Quote:
Originally Posted by Ohiogirl81
It's a caustic chemical that has no business around food. It also screws up your neighborhood wastewater treatment plant's efforts to clean the water with as few chemicals as possible.
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Wrong. Wrong. Wrong.
Clorox is a 5.25% solution of sodium hypochlorite (NaClO) (AKA chlorine, AKA 'bleach'), which is actually
used in water treatment systems for both drinking water and wastewater treatment. Your propensity to promulgate rumor, myth and disinformation, despite a lack of education in the subject being discussed, is disturbing. Unfortunately, this is an all too common occurence on the 'internet' today- too many people with too little education being far too quick to spread way too much horsepuckey around the world at near light-speed, with little or no regard for truth or accuracy. Whether this is more a problem with the education system in general, or a more fundamental deficit in general cognitive ability in the population at large I can't say. Be that as it may...
...a little bit of education for those who care to assimilate it...
Bleach is a solution of sodium hypochlorite, at a pH of about 11. Once dissolved, the sodium hypochlorite interconverts with the other chemical forms of free chlorine, mainly HOCl. Sodium hypochlorite and hypochlorous acid are strong oxidizing agents and react with flammable compounds and reducing agents.
There are many different brands of laundry bleach available, and the concentration of sodium hypochlorite can vary significantly. Clorox brand is 5.25% sodium hypochlorite, but many bargain brands have lower concentrations.
The only laundry bleach solution registered with the EPA as a tuberculocidal disinfectant is Clorox brand.
When sodium hypochlorite is dissolved in water, the resulting solution is quite basic due to the production of OH– ions by the following reaction:
NaOCl (s) + H20(l) → HOCl (aq) + NaOH (aq)
The various free chlorine components exist in equilibrium in water; the predominant form depends on the pH. When the pH is between 2 – 7, the equilibrium favors HOCL. As the pH falls below 2, the main form is Cl2. At a pH of 7.4, HOCl and OCl– are about equal, and as the pH goes above 7.4, increasing proportions of OCl– are present. Maximum disinfecting efficacy is achieved at pH 4-5, because essentially all the chlorine is present as HOCl which is two orders of magnitude more effective than OCl–. Below pH 4, increasing amounts of Cl2 are present which will evolve from solution and be lost to the system at atmospheric pressure. Chlorine gas is also quite toxic, so pH below 4 should be avoided. On balance, for safety and efficacy a pH of 5-7 works best; addition of a small amount of HCl to achieve this pH should be considered when disinfecting materials that may be contaminated with bacterial endospores or other resistant forms of microorganisms. For most routine disinfection, no adjustment of pH is necessary.
Chlorine kills microorganisms by oxidizing free sulfhydryl groups, disruption of cell membrane and wall components, and degradation of a variety of cellular macromolecules. The efficacy of the various forms of chlorine in water at killing microorganisms is as follows:
HOCl > OCl– > inorganic chloramines > organic chloramines
The above hierarchy clearly shows that free chlorine is more efficacious than combined chlorine. Also, as noted above, HOCl is 100 times more effective as a disinfectant than OCl–. Consequently, free chlorine is most effective at a pH of 5 to 7, where HOCl is the predominant form. The efficacy declines with increased pH.
Although inorganic chloramines are weaker disinfecting agents, they are more stable than free chlorine and can provide disinfection over long exposure periods.
Sodium hypochlorite solutions are unstable. When open to the air, chlorine evaporates at a high rate from the solution, rapidly reducing the concentration of free chlorine. When heated, sodium hypochlorite disintegrates. This also happens when sodium hypochlorite comes in contact with acids, sunlight, certain metals and gasses. Because it is unstable, when used for disinfection, diluted bleach should be prepared fresh daily.
For routine solid surface disinfection, a fresh 10% (v/v) solution of Clorox bleach in water is recommended. If significant amounts of organic materials are present, free chlorine will readily react to form less efficacious organic chloramines; this may require a higher concentration of bleach, perhaps 20% or more. When disinfecting a spill of aqueous liquid, such as a bacterial culture, addition of the stock solution of Clorox should be considered to achieve an approximate 10% final concentration. The oxidation reactions carried out by chlorine are relatively rapid, so
a 10% diluted bleach solution will generally achieve destruction of most common vegetative bacterial pathogens and viruses within 2 minutes at room temperatures. Temperature will affect kill time, and generally there is a doubling of reaction time for every increase in temperature of 10 degrees Celsius, so disinfection at low temperatures will require more time. A good rule of thumb is 10 minutes of contact time with 10% bleach achieves effective disinfection for most routine applications.
In drinking water systems, swimming pools, etc., sodium hypochlorite is widely used for chlorination. Hypochlorites are an alternative to chlorine gas, which is difficult to handle. In fact, the majority of municipal water supply systems use sodium hypochlorite to eradicate the pathogens that would otherwise proliferate in them. In the late 1800s, calcium hypochlorite was originally proposed and used, but in the early 1900s this was changed.
So, basically, if you consume municipal tap water, you are consuming water to which Clorox has been added. In fact, this method is recommended to purify water for drinking in the event of the failure of usual water supply systems, when water must be obtained from other sources.
So, go ahead and bleach your countertops to disinfect them. The sky is NOT falling.
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