In this work, filtration of membrane and reduction of iron nanoparticles (FeNPs) was coupled to remove dyes with different molecular weight. The FeNPs–Calcium alginate (CaAlg) composite membrane was biosynthesized using green tea. The FeNPs–CaAlg composite membrane was characterized by series of instruments. The results indicate that the FeNPs-CaAlg membrane has an excellent performance in filtrating dyes, nearly the same filtration flux with purified water and almost no flux reduction with filtration time. The FeNPs-CaAlg membrane exhibits different rejection performance for dyes with different molecular weight. The mechanism was discussed and it can be concluded that, for dyes with small molecular weight like crystal violet, besides the influence of the change in the effective channel size made by the load of FeNPs, the intensive reducibility of FeNPs also has great effect on the rejection rate.

在这项工作中，膜的过滤和铁纳米颗粒（FeNPs）的还原相结合以去除具有不同分子量的染料。FeNPs-藻酸钙（CaAlg）复合膜是用绿茶生物合成的。FeNPs-CaAlg复合膜通过一系列仪器进行表征。结果表明，FeNPs-CaAlg膜在过滤染料方面具有优异的性能，与纯净水的过滤通量几乎相同，并且随着过滤时间的减少通量几乎没有减少。FeNPs-CaAlg膜对不同分子量的染料表现出不同的排斥性能。对机理进行了讨论，可以得出结论，对于像结晶紫这样的小分子量染料，除了受FeNPs负载对有效通道尺寸的影响外，