## 3 Characterization of Synthesized Silica Nanoparticles  
Several techniques are used for the characterization of SNPs to assess their chemical composition, morphology, porosity, and other relevant indicators. We characterized SNPs using X-ray fluorescence (XRF) and the results indicate the presence of SiO\({}_{2}\) as the highest compound present in the samples, with the percentage ranging from 96% to 93%, as produced from sources. Other compounds such as K\({}_{2}\)O, SO\({}_{3}\), CaO, Fe\({}_{2}\)O\({}_{3}\), CuO, and ZnO were also present in trace amounts. XRD characterization also displayed broad diffraction peaks between 30 and 32, which are mainly associated with amorphous structures, showing the formation of SNPs in their amorphous state. Figure 3A,B show results of nano-silica formation from barley husk and barley grass, respectively, while Figure 3C,D show formation from barley wheat grass [19; 31]. It should provide a concise and precise description of the experimental results, their interpretation, as well as the experimental conclusions. We conducted Fourier-Transform Infrared (FTIR) analysis over the range of 400-4000 cm\({}^{-1}\), as shown in Figure 4A,B, where the formation of nano-silica using barley husk and barley grass is evident, while Figure 4C shows the formation of nano-silica resulting from barley wheat grass [19; 31]. A large number of FTIR peaks were identified and recorded. This study is critical for determining which other functional groups are present in nanoparticles, since the results show a dominant peak at 1076, 1060, and 1800 cm\({}^{-1}\) for nano-silica from barley wheat and rice husk sources. These peaks are attributed to vibrations that correspond to the asymmetric stretching vibrations of silicon bond (Si-O-Si), other peaks could be seen around 3280 cm\({}^{-1}\) corresponding to OH bending vibrations. Particle size assessment was also performed to identify the nanoparticle sizes. In addition, Zeta Sizer and Bruner-Emmett-Teller (BET) were used to study the surface and sizes of the nanoparticles. The particle sizes were seen to be around 70, 102, 145, 131, and 25 nm, for barley grass, wheat, barley husk, and rice husk nano-silica, respectively. Particle size is a critical characteristic because it affects the surface area of nanoparticles; the smaller the particle size, the larger the surface area, and hence the higher the adsorption capacity due to higher surface activation energy. The amount of aggregation and the surface area of the nanoparticles were also characterized using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The SEM images in Figure 5A,B showed very little agglomeration while in Figure 5D,E we observed a growing presence of agglomeration. Energy-dispersive X-ray (EDX) analyses were also conducted to determine the constituent elements and chemical compounds. Figure 4: FTIR images of synthesized silica nanoparticles for (**A**) barley husk, (**B**) barley grass, (**C**) and barley and wheat grass. Figure 3: XRD images of synthesized silica nanoparticles for (**A**) barley husk, (**B**) barley grass, (**C**) barley, and (**D**) wheatgrass. According to the acquired data from Table 1, we can see from the EDX results of silica nanoparticles the presence of silicon, as the largest peak, followed by carbon and oxygen. The compound composition of the various precursor sources, according to the results, suggests that barley contains a significant content of silica nanoparticles. Table 1 shows FTIR, XRD, particle size, and EDX results. Since nanoparticles have larger surface areas [67] with higher surface activation energy, they serve as adsorbents for the removal of contaminants in water. It is critical to carry out both X-ray fluorescence (XRF) and EDX characterization techniques since the EDX methodology alone may be inadequate to provide a complete description of the sample.