Acute toxicity of benzophenone-type UV filters and paraben preservatives to freshwater planarian,Dugesia japonica

Fourteen benzophenone-type UV filters and four paraben preservatives were selected to examine their acute toxicities on Dugesia japonica. The 48-h LC₅₀ values for planarians exposed to benzophenone-type UV filters can be ranked as oxybenzone?>?mexenone?>?5-chloro-2-hydroxybenzophenone?> 2,4-dihydroxybenzophenone?>?2-hydroxybenzophenone?>?dioxybenzone?>?benzophenone?>?2,2′,4,4′-tetrahydroxybenzophenone?>?4-hydroxybenzophenone?> 3-hydroxybenzophenone?>?4,4′-dihydroxybenzophenone?>?2,2′-dihydroxy-4,4′-dimethoxybenzophenone?>?2,3,4-trihydroxybenzophenone?>?sulisobenzone with a range from 0.9 to 145?mg?L^?1 with a similar sequence for the 96?h LC₅₀ values, ranging from 0.5 to 77?mg?L^?1. The 48 and 96?LC₅₀ values for planarians exposed to paraben preservatives can be ranked as butylparaben?>?propylparaben?>?ethylparaben?>?methylparaben. Among all the tested chemicals, oxybenzone was the most toxic and sulisobenzone the least toxic chemical to planarian at each exposure period. Most benzophenone-type UV filters are toxic to aquatic animals with 48?h LC₅₀ values less than 10 mg?L^?1, except for 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2,3,4-trihydroxybenzophenone, and sulisobenzone. Because of their common occurrence in aquatic environment, more studies on aquatic toxicities of benzophenone-type UV filters and paraben preservativs are needed to provide important information to adequately assess their ecological risk.     

Degradation of benzophenone in aqueous solution by Mn-Fe-K modified ceramic honeycomb-catalyzed ozonation

Comparative studies of ozonation alone, ceramic honeycomb-catalyzed and Mn-Fe-K modified ceramic honeycomb catalyzed ozonation processes have been undertaken with benzophenone as the model organic pollutant. The experimental results showed that the presence of Mn-Fe-K modified ceramic honeycombs significantly increased the removal rate of benzophenone and TOC compared with that achieved by ozonation alone or ceramic honeycomb-catalyzed ozonation. The electron paramagnetic resonance （EPR） experiments verified that higher benzophenone removal rate was attribute to more hydroxyl radicals generated in the Mn-Fe-K modified ceramic honeycomb-catalyzed ozonation. Under the conditions of this experiment, the degradation rate of all the three ozonation processes are increasing with the amount of catalyst, temperature and value of pH increased in the solution. We also investigated the effects of different process of ozone addition, the optimum conditions for preparing catalyst and influence of the Mn-Fe-K modified ceramic honeycomb after multiple-repeated use.     

Determination of environmental pollutants bythermal lens method

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用紫外光去除水中的二苯甲酮的研究

二苯甲酮广泛应用于医日用化工等领域,对生物机体具有重要影响,研究通过室内分析的方法,以185 nm紫外灯为光源,研究了水中的二苯甲酮在185 nm紫外光照射下的降解行为及浓度、体积、流速、pH等因素对二苯甲酮的降解效果的影响。结果表明：185 nmUV对二苯甲酮溶液有很好的降解效果,可以迅速将其降解为小分子有机物直至无机物,185 nm紫外灯为光源降解水中的二苯甲酮符合准一级动力学规律。 pH值对反应速率有很大的影响,185 nmUV对二苯甲酮溶液的TOC浓度有较好的降低效果。这种方法对水中二苯甲酮的去除率最好能够达到99％以上,是一种非常有效的去除水中二苯甲酮的方法。