Abstract
Ion exchange is one of the methods that has been successfully employed in industry for extracting heavy metals from wastewater. We conducted research into ion-exchange processes of extraction of heavy metal ions on the weak- and strong-acid cationites from distilled and tap water. Heavy metal ion concentration was less than 1 mg/dm 3 . We established that in all cases efficiency of water treatment decreased at a decrease in the starting concentration of a metal. The process took place regardless of the degree of saturation of cationites with the ions of heavy metals or hardness ions when extracting copper from water. It is proposed to apply filters with combined action. It was established that at a concentration of copper ions of 10 -2 mkg/dm 3 , copper did not sorb even when using filters with combined action. It is shown that effectiveness of the extraction of copper depends on the volume of filtering load. The concentration of copper ions in water was reduced to 0.053 mg/dm 3 . It was established that lead ions are almost completely extracted on a strong-acid cationite at concentrations less than 0.1 mkg/dm 3 . When removing lead ions, the degree of extraction grew while lowering the starting concentration of ions. Residual concentrations were below a sensitivity limit of the method − 10 -3 mkg/dm 3 (10 -9 g/dm 3 ). The processes of regeneration of strong- and weak-acid cationite were explored. Regeneration should be conducted applying the 2M solution of hydrochloric acid. Lead ion desorption efficiency reaches 100 %. It was found that the desorption efficiency increases with a decrease in the mass of sorbed lead. The degree of copper ion desorption in some cases reaches about 90 %.
Highlights
The end of XX and the beginning of XXI century brought outstanding scientific and technological achievements, and a considerable deterioration in the condition of environment as a result of its significant pollution.Ukraine has limited supplies of fresh water and has almost lost the clean surface water that would meet the requirements for water quality for household and drinking purposes
At present, the analyzed data from the scientific literature fail to evaluate the efficiency of extraction from water the ions of heavy metals employing an ionic exchange at concentrations lower than 1 mg/dm3 (at and below the level of their boundary admissible concentration (BAC) in natural waters)
Based on the known information about high efficiency of filters with combined action during deep deionization, we studied the processes of extraction of copper ions from water using a mixture of the cationite KU-2-8 in the acidic form and the anionite AV-17-8 in the basic form (Fig. 5)
Summary
The end of XX and the beginning of XXI century brought outstanding scientific and technological achievements, and a considerable deterioration in the condition of environment as a result of its significant pollution. Lakes, underground water, moderate artesian water used for drinking water supply has largely lost quality due to excessive contamination with sewage. Pollution of water bodies leads to a significant increase in the level of mineralization of the reservoir, to a significant increase in the hardness of water. Even though the compounds that are formed during the hydrolysis of heavy metals are difficult to solve, the fact that contributes to the creation of false notions about the low content of heavy metals in natural waters, the real situation is much more complicated. That is why reliable control over the content of heavy metals in water is a relevant issue, as well as determining efficiency of the known methods for purifying water at low concentrations of the ions of heavy metals
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