Radiation induced degradation of Congo red dye: a mechanistic study

Abstract

Synthetic dyes are persistent pollutants with poor biodegradability. The present study is about the degradation of direct Congo red dye in aqueous media using the Co-60 gamma radiation source. The experimental conditions such as gamma-ray absorbed doses, amount of oxidant (H 2 O 2 ) and pH conditions were evaluated. The  max of dye solution was noted as 498 nm, and then, decrease in absorbance and reduction in chemical oxygen demand (COD) were examined. The complete colour removal of dye was observed at 5 kGy, while a signifi cant COD removal was observed at 15 kGy gamma-ray absorbed dose in conjunction with oxidant for 50 mg/L concentration. It was found that pH has no infl uence on degradation effi ciency. A possible degradation pathway was proposed. The radiolytic end products were monitored by Fourier transform infrared (FTIR) and gas chromatography coupled with mass spectrometry (GC-MS) to explore the degradation mechanism. It was imperative to study the oxidative degradation pathway to provide directions for potential applicability of advanced oxidation process (AOP) in industrial wastewater treatment.

Green Synthesis of Nickel Nanoparticles using Fruit Peels of Citrus Paradise for Remediation of Congo Red Dye

“…The dye molecule is degraded via breaking of the chromophore group. After that, the intermediates are converted into low molecular weight compounds like aldehyde and ketone that are further breakdown into carbon dioxide and water [33,34].…”

Degradation and detoxification of azo dyes with recombinant ligninolytic enzymes from Aspergillus sp. with secretory overexpression in Pichia pastoris

“…The characteristic absorption peaks of the MY1 and CR molecular structures are shown in figure 4. The first group of MY1 peaks featured a peak at 3440 cm −1 , attributed to the N-H stretching of amine [42]. The second group of MY1 peaks included a peak at 1617 cm −1 , corresponding to N = N stretching; 1532 cm −1 , for aromatic C=C stretching; 1357 cm −1 , for C-N stretching and 1078 cm −1 , for C-O stretching.…”

Green synthesis of P − ZrO2CeO2ZnO nanoparticles using leaf extracts of Flacourtia indica and their application for the photocatalytic degradation of a model toxic dye, Congo red

“…Congo red has been removed from water using adsorption [7] [8] photocatalytic degradation [9] , [10] [11] [12] [13] , membrane filtration [14] , electrochemical oxidation and bio-treatment [15] , sonocatalysis [16] , catalytic reduction [17] , photo-Fenton process [18] , radiation induced degradation [19] . The conventional processes used to treat wastewater contaminated with dyes have proved to be relatively inefficient, expensive and can even cause secondary contamination.…”