The Ir/C catalyst with 30%(by mass) Ir was prepared in the CH3CH2OH and H2O binary system.The X-ray diffraction(XRD) data showed that the average sizes of the Ir particles in the Ir/C catalyst was about 2.2 nm.The results of the electrochemical measurements indicated that the electrocatalytic activity of the Ir/C catalyst for the ammonia oxidation in the neutral NaClO4 solution was similar to the Ir catalyst,while electrocatalytic stability was much better than that of the Ir catalyst.Furthermore,the peak current density of the ammonia oxidation at the Ir/C catalyst electrode showed a good linear relationship with the ammonia concentration,illustrating that the Ir/C catalyst would have a good application prospect in the potential fixed electrolytic type ammonia sensor.
In this study, sodium methylsilicate and lime were selected to prepare the same proportion of Imitation Site Soil, and according to the principle of carbonation reaction of restoration materials, the effect of carbonation reaction on the performance of restoration soil of earthen sites was studied. The study has good significance for the conservation and restoration of earthen sites. The samples were cured with CO2 concentration and curing age as variables. After curing, the samples were tested to determine their water-resistant properties, uniaxial compressive strength, and pH value and a micro scanning electron microscope was used. The results indicated that the carbonation reaction can quickly improve the water resistance and compressive strength of imitation site soil, and reduced the water absorption by 16.67% compared to the specimens conditioned at 0.03% CO2 concentration. The UCS of specimens at 5%, 10%, and 15% CO2 concentrations increased by 72.22%, 131.19%, and 219.27%, respectively, compared with those at 0.03% CO2 concentration after the specimens were environmentally maintained in the carbonation chamber at 0.03%, 5%, 10%, and 15% CO2 concentrations for 120 h, respectively. The internal particle gradation of the imitation site soil improved after carbonation. These results provide a basis for improving the restoration technology of earthen sites.
Abstract Alkalinity production is one of the most typical and widespread salinization hazards on the Loess Plateau. Based on the characterization of typical flooding sites and the results of salt monitoring, this study investigates the deterioration mechanism of salinization on Zhouqiao site. The orthogonal test was used to simulate the effects of different concentrations of MgSO 4 , NaCl and CaCl 2 under natural conditions on the quality change, salt analysis out location, surface phenomenon, strength and electrical conductivity of the soil at the Zhouqiao site, and to make a preliminary analysis on the mechanism of saline deterioration of the site soil. The results show that the soil column mass increased significantly under the action of salt, and the rate of salt absorption in the soil column decreased when the critical value was reached, and the critical values were different under the action of different kinds of salts. The rate of salt analysis is also influenced by the salt concentration and the number of cycles, which gradually increases with the increase of salt concentration and the number of cycles. The nominal strength of the soil column with the number of cycles, but occasionally increases. The conductivity increases with the number of cycles, and the magnitude distribution of the conductivity of the soil column under the action of different salts is not exactly the same.
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