INFLUENCE OF THERMAL TREATMENT OF THE BASALT TUFA ON ITS PHASE COMPOSITION AND SORPTION CAPACITY.

The results reflecting influence of thermal treatment of basalt tufa (BT) on its phase composition and capacity of some heavy metal ions (Cu2+, Mn2+, Ni2+, Pb2+, Zn2+) sorption under the static conditions are presented. It has been found that thermal modification of tufa at 400-1000 °C results in weight loss of the material from 5,79 % (at 400 °C) to 10,18 % (1000 °C) caused by changes in the mineral phase composition such as loss of the chemically bound water, decomposition of carbonates and other compounds. It has been shown that the sorption value for the heavy metal ions, being captured on surface of the thermally modified BT samples, is governed by the ion's nature and temperature of its thermal treatment. The negatively charged surface-active adsorption centers were identified for all BT samples since they exhibited the positive suspension effect. Therefore, a competition between adsorption of H+ and heavy metal ions can take place. [ABSTRACT FROM AUTHOR]