Ferrite formation from photo-Fenton treated wastewater.
Photo-Fenton oxidation followed by ferrite formation was applied for the degradation of a representative organic compound, phenol, and the subsequent removal of the Fe ions. At a phenol:Fe(II):H(2)O(2) molar ratio of 1:0.5:15, TOC analysis showed almost complete mineralization of 10.6mM phenol after 2h at a controlled pH of 3. Recalcitrant low molecular weight organic acid by-products particularly oxalic acid were destroyed. A ferrous-rich solution was generated so that alkalinization at pH 10.5 generated a pitch black sludge of lower volume and moisture content than a ferric hydroxide control of the same Fe concentration. The flocs exhibited a strong affinity for a magnet and its X-ray diffraction pattern showed a close similarity to a standard spinel magnetite. With proper monitoring of Fe(II) and dissolved oxygen, the reaction was successfully controlled to generate flocs with more than 30% magnetite content. When photo-Fenton was employed as a pre-treatment step so that residual oxalic acid remained, ferrite formation was not inhibited. The presence of oxalates even allowed ferrites to form in a solution containing Ca(2+) ions, which is well-known to be deterrent to the process.
Navarro
Ronald R
RR
National Institute of Advanced Industrial Science and Technology (AIST), 16-1, Onogawa, Tsukuba, Ibaraki 305-8506, Japan.
Ichikawa
Hiroyasu
H
Tatsumi
Kenji
K
D052918:Environmental Restoration and Remediation; D005290:Ferric Compounds / Q000737:chemistry*; D052203:Ferrosoferric Oxide / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D019815:Oxalic Acid / Q000737:chemistry; D010084:Oxidation-Reduction; D019800:Phenol / Q000737:chemistry; D055668:Photochemical Processes; D014865:Waste Disposal, Fluid / Q000379:methods*; D014961:X-Ray Diffraction
C045076:Fenton's reagent; D005290:Ferric Compounds; C001215:ferrite; D019800:Phenol; D019815:Oxalic Acid; D006861:Hydrogen Peroxide; D007501:Iron; D052203:Ferrosoferric Oxide