removal of azo dyes from aqueous solution using fenton and modified fenton processes

background fenton (fe2+ and h2o2) and modified fenton (fe3+ and h2o2) are two popular methods used in advanced oxidation processes (aop) and degradation of persistent organic pollutants (pops), such as dye compounds. in these processes, fe2+ and fe3+ as catalysts and h2o2 as the oxidizing agent are added to the reactor. objectives the aim of the current study is to assess the abovementioned methods for removal of reactive red 198 and blue reactive 19 from aqueous solutions. materials and methods this research was carried out using lab-scale. after preparation of rb-19 and rr-198 stock solutions (1000 ppm), optimum ph and temperature were determined within the range of (3-11) and (15°c - 40°c) respectively, and specific amounts of fe2+ and fe3+ (0.8, 1, 3, 7, 14 and 32 mm) were prepared by adding feso4. 7h2o and fecl3, and h2o2 30% w/w (2, 5, 11, 23, 47 and 94 mm) were added to the solutions to establish the h2o2/fe2+, fe3+ molar ratios. standard jar tests were conducted using jar test apparatus. after sedimentation time, samples were filtered through a 0.45 µm fiber membrane, and then final dye concentrations were measured using a uv/vis spectrophotometer. results the highest dye removal efficiency in both fenton and modified fenton methods were obtained at the optimum ph = 3, optimum reaction time of 10 minutes, optimum temperature at 25°c and h2o2/fe2+ and h2o2/fe3+ concentrations of 11.3 and 5.1 mm, respectively. in the fenton reaction the maximum efficiency was obtained at 94.70% and 99.31% for reactive red 198 and reactive blue 19, respectively. moreover, by the modified fenton method the maximum removal efficiency for reactive red 198 and reactive blue 19 was 94.8% and 99.43%. conclusions fenton and modified fenton processes could be used as very effective methods for removal of reactive red 198 and blue reactive 19 from aqueous solutions.