四氧化三铁活化过硫酸盐降解活性黑5

Degradation of C.I.reactive black 5 by Fe_3O_4 activated persulfate

采用水热合成法制备出了具有较高催化活性的催化剂四氧化三铁(Fe_3O_4),并利用Fe_3O_4活化过硫酸盐降解活性黑5,考察了初始pH、Fe_3O_4投加量、活性黑5初始浓度和过硫酸盐投加量对活性黑5降解效果的影响。结果表明,Fe_3O_4活化过硫酸盐降解活性黑5的最佳条件为初始pH 6、活性黑5初始质量浓度50mg/L、过硫酸盐投加量6mmol/L、Fe_3O_4投加量2.0g/L。在最佳条件下,反应180min,活性黑5的降解率达到80.2%,Fe_3O_4反复使用5次后,活性黑5的降解率仍能达到77%以上。活性黑5的降解途径为:偶氮键打开产生苯环中间产物和萘环中间产物,萘环中间产物逐步转化为邻苯二甲酸酐→邻苯二甲酸→苯甲酸;苯环中间产物逐步转化为对氨基苯磺酸→硝基苯和对氨基苯酚,对氨基苯酚转化为对苯二酚;最终被彻底氧化降解成CO_2、H_2O等无毒小分子物质。活性黑5在降解过程中对植物的毒性先升高后降低。

The catalyst Fe 3O 4 with high catalytic activity was prepared by hydrothermal synthesis.C.I.reactive black 5 was degraded under different conditions of initial pH,Fe 3O 4 dosage,C.I.reactive black 5 initial concentrations and persulfate dosage.Results showed that the optimal conditions were initial pH of 6,C.I.reactive black 5 initial mass concentration of 50 mg/L,persulfate dosage of 6 mmol/L and Fe 3O 4 dosage of 2.0 g/L.Under the optimal conditions,the degradation rate of C.I.reactive black 5 was 80.2%after 180 min.After 5 times recycling of Fe 3O 4,the degradation rate of C.I.reactive black 5 was still above 77%.The degradation pathway was that C.I.reactive black 5 broke into intermediate products with benzene ring and naphthalene ring first.Then intermediate products with naphthalene ring transformed into phthalic anhydride→phthalic acid→benzoic acid.And intermediate products with benzene ring transformed into p-aminobenzene sulfonic acid→nitrobenzene and p-aminophenol,with p-aminophenol further into p-dihydroxybenzene.C.I.reactive black 5 was degraded in CO 2,H 2O and so on,ultimately.The phytotoxicity of the intermediate products increased first and decreased then with time.