Recording an isotherm using the Sorptomatic 1990
The method below enables you to obtain a physisorption isotherm for a single sample. If you wish to do a chemisorption analysis consult the SAF.
To control the instrument you must open the Sorptomatic 1990 software from the start menu. Then follow the procedure below that leads you through the method to obtain an isotherm for you sample, first you must first run a blank and then your sample.
The analysis of your data clearly depends dramatically on the sample please consult the manuals or contact the SAF.
Blank Analysis
Sample Preparation
Degas empty burette for up to 30 mins, at about 100 oC
File Preparation
1. From the main menu follow this sequence: ‘File, Open, Yes’. Select the analysis file ‘C/CEInstruments/Sorptomatic/Data/BlankN2’.
2. From the main menu click ‘File, New.’ Tick the boxes ‘Analytical Conditions’ and ‘Delete Ads/Des Points’. Leave the other boxes unchecked. click ‘OK’. Select the directory for the file to be saved in (e.g. ‘D/Name/Blanks’) and enter a filename (e.g. ‘BlankB1’). Click ‘Save’.
3. Select the ‘Sample Information’ page and fill in the details – this is for your benefit only so you can put in as much or as little detail as you like. Leave 0 set in the boxes marked ‘Sample Mass’ and ‘Sample Density’.
4. Select ‘Analytical Conditions’ page and select the button ‘Fill with Gas Data ‘(Left hand side). Select ‘N2 Nitrogen’ and click ‘Update’. Enter the value 0 in the boxes: ‘Blank Slope’ and ‘Blank Intercept’; enter 1 in the box marked ‘Instrument Hysteresis’. Save the file by clicking ‘File, Save, Yes’.
5. Select the button ‘Sorptomatic Control’ (button with picture of the instrument) to enter the Digital Status Display (DSD Panel), this displays (in real time) the status of the instrument and allows you to communicate with the machine itself. Check that serial port display reads ‘Communication OK’. If it does not, i.e. if the computer or the instrument has been recently shut down, you will need to re-establish communication by going into ‘Instruments Serial Port, Instrument 1, Com 1’.
6. In the DSD Panel, select ‘File, Open’ and load the previously prepared blank file.
7. Select ‘Acquisition Parameters’, then ‘File in Memory’, and the page showing the acquisition parameters to be sent to the instrument is displayed. Click ‘Send to Instrument’ and at the end of the operation, click ‘Exit’.
Running the Analysis
1. Close the tap on the burette, and transfer it to the instrument’s analysis port. Check that the N2 reservoir is full, and top it up if necessary.
2. In the DSD Panel, select ‘Run, Reset’. Then degas the top of the burette by clicking on V4 and V2 (i.e. opens that part of the system to vacuum). When it has pumped down, open the tap on the burette.
3. Click ‘Cool’ to transfer liquid N2 from the reservoir. When it has finished, click ‘Run, Start’ to start the analysis.
Data Collection
1. At the end of the analysis, the data collected must be transferred from the instrument back to the computer. Go back to the main menu, click the button ‘Acquire Points’ (button next to ‘Sorptomatic Control’), select the previously prepared blank file and click ‘Acquire Points, Yes’. The page containing the parameters of the analysis set will be displayed; click ‘Continue to Save’. All the data will be transferred and saved in the file.
2. Select the ‘Analytical Conditions’ page and click ‘Blank Slope/Intercept and Inst. Hyst. Calculation’ (button with picture of calculator on it). The correct values will automatically be displayed; click ‘Yes’ to enter them in the page ‘Analytical Conditions’.
3. Select ‘File, Save, Yes’ to save the new parameters in the file.
Sample Analysis
Sample Preparation
1. This depends on the sample – the manufactures suggest organic materials should not be heated to greater than 60oC, alumina and silica are usually treated at between 150 and 180 oC, active carbons are usually treated at between 200 and 250 oC and zeolites are usually treated at between 250 and 350 oC. The time that you treat your sample for again depends on the sample sufficient time should be allowed to remove ALL the adsorbed water from the sample. The treatment is completed in one of the two furnaces control from the PC, ensure the burette stopcock is closed (to ensure the sample is not drawn out of the burette by the pump) and then click the relevant button marked ‘OUTGASSING’ located in the manual control panel. Then slowly open the stopcock and leave the sample to outgas for the required time. Allow to cool before starting the analysis.
