Heavy metals are the most dangerous biological pollutants of the environment. To remove ions of heavy metals from waste waters chemical sedimentation, aqueous extraction, ion exchange, electrodialysis are being used. All these methods have some significant disadvantages, that’s why search for the new, more developed and economical methods which allow not only removing toxic ions but also regenerating valuable components is one of the basic development courses in water treatment technologies.
Solvent sublation is a progressive development of ionic flotation. Separation of substance which was floated by bubbles (sublate) that concentrates in a layer of organic liquid on the surface of aqueous phase is a characteristic feature of solvent sublation process.
The objective of this work was the research of heavy metals solvent sublation process using copper ions as an example. Besides determination of process carrying out rational conditions, researches were aimed at the study of compounds compositions, which are formed during the process, detection of process stages and factors, which allows increasing extraction ratios, distribution and concentration of metal ions. To create sublate sodium and potassium foams of saturated carboxylic acids were used. It is known that saturated fatty acids belong to surface-active compounds (surfactants) and are used as collector during flotation for a while, thanks to their formation of insoluble compounds with metal ions and surface activity. To increase effectiveness of copper ions collectors-surfactants were chosen experimentally: sodium caprylate and potassium laurate, isoamyl alcohol as organic solvent.
Solvent sublation was carried out in cylindric glass column with diameter of 35 mm, the bottom of which was the Schott filter. Through the porous partition gas (nitrogen) was supplied from gas cylinder under pressure. Rotameter controlled nitrogen consumption. The volume of model solution equals 200 cm3, volume of organic phase equals 5 cm3. Solvent sublation process was carried out right before establishing of constant residual metal concentration, which was determined by photometric method. As effectiveness measure of solvent sublation process degree of metal extraction was chosen X, %. Patterns of Cu2+ ions extraction in concentration range of 20-200 mg/dm3 from aqueous solutions were researched by solvent sublation method. As a result of experiments it was discovered that maximum extraction ratio of sodium laurate as a collector equals 99,5 % and using potassium caprylate – 98%. Optimal pH of process is 5,2. By decreasing pH value sublate continuously dissolves and by increasing pH value sublate is also destroyed but with formation of insoluble copper hydroxide. Optimal time for process equals 15 minutes.