Research progress of ultraviolet advanced oxidation technology

SUN Yu-jie ZHANG Pei-yu

(School of Environmental Science and Engineering，Qingdao University，Qingdao，Shandong province 266071)

Introduction

Advanced oxidation process is regarded as a kind of can effectively remove the depth of the trace organic pollutants in water treatment technology it can be produced in situ to hydroxyl free radical(HO·)，represented by the strong oxidizing substances(oxidation reduction potential：2.8 eV)，and degradation and mineralization most refractory organic pollutants.

一、Advanced Oxidation Technologies

Advanced Oxidation Technologies(AOTs)are those that utilize powerful oxidizing intermediates(e.g.，the hydroxyl radical·OH)to oxidize primarily organic pollutants from contaminated air andwater.The term ‘advanced’ is used because the chemical reactions involved are essentially the same(except billions of times faster)as those that take place very slowly if these organic pollutants aredispersed into the air or water.Most of the commercially viable AOTs use ultraviolet and visiblelight to generate·OH radicals.

(一)The UV/H2O2 process

This is by far the most important commercial AOT.It is based on the direct photolysis of added hydrogen peroxide

H2O2+ hv → 2HO·

The quantum yield for generation of OH radicals is 1，and most organic pollutants can be degraded rapidly(Kim et al.，2009).Since the molar absorption coeffcients of H2O2are low，suffcient H2O2must be added(usually > 10 mg/L)so that a signifcant fraction of the UV between 200 and 300 nm is absorbed.It is important to have a UV lamp(e.g.，a medium pressure mercury lamp)that emits strongly below 250 nm.However，if the water absorbs UV strongly in the 200 - 300 nm regionand/or the alkalinity is very high(for pH > 7)，this process may not be effective.

(二)The UV/O3 process

The photolysis of ozone(O3)in the 200 - 280 nm region(UVC)can lead to the generation of HO·radicals through the reactions：

O3+ hv →1O(D)+ O2

1O(D)+ H2O→ H2O2

H2O2+ hv → 2HO·

The UV/O3process has been used commercially，particularly in the treatment of clear groundwaters containing contaminants such as trichloroethylene(TCE)，perchloroethylene(PCE)ortrinitrotoluene(TNT)；however，for most applications it is not considered economic compared tothe UV/H2O2or H2O2/O3processes.

二、conclusion

This paper introduces the commonly used mainly of advanced oxidation method is introduced and analyzed the characteristics can be expected，with the widely application of the ultraviolet disinfection technology，advanced oxidation methods also have constantly improving and changing，in can be more widely used

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