Highly efficient flow-through catalytic reduction of methylene blue using silver nanoparticles functionalized cotton

Organic dye pollution has become a serious problem threating environment and human health. Noble metal nanoparticles based catalytic degradation of organic dyes has attracted intensive attentions due to their outstanding catalytic activities. Compared with the catalytic systems using free noble metal nanoparticles, the flow-through systems based on the immobilized noble metal nanoparticles are more suitable for both high efficiency reaction and recycling of nanoparticles. In this study, the fibrous natural material cotton is selected as the support of silver nanoparticles (Ag NPs) and used for flow-through catalytic reduction of methylene blue (MB). Ag NPs were one-step immobilized onto cotton by immersing the cotton into a mixture solution of silver nitrate, poly (ethylene glycol) methyl ether thiol and dopamine. The reaction rate constant K of Ag NPs functionalized cotton towards MB reached high up to 0.478 min(-1). The flow-through system with Ag NPs functionalized cotton was operated to achieve a super high permeation flux of 2000 L m(-2) h(-1) and also a very high MB reduction of more than 99%, which is far better than the reported results (below 500 L m(-2) h(-1)). Moreover, the Ag NPs on cotton were very stable and released very slowly. After 24 h flowing-through test, only 0.9% of silver lose from the cotton. Our work provides a facile and applicable way to prepare the low-cost catalysts with high performances for continuous and efficient dye-containing waste water treatment.