Utilization of dissolved iron as catalyst during Fenton-like oxidation of pretreated pulping effluent.

Effluent arising from kraft or soda pulping section of a pulp and paper mill is difficult to treat due to the presence of recalcitrant organics such as lignin. In this study, FeCl3 pretreated pulping effluent was subjected to Fenton-like oxidation. Residual dissolved iron from pretreatment step and H2O2 were utilized as catalyst and oxidant, respectively while the initial wastewater pH was 4.0 (unadjusted). The maximum lignin and total organic carbon (TOC) removals of 85% and 48% could be achieved within 2 h of reaction. The oxidation reaction was mediated by hydroxyl radicals (HO) which were detected by electron spin resonance (ESR) spectroscopy. Moreover, the addition of tertiary butyl alcohol and chloroform (both radical scavengers) as well hydroxyl amine (a ferrous ion recycler) affected TOC removal significantly. The TOC degradation data could adequately be fit in a lumped kinetic model (LKM) and the activation energy was calculated as 50.85 kJ/mol. The nature of chemical compounds in treated wastewater was also predicted using Fourier transforms infrared (FTIR) spectroscopy. [ABSTRACT FROM AUTHOR]