## 4 Results and Discussion
### Evaporation Rate of Sorbate Sorbed on Sorbent  
As regards physical sorption, it is necessary to monitor the evaporation of sorbate sorbed on sorbent. In order to verify the thesis and quantify the phenomenon, comparative samples of the tested specimens were prepared, on which n-heptane and ethanol had been sorbed. These compounds undergo physical sorption, while ethyl alcohol on the edge and corner atoms of MgO-TiO\({}_{2}\) nanocrystallites should also undergo chemical sorption to form Mg(OH)(OC\({}_{2}\)H\({}_{5}\)) [46]. It was noticed that at the mass ratio sorbent sorbate 3:1 (which is far from maximal sorptivity), the weight loss of sorbate from FA is similar in magnitude and even greater than the weight loss recorded for evaporation from the surface of pure sorbate (Figures 5 and 6). This confirms the thesis of the decisive role played by physical sorption in the case of hydrocarbons and monohydric alcohols. However, increased evaporation could also result from the very large specific surface area. In both cases, CDE containing 0.5-1 mm grains turned out to be the sorbent releasing the least amount of vapors, which is due to the fact that the grains have a much less developed surface.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Sorbent** & **S\({}_{\text{w}}\), kg\({}^{-1}\)kg\({}^{-1}\)** & **S\({}_{\text{v}}\), dm\({}^{-3}\)dm\({}^{-3}\)** \\ \hline CDE & 1.11 & 0.52 \\ \hline PC (non-activated H\({}_{2}\)O) & 1.15 & 0.37 \\ \hline PC (activated H\({}_{2}\)O) & 2.40 & 0.78 \\ \hline EP & 4.58 & 0.31 \\ \hline FA & 1.10 & 0.45 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Maximal sorptivity relative to benzene expressed in [g/g] and [dm\({}^{3}\)/dm\({}^{3}\)] for MgO-TiO\({}_{2}\) neutralizer (FA) and selected sorbents used in rescue operators during uncontrolled release of chemical substances (CDE, PC, EP).  
Figure 5: The weight loss of the sample as a function of time during free evaporation from the Petri dish with a diameter d = 9 cm for the system: (**1**) n-heptane–pure, (**2**) CDE:n-heptane, mass ratio 3:1, (**3**) FA:n-heptane, mass ratio 3:1, (**4**) PC:n-heptane, mass ratio 3:1, (**5**) EP:n-heptane, mass ratio 3:1. Temperature T = 22 \({}^{\circ}\)C, relative humidity H = 25%.  
Studies of ethanol evaporation rate (dmdt\({}^{-1}\)S\({}^{-1}\)) at different mass ratios sorbentsorbate (configuration FA:ethanol) indicate that no mass loss occurs if ethanol content in the sample exceeds 5.58% (Figures 7 and 8). Below this ethanol concentration value the mass of arrangement starts to increase. This is due to the absorption of water vapor from the air by the FA.  
Figure 6: The weight loss of sample as function of time during free evaporation from the Petri dish with a diameter d = 9 cm for the system: (**1**) CDE:ethanol, mass ratio 3:1, (**2**) ethanol–pure, (**3**) FA: ethanol, mass ratio 3:1, (**4**) PC: ethanol, mass ratio 3:1, (**5**) EP:ethanol, mass ratio 3:1. Temperature T = 22 \({}^{\circ}\)C, relative humidity H = 25%.  
Figure 7: The loss weight of the sample as a function of time during free evaporation from the Petri dish with a diameter d = 9 cm for the system FA:ethanol with mass ratio: (**1**) 10:0.5, (**2**) 10:1, (**3**) 10:1.5, (**4**) 10:3, (**5**) 10:5. Temperature T = 22 \({}^{\circ}\)C, relative humidity H = 25%.  
Physical sorption means that comprise MgO-TiO\({}_{2}\) nanooxides do not allow achieving better results for the sorption of hydrocarbons and alcohols than sorbents used so far by rescue units. Considering the price of FA and its hygroscopicity, this limits its use during uncontrolled releases of this very numerous group of organic substances.