A spatial confinement effect of CdS nanoparticles in mesoporous alumina , which is synthesized through evaporation-induced self-assembly (EISA) method, post-impregnation approach and microwave irradiation process, was investigated to verify the enhanced catalytic activity and stability with less aggregation of CdS crystallites during decoloration of organic dyes under visible-light irradiation. In this work, we utilize inexpensive natural clays for preparing mesoporous alumina via evaporation-induced self-assembly method, and used as the host for confining CdS nanoparticles to suppress the crystallite growth and aggregation. The loading amount and grain size of CdS nanoparticles significantly altered catalytic activity and stability. CdS clusters confined inside the mesoporous channels provided abundant reactive sites for photocatalytic reaction through spatial confinement effect, quantum size effect and sulfide-support interaction, thus greatly enhancing the reaction activity. CdS/MAl composites have large special surface area, strong visible light absorption and high quantum yields . CdS/MAl-25 photocatalyst has exhibited remarkably enhanced visible light photoactivities as compared to other catalysts, and the overall decoloration rate was up to 97.5% after visible light irradiation for 60 min. The CdS/MAl composites exhibit potential applications in the wastewater treatment under visible light irradiation.
Dyes in wastewater have adverse effects on the environment and human health. Dye-decolorizing peroxidase (DyP) is a promising biocatalyst to dyes degradation, but the decolorization rates varied greatly which influencing factors and mechanisms remain to be fully disclosed. To explore an effective decolorizing approach, we have studied a DyP from Rhodococcus jostii ( Rh DyPB) which was overexpressed in Escherichia coli to decolorize four kinds of dyes, Reactive blue 19, Eosin Y, Indigo carmine, and Malachite green. We found the decolorization rates of the dyes by purified Rh DyPB were all pH-dependent and the highest one was 94.4% of Malachite green at pH 6.0. ESI–MS analysis of intermediates in the decolorization process of Reactive blue 19 proved the degradation was due to peroxidase catalysis. Molecular docking predicated the interaction of Rh DyPB with dyes, and a radical transfer reaction. In addition, we performed decolorization of dyes with whole E. coli cell with and without expressing Rh DyPB. It was found that decolorization of dyes by E. coli cell was due to both cell absorption and degradation, and Rh DyPB expression improved the degradation rates towards Reactive blue 19, Indigo carmine and Malachite green. The effective decolorization of Malachite green and the successful application of whole DyP-overexpressed cells in dye decolorization is conducive to the bioremediation of dye-containing wastewaters by DyPs. Graphical abstract
危险品化学品经营许可证（带存储）