J Environ Manage
School of Civil and Environmental Engineering, Shenzhen Key Laboratory of Water Resource Application and Environmental Pollution Control, Harbin Institute of Technology (Shenzhen), Shenzhen, 518055, China; Guangdong Water Co., Ltd, Shenzhen, 518021, China.
Published: April 2022
Siderite was applied to the binary oxidant system of siderite-catalyzed hydrogen peroxide (HO) and enhanced with persulfate (PS). In the absence of PS, methyl orange (MO) almost could not be degraded by the siderite/HO process. However, adding PS significantly improved the capacity of MO to oxidize azo-dye. The influence of individual and interaction of reaction factors have been explored with a simple response surface methodology (RSM) based on central composite design (CCD). The quadratic model with low probabilities (<0.0001) at a confidence level of 95% was satisfactory to predict MO degradation in siderite/HO/PS system, whose correlation coefficients of R and R-adj were 0.9569 and 0.9264, respectively. Moreover, the optimum operation conditions of 21.20 mM, 2.75 g/L, 3.86 mM, and 4.69 for HO, siderite, PS and initial pH, respectively with the response of C/C around 0.047. Radical scavenging experiments and electron spin resonance (ESR) determined that ·OH was crucial for MO degradation, while the contribution of SO was minor. The surface morphology and iron content of siderite before and after the oxidation process showed clear differences. Possible intermediates and a degradation pathway were proposed based on the results of UV-Vis spectral and GC-MS analysis. Moreover, the toxicity to Vibrio fischeri bioluminescent bacterium has increased in the earlier degradation stage due to the generated by-products and weaken with the continuous treatment. This study demonstrated that the siderite/HO/PS system was effective over a relatively wide pH range without producing secondary pollutants, making it a promising technology and potential environmentally benign approach to azo-dye wastewater treatment.
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http://dx.doi.org/10.1016/j.jenvman.2021.114397 | DOI Listing |
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