| | ClO2 (Chlorine Dioxide) | ||||||||||||||||||||||||||||
| Production | The get-go is the most mutual method of generating ClO2 is through the reaction of chlorine gas amongst a solution of sodium chlorite.
Theoretically, 1 lb of chlorine gas is required for each 2.6 lb of sodium chlorite. However, an excess of chlorine is oft used to lower the pH to the required minimum of 3.5 in addition to to drive the reaction to completion. Sodium hypochlorite tin live used inwards house of the gaseous chlorine to generate chlorine dioxide. This procedure requires the add-on of sulfuric or muriatic acid for pH control. If allowed to dry out Liquid NaClO2, this powerful oxidizing agent forms a powdered residue that tin ignite or explode if contacted past times oxidizable materials. | - By dissolving common salt inwards softened water, which results inwards a concentrated brine solution. The solution is electrolyzed in addition to forms a sodium hypochlorite solution inwards water. This solution contains 150 g active chlorine (Cl2) per liter. During this reaction the explosive hydrogen gas is every bit good formed. | |||||||||||||||||||||||||||
| The 2d is the possibility to guild Chlorine dioxide inwards its stabilised shape (SCD). SCD is activated on-site whenever its usage is desirable. It tin live dosed into an existing or novel procedure where disinfection is required. This makes it an easy-to-use, prophylactic in addition to versatile disinfectant. | - By adding chlorine gas (Cl2) to caustic soda (NaOH). When this is done, sodium hypochlorite, H2O (H2O) in addition to common salt (NaCl) are produced according to the next reaction: Cl2 +2NaOH → NaOCl+ NaCl+ H2O | ||||||||||||||||||||||||||||
| Process | Chlorine dioxide is to a greater extent than oft than non applied straight into the suction of the cooling system's recirculating pump. Alternatively, it may live applied beneath the H2O inwards the sump every bit but about the heart intake every bit possible. | Sodium hypochlorite solution is diluted amongst H2O inwards a mixing/holding tank. The diluted solution is injected past times a chemic heart into the H2O furnish pipage at a controlled rate. Adequate mixing in addition to contact time must live provided | |||||||||||||||||||||||||||
| Advantages | It is a real powerful disinfectant in addition to biocide; Unlike chlorine, Chlorine dioxide is effective at pH betwixt four in addition to 10. No dumping in addition to filling amongst fresh H2O required; The corrosive effects of chlorine dioxide are minimal compared to the corrosive effects of manifestly tap water; The bactericidal efficiency is relatively unaffected past times pH values betwixt four in addition to 10. Acidisation, thus is non required; Chlorine dioxide tin live used every bit a spray. All parts therefore, tin easily live reached; And final but non least: less environmental impact. Chlorine dioxide an splendid choice for cooling H2O that has a high pH, or that has high levels of organic or ammoniacal contamination. | It tin easily in addition to live stored in addition to transported when it is produced on-site. Dosage is simple. Transport in addition to storage of sodium hypochlorite are safe. Sodium hypochlorite is every bit effective every bit chlorine gas for disinfection. Sodium hypochlorite produces residue disinfectant. | |||||||||||||||||||||||||||
| Disadvantages | Rather than hydrolyzing inwards H2O every bit chlorine does, chlorine dioxide forms a truthful solution inwards H2O nether typical cooling tower conditions. For this reason, chlorine dioxide is volatile (700 times to a greater extent than volatile than HOCl) in addition to may live easily lost from treated H2O systems, peculiarly over cooling towers | Due to the presence of caustic soda inwards sodium hypo chlorite, the pH of the H2O is increased. The stability of hypochlorite solutions is adversely affected past times heat, light, pH, in addition to metallic contamination. The charge per unit of measurement of decomposition of 10% in addition to 15% solutions nearly doubles amongst every 10°F ascent inwards the storage temperature. Sunlight reduces the half-life of a 10%-15% hypochlorite solution past times a constituent of three to 5. If the pH of a stored solution drops below 11, decomposition is to a greater extent than rapid. As fiddling every bit 0.5 ppm of atomic let on 26 causes rapid deterioration of 10-15% solutions. The add-on of concentrated ferric chloride to a tank of sodium hypochlorite causes the rapid generation of chlorine gas. Normal industrial grades of sodium hypochlorite may live fed neat or diluted amongst low-hardness water. The purpose of high-hardness waters for dilution tin displace atmospheric precipitation of calcium salts due to the high pH of the hypochlorite solution. Hypochlorite solutions decompose in addition to should non live stored for to a greater extent than than 1 month. It must live stored inwards a cool, dark, dry out area. | |||||||||||||||||||||||||||
| Safety Issues | Chlorine dioxide is explosive nether pressure. It is hard to carry in addition to is commonly manufactured on site. Chlorine dioxide is commonly produced every bit a watery solution or gas. As a gas, chlorine dioxide is to a greater extent than irritating in addition to toxic. Chlorine dioxide inwards air is detectable past times scent at 14-17 ppm, irritating at 45 ppm, fatal inwards 44 2d at 150 ppm, in addition to chop-chop fatal at 350 ppm. Concentrations greater than 14% inwards air tin sustain a decomposition moving ridge laid off past times an electrical spark. | Sodium hypochlorite is a unsafe in addition to corrosive substance. While working amongst sodium hypochlorite, security measures possess got to live taken to protect workers in addition to the environment. Sodium hypochlorite should non come upward inwards contact amongst air, because that volition displace it to disintegrate. Sodium hypochlorite should live stored amongst assist in addition to kept away from equipment that tin live damaged past times corrosion. | |||||||||||||||||||||||||||
| Equipment | | A basic liquid chlorination system, or hypochlorinator, includes two metering pumps (one serving every bit a standby), a solution tank, a diffuser (to inject the solution into the water), in addition to tubing. | |||||||||||||||||||||||||||
| Quantity | | Approximately 1 gal of industrial forcefulness sodium hypochlorite is required to supersede 1 lb of gaseous chlorine. | |||||||||||||||||||||||||||
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