title: Lead immobilization by geological fluorapatite and fungus Aspergillus niger.
abstract: Phosphate solubilizing fungi have high ability to secrete organic acids. In this study, fungus Aspergillus niger and geological fluorapatite were applied in lead remediation in aqueous solution. Formation and morphology of the lead minerals, e.g., pyromorphite and lead oxalate, were investigated by SEM, XRD, and ATR-IR. The total quantity of organic acids reached the maximum at the sixth day, which improved the concentration of soluble P up to ∼370mg/L from ∼0.4mg/L. The organic acids, especially the oxalic acid, enhance the solubility of fluorapatite significantly. The stable fluoropyromorphite [Pb5(PO4)3F] is precipitated with the elevated solubility of fluorapatite in the acidic environment. Furthermore, A. niger grows normally with the presence of lead cations. It is shown that >99% lead cations can be removed from the solution. However, immobilization caused by the precipitation of lead oxalate cannot be ignored if the fungus A. niger was cultured in the Pb solution. This study elucidates the mechanisms of lead immobilization by FAp and A. niger, and sheds its perspective in lead remediation, especially for high Pb concentration solution.
authors: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China; State Key Laboratory for Mineral Deposits Research, Nanjing University, Nanjing, Jiangsu 210046, China. Electronic address: lizhen@njau.edu.cn.
authors: Zhen
authors: Z
authors: Li
authors: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
authors: Fuwei
authors: F
authors: Wang
authors: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
authors: Tongshuo
authors: T
authors: Bai
authors: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
authors: Jinjin
authors: J
authors: Tao
authors: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
authors: Jieyun
authors: J
authors: Guo
authors: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
authors: Mengying
authors: M
authors: Yang
authors: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China; Jiangsu Key Lab for Organic Solid Waste Utilization, Nanjing Agricultural University, Nanjing 210095, China.
authors: Shimei
authors: S
authors: Wang
authors: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China; Department of Plant Pathology, North Carolina State University, Raleigh, NC 27695, USA.
authors: Shuijin
authors: S
authors: Hu
mesh_terms: D001031:Apatites / Q000737:chemistry*; D001234:Aspergillus niger / Q000737:chemistry*; D007854:Lead / Q000302:isolation & purification*; D008855:Microscopy, Electron, Scanning; D013055:Spectrophotometry, Infrared; D014961:X-Ray Diffraction
chemical_list: D001031:Apatites; D007854:Lead; C025105:fluorapatite
keywords: Aspergillus niger; Fluorapatite; Immobilization; Lead; Pyromorphite