Effect of Fenton's treatment on the biodegradability of chromium-complex azo dyes


ARSLAN-ALLATON I., KABDASLI I., Teksoy S.

WATER SCIENCE AND TECHNOLOGY, cilt.55, ss.107-112, 2007 (SCI İndekslerine Giren Dergi)

  • Cilt numarası: 55 Konu: 12
  • Basım Tarihi: 2007
  • Doi Numarası: 10.2166/wst.2007.388
  • Dergi Adı: WATER SCIENCE AND TECHNOLOGY
  • Sayfa Sayısı: ss.107-112

Özet

Pretreatment of an acid dyebath effluent bearing a new generation chromium complex azo dyestuff (C-o = 350 mg/L) with Fenton's reagent was investigated. Preliminary optimisation (baseline) experiments were conducted to determine the Fe2+, H2O2 concentrations and pH required to the highest possible COD and colour removals. Kinetic studies were carried out at varying temperatures (20 degrees C < T < 70 degrees C) to establish a relationship between COD abatement and H2O2 consumption. The activation energy found for catalytic H2O2 decomposition (E-a = 9.8 kJ/mol) appeared to be significantly less than that of fermentative (E-a = 23 kJ/mol) and of thermal (E-a = 76 kJ/mol) H2O2 decomposition, implying that H2O2 decomposition during the Fenton's reaction occurs more spontaneously. The experimental studies indicated that approximately 30% COD and complete colour removal could be achieved under optimised Fenton pretreatment conditions (Fe2+ = 2 mM; H2O2 = 30 mM; pH = 3; at T = 60 degrees C). Long-term activated sludge experiments revealed that although the raw and pretreated acid dyebath effluent contained practically the same amount of "readily biodegradable" COD (inert COD fraction <= 10%), biodegradation of the chemically pretreated acid dye effluent proceeded appreciably faster than that of the untreated acid dyebath effluent.