Oxidative degradation of 2,4-D in water by Fe/Co bimetallic nanocomposite-activated peroxymonosulfate
To alleviate environmental pollution caused by the organic chlorinated herbicide 2,4-dichlorophenoxyacetic acid(2,4-D),in this study,iron-cobalt bimetallic nanoparticles(n-Fe/Co)were prepared by liquid-phase reduction,and the degradation performance of 2,4-D via the activated peroxymonosulfate(PMS)system was optimized by adjusting the synthesis ratio of iron and cobalt.The results showed that 2,4-D(10 mg·L-1)was completely removed within 30 min using 0.03 g·L-1 of n-Fe/Co and 0.5 mmol·L-1 of PMS at pH 4.5,and the removal of 2,4-D was enhanced by 60.9 percent compared with the application of nano zero-valent iron(nZVI)alone.We found that n-Fe/Co could effectively remove 2,4-D over a wide pH range(2-9)and under complex anion conditions.Free radical inhibition experiments revealed that hydroxyl radicals were the main active species involved in the reaction,with a contribution rate of 62.2%.On the basis of our analysis of intermediate products,we propose a degradation mechanism and the degradation pathway of 2,4-D in the n-Fe/Co-PMS system.The findings of this study indicate that the n-Fe/Co nanocomposite-activated PMS system has considerable application potential for the treatment of 2,4-D herbicide pollution in water.
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