remazol-black-b and peroxymonosulfate

Recently, activated carbon was investigated as an efficient heterogeneous metal-free catalyst to directly activate peroxymonosulfate (PMS) for degradation of organic compounds. In this paper, the reuse performance and the possible deactivation reasons of granular-activated carbon (GAC) and activated carbon fiber (ACF) in PMS activation were investigated. As results indicated, the reusability of GAC, especially in the presence of high PMS dosage, was relatively superior to ACF in catalyzed PMS oxidation of Acid Orange 7 (AO7), which is much more easily adsorbed by ACF than by GAC. Pre-oxidation experiments were studied and it was demonstrated that PMS oxidation on ACF would retard ACF's deactivation to a big extent. After pre-adsorption with AO7, the catalytic ability of both GAC and ACF evidently diminished. However, when methanol was employed to extract the AO7-spent ACF, the catalytic ability could recover quite a bit. GAC and ACF could also effectively catalyze PMS to degrade Reactive Black 5 (RB5), which is very difficult to be adsorbed even by ACF, but both GAC and ACF have poor reuse performance for RB5 degradation. The original organic compounds or intermediate products adsorbed by GAC or ACF would be possibly responsible for the deactivation.

Topics: Adsorption; Azo Compounds; Benzenesulfonates; Carbon; Catalysis; Coloring Agents; Naphthalenesulfonates; Oxidation-Reduction; Peroxides; Recycling; Waste Disposal, Fluid; Water Pollutants, Chemical; Water Purification

In order to generate powerful radicals as oxidizing species for the complete decolorization and degradation of azo dye Reactive Black B (RBB) at near neutral pH (pH 6), homogeneous activation of peroxymonosulfate (Oxone: PMS) by the trace Co2+-catalysts was explored. We not only took advantage of the high oxidation-reduction potential of produced hydroxyl and sulfite radicals but also an opportunity to oxidize RBB to less complex compounds with extremely low dosages, especially the ppb level of the Co2+-catalyst (stoichiometric ratio: [Co2+](0)/[RBB](0)=1.7 x 10(-6)-1.7 x 10(-5); [PMS](0)/[RBB](0)=8-32). Anion effects and pH effects were also carried out and discussed to simulate an actual application such as that of a textile waste stream. Both the degradations of RBB and its derivative aromatic fragments were illustrated successfully at UV-visable absorptions of 591 and 310 nm, respectively, and the possible relationships between them were also proposed and discussed, based on the experimental results. The RBB degradation in this Co2+/PMS oxidative process successfully formulated a pseudo-first-order kinetic model at an isothermal condition of 25 degrees C with or without different anions present. The initial rate and rate constant were calculated under different comparative conditions, and the results indicate that the activity of both RBB decolorization and its degradation are not obviously dependent on the PMS concentration, but rather are related to the Co2+ dosage.

Topics: Alkalies; Catalysis; Cobalt; Color; Coloring Agents; Feasibility Studies; Halogens; Hydrocarbons, Aromatic; Hydrogen-Ion Concentration; Models, Chemical; Naphthalenesulfonates; Oxidation-Reduction; Peroxides; Spectrophotometry, Ultraviolet; Sulfites