## 3 Results and Discussion  
### Effect of Length and Density of Textile Fabrics  
Figure 7 shows the number of A1 particles with respect to the time. The decrease in the number of A1 particles obtained from the chamber without a specimen was less than 17% in the first 20 min. The decrease dramatically increased after that. The decrease at 30 min was approximately 78%. The point in time at which the decrease began to increase dramatically and the decrease became more notable occurred earlier as the length and density of the textile fabrics increased. The number of A1 particles dramatically decreased at 12 min for the specimen with 3.5 mm length and 4 layers, and at 7 min for the specimen with 12 mm length and 4 layers.  
Figure 5: Machine for measuring SOx and NOx removal by the textile fabric.  
Figure 6: Variation of gas concentration with respect to time.  
The time at which the number of A1 particles reached zero was 29 min for the specimen with 3.5 mm length and 4 layers, and 26 min for the specimen with 3.5 mm length and 8 layers. The corresponding values were 25 min for the specimen with 12 mm length and 4 layers, and 22 min for the specimen with 12 mm length and 8 layers. Table 4 summarizes the results for the number of A1 particles. Due to the large scatter observed in the number of A1 particles with respect to time, the fine dust particle removal rate was evaluated by comparing the ratios (\(R_{n}\)) of the number of A1 particles obtained from the chamber with the specimen to that without the specimen between 10 and 30 min when the number of A1 particles decreased dramatically. The results are shown in Figure 7. At the end of the test, approximately 77.5% of the A1 particles were removed from the chamber without a specimen whereas all the particles were removed from the chamber with a specimen. Between 10 and 30 min, the \(R_{n}\) value increased with the length of the textile fibers, indicating that the increase was more notable for the specimens with denser textile fibers. The \(R_{n}\) of the specimen with 12 mm length and 4 layers was 1.8 times higher than that with 3.5 mm length and 4 layers. In addition, the \(R_{n}\) of the specimen with 12 mm length and 8 layers arrangement was 2.47 times higher than that with 3.5 mm length and 8 layers.  
Figure 8 shows the SEM image and EDS spectra of the textile fibers before and after adsorbing the fine dust particles. Before adsorbing the fine dust particles, C and O were present at the proportions of 63.6% and 36.4%, respectively. After adsorbing the fine dust particles, the additional presence of 10.1% Si, 4.1% Al, and 3.3% K was observed. This implies that the definite adsorption of the fine dust particles on the surface of the textile fabrics because Si and Al were the main components of the fine dust particles. The adsorption of the fine dust particles was also confirmed from the SEM image.  
\begin{table}
\begin{tabular}{c c c c} \hline \multirow{2}{*}{**Specimens**} & **Removal Rate of A1 Particles** & **Time which the Number of A1** & \multirow{2}{*}{**\(R_{n}\) (\%)**} \\  & **at Termination of Test (\%)** & **Particles Reached Zero (min)** & \\ \hline C & 77.5 & - & - \\
3.5–4 & 100 & 29 & 20 \\
3.5–8 & 100 & 26 & 21 \\
7.0–4 & 100 & 26 & 23 \\
7.0–8 & 100 & 25 & 33 \\
12–4 & 100 & 25 & 36 \\
12–8 & 100 & 22 & 52 \\ \hline \end{tabular} \(R_{n}\) = The ratio of the number of A1 particles obtained from the chamber with specimen to that without a specimen between 10 and 30 min.  
\end{table}
Table 4: Summary of the number of A1 particles adsorbed on the textile fabrics.  
Figure 7: Number of A1 particles with respect to time.