This study reports for the first time on the synthesis of novel resin@P-Ag2O material and its application for reducing the chloride effect on COD determination of high salinity water. This engineered core–shell nanomaterial with cationic ion exchange resin core and porous Ag2O shell was prepared by facile ion exchange and silver oxidation method at ambient temperature without using toxic chemicals. The material was characterized by FTIR, XRD, SEM, and SEM–EDX mapping. In the chloride removal test, this material gave a high adsorption capacity of ca. 244 mgCl/gAg at the mild condition with high durability after several adsorption–desorption cycles. Moreover, resin@P-Ag2O was applied for removing chloride in water to improve the accuracy of the SMEWW 5220C:2012 method for COD determination of high salinity water. The result showed that the COD of a water sample with salt content after being treated by the material had a low error (≤ 10%) as compared to the sample without salt. Meanwhile, the COD of salty water measured by the dilution method had an error of around 15%. These results indicate that resin@P-Ag2O material has a very potential application for chloride removal and COD determination of high salinity water.
The CuO, CuMnOx and MnOx catalysts were anchored on the manganese oxide support with the structure of octahedral molecular sieves (OMS-2), which were synthesized using MnSO4 and KMnO4 as precursors by are flux method under acidic conditions, by an impregnation method and tested for CO oxidation. These catalysts and OMS-2 support were characterized by the advanced analyzations of X-ray diffraction and FTIR patterns; and SEM performances; and H2-TPR profiles. For CO oxidation reaction, CuO and CuMnOx catalysts showed extremely higher activities than that of MnOx catalyst and OMS-2 support. For the lowest temperature for 100% conversion of CO (T100), the CuO and CuMnOx catalysts were observed at 55 oC and 65 oC, respectively. Due to the present of Cu2+– O2− – Mn4+ ↔ Cu+–□–Mn3+ + O2 redox couple in the structure of these solid catalyst. Additionally, the CuMnOx catalyst showed higher activity (~ 1.74 folds) and better stability than that of CuO catalyst in CO oxidation. Due to the advance functional of binary oxide structure of CuMnOx catalyst As known, CO oxidation may follow the Mars-van-Krevelen mechanism with Cu2+– O2− – Mn4+ ↔ Cu+–□–Mn3+ + O2 redox couple. This study shows the high applicating potential of CuMnOx/OMS-2 material in exhaust treatment for environmental safety.
In this study, mixed oxides of Mn-Cu and Fe-Cu on OMS-2 support having an octahedral structure were synthesized by the refluxing and impregnation methods. The characteristics of the materials were analyzed by XRD, FTIR, SEM, EDX, and H2-TPR. In the CO oxidation test, CuFeOx/OMS-2 had slightly higher catalytic activity but is significantly more stable than CuMnOx/OMS-2 and CuO/OMS-2. Due to its lower reduction temperature in H2-TPR analysis, the Mars-Van-Krevelen mechanism for CuFeOx/OMS-2 (Cu2+–O–Fe3+ ↔ Cu+–□–Fe2+) could take place more energetically than CuO/OMS-2 and CuMnOx/OMS-2 (Cu2+–O2−–Mn4+ ↔ Cu+–□–Mn3+). In addition, the interaction between Fe and Cu in the catalyst could improve the durability of the surface oxides structure in comparison with that between Mn and Cu. With the high specific rate and TOF of 28.6 mmol/h.g and 0.508, respectively, CuFeOx/OMS-2 has a great potential as an effective catalyst for low-temperature oxidation application in CO and possible VOCs removal.
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