## 3 Results and Discussion  
### Investigation of the Mechanism of Sediment Formation in Sediment-Gelling Compositions  
The purpose of this series of research was to study and evaluate the effect of the concentrations of polyacrylamide and alkali on the amount of precipitation. The amount of precipitate formed upon contact of the polymer and alkali was determined using a preweighed paper filter placed on a glass plate at the bottom of a 1 L beaker. An amount of 1 L of a polymer solution of a given concentration was poured into a beaker; then, a certain amount of NaOH was added to achieve the required alkali concentration. After holding the prepared composition for 48 h, the glass plate with the paper filter was removed from the beaker and placed in a drying cabinet, where it was dried at a temperature of 105 \({}^{\circ}\)C and then weighed again, and the amount of precipitate formed was determined by the difference in weights before and after it was placed in the beaker. The results obtained, expressed in milligrams per 1 L of solution, are presented in Table 1. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{6}{c}{**PAA Concentration, \%**} \\ \cline{2-6}
**Alkali** & **0.025** & **0.05** & **0.075** & **0.1** & **0.15** \\ \cline{2-6}
**Concentration, \%** & \multicolumn{6}{c}{**Sediment Amount, mg/L**} \\ \hline
0.1 & 0.285 & 0.245 & 0.22 & 0.16 & 0.14 \\ \hline
0.12 & 0.25 & 0.23 & 0.195 & 0.18 & 0.15 \\ \hline
0.15 & 0.24 & 0.21 & 0.19 & 0.185 & 0.16 \\ \hline
0.25 & 0.17 & 0.15 & 0.18 & 0.25 & 0.28 \\ \hline
0.5 & 0.35 & 0.255 & 0.23 & 0.33 & 0.457 \\ \hline
0.75 & 0.45 & 0.36 & 0.31 & 0.47 & 0.615 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Dependence of the amount of precipitate formed on the concentrations of the polymer and alkali components of SGCs [1,2]. As can be seen from Table 1, at polymer concentrations in solution of 0.025-0.075%, an increase in alkali concentration from 0.1 to 0.25% leads to a decrease in sediment; with its further increase to 0.75%, an increase in the amount of sediment is observed. At polymer concentrations in the solution of 0.1-0.15%, with an increase in the concentration of alkali in the solution from 0.1 to 0.75%, only an increase in precipitation is observed. The results of these experimental studies were processed by us, using the methods of mathematical statistics. Moreover, partial dependences of the amount of sediment on the concentration of alkali were built at constant values of the PAA concentration given in the table. An analytical dependence of the amount of sediment on the concentration of alkali was established for different cases. Next, the dependence of the parameters of this expression on the PAA concentration was determined. Thus, we obtained the dependence of the amount of sediment on the concentrations of alkali and PAA in the following form:  
\[v=f(k_{NaOH},\;k_{PAA}), \tag{1}\]  
Below are the results of the calculations. Figure 1 demonstrates graphs of the noted dependences of the volume of the precipitate on the concentration of alkali at constant concentrations of polyacrylamide. Approximations of each of the dependences shown in the figure were obtained by statistical processing. The most suitable in this case and common for all cases is the dependence in the form of a power law, expressed as follows:  
\[V_{sd}=aC_{NaOH}^{b}, \tag{2}\]  
where parameter \(b\) depends on the concentration of polyacrylamide. The values of parameter b depend on the concentration of polyacrylamide.