Determination of the influence of basic parameters on the solvent sublation of anionic dye

The object of research is wastewater contaminated with anionic dyes. Traditional methods of wastewater treatment from dyes are imperfect and inefficient or non-existent. Therefore, the need to develop and implement effective and inexpensive to use and operate dye removal technologies is important. The biggest problem in dye removal is when large volumes of low concentration wastewater have to be treated. To purify just such effluents, a combined method, solvent sublation, has been proposed. It combines flotation and extraction methods and has the benefits of both. The essence of the method is the passage of gas bubbles through the aqueous phase and the transport of a hydrophobic complex (sublate) formed by a dye and a surfactant into the organic phase. The study used imitates of wastewater contaminated with an anionic dye, active bright blue in the concentration range of 5–50 mg/dm3. The influence of the main parameters on the degree of dye removal was studied: the pH of the initial solution, the molar ratio of surfactant: dye, the size of air bubbles, the gas flow rate, the initial concentration of the dye, the duration of solvent sublation. Rational parameters of the process have been established, which are advisable to use in solvent sublation: – purification process must be carried out in the presence of a cationic collector hexadecyltrimethylammonium bromide; – extractant – isoamyl alcohol; – molar ratio Dye: surfactant=1:1.5; – pH 5.5; – generation of gas bubbles by a Schott filter with a porosity of 40 µm; – gas flow rate – 127 cm3/min. Under such conditions, the removal efficiency of active bright blue is 97 % at a process time of 10–25 min. The results obtained confirm the promise of the proposed method for the effective removal of dyes from low-concentration aqueous solutions. The method has a number of advantages: it requires a small amount of extractant compared to liquid extraction; ions are concentrated in small volumes of an organic solvent; the process proceeds without phase mixing, so no emulsions are formed.