For the preparation of the catalyst, tetraethylorthosilicate (TEOS, Merck; purity> 99.9%) was dissolved in anhydrous ethyl alcohol (CH3CH2OH, Merck; purity>99.9%) under stirring for homogenization within 15 min at room temperature. After that, 3-aminopropyl(trimethoxy)silane (APS) was added to the ethanolic solution and mixed for >15 min. Then, Salicylaldehyde was added to the solution of TEOS and APS. The molar ratio of TEOS/APS/ Salicylaldehyde was 5:1:1. Then, Fe(NO3)3·9H2O (0.5mol) was added to above solution and was kept at 80 °C for 12h under reflux. The obtained red-brown solid was filtered and washed for three times with methanol and DMF, then dried in air. The as-prepared photocatalyst was characterized by SEM (VP-1450), EDX (type …show more content…
However, in order to accommodate larger samples, the inner width of the reactor was made to be 10 cm that is larger than the standard one (7 cm). The test setup was designed to provide a constant concentration of test gas flow into the reactor and over the sample surfaces. The ambient light was used as an illumination source to test the photocatalytic activity of materials toward nitric oxide. The produced gases in the photocatalytic oxidation of the nitric oxide analysed using NOx analyser (THERMO Scientific Model 42i NO-NO2-NOx Analyser). The experiment was conducted in the following manner: The test sample placed in the photoreactor and, the glass window was attached. Simultaneously, the flow was stabilised in an empty line that directly connected to the NOx analyser. Next, the test gas was allowed to flow over the sample in darkness and the change in the volume fraction of NO and NOx was recorded. After maintaining of the gas flow, the sample was exposed to ambient light for 60 minutes and the NOx volume fraction was recorded under this conditions; the percent yield of photocatalytic NO oxidation was conducted …show more content…
Microcalorimetry experiment was performed on Setaram−C80 heat flow calorimeter coupled to a multiport high-vacuum homemade glass manifold. A specific amount of the sample (approx. 500 mg) was taken into a sample cell, reference cell was taken as empty and together they are connected with Pyrex tee. The sample was heated from room temperature to 200°C under vacuum and kept for 2 h, then 3-4 doses of helium gas were introduced into the system to remove any excess residue such as moisture or organic impurity from the system. The system was heated for 4-5 hr under vacuum at 200°C and then cooled down to the temperature (50°C) where we want to perform the adsorption study. Small doses of test gases consecutively introduced to the system and gradually increased up to 50 Torr until an equilibrium pressure was reached. Then the obtained differential heats of the test gases adsorption were recorded as a function of its coverage. Further, the manifold degassed under vacuum for almost 30 minutes; adsorption was conducted in the same manner. Finally, the number and strength of active surface are obtained from the difference between the adsorbed gases from the first and second