HYDROGEN PEROXIDE PRODUCTION UNDER VARYING CONDITIONS OF IRRADIATION 



eoor 



Figure 2. Hydrogen peroxide formed 

 in water, various gas treatments 



process which appears to be independent of chemical conditions. The second 

 mechanism B leads to radical formation. Oxygen is then needed for the 

 formation of hydrogen peroxide. 



A 2H2O -^ 



HgOg + H2 



H + OH 



H + O2 

 2H02^ 

 H + HO2 



->H02 

 H2O2 + O2 



H,0, 



. (1) 



• (2) 



• (3) 



Reactions leading to the break-down of hydrogen peroxide involve all the 

 radicals produced by irradiation in water : 



H2O2 + OH -> H2O + HO2 

 H+ + O2- or HO2 - 



HO2 

 H2O2 

 H2O2 + H 



+ 0, 



-> OH + OH 

 H2O + OH 



-OH 

 + O2 



H2O + O2- 



(4) 

 (5) 

 (6) 

 (7) 



Some of the experimental evidence suggests that reaction (6) is more likely 

 to occur than a direct interaction between hydrogen peroxide and 

 the radical HOa*- ^ ^ 



The simplified scheme set out implies that hydrogen peroxide is formed by 

 radical interactions only in the presence of oxygen. Any hydrogen peroxide 

 formed by direct interaction of excited water molecules wovild, in the 

 absence of oxygen, be decomposed via (4) and (7). With oxygen present 

 reaction (1) will occur giving rise to hydrogen peroxide formation via (2) and 

 (3), and the rate of reaction (7), decomposition of hydrogen peroxide, will 

 become slower as the hydrogen radicals are removed by reactions (1) to (3). 



Hydrogen and oxygen — To study the effect of hydrogen on the formation of 

 hydrogen peroxide^", hydrogen alone and mixtures of hydrogen and nitrogen, 

 and of hydrogen and oxygen were bubbled through neutral water. No 



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