Degradation of aromatic amines in textile-dyeing sludge by combining the ultrasound technique with potassium permanganate treatment

Textile-dyeing sludge has raised serious concerns regarding their adverse effect on environment, which has been listed as a pollutant in the legislation of Strict Control Waste in Guangdong Provinces, China. Aromatic amines... [ view full abstract ]

Textile-dyeing sludge has raised serious concerns regarding their adverse effect on environment, which has been listed as a pollutant in the legislation of Strict Control Waste in Guangdong Provinces, China. Aromatic amines are one of the characteristic pollutants in textile-dyeing sludge, and our recent study has elucidated that trace levels of aromatic amines in textile-dyeing sludge may pose a high risk to the soil ecosystem after being discarded into soil or in a landfill. To address this risk, for the first time, a combined ultrasound and potassium permanganate (US-KMnO4) system was developed for degradation of aromatic amines in textile-dyeing sludge. The results indicated that there was a synergistic effect between US and KMnO4. US treatment greatly enhanced KMnO4 degradation of aromatic amines in textile-dyeing sludge, resulting in apparent sludge disintegration and separation of pollutants from sludge. In addition to accelerating Mn(Ⅶ) reaction with pollutants in the filtrate, US also caused Mn(Ⅶ) to enter the porous sludge and sufficiently facilitated the reaction of Mn(Ⅶ) with the strongly absorbed aromatic amines. The combined US-KMnO4 treatment was effective in the degradation of aromatic amines in textile-dyeing sludge. On average, 58.7% of monocyclic anilines, 88.3% of other forms of aromatic amines and 24% of TOC were removed under the optimal operating parameters of KMnO4 dosage of 12 mM, an ultrasonic density of 1.80 W/cm3 and pH 5. The present study proposed the US-KMnO4 treatment as a practical method for disposal of aromatic amines in textile-dyeing sludge.