Structure of a novel Co-based heterogeneous catalyst via Mn3(PO4)2 as a carrier to efficiently activate peroxymonosulfate for improving degradation of sulfonamides.

Effective degradation of sulfonamides (SAs) in water is of global importance for decreasing its pathogenicity and bioaccumulation. In this study, Mn3(PO4)2 was used as a carrier to fabricate a novel and high-efficient catalyst with Co3O4 anchored (Co3O4@Mn3(PO4)2) for the activation of peroxymonosulfate (PMS) to degrade SAs. Surprisingly, the catalyst exhibited superior performance, and nearly 100% of SAs (10 mg L-1) including sulfamethazine (SMZ), sulfadimethoxine (SDM), sulfamethoxazole (SMX), and sulfisoxazole (SIZ) was degraded by Co3O4@Mn3(PO4)2-activated PMS within 10 min. A series of characterization of the Co3O4@Mn3(PO4)2 composite were conducted and the main operational parameters of SMZ degradation were investigated. SO4•-, •OH, and 1O2 were determined to be the dominating reactive oxygen species (ROS) responsible for the degradation of SMZ. Co3O4@Mn3(PO4)2 also exhibited excellent stability and the removal rate of SMZ still maintained over 99% even in the fifth cycle. The plausible pathways and mechanisms of SMZ degradation in the system of Co3O4@Mn3(PO4)2/PMS were deduced on the basis of the analyses of LCMS/MS and XPS. This is the first report on high-efficient heterogeneous activating PMS by mooring Co3O4 on Mn3(PO4)2 to degrade SAs, which provides us with a strategy to structure novel bimetallic catalysts for PMS activation.

Decorating S-doped Cu-La bimetallic oxides with UIO-66 to increase the As(III) adsorption capacity via synchronous oxidation and adsorption.

Arsenite (As(III)) is more toxic and difficult to remove than arsenate (As(V)). In this study, an S-doped Cu-La bimetallic oxide (S-CuLaO) decorated with metal-organic framework (MOF) composite (S-CuLaO@UIO-66) was synthesized and applied for the adsorption of As(III). The maximum adsorption capacity of As(III) by S-CuLaO@UIO-66 was as high as 171 mg/g, which was much higher compared with other MOF compounds reported to date. The UIO-66 support improved the dispersion and reduced the size of the S-CuLaO particles, which increased the number of exposed adsorption reactive sites. Study of the mechanism revealed that the synchronous oxidation and adsorption significantly increased the removal of As(III). O2∙- was produced by the receiving electron from the dissolved oxygen from Cu(I) in S-CuLaO, which converted As(III) to As(V). Furthermore, the stability and reusability S-CuLaO@UIO-66 (without regeneration) was investigated at a low As(III) concentration (approximately 1000 µg/L) in deionized water and well water. The residual arsenic concentration ranged from 0.8 to 2.8 µg/L in deionized water and 3-58.2 µg/L in well water within 240 min during three cycles. Generally, this study suggests that combining an optimal oxide with a stable MOF is a promising approach for the fabrication of composite adsorbents.

Polar group and defect engineering in a metal-organic framework: synergistic promotion of carbon dioxide sorption and conversion.

A sulfone-functionalized metal-organic framework (MOF), USTC-253, has been synthesized that exhibits a much higher CO2 uptake capacity (168-182 %) than the corresponding unfurnished MOFs. The introduction of trifluoroacetic acid (TFA) during the synthesis of USTC-253 affords defect-containing USTC-253-TFA with exposed metal centers, which has an increased CO2 uptake (167 %) compared to pristine USTC-253. USTC-253-TFA exhibits a very high ideal adsorption solution theory selectivity (S=75) to CO2 over N2 at 298 K. In addition, USTC-253-TFA demonstrates good catalytic activity and recyclability in the cycloaddition of CO2 and epoxide at room temperature under 1 bar CO2 pressure as a result of the presence of Lewis and Brønsted acid sites, which were evaluated by diffuse reflectance infrared Fourier transform spectroscopy with a CO probe molecule. We propose that the CO2 adsorption capability has a positive correlation with the catalytic performance toward CO2 conversion.