THE pH AND MEDIUM COMPOSITION IMPACT ON THE EFFICIENCY OF ELECTROFLOTATION-BASED EXTRACTION OF SLIGHTLY SOLUBLE IRON, CHROMIUM AND MANGANESE COMPOUNDS FROM WATER SOLUTIONS AND PHYSICAL-CHEMICAL PROPERTIES OF THESE COMPOUNDS

The study demonstrates the pH and solution ion composition impact on the average hydrodynamic diameter dm and electrokinetic potential (5-potential) of the dispersed phase of slightly soluble ferrous metals compounds. VW examined formation dispersed phases of slightly soluble Fe (III), Cr (III), and Mn (II) compounds in the presence of OH-, CO32-, PO43- ions as precipitating agents and anionic, cationic, and non-ionic flocculating agents. The electroflotation-based extraction of slightly soluble ferrous metals compounds was found to be directly linked to dispersity and electrokinetic potential of particles, that depend on acidity and ionic medium composition. The maximal hydrodynamic diameter of dispersed phases of the slightly soluble Fe (III), Cr (III), and Mn (II) compounds were observed at isoelectric point and corresponded with pH value of the minimal dispersed phase solubility In this case, electroflotation-based extraction was more efficient, the iron (III), manganese (II), and chromium (III) removal a reached 98, 96, and 83 %, respectively Cationic flocculating agent additives increased the iron, manganese, and chromium extraction up to 99, 98, and 94 %, respectively. If carbonate and phosphate ions were added, the electrokinetic potential of compounds of all examined slightly soluble metals changed to negative value& -(12 -19) mV in the presence of CO32- ions and -(35-43) mV in the presence of PO32- ions. This shift hindered coagulation and decreased electroflotation-based extraction of the dispersed phases, especially in case of manganese compounds (a 5 10%). Cationic and non-ionic flocculating agents additives balanced the high negative charge of the dispersed phases of slightly soluble ferrous metals compounds, enlarged the removal up to 98% depending on the dispersed phase and flocculating agent.

Automated summary

The study demonstrated the impact of pH and solution ion composition on the average hydrodynamic diameter and electrokinetic potential of slightly soluble ferrous metals compounds. Cationic flocculating agents increased the extraction efficiency, while carbonate and phosphate ions resulted in a negative shift in electrokinetic potential and decreased extraction efficiency. Balancing the negative charge of the dispersed phases with cationic and non-ionic flocculating agents led to an increase in removal efficiency.