Potassium iodide is white cubic crystal or powder. It has the water absorbability in moist air. It will separate out free iodine and turn yellow after long precipitation. And trace iodate can be formed. Light and moisture can accelerate the decomposition. Its aqueous solution was neutral or slightly alkaline and it can dissolve iodine. Hydrogen peroxide is commonly known as the aqueous solution of H₂O₂ and is colorless transparent liquid. It’s applicable to medical wound disinfection, environmental disinfection and food disinfection. It is a kind of "green" oxidant. If excessive H₂O₂doesn’t be treated properly in industrial process, it will affect the reaction process or cause the harm to the environment. So researching catalytic decomposition of H₂O₂under various conditions is not only has important theoretical significance, but also has great application value.

 

Potassium iodide and sodium tungstate composite catalysts have a drastic catalytic decomposition of hydrogen peroxide and show strong synergies effect under alkaline conditions. The experimental methods can be listed as follows: use soap film flowmeter in magnetic stirring, under the condition of constant temperature water bath or ice bath determination of catalytic decomposition of H₂O₂release O2 volume.

1. Match the KI, Na2WO4.2H2O, H₂O₂to a certain concentration of solution. At the reaction time, take 25 mL H₂O₂, 25 mL H2O and a certain quality of Na2CO3 in a 100 mL bottle and start the magnetic stirrer and constant temperature water.

2. At the same time, measure the catalyst (10 mL) and put it in the test tube under constant temperature. When temperature achieves expected temperature, catalyst should be added to reactor quickly. Soap film meter quickly pressures out a soap film. When soap film reaches scale, it’s beginning with a stopwatch time. Oxygen volume which is emitted by H₂O₂ decomposition should be read by the amount of the trachea.

3. Record the data once every one minute. When the gas production rate is less than 1 mL every minute, stop recording data. Continue responding until no gas emission. Then record the volume. Use precision digital pressure thermometer to measure the temperature and atmospheric pressure and converse the amount of gas volume into volume under standard conditions.

 

According to the above operation, we can draw the following conclusions:

1. Matching potassium iodide and sodium tungstate with certain proportion has a drastic catalytic decomposition of H₂O₂. It explains that slow steps are improved greatly when peroxy-tungsten makes KI to catalytic decomposition of H₂O₂.

2. With the reduction of H₂O₂ concentration in the process of catalytic decomposition, the rate of H₂O₂ reaction has obvious turning point. This could be due to Na2WO4 generating different tungsten oxides under different concentrations of H₂O₂

3. Catalyst concentration and reaction rate have a relation of square times in the range of the experimental concentration.