LIGNITE AS A RAW MATERIAL FOR THE PRODUCTION OF WATER-SOLUBLE SORBENTS

Abstract

Large lignite reserves are concentrated in the Dnipro lignite basin of Ukraine. It is profitable to extract it by open-pit mining, as the seams are shallow. Ukrainian lignite is predominantly earthy, subbituminous, which in turn is characterized by a high content of free humic acids. Despite the significant lignite reserves in Ukraine and favourable conditions, its production is insignificant. Most of the lignite is used as fuel, and a small part of it is used as raw material. We have studied the lignite of the Oleksandriya deposit of Ukraine, which contains a large amount (about 80 %) of humic acid, which is the basis to produce effective water-soluble sorbents. The article investigates and determines the efficiency of using lignite from the Oleksandriya deposit to produce humic substances, their elemental composition, and the yield of humic acids from them. The efficiency of the use of humic substances obtained from lignite of the Alexandria deposit in the binding of heavy metal ions (Pb2+, Cd2+) using the method of complexation - ultrafiltration - was determined. The performance of ultrafiltration membranes with a humate solution was determined. The retention coefficient of metal ions, which depends on the concentration of humic substances, was calculated. The conducted studies allow us to assert that the application of the ultrafiltration-complexation method using complexing agents based on humic substances of lignite from the Alexandria deposit can significantly increase the degree of purification of aqueous solutions from heavy metal ions. These studies are relevant and expand the possibilities of using lignite. It has been shown that Ukrainian lignite can be used to produce an environmentally friendly and cheap complexing agent. An important priority for the use of water-soluble humic substances is the large lignite reserves in Ukraine, which can also contribute to improving economic performance. Also, the studies conducted suggest that the application of a combined method that combines ultrafiltration with complexation when using complexing agents based on lignite humic substances can significantly increase the degree of purification from heavy metal ions.