Study of the Sorption and Desorption Processes of Sulfites on the Anion-exchange Redoxites

At present, one of the promising methods for conditioning natural waters is the stabilization that employs redoxites based on the ion-exchange materials. This method of water treatment makes it possible to significantly reduce corrosion aggressiveness of water. The use of modified cationites and anionites enables a more efficient process of purification, helps reduce economic expenses in the operation of water treatment equipment.We investigated dependence of sorption capacity of the high-base anionite in the salt form AB-17-8 for sulfites on the starting concentration of the latter in a solution. It is shown that sorption is determined by the concentration factor. Thus, at an increase in the concentration of sodium sulfite to 10 %, the anionite capacity increases to 4,200 mg-equiv./dm3.When using weakly-acidic anionites in the salt form and basic form (Dowex Marathon WBA and AMBERLITE IRA 96), the sorption capacity of ionites for sulfites increases with an increase in the concentration of solutions and reaches 5,000 mg-equiv./dm3.We estimated effect of the concentration of chlorides, sulfates in water, which is fed for deoxygenation, on desorption of sulfite-anions form the high-base anionite AB-17-8 and the low-base anionite Dowex Marathon WBA. It is demonstrated that during filtration of solutions of chlorides and sulphates with different concentration the washout of sulfites occurs through the given anionites. Therefore, to prolong the time of use of the obtained redoxites, modified with sulfites, it is recommended to utilize desalinated water or water with an insignificant content of anion

Study of Effectiveness of Heavy Metals Ions as the Inhibitors of Steel Corrosion

The effect of ions of d-metals on the processes of corrosion in a movable and immovable neutral aqueous environment has been investigated. It was shown that a number of ions, such as zinc, chromium, lead, under conditions of high aeration and temperature of 20 ºС at concentrations of 2−5 mg/dm3, are effective inhibitors of steel corrosion. This is due to the formation of a passivation oxygen film on the surface of metal. The degree of corrosion protection is maintained at the level of 80−90 %. In the case of elevating the temperature to 50 ºС, a significant (up to 40 %) decrease in the inhibitory properties of ions of d-metals is observed. This is due both to the destabilization of the oxygen passivation film and the growth of oxidation rate of steel with increasing temperature.It was demonstrated that phosphonic acids, such as oxyethyldidiphosphone acid, nitrilotrimethylphosphonium acid, due to the interaction of complexons with the surface of metals, stabilize the passivation oxygen film, providing a degree of protection against corrosion at 95−98 % at acid dose of 10 mg/dm3. However, when the temperature rises to 50 °C, a protective effect is reduced.It was established that the use of compositions based on OEDPhA/NTMPhA and Zn/Pb/Cr ions in the range of temperatures 20−50 oC provides a degree of protection of steel from corrosion at the level of 90 %. This is explained by the formation of three-dimensional complexes of phosphonic acids with metal ions and corroded iro

Efficiency Estimation of Cation-exchange Recovery of Heavy Metals From Solutions Containing Their Mixtures

The object of research is the washing waste water of galvanic plants containing heavy metal cations. The most common reagent methods for purification of galvanic drains do not provide the required degree of water purification, are accompanied by the loss of valuable components and the formation of significant amounts of toxic sludge. Ion exchange is promising in development of wastewater treatment of galvanic productions.One of the most important problems of ion-exchange technology is the processes of regeneration of ion exchangers, and, in particular, the recycling of spent regeneration solutions. The most promising in the recovery of regeneration solutions is the electrochemical method. However, electroextraction of zinc and nickel is practically impossible from acidic solutions without separation of the electrode space by the membrane. In addition, effluents from the galvanic industry contain mixtures of heavy metal ions. This complicates the process of wastewater treatment and the return of valuable components to production.In the course of the study, a strongly acidic cation exchanger KU-2-8 in the Na+-form is used to study the processes of combined sorption of heavy metal ions. Regeneration of the cation exchanger is carried out with solutions of sulfuric and hydrochloric acids. Electroextraction of zinc and nickel from acid regeneration solutions is carried out in a two-cell electrolyzer with an anion-exchange membrane MA 41.The obtained results indicate that under conditions of the concentration of heavy metals on cation exchanger KU-2-8, efficient separation can't be achieved. It is established that ions of heavy metals are sorbed individually and in mixtures with other ions of heavy metals are effectively desorbed by solutions of sulfuric and hydrochloric acids.The use of a two-cell electrolyzer, in contrast to carrying out electrolysis processes without separation of the electrode space, almost completely eliminates zinc and nickel ions from acidic regenerative rods. And to obtain a solution of sulfuric acid in the anode chamber at a concentration of 239–651 meq/dm3