Oxidants Solution
The special patented construction of electrochemical reactors consisting of flow electrochemical modular elements FEM-7, as well as fundamentally new technology of electrochemically activated oxidant mixture solution synthesis – that is, ion-selective electrolysis with diaphragm, permit to obtain oxidants mixture solution which possesses unique efficiency and unique properties and is irreplaceable for drinking water, swimming-pools water and waste waters disinfection, and is applied, more particularly, in technological processes that are implemented in food industry and in other industries, as well.
There is electrochemically activated oxidants mixture generated in AQUACHLOR devices – that is, metastable humid gaseous oxidants mixture, represented by chlorine (95%), chlorine dioxide (3%), ozone (1,5%), hydroperoxide compounds (hydrogen peroxide, singlet oxygen, superoxide radicals), contained in micro-drops of moisture (0,2 – 0,5%), this mixture being generated under the pressure of 0,8 to 1,2 kilogram-force/cm2 in anodic chambers of compact flow modular elements FEM-7 equipped with ceramic zirconium-oxide diaphragms.
Electrochemically activated oxidants mixture solution is a metastable solution with ðÍ equal to 2,0 to 3,5, obtained by means of water and humid gaseous oxidants mixture mixing in ejector mixer of AQUACHLOR devices and represented by hypochlorous acid and molecular chlorine, for the most part. Within a short period of time after its generation (up to 1 hour) there could be ozone, atomic oxygen, chlorine dioxide found in aqueous solution of oxidants mixture in the ratios proportionate to quantitative composition of gaseous oxidants mixture, as well as a very low quantity of hydroperoxide compounds contained in moisture microdrops of gaseous oxidants mixture.
The new technological process implemented in AQUACHLOR devices – that is, ion-selective electrolysis with diaphragm, – ensures complete separation of the parent salt solution having concentration equal to 180 to 250 g/l in modular reactors FEM-7 within the one processing cycle (without returning to anolyte regeneration, without salt freezing-out from catholyte and without salt being returned to the process, without acid adding to anodic circuit, without high-quality purification of salt solution and so on), salt solution being separated into humid mixture of gaseous oxidants (chlorine, chlorine dioxide, ozone) and sodium hydroxide solution with the concentration of 150 – 170 g/l, with the salt conversion level being equal to 98 to 99,5 % and electric energy consumptions lying within the limits of 2 – 3 kWatt·hour per kilogramme of gaseous oxidants mixture. These indices are very close to theoretically achievable values, that is why AQUACHLOR devices do not have any competitors among well-known electrochemical systems and technologies.
There is no less than 0,5 kg of oxidants mixture manufactured of each kilogramme of consumable salt obtained from the parent aqueous solution of sodium chloride having concentration of 200 – 250 g/l. At the same time there is approximately 0,7 kg of sodium hydroxide (NaOH) simultaneously generated in the form of solution having concentration equal to 150 – 170 g/l, along with 17,5 grams of hydrogen, the latter being discharged via special hose out of the premises area where AQUACHLOR device is installed.
The main reaction which takes place in electrochemical reactor of AQUACHLOR devices is the reaction of molecular chlorine emission in anodic chamber and sodium hydroxide generation in cathodic chamber:
NaCl + H2O – e —› NaOH + 0,5 H2 + 0,5 Cl2
Simultaneously with this process there go the reactions of chlorine dioxide synthesis directly from salt solution, as well as from hydrochloric acid which is generated during the process of molecular chlorine dilution in the near-anode medium (Cl2 + H2O ‹—› HClO + HCl), with the current efficiency being a bit lower:
2NaCl + 6H2O – 10e —› 2ClO2 + 2NaOH + 5 H2 ; HCl + 2H2O - 5e —› ClO2 + 5 H+ .
Furthermore, ozone generation takes place in anodic chamber owing to the process of direct water decomposition and owing to generated oxygen oxidation:
3H2O - 6e —› O3 + 6H+ ; 2H2O - 4e —› 4H+ + O2 ; whereof
O2 + Í2O - 2e —› O3 + 2 Í+ .
There go the reactions of active oxygen compounds generation, with the current efficiency being low:
H2O - 2e —› 2H+ + O• ; Í2Î - å —› HO• + Í+ ; 2H2O - 3e —› HO2 + 3H+ .
Oxidants mixture solution produced by AQUACHLOR devices is an antimicrobial and oxidizing reagent which is more efficient than monoagents aqueous solutions which are generated when only chlorine, only chlorine dioxide or only ozone are dissolved in water, because chemical reactions in which it is used submit to synergism principles, and the presence of low quantity of oxidizing substances which are more strong than chlorine prevents trihalomethanes generation during processing of water which contains great quantity of humus compounds.
In this connection, local authorities and institutions of State Sanitary and Epidemiological Service are recommended to periodically obtain a more precise definition to cumulative oxidants concentration in processed water, required for water disinfection, the definition to be directed towards its reduction, in comparison with exiting standards.
The cumulative oxidants concentration in solution produced by AQUACHLOR devices shall be determined with the help of any of the following methods:
- titrimetric method of cumulative concentration determination for strong oxidizing agents, expressed as equivalent of “active chlorine” concentration;
- photometric express method of cumulative concentration determination for strong oxidizing agents, expressed as equivalent of “active chlorine” concentration”.
Oxidants concentration in water being disinfected shall be determined in compliance with standardized procedures provided for and approved by the respective normative documents, in accordance with established procedure.
