# Removal of Phosphate from Aqueous Solution by
## 3 Results and Discussion
### Physicochemical Characterization of Zeolite, Biochar, and PZC 7:3
#### 3.1.3 FTIR Analysis  
The FTIR spectra of zeolite, biochar, and PZC 7:3 before phosphate adsorption are shown in Figure 3. Compared to zeolite, the absorption peaks of 2926 and 1441 cm\({}^{-1}\) were found in PZC 7:3. The absorption peaks of 3630, 1040, and 519 cm\({}^{-1}\) were discovered in PZC 7:3 but were not seen in biochar. According to a previous publication, the stretching vibration of O-H was evinced in the range of 3628-3634 cm\({}^{-1}\)[48]. Both the C-H stretching  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Sample** & **pH** & **EC (\(\mu\)s cm\({}^{-1}\))** & **H/C** & **Zeta Potential (mV)** \\ \hline zeolite & 8.23 \(\pm\) 0.08 \({}^{\rm c}\) & 58.48 \(\pm\) 1.25 \({}^{\rm c}\) & - & \(-\)29.3 \(\pm\) 0.42 \({}^{\rm b}\) \\ \hline biochar & 10.10 \(\pm\) 0.03 \({}^{\rm a}\) & 5490.00 \(\pm\) 106.54 \({}^{\rm a}\) & 0.13 \(\pm\) 0.01 \({}^{\rm a}\) & \(-\)35.43 \(\pm\) 0.4 \({}^{\rm a}\) \\ \hline PZC 7:3 & 9.46 \(\pm\) 0.03 \({}^{\rm b}\) & 1690.75 \(\pm\) 3.57 \({}^{\rm b}\) & 0.09 \(\pm\) 0.00 \({}^{\rm b}\) & \(-\)29.3 \(\pm\) 0.35 \({}^{\rm b}\) \\ \hline \hline \end{tabular} All data represented are means \(\pm\) SD (\(n\) = 4). The various superscript letters indicate statistically significant differences between treatment groups (\(p\) < 0.05).  
\end{table}
Table 1: Physicochemical properties of materials.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Sample** & **SSA (m\({}^{2}\) g\({}^{-1}\))** & **Pore Volume (cm\({}^{3}\) g\({}^{-1}\))** & **Pore Size (nm)** \\ \hline zeolite & 30.27 \(\pm\) 0.96 \({}^{\rm a}\) & 0.0438 \(\pm\) 0.0007 \({}^{\rm b}\) & 5.80 \(\pm\) 0.10 \({}^{\rm c}\) \\ \hline PZ & 29.86 \(\pm\) 0.43 \({}^{\rm a}\) & 0.0499 \(\pm\) 0.0003 \({}^{\rm a}\) & 6.69 \(\pm\) 0.06 \({}^{\rm b}\) \\ \hline biochar & 2.23 \(\pm\) 0.14 \({}^{\rm b}\) & 0.0033 \(\pm\) 0.0004 \({}^{\rm d}\) & 6.02 \(\pm\) 0.15 \({}^{\rm c}\) \\ \hline PZC 7:3 & 2.35 \(\pm\) 0.02 \({}^{\rm b}\) & 0.0056 \(\pm\) 0.0001 \({}^{\rm c}\) & 9.47 \(\pm\) 0.33 \({}^{\rm a}\) \\ \hline \hline \end{tabular} All values represented are means \(\pm\) SD (\(n\) = 4). The various superscript letters indicate statistically significant differences between treatment groups (\(p\) < 0.05).  
\end{table}
Table 2: Pore structure parameters of materials.  
Figure 2: The SEM and EDS images of zeolite, biochar, and PZC 7:3 (SEM images of (**a**–**c**) biochar, zeolite, and PZC 7:3, and EDS images of (**d**–**f**) biochar, zeolite, and PZC 7:3, respectively).  
bands in the range of 2800-3000 cm\({}^{-1}\) and the bands in the range of 1000-1400 cm\({}^{-1}\) were created by the combination and overlapping of C=O stretching bands as well as numerous deformations [49; 50]. In the PZC 7:3, the Si-O-Si skeleton vibration at 1040 and 519 cm\({}^{-1}\) represented the Si-O or Al-O bending vibration [18; 51]. PZC 7:3 not only retained the stabilizing properties of zeolite, but also combined the oxygen-containing functional groups such as -COOH and -OH of biochar, indicating that PZC 7:3 might be beneficial for phosphate removal.