Biosorption mechanism of Zn2+ from aqueous solution by spent substrates of pleurotus ostreatus

To solve the problem of heavy metal pollution and agricultural wastes reclamation, spent substrate of pleurotus ostreatus (SSPO) was used as adsorbent to remove Zn2+ from aqueous solution. The biosorption of zinc ions on SSPO was studied as a function of the solution pH, temperature and initial Zn2+ concentration. The equilibrium sorption data were well represented by linear Langmuir isotherm models with R-2 value of 0.9955 and non-linear Freundlich with R-2 value of 0.9973. The BET surface area of SSPO can reach 51.16 m(2) g(-1). SEM-EDX and XRD revealed that (NH4)(2) Zn center dot H2O and Zn2PO4(OH) were the main compounds in metal-loaded SSPO. FTIR analysis indicated the governing functional groups such as O-H, N-H and P=O played an important role in biosorption. The desorption studies showed the reversibility of SSPO. The results indicate that SSPO is a potential adsorbent in wastewater treatment due to its great sorption capacity and low cost.