Alum is a familiar folk purifying agent , which is a kind of aluminum sulfate and potassium sulfate complex salt . Then it is how to use water purification , and its use What is the principle . But also how to use it produced . We together look.
Alum water principle
Alum can be ionized in water, two metal ions : KAl (SO4) 2 = K + + Al3 + + 2SO4 4 -. And Al3 + is easily hydrolyzed carbon black powder to form colloidal aluminum hydroxide Al (OH) 3: Al3 + + 3H2O = Al (OH) 3 ( gel ) + 3H +. Aluminum hydroxide colloid strong adsorption capacity , can absorb impurities suspended in the water , and the precipitate formed , the water clarification. Therefore , a better purifying agent is alum .
Aluminum sulfate alum was prepared using 1 , aluminum sulfate is added in an excess of ammonia , to obtain aluminum hydroxide precipitate potassium sulfate and ammonium sulfate solution, a 2 , a solid aluminum hydroxide was filtered , washed with dilute sulfuric acid obtained by adding an appropriate amount of aluminum sulfate , evaporation and iron oxide yellow crystallization 3 , to the filtrate was added an excess of potassium hydroxide and heated , the ammonia evaporated to give potassium sulfate solution , evaporation and crystallization . Due to the use of the prepared aluminum sulfate alum ( potassium aluminum sulfate ) will affect the body iron, calcium absorption components , leading to osteoporosis , anemia, and even affect the development of nerve cells . Therefore , it is now generally used for drinking water alum . Of course, the same rationale containing aluminum ions chloride, aluminum chloride is not used for drinking water purification.
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