The removal of COD from bleaching effluents by Fenton's reagent: Effect of system parameters and kinetic study

Abstract

Fenton's reagent was now being used as a posttreatment procedure to eliminate the intractable pollutants in the bleaching effluents from pulp mills. To establish cost-efficient operating conditions for the application of Fenton's reagent, the effects of operating conditions such as the dosages of H 2 O 2 , the molar ratio of [Fe 21 ]/[H 2 O 2 ], the value of solution pH and the system temperature on the removal of COD were evaluated systematically. The results showed a suitable operating condition that yields 88.7% of COD removal was obtained at [5 20:1, pH3, 908C, reaction time 120 min. A kinetic study was carried out using a modified pseudo-first-order model. The results showed the COD removal for bleaching effluents by Fenton's reagent followed the first-order reaction kinetics, and the activation energy E a was detected to be 1.68 kJ mol 21 based on the experiments performed at different temperatures. In addition, the results of GC/MS analysis showed organic pollutants in effluents were degraded into organic acids of lower molecular weight under the attack of hydroxyl radicals generated in Fenton's reaction. The results of biodegradability assay indicated the bio-toxic substances in the bleaching effluents were eliminated.

Free radical nano scavenger based on amphiphilic novolacs

“…64,65 To study the property of novolacs-PEG to scavenge radicals, Fenton reagents 66 (hydrogen peroxide and ferrous sulfate) were used to generate hydroxyl radical, a typical ROS in the body. 67,68 Due to the fact that hydroxyl radical is so bleaching to be used in treating fabrics, 69 removing dyes 70 and pollutants, 71 it would be expected to see a quickly fading out of color of crystal violet aqueous solution as designed in this experiment when Fenton reagents are added. By scavenging the culprit hydroxyl radicals, the color would be retained, the higher concentration of scavengers, the deeper the color remained.…”

Yarn dyed wastewater treatment using hybrid electrocoagulation-Fenton method in a continuous system: Technical and economical viewpoint

“…Wastewater-iron solution and 30% hydrogen peroxide solution were separately fed into the reactor. The flow rates of wastewater-iron solution were varied while the flow rates of hydrogen peroxide were calculated based on optimum hydrogen peroxide dosage [9], which were 8 mL/h, 15 mL/h and 22 mL/h. The parameters used for the study were molar ratio of Fe(II)/H 2 O 2 (1:4.5 and 1:10), initial pH of wastewater (3.0 and 5.0), and wastewater flow rate (30 mL/min; 60 mL/min and 90 mL/min).…”

“…A previous work which has been carried in a batch system showed the rate constant of 0.0053 min -1 [7]. Other studies using Fenton process to treat coking, bleaching, and olive mill wastewater were carried out in a batch system and has demonstrated good COD removal efficiency [8][9][10]. The operational cost of hybrid electrocoagulation-Fenton method in continuous system was also estimated in this study.…”

Efecto de distintas especies reactivas generadas fotoquímicamente sobre la eliminación de contaminantes presentes en aguas naturales.

“…También se ha empleado en el tratamiento aguas generadas en diversas industrias como por ejemplo en efluentes de la industria papelera (Catalkaya E. C. et al 2007;Wang Z. et al 2011) o en efluentes de la industria del aceite (Özdemir C. et al 2010;Martins R. C. et al 2011).…”