# Dye Adsorbent Materials Based on Porous Ceramics from Glass Fiber-Reinforced Plastic and Clay
## 2 Materials and Methods
### GFRP/Clay Ceramic Specimens Used for MB Dye Adsorption Tests
In addition, to evaluate the MB dye adsorption ability of the GFRP/clay ceramics, we produced a ceramic control sample, in which only clay was fired in an oxidizing atmosphere. Figure 2 shows microscope (SZX10, Olympus Corporation, Tokyo, Japan) images of the granular ceramic specimens, which were produced with exposure to the conditions listed in Table 2, and scanning electron microscope (SEM, S5500, Hitachi High-Technologies Corporation, Tokyo, Japan) images of their surface structures. The ceramic specimens fired oxidatively were brown, whereas the specimens fired reductively were black because a part of the GFRP resin component was not decomposed and remained in the clay structure as carbides. In both ceramics fired oxidatively and reductively, glass fibers in the structure were partially sintered [7]. Figure 3 shows the particle size distributions of ceramic specimens. Here, the particle size distribution was obtained by the following methods. First, 50 samples were randomly selected from  
Figure 2: The appearance of the clay and GFRP/clay ceramics. (**a**) Microscope images of the granular GFRP/clay ceramics. (**b**) SEM images of the GFRP/clay ceramic surface structures. the sieved samples, and the maximum diameter of each sample was measured with a microscope (SMZ800, NIKON Instech Co., Ltd., Tokyo, Japan). Next, the maximum diameter distribution on the 50 samples was determined statistically. From Figure 3, the maximum length of the ceramic specimens sifted with 0.5 and 1.0 mm, 1.0 and 1.4 mm, and 1.4 and 2.0 mm mesh screens were approximately 1.1 mm, 1.7 mm, and 2.4 mm, respectively. Table 3 shows the inorganic chemical compositions of the ceramic specimens. The main chemical components of the clay ceramic were SiO\({}_{2}\) and AlO\({}_{3}\). The GFRP/clay ceramics had similar chemical components to those of the clay ceramic; however, the GFRP/clay had a larger CaO component. The ratio of the CaO component to total ceramic mass increased as the GFRP mixing ratio increased due to increasing glass fiber contents. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Oxidatively Fried**} & \multicolumn{4}{c}{**Reductively Fried**} \\ \cline{2-9}
**Component** & **Clay** & **20\%** & **40\%** & **60\%** & **20\%** & **40\%** & **60\%** \\  & **GFRP/Clay** & **GFRP/Clay** & **GFRP/Clay** & **GFRP/Clay** & **GFRP/Clay** & **GFRP/Clay** \\ \hline SiO\({}_{2}\) & 63.5 & 62.6 & 59.1 & 50.0 & 62.2 & 61.2 & 56.2 \\ Al\({}_{2}\)O\({}_{3}\) & 23.9 & 22.1 & 20.7 & 17.7 & 18.5 & 9.13 & 4.79 \\ Fe\({}_{2}\)O\({}_{3}\) & 5.13 & 4.87 & 4.16 & 4.09 & 6.13 & 7.56 & 7.34 \\ K\({}_{2}\)O & 3.76 & 3.26 & 2.91 & 2.00 & 3.73 & 3.77 & 3.11 \\ MgO & 1.79 & 1.66 & 1.75 & 1.51 & 2.24 & 2.43 & 2.14 \\ CaO & 0.51 & 4.02 & 9.93 & 23.2 & 5.34 & 12.9 & 22.7 \\ TiO\({}_{2}\) & 1.11 & 0.86 & 0.80 & 1.03 & 1.21 & 1.56 & 1.49 \\ Others & 0.27 & 0.58 & 0.71 & 0.45 & 0.65 & 1.46 & 2.22 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The inorganic chemical compositions of the ceramic specimens. Figure 3: Particle size distribution of granular ceramics. Figure 4 lists the compressive strengths of the GFRP/clay ceramics. Here, cylindrical specimens, with a diameter of 14 mm and length of approximately 30 mm, were used for the compressive tests. Cylindrical specimens were compressed using a universal testing machine (AG-X50 kN, Shimadzu Corporation, Kyoto, Japan) with a crosshead speed of 0.5 mm min\({}^{-1}\). Load cell capacity of the machine was 50 kN, and the precision of the test force was within \(\pm\)1% of displayed test force for 1/1 to 1/1000 of the load cell capacity, which conforms to JIS B7721 Class 1 and ISO 7500-1 Class 1. Compressive strength was determined by dividing the measured maximum compressive load by the specimen cross-sectional area. The data points are the average compressive strengths calculated from measurements of the four specimens.