The Character Of Pb(â…¡) And Cd(â…¡) Biosorption By Aspergillus Aculeatus

Along with the fast development of the industry and mining, the heavy metal waste water has become one kind industrial waste water which has extremely harm on the ecological environment. The traditional heavy metal technologies, such as chemical precipitation and ion exchange, are relatively expensive and ineffective especially when the concentration of heavy metal ions is relatively low. In recent years, duo to the advantages such as low operating cost and high efficiency of removing low concentration heavy metal from waste water, also and no second pollution, biosorption has received more attention. Now, there are more and more studies on biosorption, but, majority of them are doing about the investigation of operating conditions and machines by IR, SEM and TEM etal. Few of them is about character of the biosorption's process.Seven strains had been isolated from the soil of tailings in TaoLin of YueYang county, HuNan province. By selection, the 2# strain was the best one, and with the identification of 26S rRNA D1/D2 gene sequence, the strain was identified as Aspergillus aculeatus. So, the present study used Aspergillus aculeatus as the adsorbent and Pb(II) and Cd(II) as adsorate for investigation of the character of the biosorption.The isotherms, kinetics, thermodynamics and desorption rates of Pb(II) and Cd(II) biosorption by Aspergillus aculeatus were investigated in a batch system for the character of the biosorption. The effects of pH, initial metal ions concentration, biomass dose, contact time and temperature on the biosorption were also studied. This text also maked sure the Pb(II) and Cd(II) to Aspergillus aculeatus'minimal inhibitory concentration (MIC), and the Aspergillus aculeatus'growth in the medium.The study found Aspergillus aculeatus got to the peak of the growth in 120h, it could resist Pb of 500mg/L and Cd of 400mg/L, and the removing of Pb(II) and Cd(II) was the highest efficiency at pH 5 and 30℃. The biosorption of Pb(II) and Cd(II) ions by Aspergillus aculeatus increased with increasing initial metal concentration, and became saturated finally. The adsorption were well described by Langmuir model, the biosorption capacity of Aspergillus aculeatus biomass for Pb(II) and Cd(II) was found to be 71.2 mg/g and 59.8 mg/g, respectively. The results of the kinetic studies of all metal ions at different temperature showed that the rate of adsorption followed the pseudo second-order kinetics well, the adsorption reach equilibrium in 3h. The thermodynamics constants of the adsorption process showed that the biosorption were endothermic and spontaneous.