Development of regenerative dye impregnated mesoporous silica materials for assessing exposure to ammonia

Figures & data

Figure 1. Schematic diagram of a laboratory set-up for NH₃ gas detection via a detector tube.

Figure 2. Powder X-ray diffraction patterns. (a) MCM-41 and dye-impregnated MCM-41/BG (b) SBA-15 and dye-impregnated SBA-15/BG.

Table 1. Physical characterization properties of MCM-41 and SBA-15

Sample name	S BET ^a (m^2/g)	Vp ^b (cm^3/g)	d BJH ^c (nm)	Mode diameter (nm)	d 100 ^d (nm)	a, Unit cell ^e (nm)
MCM-41	1079	1.00	3.2	2.7	4.0	4.6
SBA-15	460	0.85	8.1	4.7, 9.3	11.8	13.6
Notes: ^aBET surface area. ^bPore volume. ^cPore diameter calculated by BJH theory. ^dd-Spacing between (1 0 0) planes. Calculated from 2d sinθ = nλ. ^eHexagonal unit cell. Calculated from a = 2d 100/√3.

Figure 3. N₂ adsorption/desorption isotherms of MCM-41 and SBA-15.

Figure 4. BJH pore size distributions of MCM-41 and SBA-15.

Figure 5. Scanning electron microscope images of (a) MCM-41 and (b) SBA-15.

Figure 6. Transmission electron micrographs of (a) MCM-41, (b) Dye-impregnated MCM-41/BG, (c) SBA-15, and (d) dye-impregnated SBA-15/BG. The scale bars for all images are 20 nm except for (a), where the scale bar is 50 nm.

Figure 7. The effect of relative humidity on the response time of dye impregnated materials of MCM-41/BG and SBA-15/BG. The response time was defined by per 1 cm change in color from yellow to blue in the detector tube at a flow rate of 1000 ml min⁻¹. The inlet ammonia concentration was 10 ppmv and the temperature was 25°C.

Figure 8. The effect of ammonia concentration on the response time of dye impregnated materials in the detector tube. The relative humidity was 50%. The response time was defined by per 1 cm change in color from yellow to blue in the detector tube at a flow rate of 1000 mL min⁻¹.

Figure 9. Reversibility tests of the dye impregnated materials. The inlet ammonia concentration was 10 ppmv and the relative humidity was 80%. The response time was defined by per 1 cm change in color from yellow to blue in the detector tube at a flow rate of 1000 mL min⁻¹.