title: Removal of Cr(VI) and Ni(II) from aqueous solution by fused yeast: study of cations release and biosorption mechanism.
abstract: Biosorption of Cr(VI) and Ni(II) by a fused yeast from Candida tropicalis and Candida lipolytica under varying range of pH, initial metal concentration and reaction time was investigated. Net cation release and Cr removal reached 2.000 mmol/l and 81.37% when treating 20mg/l Cr(VI) at pH 2 with 25mg/l biomass for 30 min, while for Ni were 0.351 mmol/l and 64.60%, respectively. Trace metal elements such as Co, Cu, Mn, Mo, Se and Zn played active role in biosorption as important ingredients of functional enzymes. Cr(VI) was reduced to less toxic Cr(III) and chelated with extracellular secretions, and further accumulated inside the cells. For Ni biosorption, however, largely a passive uptake process influenced by ion gradient led to lower adsorption capacity and cations release. Fourier transform infrared (FTIR) spectrum analysis indicated that amide and pyridine on cells were involved in binding with Cr, but for Ni, bound-OH and nitro-compounds were the main related functional groups. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis confirmed that considerable amounts of metals precipitated on cell surface when dealing with high concentration metals.
authors.affiliation: Department of Environmental Engineering, Jinan University, Guangzhou 510632, China. thyin@jnu.edu.cn
authors.forename: Hua
authors.initials: H
authors.lastname: Yin
authors.forename: Baoyan
authors.initials: B
authors.lastname: He
authors.forename: Hui
authors.initials: H
authors.lastname: Peng
authors.forename: Jinshao
authors.initials: J
authors.lastname: Ye
authors.forename: Feng
authors.initials: F
authors.lastname: Yang
authors.forename: Na
authors.initials: N
authors.lastname: Zhang
mesh_terms: D002175:Candida / Q000378:metabolism*; D002412:Cations; D002857:Chromium / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D009532:Nickel / Q000302:isolation & purification*; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water / Q000737:chemistry
chemical_list: D002412:Cations; D012996:Solutions; D014867:Water; D002857:Chromium; D009532:Nickel