Kharkov National Automobile and Road University (Kharkov, Ukraine):

E. B. Khobotova, Dr. Chem., Prof., Dept. of Technology of Road Construction Materials and Chemistry, E-mail: elinahobotova@gmail.com; chemistry@khadi.kharkov.ua
I. V. Graivoronskaya, Cand Eng., Associate Prof., Dept. of Metrology and Safety of Life Activity, E-mail: inna_gra@ukr.net

Industrial waste accumulating in dumps, in many cases, have valuable technical properties, so they can be considered as secondary resources. If the waste contains mineral phases with sorption activity, they can be used in sorption technologies for wastewater treatment. This approach solves a number of problems: stimulating resource conservation, eliminating waste dumps and treating wastewater. The choice of metallurgical slags as sorbents is relevant. The purpose of the research is the substantiation of the principled possibility of utilization of metallurgical slags as sorbents of organic pollutants from wastewater using the example of metallurgical slag from the production of the “iron – nickel” alloy of the “Pobuzhsky Ferronickel Plant” (PFP), Ukraine. For the slag the necessary requirements for sorbents are met: no toxic elements, the presence of calcium and magnesium aluminosilicates (mineral diopside), the presence of an amorphous state of substances, compliance with the requirements of radiation safety standards (radiation hazard class I). Slag is quite stable in the liquid phase. With prolonged exposure to water, in addition to diopside, additional phases are formed: quartz SiO₂, albite NaAlSi₃O₈, margarite Ca_0.88Na_0.12Al₂(Si_2.12Al_1.88O₁₀)(OH)₂ and illite KAl₄Si₂O₉(OH)₃ with a total content of 7.6%.The sorption activity of slag with respect to organic compounds was studied by the example of the methylene blue dye (MB). To increase the sorption activity the chemical activation of the sorbent surface was used. The activators were solutions of inorganic acids and alkali NaOH at different temperatures. During chemical activation silicate acid is formed in a colloidal state, the content of elements decreases: Mg and Fe (activation of H₂SO₄ and NaOH), K and Mn (H₂SO₄); the total decrease in the content of elements: 11.52% in an alkaline medium and 5.78% — in acidic. The greatest loosening of the sorbent surface is observed with alkaline and acid activation, when polyfractional crystals are recorded. Increasing the surface area of the slag increases its sorption activity. The optimal conditions for slag activation were determined: activating agent — 0.5 M H₂SO₄ solution; temperature is 20 °C. The slag sorption exchange capacity for 10 days reaches a maximum value of 0.194 mg/g, corresponding to a 97% purification of the solution from MB in the absence of its desorption. PFP metallurgical slag exhibits sorption activity with respect to organic compounds due to the large surface area and the presence of the amorphous phase and can be used as an adsorbent in technological processes.

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