Ozonation of azo dye acid black 1 under the suppression effect by chloride ion

Abstract

O objetivo deste estudo é determinar a cinética degradação do corante Acid Black 1 por ação oxidante do ozônio e avaliar a influência da contaminação de íons cloreto na degradação deste corante. Foram observadas cinéticas de pseudo-primeira ordem, tanto para a degradação das estruturas cromóforas (620 nm), quanto das aromáticas (321 nm). A completa remoção da coloração foi verificada em 25 min ([corante] 0 = 1,8 × 10 -5 mol L -1 ), enquanto que as estruturas aromáticas foram degradadas com menor velocidade. A presença de íon cloreto, principal impureza do reagente sólido, influencia significantemente a velocidade de ozonização (-42%), mesmo em baixa concentração (5,6 × 10 -4 mol L -1 ). O mecanismo mais provável para o efeito supressor do íon cloreto envolve a direta reação entre O 3 e Cl -gerando HOCl, dentre outros subprodutos. Apesar deste aspecto, a ozonização pode ser um processo de degradação competitivo para este corante.The aim of this study is to determine the kinetics of the Acid Black 1 dye by oxidizing action of ozone and to evaluate the influence of chloride ion contamination on the dye degradation. Pseudofirst order kinetics was observed for both decolorization (620 nm) and aromatic structure (321 nm) degradations. A complete color removal was verified in 25 min ([dye] 0 = 1.8 × 10 -5 mol L -1 ), while aromatic structures degraded at slower rates. The presence of chloride ion, the principal impurity of the solid dye reagents, influences significantly the ozonation rate (-42%), even at low chloride concentration (5.6 × 10 -4 mol L -1 ). The most probable mechanism for the chloride suppression effect involves a direct reaction between O 3 and Cl -generating HOCl, among other by-products. In despite of that, ozonation could be a competitive degradation process for this dye.

Electroactive Polyhydroquinone Coatings for Marine Fouling Prevention—A Rejected Dynamic pH Hypothesis and a Deceiving Artifact in Electrochemical Antifouling Testing

“…It was further found that distinct peaks appeared in the UV spectrum after the application of APs (Figure b). It is known that antibacterial reactive chlorine species, for example, hypochlorite can be electrochemically generated and that they may have distinct UV signals. − It was recognized that the UV absorption signals of hypochlorite change upon protonation. We confirmed this mechanism by recording the UV–vis spectrum of hypochlorite in artificial seawater at low (pH ≈ 2.6) and high pH (pH = 8.1), see Figure c.…”

Dye decomposition by combined ozonation and anaerobic treatment: Cost effective technology

“…Decolourization efficiency was 94% after 25 min of ozonation investigated in this study. Ozonation treatment leads to a complete decolourization of the Acid Black 1 dye solution in 25 min (Paprocki, Dos Santos, Hammerschitt, Pires, & Azevedo, 2010). A rapid decline in color (Pt-Co scale) and absorbance shows that the decolouration dynamics in Figure 5.…”

Nano‐Catalytic Ozonation of 4‐Nitrochlorobenzene in Aqueous Solutions

“…Concentration of nitrate formed during reaction was monitored ( Figure 6) and results showed much formation of nitrate ions is obtained at pH 3 (4.15 mg/L). The remaining nitrogen atoms could be in nitro form or may be converted to nitro-intermediates that more resistant to ozone attack 21 .…”