## 3 Results and Discussion
### Adsorption Isotherms of MIPs  
The adsorption isotherms of MIPs and NIPs are presented in Figure 4A. The adsorption isotherm was obtained via the binding experiment using 10 mg of the MIP1 and NIP1 with the gossypol methanol solution. As shown in Figure 4A1, the gossypol adsorption capacity of MIPs and NIPs both increased at equilibrium time with increasing concentration of gossypol. The binding capacity of MIPs was 13-15% higher than that of NIPs for gossypol. Results supported the hypothesis that imprinted sites were indeed generated and were beneficial for gossypol recognition and rebinding in MIPs. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multirow{2}{*}{\(Q_{\mathrm{e}}\), exp} & \multicolumn{3}{c}{**Pseudo-First-Order**} & \multicolumn{3}{c}{**Pseudo -Second-Order**} \\  & & **(mg g\({}^{-1}\))** & **(mg g\({}^{-1}\))** & **(min\({}^{-1}\))** & **(mg g\({}^{-1}\))** & **(g mg\({}^{-1}\) min\({}^{-1}\))** & **\(R^{2}\)** \\ \hline MIP1 & 139.00 & 126.82 & 0.01869 & 0.9006 & 138.56 & 1.84\(\times 10^{-4}\) & 0.9633 \\ MIP2 & 77.05 & 74.94 & 0.5490 & 0.9936 & 76.54 & 0.02523 & 0.9976 \\ MIP3 & 50.95 & 39.36 & 0.3924 & 0.9750 & 49.30 & 0.01772 & 0.9915 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Kinetic parameters for the adsorption of gossypol onto MIPs and NIPs prepared on 60 \(\upmu\)m spherical silica gel support. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Samples** & **\(\mathbf{f_{e}}\) (min)** & **\(\mathbf{Q_{\mathrm{MIP-e}}\) (mg\(\cdot\)g\({}^{-1}\))** & **\(\mathbf{Q_{\mathrm{NIP-e}}\) (mg\(\cdot\)g\({}^{-1}\))**} & **IF** \\ \hline MIP1 & 720 & 139.00 & 122.00 & 1.14 \\ MIP2 & 40 & 77.05 & 30.50 & 2.53 \\ MIP3 & 140 & 50.95 & 41.95 & 1.22 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Adsorption equilibrium times (\(t_{\mathrm{e}}\), min), adsorption capacities at equilibrium (\(Q_{\mathrm{e}}\), mg\(\cdot\)g\({}^{-1}\)), and imprinting factors (IF) of MIP 1, MIP2, and MIP3. The binding isotherm was also obtained to establish the relationship between the binding capacity and equilibrium concentration for MIP2. The equilibrium adsorption capacity increased with increasing initial concentration of gossypol (Figure 4A2), which was reasonable considering the concentration gradient could be an effective driving force that would propel the diffusion of the template gossypol into the channels and cavities in MIP2 [32]. The amount of gossypol adsorbed by MIP2 once it reached saturation was 120 mg g\({}^{-1}\) at 1600 mg L\({}^{-1}\) gossypol concentration. The absorption isotherm of NIP2 was also obtained. The saturated adsorption capacity was 42 mg g\({}^{-1}\), which was much lower than that of MIP2. This result supported the formation of the gossypol imprinted sites in MIP2 compared to the control of NIP2. Additionally, MIP2 showed significantly higher adsorption capacity compared to that of NIP2 throughout the whole concentration range. This indicated that the molecularly imprinted polymer exhibited a strong memory effect and excellent imprinting for template gossypol. The adsorption capacities of MIP3 and NIP3 were compared with MIP1, NIP1, MIP2, and NIP2. As shown in Figure 4A3, when the MIP3 was made via the sol-gel process without adding the silica gel support, the difference in adsorption capacity between MIP3 and NIP3 was relatively small. MIP3 still exhibited a relatively higher adsorption capacity than that of NIP3, suggesting the formation of imprinted sites. The maximum adsorption capacities of MIP3 and NIP3 for gossypol were 61.8 mg g\({}^{-1}\) and 51.8 mg g\({}^{-1}\), which were much lower than those of MIP1 (\(Q_{\text{exp}}\) = 564 mg g\({}^{-1}\)) and MIP2 (\(Q_{\text{exp}}\) = 120 mg g\({}^{-1}\)). Figure 4: **(A)** Adsorption isotherms of MIPs and NIPs for gossypol; **(B)** evaluating binding models by nonlinear fitting of binding isotherm for MIPs and NIPs for gossypol (**A1**, **A2**, and **A3**: 10 mg of absorbents in 5.0 mL gossypol in methanol at different concentration for 12 h).