ADSORPTION OF HEAVY METAL IONS BY BENTONITE MODIFIED WITH CARBON NANOTUBES AND ACTIVATED WITH ACID
At present, there is no doubt about the need to search for new, more advanced methods and means of treating industrial wastewater. The adsorption method is one of the effective methods for purifying the aquatic environment. One of the sorption materials is bentonite, modified in different ways (by roasting, adding organic components, etc.). Laboratory studies were carried out on the bentonite of the Sarigyukh deposit (Republic of Armenia). The adsorption capacity of bentonite modified with carbon nanotubes with roasting at a temperature of 550°C and subjected to activation with HCl acid was investigated experimentally. It was found that acidic (HCl) activation of bentonite modified with carbon nanotubes and calcined at 550°C promotes an increase in its adsorption activity towards nickel (II) and cadmium (II) ions. The degree of adsorptive extraction of nickel (II) ions after activation of the specified adsorbent with HCl increases by 10%, and the degree of adsorptive extraction of cadmium (II) ions after a similar activation increases by 11%. The characteristics of the efficiency of adsorption of nickel (II) and cadmium (II) ions under static conditions were found with bentonite modified with carbon nanotubes and fired at 550°C, subjected to acid activation with HCl and without it. Bentonite modified with carbon nanotubes, calcined at 550°C and activated with HCl acid showed the greatest adsorption effect with respect to the ions of these metals. Its parameters: in relation to Ni <sup>2+ </sup>ions: СОЕ = 852.0 mg-eq/g, Kd = 243.42 mg/dm<sup>3</sup>, S = 95.4%; to Cd<sup>2+</sup> ions: COE = 950 mg-eq/g, Kd = 263.89 mg/dm<sup>3</sup>, S = 92.0%. The results of laboratory studies made it possible to recommend bentonite modified with carbon nanotubes, fired at 550° C and activated with HCl acid as a sorption material for purifying wastewater from nickel (II) and cadmium (II) ions.