Selenium Purification by Chloride Method
Selenium is a trace element essential for human health. It is a natural component of some foods, and is present in drinking water in varying concentrations throughout the world. Selenium works in conjunction with other essential nutrients, especially vitamin E, in the formation of antioxidant enzymes that protect the body from damage caused by free radicals. It is also required for the synthesis of certain enzymes involved in cell metabolism and for the modulation of thyroid hormone.
Despite these benefits, Selenium can become hazardous when its accumulation in the body exceeds the recommended levels. In particular, Selenium can become toxic when it is present in drinking water at concentrations above 50 micrograms per liter. It is for this reason that many countries have established water quality standards for Selenium content and require the implementation of processes to reduce high concentrations.
One of the most commonly used methods for removing Selenium from water is the Chloride Method. In this method, the water is treated with chlorine to form soluble Selenium chloride complexes that can then be removed by adsorption or ion exchange resins. This method is preferred because it is relatively inexpensive and simple to use.
The Chloride Method is based on the fact that when chlorine is added to water, soluble Selenium chloride complexes are formed that can then be selectively collected by adsorption or ion exchange resins. An additional benefit of using this method is that it can reduce the levels of other hazardous compounds, such as arsenic and lead, that may also be present in the water.
The Chloride Method involves a series of steps. First, the water is aerated to break down organically bound Selenium and then a measured quantity of sodium hypochlorite or chlorine gas is added. This reaction produces soluble Selenium chloride complexes. The water is then pumped through a bed of adsorption or ion exchange resins that selectively collect and remove the Selenium. The last step is to monitor the water output to ensure that the process has been effective in reducing the Selenium content of the water.
The Chloride Method is an effective and inexpensive way to reduce high levels of Selenium in drinking water, and it can also be used to remove other hazardous compounds. Despite its effectiveness, it is important to note that the method is not without its limitations. For instance, the chlorine can interact to form other compounds, such as chlorinated hydrocarbons, that can be toxic. Additionally, the method does not remove all of the Selenium from the water and levels can still remain above the recommended thresholds. Therefore, it is important to monitor the water output to ensure that effective removal has occurred.
In conclusion, the Chloride Method is an effective and inexpensive method for removing Selenium from drinking water when concentrations are above the recommended levels. However, it is important to note its limitations and to monitor the water output to ensure that the process has been effective.
