The thesis is devoted to water purification reagents based on wastes of alumina production (red mud) creation and research, checking their efficiency and creation a technological sequence of wastewater treatment from organic pollutants of various nature by synthesized water purification reagents. The principle of creating water purification reagents as coagulants (in solid and liquid form) and as sorption materials are presented and substantiated in the thesis. The choice of red mud as a raw material for the synthesis of such reagents is shown and grounded.
Rational conditions for obtaining a solid complexed iron-aluminum coagulant (TK) by partial acid-thermal activation with acid deficiency was established. It was found that in the resulting product due to the partial conversion of the oxide form of metals into chloride, only a part of the metals hydrolyzes, the remainder acts as a damping agent, increasing the centers of crystallization, but necessitates an increase in the coagulant dose. The rational conditions for obtaining liquid complexed iron-aluminum coagulant (PK) by acid activation of red mud with chloride or sulfate acid was established. The elemental composition of the PK according to the main components was determined by X-ray fluorescence method, characterized by the following chemical composition (according to the main components): coagulant of PK(SO4) - Fe - 83,24%, Al - 1,95%; Ti - 1.44%, and PK(Cl) - Fe - 82.87%, Al - 5.12%, Ti - 0.98%, Ca - 1.78%.
It was found the rational conditions for obtaining sorption material CM: obtaining the solution of acidic activation of red mud in the form of chlorides (or sulfates) of iron and aluminum (RK), followed by impregnation of activated carbon Filtrasorb 300 and precipitation of iron salts and addition of a solution of ammonia, followed by heat treatment with steam at temperature 320 °C. By Boem method was determinate the presence of surface groups for AB and CM. It was established that when fixing iron oxides and aluminum on the surface of activated carbon, its anion sorption exchange capacity increases as a result of the formation of carboxylic and phenolic groups, which contributes to more complete capture of organic pollutants on the material surface. The mechanism of fastening of components of red mud on the surface of activated carbon is proposed, namely, through the disclosure of lactone groups and the formation of the connection with iron compounds, which is confirmed by the establishment of presence of surface groups and an increase of ASEC by 1.15 times and an increase in phenolic and carboxylic groups; as well as due to the donor-acceptor interaction between the electronic density of aromatic rings near the heteroatoms.
It was found that SM is effective in sorption of organic dyes as a cationic type, for example, methylene blue and anionic dye, for example, active bright blue HF, since the limiting sorption increases in comparison with carbon in 1,12 times for methylene blue and in 2,54 times for the active bright blue HF. At the same time, in the case of anionic dye (Congo-red) decreases by 12,2 times. The Freundlich constant indicates favorable conditions for CM and Temkin's energy for physical sorption. On the basis of the received regularities of structural-sorption characteristics, the rational conditions for conducting sorption processes, namely the removal of both natural and synthetic organic matter, were investigated.
It was estimated the economic efficiency of using the obtained reagents in water treatment, technical and economic indicators were calculated. Thus, the specific cost of the reagents received per/kg of products was set at 9 UAH 10 coins for PK and almost UAH 89 for CM in comparison with the known products of aluminum sulfate 15 UAH and ABF300 196 UAH respectively. The economic effect for the PK is almost UAH 6000, for CM UAH 279 463, which proves the feasibility of using such reagents in comparison with the use of known commodity products.
It was first discovered that as a result of the application of activated carbon on the surface of iron oxides derived from alumina waste, the amount of anionic groups increased by 13% due to an increase of 50% carboxyl groups and 62,% phenol groups with bond breakage in lactone groups, which contributes to the increase of the sorption efficiency by increasing the positive charge of the surface and the emergence of additional interaction of the surface functional groups of the material with the pollutant molecules.
Key words: water purification reagents, complex coagulants, sorption materials, industrial waste, red mud, wastewater, coagulants, sorbents.
