Home – Home – Jornals – Chemistry for Sustainable Development 2022 number 2

The mechanisms of the coagulation-based water purification using titanium-containing coagulants were studied. Investigation of colloidal systems formed during hydrolysis of traditional coagulants based on aluminium and iron compounds, as well as innovative and promising titanium-containing coagulants, was carried out. The surface characteristics (surface charge, specific surface area) of hydrolysis products of titanium compounds were determined under conditions close to those of the coagulation water purification. The surface characteristics of the products of hydrolysis of traditional and titanium coagulants were compared. It has been established that the hydrolysis products of titanium compounds carry a negative charge on their surface, and their surface that is extremely developed in comparison with traditional coagulants, which indirectly confirms their ability to adsorb pollutants. The sedimentation characteristics of the resulting hydrolysis products of various coagulants were studied. It was shown that the coagulation slimes formed as a result of the use of titanium-containing reagents have a larger flake size, which means they quickly settle to the bottom during settling. The increased efficiency of complex titanium-containing coagulants (Al-Ti) due to the phenomena of charge neutralization and nucleation on the surface of hydrolysis products of titanium compounds has been confirmed and scientifically substantiated. Evaluation of the efficiency of titanium-containing coagulants in the purification of drinking water from the Moscow water intake was carried out. It was found that in the purification of water from the surface water intake, titanium-containing reagents significantly exceeded traditional reagents in the effectiveness (a decrease in the content of suspended solids, colour index), and residual concentrations of titanium compounds in purified water meet the requirements of drinking water quality standards (0.1 mg/L). The sediments obtained with the use of titanium-containing coagulants were distinguished by an increased sedimentation rate and more readily gave up moisture during the filtration process, which would allow reduction of the dimensions of the treatment equipment.