## 3 Results and Discussion
### Synthesis of the MIPs on Lead Nitrate  
The formation of a stable complex between the monomer and the template molecules before polymerization is an essential requirement for the production of MIPs. That is why different molar ratios of raw materials were studied in order to obtain an effective MIP with stable bonding with the template. At first, the synthesis was carried out with proportions of 1:2:2:8 (template/monomer-1/monomer-2/cross-linker), but the polymer did not turn out. Then, synthesis was tried with 1:4:4:8, but the polymer structure turned out to be insufficiently porous. It was decided to increase the ratio to 1:5:5:8, and the result was positive. The results of these syntheses are summarized in Table 2. From these results, it can be concluded that the ratios of template and monomers of 1:2 and 1:4 are not enough to make MIP, i.e., the amount of monomers is not enough to make a pre-polymerization complex with a template. Briefly, synthesis was carried out according to the following scheme. Firstly, the template lead(II) nitrate, monomers MAA and 2-VP, and cross-linker DVB were measured and weighed in a molar ratio of 1:5:5:8, respectively. Then, the template dissolved in distilled water and the monomers were mixed in a three-necked round-bottom flask using a magnetic stirrer until homogeneity. Afterwards, toluene and HEC were added as porogens and the mixture was stirred for 15 min. DVB and initiator AIBN were added. Then, the system was blown up by argon. The flask was placed in a water bath and kept for 6 h at 60 \({}^{\circ}\)C with constant stirring. The resulting mixture was centrifuged in order to separate the oil part from the water part. To remove the unreacted substances and template, the dialysis process was used. To accomplish this, the water part was poured into the cellulose membranes, making them into a shape similar to \"sausages\". Then, dialysis was carried out for 4 days, the first day in ethanol, the second in water, the third in a weak solution of nitric acid, and the last day in water. The solvent for the dialysis was changed several times during a day for better purification of the copolymer. After this, the MIPs were freeze-dried. After freeze-drying, porous, white-colored cotton-wool-like structures were obtained, as shown in Figure 3. Along with this, an organoleptic analysis of the resulting MIP was carried out (Table 3). In order to study the structure of the obtained MIP, the samples were transferred to IR spectroscopy for analysis of the MIP composition. The results of the IR spectroscopy analysis are shown in Figure 4, and the description of the IR spectra is indicated in Table 4.  
According to the obtained IR spectra (Figure 4) of the MIP on lead(II) nitrate, the following description can be made. The broad band with a peak at 3433.32 cm\({}^{-1}\) could be defined as an -OH group with hydrogen bonding. The band at 1626.25 cm\({}^{-1}\) is characteristic of carboxylate anion. Also, a narrow peak is observed at 1474.38 cm\({}^{-1}\), which can be \begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{1}{c}{**Functional Group**} &
\begin{tabular}{c} **Wavenumber, cm\({}^{-1}\)** \\ **(Theoretical Data)** \\ \end{tabular} & **Wavenumber, cm\({}^{-1}\)** \\ \hline -OH & 3550–3400 & 3433.32 \\ \hline -CH\({}_{2}\)- & 2940–2915 & 2926.46 \\ \hline -COO\({}^{\prime}\) & 1650–1550 & 1626.25 \\ \hline -CH\({}_{2}\)-CO- & 1440–1400 & 1474.38 \\ \hline Pyridine ring & 1100–1000 & 1063.98 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Characteristics of the IR spectrum frequencies for MIP of lead(II) nitrate. Figure 4: IR spectroscopy of the MIP of lead(II) nitrate. relative to an -CH\({}_{2}\)-CO- group. All these bands could characterize the functional group of methacrylic acid. The second monomer 2-VP could be defined in the IR spectrum by the intensive broad band at 1063.98 cm\({}^{-1}\). The valence oscillation of the -CH\({}_{2}\)- group is usually in the form of several either weak or variable-intensity bands with a wavenumber of 2926.46 cm\({}^{-1}\).