The use of brown coal in Ukraine to obtain water-soluble sorbents

Abstract

Purpose. To develop a method of using salts of humic acids obtained from brown coal of Ukraine for sorption of heavy metal ions and their extraction using ultrafiltration membranes. Methodology. Unique laboratory equipment has been developed to determine the sorption capacity of humic substances with a concentration of 0 to 20 mg/l in relation to heavy metal ions (Cu2+, Pb2+, Cd2+, Hg2+, Zn2+, Co2+) with a concentration of 5 mg/l. The results of proximate and ultimate analyzes, as well as infrared and optical emission spectroscopy were used to assess the quality of brown coal, humic substances and the solution of humic substances with heavy metal ions. Findings. Ukrainian brown coal of Oleksandriia geological-industrial district contains a large amount (about 80%) of humic acid, which is the basis for obtaining effective water-soluble sorbents. It is proved that humic substances obtained from brown coal of Ukraine allow binding up to 99% of heavy metal ions in complexes. The most optimal concentration of humic substances in terms of their concentration and selectivity of heavy metal ions extraction is 5 mg/l. Originality. The possibility of practical using of humic substances obtained from brown coal of Ukraine for sorption of heavy metal ions has been proved. As ultrafiltration membranes, UF-20-PAN membranes are used, which are porous polymer films based on polyacrylonitrile with a pore size of 20 m, the working surface area of the membrane is 28.26 10-4 m2. Practical value. The introduction of the developed technology will allow, firstly, restoring the practical use of large deposits of brown coal in Ukraine, and secondly, introducing deep treatment of industrial and wastewater.