# The Experimental Study of Innovative Methods Regarding the Removal of Sm(III)
## 2 Materials and methods  
### Ion Flotation  
According to data by foreign researchers, an increase of effectiveness in current technologies at the expense of accompanying extraction of valuable components from production wastes [7; 8] is possible when using ion flotation methods [17] in the mining industry. The consequence of the decrease of REE toxicity and risk of damaging the environment is presumed. In papers [5; 6; 7], the ion flotation method is proposed for REE removal from apatite sulphuric acid processing products by different anion surfactants. At the production scale, the ion flotation process permits the preventing of sediment formation, REE loss, and usage of expensive extractants.  
In particular, the ion flotation method is commercially used for the removal of non-ferrous, rare-earth, and radioactive metal cations from industrial and residential wastewaters [11]. In addition, when using different types of flocculants and coagulants, wastewater treatment for petroleum and oil impurities by the ion flotation method is possible [12]. When reaching certain conditions, the ion flotation process provides almost a 100% recovery of precious metals from solutions [18; 19].  
This work studies the distribution of Sm+3 ions in \"water phase\"--\"froth phase\" systems formed by standardized test solutions containing Sm3+ ions and a surfactant--sodium dodecyl sulphate. A diagram of the lanthanide flotation machine is shown in Figure 2. NaDS is used as one of the most common and well-studied surfactants. (CCM) is 8 \(\times\) 10\({}^{-3}\) mol\(\cdot\)kg\({}^{-1}\) at 20 \({}^{\circ}\)C [1]. It is evident that this permits using solutions with a concentration below this value.  
Figure 1: World’s consumption pattern of REM [3].  
For reasons of the surfactant economy and achievement of the concentration effect, it is reasonable to use a minimum amount of collector, close to its stoichiometric consumption in accordance with the reaction:  
\[\text{Me}^{3+}+3\text{C}_{12}\text{H}_{25}\text{OSO}_{3}\text{Na}=\text{Me}[ \text{C}_{12}\text{H}_{25}\text{OSO}_{3}]_{3}+3\text{Na}^{+} \tag{1}\]  
The chemically pure grade samarium nitrate hexahydrate was used. The initial concentration of samarium nitrate solution was 0.001 mol/L and the sodium dodecyl sulphate concentration was three times higher: 0.003 mol-L\({}^{-1}\) or 0.864 g/L (DS\({}^{-}\), dodecyl sulphate ion). The pH value of the solution was monitored by the \"Anion 7010\" ion meter with a glass electrode [18]. To find out the pH value of the solution, the nitric acid solution or sodium hydroxide solution were used.  
The ion flotation process was conducted on the flotation machine (Figure 2) [19]. In total, 200 mL of samarium nitrate solution with the concentration of 0.001 mol/L and dry NaDS were added to the cuvette. The process continued for no more than 5 min. The picked-out froth was broken by 5 mL sulphuric acid solution with the concentration of 1 mol\(\cdot\)L\({}^{-1}\). The obtained solution (froth pulp) and the solution remained in the cuvette after flotation (chamber residue) and were analyzed for REE content by using the method in [20] and for dodecyl sulphate ion content by the potentiometer method [21; 22].