Degradation of anthraquinonic dye in water by photoactivated periodate

Abstract

In this work, the degradation of Acid blue 25 (AB25), an anthraquinonic dye and a widely used colorant in many industries, by photoactivated periodate (UV/IO À 4 ) process was investigated. Experiments were conducted in batch mode using a low-pressure mercury lamp emitting mainly at 253.7 nm. The effects of the operational conditions such as periodate ions concentration, initial dye concentration, initial pH of the solution, and tert-butanol addition on the degradation of AB25 were examined. The results have shown that the degradation rate was increased in the presence of UV/IO À 4 compared to UV irradiation alone. The degradation rate increased with the increase in periodate concentration to 1 mM and decreased slightly at higher values (>1 mM). The degradation of AB25 decreased when the dye concentration increased. The extent of degradation was found to be inversely proportional to the initial concentration of dye. AB25 degradation was significantly affected by varying the initial solution pH. The fastest degradation was obtained at natural pH (6.4). The degradation of the dye was not appreciably affected by the addition of tert-butanol, known as an effective scavenger of Å OH radicals, even at high concentration. Thus, the degradation of AB25 by photoactivated periodate technique was not dominated by an Å OH pathway.

Exploring the intensifying effect of periodate/hydroxylamine oxidation process for the effective mineralization of textile dyes effluents with consideration of environmental matrices

“…PI activation techniques is an ongoing area of research and innovation. PI can be activated by different methods; the most known of them are UV radiation, 15–19 alkali, 20 ultrasound, 21,22 and transition metals 17,23 . Granular activated carbon (alone or doped with iodine), Co/N‐doped graphene, and Fe, N‐doped carbonaceous are among other developed catalytic techniques for efficient PI activation for organic destruction 24–26 .…”

“…The study showed that various ROS, including • OH, HO 2 • and 1 O 2 , are the primary oxidants in the PI/HA system. Although IO 3 • has been identified as the primary reactive species in several PI‐based AOPs, 15–19,21,24,26 no evidence of IO 3 • production was observed in the PI/HA system 31 . Tert‐butyl‐alcohol (TBA) was used as a scavenger to test IO 3 • production since it is unreactive with IO 3 • .…”

“…13 Alternatively, periodate (PI)-based AOPs have recently gained attention as they can generate multiple reactive species, including periodyl radical (IO 3 • ) and reactive oxygen species (ROS: • OH, HO 2 14 PI activation techniques is an ongoing area of research and innovation. PI can be activated by different methods; the most known of them are UV radiation, [15][16][17][18][19] alkali, 20 ultrasound, 21,22 and transition metals. 17,23 Granular activated carbon (alone or doped with iodine), Co/N-doped graphene, and Fe, N-doped carbonaceous are among other developed catalytic techniques for efficient PI activation for organic destruction.…”

“…• has been identified as the primary reactive species in several PI-based AOPs, [15][16][17][18][19]21,24,26 no evidence of IO 3…”

“…TBA and 2-prop react rapidly with • OH with rate constants of 6 Â 10 8 M À1 s À1 and 1.9 Â 10 9 M À1 s À1 , respectively. 13 However, these compounds do not react at all with IO 3 • , [15][16][17]19 making alcohols a useful tool to differentiate between reactions with • OH or IO 3…”