SORPTION PROPERTIES OF OXIDIZED AND NON-OXIDIZED ACTIVATED CARBON FOR COPPER(II) IONS

Abstract

The problem of obtaining effective sorption materials is relevant in connection with the growing volumes of industrial wastewater and the development of individual technologies for their purification, including sorption methods. Activated carbon has established itself as a unique sorbent with a high sorption capacity for compounds of various nature. Modification of its surface, its oxidation leads to an increase in adsorption activity. The aim of this work is to compare the sorption properties of oxidized and non-oxidized activated carbon with respect to copper(II) ions. The concentration of Cu(II) ions in the solution was determined by atomic absorption analysis on an MGA-915 spectrometer. The degree of coal oxidation was characterized by the value of the static exchange capacity. Studies on the model synthetic nitrogen-containing carbon SKN showed the presence of different amounts of oxygen-containing surface functional groups: weakly acidic (lactonic) ‒COO‒; strongly acidic (carboxylic) ‒COOH; phenolic ‒OH. It is shown that without access to oxygen, the mechanisms of interaction of activated carbon of different oxidation states with Cu(II) ions are different: when weakly oxidized carbon is used, reductive sorption occurs, and if highly oxidized carbon serves as a sorbent, ion exchange occurs. It was found that for SKN coal with a low oxygen content, the boundary sorption of Cu(II) ions in a deaerated medium is about 40 mg/g; in the presence of oxygen, it decreases to 6 mg/g. An increase in the proportion of carboxyl and phenolic groups leads to an increase in the sorption of Cu(II) ions. Reductive sorption of copper(II) from aerated solutions is thermodynamically prohibited. It is recommended to use additional oxidation of coal to increase the content of PFG and the sorption capacity of the sorbent. For the extraction of copper(II) from aqueous technological solutions, carbon materials with a sufficient amount of oxygen-containing functional groups of various nature are most effective.