Adsorption Of Pb(Ⅱ) By Iron Oxide Nanoparticles Immobilized Phanerochaete Chrysosporium

Recent industrial and urban activities have led to a rapid expansion of a widerange of contaminants in surface and groundwater. Parallel to control of harmfuleffects of contaminants and immediate improvement of human living environmenttherefore would be necessary. Heavy metals releasing to the environment causeserious environmental and health risks, because of their toxicities in relatively lowconcentration, nonbiodegradable and tendency for bioaccumulation. Consequently,the need for contaminants removal has become a must. Phanerochaete chrysosporium(P. Chrysosporium), which is well known to be capable of lignin degradation, is alsoin possession of available capacity to heavy metals, especially Pb(Ⅱ). But it is worthnoting that the biosorption capacity of P. Chrysosporium is limited.In our study, a novel biosorbent was successfully prepared by the immobilizationof Phanerochaete chrysosporium with iron oxide nanoparticles and Ca–alginate,which was confirmed by ESEM, EDS, FTIR and XRD characterization. ESEMmicrograph showed the P. chrysosporium hyphae micrograph covered at the surface ofbiosorbents, it was found that the hyphae of immobilized P. chrysosporium werepacked loosely. The intracellular of the biosorbents had lots of tiny interspaces,offering more adsorptive sites for heavy metals. MNPs were in infinitesimal size andwell dispersed in the inside of P. chrysosporium hyphae pellet. Additionally, FTIR andXRD characterization further suggested that P. chrysosporium was successfullyimmobilized by MNPs and Ca–alginate, and the immobilization process did notsignificantly result in the phase change of Fe3O4.Optimum adsorption conditions were determined as a function of pH, contacttime and initial concentration of Pb(Ⅱ). The biosorption efficiency was highly pHdependent and increased with an increase of pH in the range of2.0–5.0. The optimaladsorption occurred at pH5.0and35°C, and the adsorbent dosage was1.8g/L. Theoptimum adsorption capacity for Pb(Ⅱ)(188.25mg g–1) was significantly higher thanconventional adsorbents, at the Pb(Ⅱ) concentration of500mg/L. Possibly, theimmobilization of P. chrysosporium with iron oxide nanoparticles and Ca–alginateendowed the adsorbents with higher adsorption capacities and good reusability, by theintroduction of Fe–O groups and enhanced interior accumulation. Even after fivecycles of adsorption desorption, the adsorption ability was regained completely and the adsorption efficiency of Pb(Ⅱ) was maintained above90%.Batch adsorption experiments were conducted to investigate the adsorptionprocess of Pb(Ⅱ) ions from aqueous solution. With respect to the suitability ofpseudo second order kinetic models for adsorption of Pb(Ⅱ), it was determined thatadsorption obeys pseudo second order kinetics which belongs to higher correlationcoefficients. The Langmuir and Freundlich adsorption isotherm models were used forthe description of the adsorption equilibrium of Pb(Ⅱ) ions onto the preparedadsorbents. As a result, Langmuir model, capable of representing the data moresatisfactorily, yielded a somewhat better fit than the Freundlich model. According tothe thermodynamic studies, it was determined that the adsorption process took placespontaneously with a negative free energy. A positive value of standard enthalpychange showed the endothermic nature of adsorption process. The FTIR results wereavailable to demonstrate that both the functional groups of P. chrysosporium and theembedded iron oxide nanoparticles played part in the adsorption process. Inconclusion, as-prepared adsorbents showed a promising prospect for application inheavy metal-containing wastewater treatment.