to produce the SFNPW-immobilized fungal biosorbent system indicate the potential application of this biosorbent for the treatment of wastewaters containing heavy metals.