Scholarly record

EFFECTS OF ELECTROKINETIC POTENTIAL, SIZE AND SOLUBILITY OF THE DISPERSED PHASE OF SLIGHTLY SOLUBLE COMPOUNDS OF ALUMINUM (III), ZINC (II) AND PLUMBUM (II) RELATED TO EFFICIENCY OF THEIR SOLIDARY EXTRACTION FROM THEIR AQUEOUS SOLUTIONS THROUGH ELECTROFLOTATION AND FILTRATION

V. А. Brodskiy

Abstract

The research studied the effects of solubility, disperse features (Z average diameter dav, and charge (?-potential) of the particles of heavy-metal slightly soluble compounds exemplified by aluminum (III), zinc (II) and plumbum (II) hydrates related to efficiency of their removal from aqueous solutions in the composition of 2- and 3-component systems by means of electroflotation and filtration within a wide pH-range (5 ? 12). The metals in question demonstrate various pH-values of hydrates formation and solution. This finding allowed to assess contribution of intersorption of hydroxides into efficiency of electroflotation and filtration processes. The research showed that there are three main factors affecting the efficiency of elecroflotation-based removal of slightly soluble compounds of aluminum (III), zinc (II) and plumbum (II) in 2- and 3-component compounds, including the solubility value, disperse features and charge (?-potential) of the dispersed phase of multi-component systems. In turn, these factors are in direct relation to the pH value of the medium. It was found that slightly soluble plumbum (II) compounds can be removed from aqueous solutions only together with slightly soluble compounds of associated metals. High efficiency of electroflotation-based Pb(II) removal from aqueous solutions in the full pH range is determined by sorption of ions and the dispersed Pb(II) phase on the Al(III) and Zn(II) dispersed phase. The size of the disperse phase of multi-component systems is averaged compared to that of individual compounds. So, the size of Pb(OH)2 particles within the whole pH range does not exceed 10 ?m. The maximum particle size of the dispersed phase of multi-component systems comprising Al (III) and Pb (II) hydroxides reaches 24 ?m, Al (III), Zn (II) and Pb (II) hydroxides ? 36 ?m within the pH range 7.5 ? 8.5. At the same time, the particle size of the multi-component systems? dispersed phase is lower than that of aluminum (III) and zinc (II) hydroxides. The same is true for averaging the electrokinetic potential which falls within the range of ?(2 ? 4) mV for all studied systems within the pH range 7.5 ? 8.5. The research showed that the efficiency of removal of aluminum (III), zinc (II) and plumbum (II) compounds from wastewater through electroflotation reaches 90% to 97% within the pH range 7.5 ? 8.5. Further filtration of solutions allows to increase removal to 98% and more. pH increase leads to decreased efficiency of elecroflotation-based treatment of aqueous solutions, due to starting solution of aluminum hydrate, which serves as a coagulant for Pb (II) ions and slightly soluble compounds.

Publication details

Back to publication list