Abstract
Degradation of dyes is an important environmental issue. In order to avoid the carcinogenic risks in anaerobic-aerobic biological process for wastewater containing azo dyes, a hemin based biomimetic oxidative degradation of azo dyes was developed. Acid orange 7 (AO7) was selected as the model for azo dye and the high efficient degradation was achieved in hemin/H2O2 system at pH 11.0. Degradation could be described by a pseudo-first-order kinetic model. The order of dependence on H2O2 concentration was significantly larger than that of hemin. Coexisting anions sulphate and chloride had little effect on the degradation, but reductive sulphite dramatically inhibited the degradation. The protic solvent 2-prophanol obviously promoted the degradation. Azo chromogenic group was destroyed quickly and some smaller intermediates formed. Active species oxoferryl porphyrin p-cation radical +PFeIV=O generated from heterolytic cleavage of O-O in H2O2 catalyzed by hemin play the main roles in degradation and reaction pathways were proposed.
Highlights
The removal of dyes from water is one of the most important issues for industries such as textile, paper, leather, pharmaceutical, food and so on [1]-[5]
Acid orange 7 (AO7) was selected as a model for azo dye [3] and efficient oxidation system with low concentration of hydrogen peroxideunder hemin catalysis were investigated in this work
De Villiers et al [20] observed a maximum of the dimerization constant of ferriprotoporphyrin IX in aqueous solution at pH 7, decreasing afterward, so increased pH may be associated with disaggregation of hemin dimmers, which account for higher availability to substrate attack
Summary
The removal of dyes from water is one of the most important issues for industries such as textile, paper, leather, pharmaceutical, food and so on [1]-[5]. Most wastewater containing azo dyes is treated in wastewater treatment plants by traditional biological methods based on anaerobic-aerobic process [6]. These processes are relatively ineffective in degradation of dyes and significant parts of azo dyes release carcinogenic aromatic amines by microbial reductive cleavage of –N=N– under anaerobic condition and toxicity increases instead [7] [8]. (2016) Hemin Based Biomimetic Oxidative Degradation of Acid Orange 7. Acid orange 7 (AO7) was selected as a model for azo dye [3] and efficient oxidation system with low concentration of hydrogen peroxideunder hemin catalysis were investigated in this work. Based on the kinetic and characteristic analysis of degradation process, the possible degrading pathway was proposed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
