TY - JOUR
T1 - Effect of the Fe3+/Cu2+ ratio on the removal of the recalcitrant oxalic and oxamic acids by electro-Fenton and solar photoelectro-Fenton
AU - Garcia-Segura, Sergi
AU - Brillas, Enric
AU - Cornejo-Ponce, Lorena
AU - Salazar, Ricardo
N1 - Funding Information:
The authors thank the financial support of FONDECYT Grant 1130391 , FONDAP CONICYT SERC Chile 15110019 and DICYT-USACH to carry out this work. The authors are also indebted to MINECO (Spain) for financial support under project CTQ2013-48897-C2-1-R , co-financed with FEDER funds. S. Garcia-Segura thanks the grant awarded from MEC (Spain).
Publisher Copyright:
© 2015 Elsevier Ltd.
PY - 2016/2/1
Y1 - 2016/2/1
N2 - The degradation of 100mL of 2.08mM oxalic acid (OXL) and oxamic acid (OXM) solutions in 0.10M Na2SO4 at pH 3.0 has been studied by solar photolysis (SP), electro-Fenton (EF) and solar photoelectro-Fenton (SPEF). EF and SPEF experiments were performed with a stirred electrochemical cell containing a 3cm2 boron-doped diamond (BDD) anode and a 3cm2 air-diffusion cathode that generates H2O2. Natural sunlight was directly exposed to the solution in SP and SPEF. Catalytic contents of 0.50mM Fe3+, 0.50mM Cu2+ or mixtures up to 0.50mM of both metallic ions were added to the solution and a current density of 33.3mAcm-2 was applied in EF and SPEF. OXM presented a remarkable slower decay than OXL by SP due to the lower photoactivity of metallic-oxamate complexes. OXL concentration decayed 90% in the presence of Fe3+ and Fe3+/Cu2+ mixtures, whereas the OXM drop decreased directly with increasing Cu2+ concentration. In EF, OXL was more slowly removed than OXM due to higher recalcitrant character of the Fe(III)-oxalate complexes which can only be mineralized by OH formed at the anode surface but not by those generated from Fenton's reaction in the bulk. Upon Cu2+ addition, higher removal percentages were found because Cu(II)-carboxylate complexes are attacked by OH, thus accelerating the mineralization. In contrast, OXL destruction was largely enhanced in SPEF using the mixture of catalysts as a result of the photolysis of Fe(III)-oxalate complexes and the parallel mineralization of Cu(II)-carboxylate complexes by the high quantity of oxidant OH induced from photolysis of Fe(III)-aquo species. In all cases, the decay of OXL and OXM concentration obeyed a pseudo-first-order reaction, with an apparent rate constant dependent on the applied current in EF and SPEF.
AB - The degradation of 100mL of 2.08mM oxalic acid (OXL) and oxamic acid (OXM) solutions in 0.10M Na2SO4 at pH 3.0 has been studied by solar photolysis (SP), electro-Fenton (EF) and solar photoelectro-Fenton (SPEF). EF and SPEF experiments were performed with a stirred electrochemical cell containing a 3cm2 boron-doped diamond (BDD) anode and a 3cm2 air-diffusion cathode that generates H2O2. Natural sunlight was directly exposed to the solution in SP and SPEF. Catalytic contents of 0.50mM Fe3+, 0.50mM Cu2+ or mixtures up to 0.50mM of both metallic ions were added to the solution and a current density of 33.3mAcm-2 was applied in EF and SPEF. OXM presented a remarkable slower decay than OXL by SP due to the lower photoactivity of metallic-oxamate complexes. OXL concentration decayed 90% in the presence of Fe3+ and Fe3+/Cu2+ mixtures, whereas the OXM drop decreased directly with increasing Cu2+ concentration. In EF, OXL was more slowly removed than OXM due to higher recalcitrant character of the Fe(III)-oxalate complexes which can only be mineralized by OH formed at the anode surface but not by those generated from Fenton's reaction in the bulk. Upon Cu2+ addition, higher removal percentages were found because Cu(II)-carboxylate complexes are attacked by OH, thus accelerating the mineralization. In contrast, OXL destruction was largely enhanced in SPEF using the mixture of catalysts as a result of the photolysis of Fe(III)-oxalate complexes and the parallel mineralization of Cu(II)-carboxylate complexes by the high quantity of oxidant OH induced from photolysis of Fe(III)-aquo species. In all cases, the decay of OXL and OXM concentration obeyed a pseudo-first-order reaction, with an apparent rate constant dependent on the applied current in EF and SPEF.
KW - Carboxylic acids
KW - Electro-Fenton
KW - Iron and copper complexes
KW - Solar photolysis
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U2 - 10.1016/j.solener.2015.11.033
DO - 10.1016/j.solener.2015.11.033
M3 - Article
AN - SCOPUS:84951089911
SN - 0038-092X
VL - 124
SP - 242
EP - 253
JO - Solar Energy
JF - Solar Energy
ER -