title: Stabilization and phase transformation of CuFe2O4 sintered from simulated copper-laden sludge.
abstract: The feasibility of stabilizing copper-laden sludge by high-temperature CuFe(2)O(4) ferritization process is investigated with different sintering temperature, and the prolonged leaching test. The thermal behavior, structural morphology, phase composition, and phase transformation of the stabilized sludge were investigated by using thermal gravimetry-differential scanning calorimetry, scanning electron microscopy and X-ray diffraction. The leaching behavior of the stabilized sludge under acidic environment was evaluated by modified Toxicity Characteristic Leaching Procedure (TCLP). The results indicated that CuFe(2)O(4) could be effectively formed at around 800°C by the iron oxide precursor with a 3h of short sintering. The transformation was discovered on crystallographic spinel structures: the low-temperature (800-900°C) tetragonal phase (t-CuFe(2)O(4)) and the high-temperature (∼ 1000°C) cubic phase (c-CuFe(2)O(4)). At higher temperatures (∼ 1100°C), the formation of cuprous ferrite delafossite phase (CuFeO(2)) from the dissociation of CuFe(2)O(4) was also noticed. Both CuFe(2)O(4) spinel and CuFeO(2) delafossite phase have a better intrinsic resistance to acidic environment when compared to that of CuO phase by the modified TCLP test. The sintering strategy designed for copper-laden sludge is proven to be beneficial in stabilizing copper.
authors.affiliation: Graduate Institute of Environmental Engineering, National Taiwan University, 71, Chou-Shan Rd., Taipei 106, Taiwan, ROC.
authors.forename: Nien-Hsun
authors.initials: NH
authors.lastname: Li
authors.forename: Shang-Lain
authors.initials: SL
authors.lastname: Lo
authors.forename: Ching-Yao
authors.initials: CY
authors.lastname: Hu
authors.forename: Ching-Hong
authors.initials: CH
authors.lastname: Hsieh
authors.forename: Ching-Lung
authors.initials: CL
authors.lastname: Chen
mesh_terms: D003300:Copper / Q000737:chemistry*; D003460:Crystallization; D005296:Ferrous Compounds / Q000737:chemistry*; D044367:Phase Transition; D012722:Sewage / Q000737:chemistry*; D013696:Temperature
chemical_list: C523076:CuFe2O4; D005296:Ferrous Compounds; D012722:Sewage; D003300:Copper