## 3 Results and Discussion  
The changes in concentration of tested vapours in all the tested cases were characterised by expotential fading in kinetic range. The authors of the article postulate that the course of the process may be described with the use of a differential equation similar to reaction of the pseudo first order in which the apparent constant absorption rate \(k_{p}\) comprises the effectiveness of the water curtain, droplet distribution of droplets forming the absorption surface \(S_{w}\) within a time unit, coefficient of jet geometry, and time of droplet falling through the gas cloud according to Equation (1):  
\[-\frac{d[A]}{dt}=-k_{p}[A]=-k_{G}S_{w}t_{f}[A]=-kGt_{f}S_{w}[A] \tag{1}\]  
in which  
* concentration of vapours of the tested substance in the chamber [ppm]
* coefficient of jet geometry understood as a volume covered by the jet of the curtain in relation to the volume of the measurement chamber
* actual constant of the rate of absorption process [m\({}^{-2}\) s\({}^{-1}\)]
* apparent constant of the rate of absorption process [s\({}^{-1}\)]
* geometric constant of the rate of absorption process [m\({}^{-2}\) s\({}^{-1}\)]
* absorption surface generated in a time unit [m\({}^{2}\) s\({}^{-1}\)]
* time of droplet passage through gas cloud [s]  
A similar exponential nature of curves depicting concentration dependencies in the function of time has already been recorded beforehand for ammonia [19]. Such an assumption appears to be justified and results from the conditions of the experiment. Continuous administration of water in significant excess to sorbed substances causes its concentration to be considered constant. Furthermore, the rate of the absorption process could depend on such elements as speed of substance diffusion to the surface of the falling droplet, process of substance bonding on the droplet surface, local changes of pressure connected with splaying the liquid jet from the curtain that hasten the diffusion rate, permeation of the substance inside the droplet, time of droplet dropping from the curtain to the ground surface, and geometry of jet from the nozzle in relation to the geometry of the measurement chamber. Since gas is intensively mixed by the stream of the water curtain, the process speed will not be controlled by diffusion but instead by the sorption rate. In this case, a linear dependence of the sorption rate vs. time can be expected. Therefore, the amount of absorbed substance on the droplet surface should be directly proportional to the flight time of the drop in a cloud of sorbed gas. The same relationship occurs, for example, for electrochemical processes in which the rate of processes controlled by adsorption is directly proportional to the rate of change of potential [20; 21]. For diffusion-controlled processes, mixing solutions with inert gas increases the diffusion rate. Under these conditions, the process rate is controlled by other steps (e.g., adsorption or chemical reaction) [20]. After a longer time of curtain operation, the absorption rate of vapours also depends on the dynamic balance state between liquid vapours and the solution formed from the curtain (if the solution is not drained from the chamber, what is equivalent to a situation of faulty work of a sewer on warehouse area). The effectiveness of the water curtain in a time unit (\(q\)) is in proportion to the number of droplets (\(n\)) administered in a time unit and the average volume of a single droplet (\(V_{k}\)) according to Equation (2):  
\[q=\frac{n\cdot V_{k}}{t}=\frac{4n\pi R^{3}}{3t} \tag{2}\]  
in which  
* effectiveness of the water curtain in time unit [m\({}^{3}\)/s]\(V_{k}\):average volume of single droplet [m\({}^{3}\)]  
\(R\):average radius of single droplet [m]  
The sorption surface generated in a time unit by the stream of falling droplets \(S_{w}\) may be related to the water effectiveness of the curtain \(q\), time of half-life concentration reduction \(\mathbf{t_{1/2}}\), and geometric constant of process rate \(k_{G}\), which is presented in Equations (3) and (4).