2. To get an accurate sample weight (i.e. weight of sample without adsorbed species) evacuate the burette first, weigh it under vacuum, then put the sample in, degas/heat it and weigh it again (also under vacuum) just before starting the analysis and take the difference. This procedure is essential to obtain an accurate sample weight.
File Preparation
1. From the main menu follow this sequence: ‘File, Open, Yes’. Select an analysis file from ‘C/CEInstruments/Sorptomatic/Data’ i.e. High Surface, Medium Surface, Low Surface, depending on your sample. This will not significantly change the analysis as the instrument automatically calculates the amount of gas to introduce from the previous measurements
2. From the main menu click ‘File, New’. Tick the boxes ‘Analytical Conditions’ and ‘Delete Ads/Des Points’. Leave the other boxes unchecked. Click ‘OK’. Select the directory for the file to be saved in (e.g. ‘D/Name/Samples’) and enter a filename (e.g. ‘ABC1’). Click ‘Save’.
3. Select the ‘Sample Information’ page and fill in the details. Enter the sample mass in the box marked ‘Sample Mass’ and enter the value 1 in the box marked ‘Sample Density’.
4. Select the page ‘Analytical Conditions’ and select the button ‘Fill with Gas Data ‘(Left hand side). Select ‘N2 Nitrogen’ and click ‘Update’. Enter the data from the blank analysis by clicking ‘Load from Disk Blank Slope/Intercept and Inst Hyst’ (button with picture of disk and red arrow on it) and selecting the blank file you wish to use. Save the file by selecting ‘File, Save, Yes’.
5. Select the button ‘Sorptomatic Control’ (button with picture of the instrument on it) to enter the Digital Status Display (DSD Panel) that displays in real time the status of the instrument and allows you to communicate with the machine itself. Check that serial port display reads ‘Communication OK’. If it does not, i.e. if the computer or the instrument have been recently shut down, you will need to re-establish communication by going into ‘Instruments Serial Port, Instrument 1, Com 1’.
6. In the DSD Panel, select ‘File, Open’ and load the previously prepared file.
7. Select ‘Acquisition Parameters’, then ‘File in Memory’, and the page showing the acquisition parameters to be sent to the instrument is displayed. Click ‘Send to Instrument’ and at the end of the operation, click ‘Exit’.
Running the Analysis
1. Close the tap on the burette, and transfer it analysis station of the instrument. Check that the N2 reservoir is full, and top it up if necessary.
2. In the DSD Panel, select ‘Run, Reset’. Then degas the top of the burette by clicking on V4 and V2 (i.e. opens that part of the system to vacuum). When it has pumped down, open the tap on the burette.
3. Click ‘Cool’ to transfer liquid N2 from the reservoir. When it has finished, click ‘Run, Start’ to start the analysis.
Data Collection
1. At the end of the analysis, the data collected must be transferred from the instrument back to the computer. Go back to the main menu, click the button ‘Acquire Points’ (button next to ‘Sorptomatic Control’), select the previously prepared blank file and click ‘Acquire Points, Yes’. The page containing the parameters of the analysis set will be displayed; click ‘Continue to Save’. All the data will be transferred and saved on file.
2. Select ‘File, Save, Yes’ to save the new parameters in the file.
3. To view results, select the buttons ‘View Results’ or ‘View Graphs’. To convert the *.199 file into a spreadsheet, e.g. Excel file, select ‘Report, Creation’. Choose which results you want to have in the new file (from tabbed sections) then click ‘Sheet’. Then select ‘File, Save As’ to save it as a spreadsheet file.
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