## 3 Results
### Crystalline Structure of Anthracite, Modified Zeolite and Magnetized Zeolite
The optimized zeolite yield rate of as high as 42% can be observed for the hydrothermal reaction with 10% of alkaline solution at a crystallization temperature of 120 \({}^{\circ}\)C for 8 h as denoted by the XRD analysis and corresponding Table 6. The corresponding XRD analysis for the modified zeolite indicates a major crystalline phase of zeolite, followed by Heulandite-Ca, cristobalite-SiO\({}_{2}\), and silicon dioxide-SiO\({}_{2}\), suggesting a complete re-crystallization and transformation reaction occurred [29]. On the other hand, the corresponding XRD profiles for the magnetized zeolite, as shown in Figure 9, further denote strong characteristic peaks indexed as iron oxides (magnetic Fe\({}_{2}\)O\({}_{3}\)) (PDF#00-019-0629) with an FCC crystalline structure, suggesting successful magnetization with the existence of iron oxide (Fe\({}_{2}\)O\({}_{3}\)). The iron incorporated as magnetite in the zeolite matrix can be further confirmed by previous research that suggested that Fe(III) dominated the crystalline phase agglomerated in the zeolite layer structure, according to XPS [30]. The corresponding semi-quantitative analysis by Rietwald peak refinement indicated the highest amount of magnetite can be seen for the magnetized zeolite B, followed by magnetized zeolite C and A, with corresponding compositions of 15 wt%, 13 wt% and 12 wt%, respectively, consistent with the XRD peak intensity as shown in Figure 9. In addition to the zeolite and magnetite, other crystalline phases of cristobalite, silica, and Heulandite can be further confirmed by the XRD profile and the semi-quantitative analysis. The XRF analysis demonstrates the composition of magnetite decreases from magnetized zeolite C to A, consistent with the XRD results, suggesting higher iron incorporation resulted from the particle size subdivision, as denoted in Table 7.  
The FTIR spectra of the modified zeolite and magnetized zeolite demonstrate the existence of hydroxyl (OH-), water (O-H-O), and chemical bonding with a corresponding wave number higher than 3000 cm\({}^{-1}\), while the peaks between 2000-1000 cm\({}^{-1}\) and below 1000 cm\({}^{-1}\) can be further attributed to Si(Al)-O vibration and Si-O-Si(Al) vibration separately [31], consistent with the FTIR spectra of typical Na-P1 zeolite with a chemical \begin{table}
\begin{tabular}{l c c c c c c c} \hline  & & **Zeolite** & **Magnetic** & **Silicon** & **Cristobalite** & **Heulandite-Ca** & **Microcline** \\ \hline Magnetized A & 60–80 mesh & 18\% & 15\% & 13\% & 10\% & 20\% & 24\% \\ Magnetized B & 1–3 mm & 53\% & 12\% & 16\% & 19\% & - & - \\ Magnetized C & 120 mesh & 26\% & 13\% & 8\% & 9\% & 31\% & 13\% \\ Modified A & 1–3 mm & 26\% & - & 10\% & 10\% & 38\% & 16\% \\ Modified B & 60–80 mesh & 42\% & - & 12\% & 14\% & 21\% & 12\% \\ Modified C & 120 mesh & 23\% & - & 10\% & 12\% & 36\% & 19\% \\ \hline \end{tabular}
\end{table} 
Table 6: Semi-quantitative analysis of the zeolite derived from hydrothermal reaction from the XRD profiles (wt%). \begin{table}
\begin{tabular}{l c c c c c c c c c c} \hline
**Sample Number** & **Si** & **Al** & **Fe** & **K** & **Ti** & **Na** & **Mg** & **Ca** & **Sr** & **Zr** & **Mn** \\ \hline Magnetic zeolite A & 39.68 & 7.74 & 30.87 & 1.38 & 0.25 & 2.72 & 1.04 & 2.40 & 0.13 & 0.06 & 0.23 \\ Magnetic zeolite B & 59.94 & 11.35 & 11.02 & 2.56 & 0.23 & 2.91 & 0.77 & 1.85 & 0.02 & 0.02 & 0.12 \\ Magnetic zeolite C & 58.20 & 11.79 & 10.84 & 2.52 & 0.16 & 3.40 & 0.85 & 1.95 & 0.02 & 0.01 & 0.10 \\ Modified zeolite A & 70.25 & 12.50 & 0.83 & 3.78 & 0.15 & 2.76 & 0.44 & 0.96 & 0.02 & 0.02 & 0.07 \\ Modified zeolite B & 70.62 & 12.37 & 1.07 & 3.04 & 0.08 & 3.31 & 0.42 & 1.37 & 0.06 & 0.03 & 0.06 \\ Modified zeolite C & 69.06 & 13.56 & 1.13 & 3.28 & 0.11 & 0.78 & 0.78 & 2.57 & 0.02 & 0.01 & 0.05 \\ \hline \end{tabular}
\end{table} 
Table 7: XRF data of magnetized zeolite (wt%). formula of Na\({}_{6}\)Al\({}_{6}\)Si\({}_{10}\)O\({}_{32}\):12H\({}_{2}\)O [32].