## 3 Results and Discussion
### Comparison  
In the literature, the comparison of adsorbents is mainly based on the contaminant uptake capacity, which is mostly reported on the basis of per unit mass. Uptakes as high as 500 to 600 mg/g have been reported when using activated carbon cloth [12], while employing a relatively high initial concentration of the antibiotics. However, [PERSON] et al. [13] recently used the adsorbent surface \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Kinetic Models** & **MNZ** & **DMZ** & **RNZ** & **TNZ** \\ \hline \(\theta_{\text{experimental}}\) (mg/g) & 27.04 \(\pm\) 0.049 & 26.10 \(\pm\) 0.100 & 25.02 \(\pm\) 0.072 & 24.00 \(\pm\) 0.042 \\ \hline Pseudo-first-order & & & & \\ \(q_{e}\) (mg/g) & 23.19 & 21.97 & 21.74 & 21.72 \\ \(k_{1}\) (1/min) & 0.1651 & 0.1457 & 0.14650 & 0.1324 \\ \(R^{2}\) & 0.9723 & 0.9537 & 0.9579 & 0.9720 \\ \hline Pseudo-second-order & & & & \\ \(q_{e}\) (mg/g) & 31.38 & 30.72 & 30.07 & 30.17 \\ \(k_{2}\) (g/(mg min)) & 0.0089 & 0.0079 & 0.0072 & 0.0055 \\ \(R^{2}\) & 0.9954 & 0.9862 & 0.9827 & 0.9784 \\ \hline Intraparticle & & & & \\ diffusion & & & & \\ \(K_{i}\) (mg/g-min\({}^{0.5}\)) & 3.5283 & 3.1826 & 3.2955 & 3.7271 \\ C & 11.273 & 10.934 & 9.469 & 6.298 \\ \(R^{2}\) & 0.9989 & 0.9773 & 0.9583 & 0.9783 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Kinetic parameters for nitroimidazole adsorption onto SiC NPs. Figure 6: Pseudo-second order kinetic model for nitroimidazole adsorption onto SiC NPs (\(C_{0}\) = 30 mg/L, \(T\) = 25 \({}^{\circ}\)C; adsorbent dose = 0.1 g, pH = 8). area as a basis for evaluating the adsorbent performance. The reported uptake in their case reached \(567\times 10^{-3}\)mg/m\({}^{2}\), which was higher than the other adsorbents previously reported in the literature. In the present case, the adsorption capacity varied from 115 to 127 mg/g, which in terms of the surface area, is \(2907\times 10^{-3}\) to \(3211\times 10^{-3}\)mg/m\({}^{2}\). Thus, the values obtained in the present investigation are several times higher than the highest reported so far [13]. Moreover, as pointed out earlier, adsorbents with faster contaminant removal rates are of paramount importance for an efficient and cost-effective implementation of the adsorption-based separation process. Since previous research has focused on improving the adsorption capacity, most adsorbents developed so far generally show a slow uptake of the nitroimidazoles. For example, activated carbon samples using Siris seed pods with second order adsorption kinetics, took almost 180 min to reach equilibrium [10; 11]. On the other hand, the adsorption kinetics of activated carbon cloth with one of the highest adsorption capacities per unit mass, was even slower; taking as long as 220 min to reach equilibrium. The adsorbents prepared by [PERSON] et al. [13], with an equilibrium time of 50 min, appear to be faster than most other previously reported adsorbents. However, in the present case, the adsorption kinetics were even faster. The rate constants were 0.0089, 0.0079, 0.0072, and 0.0055 g/(mg min), for MNZ, DMZ, RNZ, and TNZ, respectively. These values are several times higher than those reported by [PERSON] and [PERSON] [10; 11]. Therefore, the time to reach equilibrium in the present case of the SiC adsorbent was only 20 min, which appears to be shorter than most other adsorbents with a similar adsorption capacity reported in the literature. Since the adsorption is a surface-based rate process, which depends upon the availability of vacant sites on the surface, an adsorbent with a large surface area usually yields a high removal capacity. On the other hand, as far as the removal kinetics are concerned, easy access to the available vacant sites is of paramount importance, owing to the presence of the mass transport resistances, which hinder the movement of adsorbate molecules. Of particular concern is the internal mass transport resistance occurring inside the pores of the adsorbent.