TY - JOUR
T1 - A new approach to increasing the efficiency of low-pH Fe-electrocoagulation applications
AU - Gendel, Youri
AU - Lahav, Ori
PY - 2010/11
Y1 - 2010/11
N2 - Incomplete oxidation of Fe(II) species released from the anode to Fe(III) may impede iron electrocoagulation processes conducted under low dissolved oxygen and/or pH<7 conditions, accompanied by the typically high buffering capacity of wastewater. This paper introduces a new approach to overcome this drawback by applying a second electrochemical cell (Ti/RuO2 anode and Ti cathode) to be operated in parallel to the electrocoagulation cell. The second unit oxidizes Cl- ions invariably present in the water to HOCl, which is capable of oxidizing Fe(II) species at a high rate, irrespective of pH or O2(aq) concentration. An electrolytic cell with a Ti/RuO2 anode and Ti cathode was shown to successively operate in parallel to a sacrificial electrocoagulation cell (Fe anode and Ti cathode) to attain complete Fe(II) conversion to Fe(III) under low-pH conditions, in which, in the absence of the 2nd cell, unwanted Fe(II) species would have dominated the dissolved iron species. Current efficiency for Cl2 production was 12.4% and 45.7% at 200 and 1000mg Cl/l, respectively. Under three practical conditions (pH 6, [Cl-]=200mg/l; pH 6, [Cl-]=400mg/l; pH 5, [Cl-]=600mg/l) the power demand of the combined system was 25.29, 12.7 and 8.1kWh/kg Fe(III)produced, respectively, suggesting that the presented approach is competitive at [Cl-]>~600mg/l.
AB - Incomplete oxidation of Fe(II) species released from the anode to Fe(III) may impede iron electrocoagulation processes conducted under low dissolved oxygen and/or pH<7 conditions, accompanied by the typically high buffering capacity of wastewater. This paper introduces a new approach to overcome this drawback by applying a second electrochemical cell (Ti/RuO2 anode and Ti cathode) to be operated in parallel to the electrocoagulation cell. The second unit oxidizes Cl- ions invariably present in the water to HOCl, which is capable of oxidizing Fe(II) species at a high rate, irrespective of pH or O2(aq) concentration. An electrolytic cell with a Ti/RuO2 anode and Ti cathode was shown to successively operate in parallel to a sacrificial electrocoagulation cell (Fe anode and Ti cathode) to attain complete Fe(II) conversion to Fe(III) under low-pH conditions, in which, in the absence of the 2nd cell, unwanted Fe(II) species would have dominated the dissolved iron species. Current efficiency for Cl2 production was 12.4% and 45.7% at 200 and 1000mg Cl/l, respectively. Under three practical conditions (pH 6, [Cl-]=200mg/l; pH 6, [Cl-]=400mg/l; pH 5, [Cl-]=600mg/l) the power demand of the combined system was 25.29, 12.7 and 8.1kWh/kg Fe(III)produced, respectively, suggesting that the presented approach is competitive at [Cl-]>~600mg/l.
KW - Chlorination
KW - Electrocoagulation
KW - Electrolysis
KW - Fe(II) oxidation
KW - Low pH
UR - http://www.scopus.com/inward/record.url?scp=77956436899&partnerID=8YFLogxK
U2 - 10.1016/j.jhazmat.2010.07.066
DO - 10.1016/j.jhazmat.2010.07.066
M3 - 文章
C2 - 20800348
AN - SCOPUS:77956436899
VL - 183
SP - 596
EP - 601
JO - Journal of Hazardous Materials
JF - Journal of Hazardous Materials
SN - 0304-3894
IS - 1-3
ER -