BackgroundPeroxidases are emerging as an important class of enzymes that can be used for the efficient degradation of organic pollutants. However, detailed studies identifying the various intermediates produced and the mechanisms involved in the enzyme-mediated pollutant degradation are not widely published.ResultsIn the present study, the enzymatic degradation of an azo dye (Crystal Ponceau 6R, CP6R) was studied using commercially available soybean peroxidase (SBP) enzyme. Several operational parameters affecting the enzymatic degradation of dye were evaluated and optimized, such as initial dye concentration, H2O2 dosage, mediator amount and pH of the solution. Under optimized conditions, 40 ppm dye solution could be completely degraded in under one minute by SBP in the presence of H2O2 and a redox mediator. Dye degradation was also confirmed using HPLC and TOC analyses, which showed that most of the dye was being mineralized to CO2 in the process.ConclusionsDetailed analysis of metabolites, based on LC/MS results, showed that the enzyme-based degradation of the CP6R dye proceeded in two different reaction pathways- via symmetric azo bond cleavage as well as asymmetric azo bond breakage in the dye molecule. In addition, various critical transformative and oxidative steps such as deamination, desulfonation, keto-oxidation are explained on an electronic level. Furthermore, LC/MS/MS analyses confirmed that the end products in both pathways were small chain aliphatic carboxylic acids.
A B S T R A C TWastewater effluents of many industries are usually composed of dye mixtures and their removal poses a significant challenge. The present study reports on the use of an advanced oxidation process namely UV/H 2 O 2 to degrade Malachite Green (MG) (k = 0.0518 min −1 ) and Thiazole Yellow G (TYG) (k = 0.0367 min −1 ), and their binary mixture in aqueous solutions. Interestingly, it was seen that the photolytic degradation of dyes in binary solution was slower (by 10% for MG and by 46% for TYG) than that in neat solutions under comparable conditions. The total organic carbon analysis (TOC) was also carried out in both the neat dyes (38.5% decrease for MG and 13% decrease for TYG), and in mixture the TOC change was 40%. HPLC analyses confirmed the formation of intermediates in both individual dye solutions, which were however not seen in binary mixtures. The present work shows that dye mixtures behave very differently than neat dyes, and highlights the importance of studying complex dye mixtures and the possible deleterious interactions between dye intermediates during the remediation process.
The industries, such as plastics, paper, dyestuffs, and textile use dyes for their products by consuming substantial volumes of water. Subsequently, they cause a considerable amount of colored wastewater. Therefore, wastewater from industries must be treated before being discharged into the environment. The modern consideration has been focused on the direction of numerous natural solid constituents that are proficient in eradicating contaminants from water at low cost. Such adsorbent which can be used for dye removal from the wastewater is sugarcane bagasse. Our findings revealed that the sugarcane bagasse acts as an efficient adsorbent. It was very efficient to adsorb the direct yellow 12. Dyes removal ability of adsorbent at diverse flow degree, initial dye concentration, contact time, particle size and pH were studied, and superior results were found.
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