生物炭催化过硫酸盐脱色偶氮染料金橙Ⅱ

摘要

As a kind of inexpensive material-biochar,the function of soil restoration and other aspects has caused wide public concern,but its catalytic role has been studied rarely.The feasibility of persulfate (PS)catalyzed by biochar(BC)to decolor an azo dye (acid orange (AO7))was studied.Some factors influencing the decolorizing efficiency of PS/BC system were evaluated, including pH, concentration of biochar and PS/AO7 mole ratio.What’s more,the recycle effect and characteristics of biochar were studied.Results showed that the decolorizing effect of the PS/BC system was obviously better than the only PS system.The decoloration of AO7 by both reaction systems followed first order reaction kinetics. The optimum pH of PS/BC system was near-neutral. The higher the biochar concentration,the better the decolorizing effect was.Similar trend was observed for the PS/AO7 mole ratio,whereas the catalytic effect did not increase accordingly.The reused biochar could still decolor %生物炭作为一种廉价易得的材料,在土壤修复等各方面的功能已引起广泛关注,但其催化作用却鲜有研究。首次对生物炭(biochar BC)催化过硫酸盐(Na2 S2 O8 PS)使偶氮染料金橙Ⅱ(AO7)脱色的可行性进行研究,对影响催化体系脱色效率的因素(包括 pH、生物炭质量浓度和 PS/AO7摩尔比)进行探讨,同时研究了生物炭的重复利用效果及前后性质变化。结果表明：PS/BC 体系明显比单独的 PS 体系脱色效果好；两个反应体系都遵循一级反应动力学；PS/BC 体系反应的最适 pH 接近中性；生物炭质量浓度越大,脱色效果越好；PS/AO7摩尔比越大,脱色效果越好,但是催化效果却没有相应的改善；生物炭重复利用后对 AO7仍然有脱色效果；BC 的孔大多位于层状结构表面,且为小孔,重复使用后,表面孔会堵塞；除了灰分和氧元素外,其他元素(C、N、H、S)含量都有一定程度的减小；BC 表面官能团种类很多,主要有C=O、C=C、C-O、C-H,芳香族 C=C 和 C-H 以及-OH 官能团；BC 重复使用后-OH 峰会消失。综上述,生物炭可以催化过硫酸盐对偶氮染料 AO7进行脱色,原理是 BC 表面的-OH 官能团与 PS 反应生成硫酸根自由基去除 AO7。