| Trace organic pollutants such as antibiotics,pesticides and endocrine disruptors have been widely detected in drinking water sources.These pollutants could be enriched in the human body,which in turn poses a serious hazard to human health.Ozone/ultraviolet process?O3/UV?has a strong oxidation ability on trace organic pollutants and does not require the addition of chemical agents.Therefore,it has gradually gained wide attention in the removal of trace organic pollutants.Nevertheless,in the present researches,both UV and O3 were studied on single-process reactors?such as quasi-collimated beam apparatus and O3 generator?,which can only measure reaction kinetic parameters,the impacts of various factors,and the reaction mechanism of a single process?such as UV irradiation or O3 oxidation?rather than the combination of UV and O3,i.e.,O3/UV process.Hence,developing an innovative O3/UV bench-scale reactors and investigating the typical pollutant degradation by O3/UV process,could provide effective guidance for degradation of organic pollutants by O3/UV process.Furthermore,vacuum UV/UV?VUV/UV?has the ability to photolysis the water or O3 to produce hydroxyl radicals?HO??,as a result,VUV/UV has been regarded as an emerging high-efficiency UV light source in advanced oxidation technology.At present,it has been combined with other technologies to improve the removal rate of organic pollutants.Therefore,based on the conducted researches on O3/UV process,the enhancement of VUV/UV light source on O3/UV has been explored.Firstly,the modularized O3/UV mini-fluidic equipment has been set up.The reaction irradiation mode could be switched between O3/UV and O3/VUV/UV without changing UV lamp.Moreover,the O3 contact membrane was used for O3 contact to achieve rapid mixing between O3 and water with no bubble generation,and the concentration of O3dissolved in water was relatively stable,which has beneficial to ensure the stability of subsequent experiments.Secondly,based on the developed modularized O3/UV mini-fluidic experimental device,the degradations of methylene blue?MB?,acesulfame-K?ACE-K?and pyruvic acid?PA?by O3/UV process were investigated.MB and PA cannot be degraded?less than 5%?under UV irradiation alone,while ACE-K could be photolyzed fast?about 75%?.When the O3 dosage was 2.0 mg L-1,the removal rates of MB,ACE-K,and PA were increased by55.8%,24.5%and 27.0%in O3/UV process,respectively,compared with UV Irradiation.The ACE-K and PA have low reaction rates with O3,thus are difficult to be directly O3oxidized,while the MB has faster ones.Therefore,during various pollutants degradation by the O3/UV process,the O3 can degradation of the MB while for ACE-K and PA,the residual O3 in the solution can produce HO?under UV irradiation to improve the removal efficiency.In addition,the effects of O3 concentration,irradiation dose,pH,initial concentration of pollutants on HO?production and pollutant degradation efficiency were discussed.Finally,the enhancement effect of VUV/UV on O3/UV process was explored.VUV/UV can photolyze 76.5%MB and 25.0%PA,while O3/VUV/UV(O3=2.0 mg L-1)can removal 96.8%MB and 50.0%PA.Moreover,In addition,the effect of O3concentration on O3/VUV/UV was investigated and the remaining O3 concentration was analyzed.When the UV dose was 20 mJ cm-2,the VUV/UV light source can completely decompose the remaining O3 in the solution,and effectively promote the decomposition of O3 and the target pollutant,as well as shorten the time required for the reaction.Therefore,according to the oxidation ability from large to small,the order was:O3/VUV/UV>VUV/UV>O3/UV.Hence,O3/VUV/UV has a higher oxidation efficiency than VUV/UV and O3/UV.In addition,the effects of pH and inorganic ions on the degradation process were discussed to investigate the potential application of O3/VUV/UV process in practical water treatment applications.Based on the developed experimental equipment,the reaction kinetics and mechanism of different organic pollutants under O3/UV process were clarified,and the strengthening effect of the new VUV/UV source on O3/UV was discussed.This study could present a potential high-effiency advanced oxidation process,which could play an important role in the efficient removal of trace contaminants from water. |
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